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Publications

2024

Exploring the dynamics of the Kelvin-Helmholtz instability in paraxial fluids of light

Authors
Ferreira, TD; Garwola, J; Silva, NA;

Publication
PHYSICAL REVIEW A

Abstract
Paraxial fluids of light have recently emerged as promising analog physical simulators of quantum fluids using laser propagation inside nonlinear optical media. In particular, recent works have explored the versatility of such systems for the observation of two-dimensional quantum-like turbulence regimes, dominated by quantized vortex formation and interaction that results in distinctive kinetic energy power laws and inverse energy cascades. In this manuscript, we explore a regime analog to Kelvin-Helmholtz instability to examine in further detail the qualitative dynamics involved in the transition from smooth laminar flow to turbulence at the interface of two fluids with distinct velocities. Both numerical and experimental results reveal the formation of a vortex sheet as expected, with a quantized number of vortices determined by initial conditions. Using an effective length transformation scale we get a deeper insight into the vortex formation phase, observing the appearance of characteristic power laws in the incompressible kinetic energy spectrum that are related to the single vortex structures. The results enclosed demonstrate the versatility of paraxial fluids of light and may set the stage for the future observation of distinct classes of phenomena recently predicted to occur in these systems, such as radiant instability and superradiance.

2024

Assessment of Intuitive Eating and Mindful Eating among Higher Education Students: A Systematic Review

Authors
Rezende, F; Oliveira, BMPM; Poínhos, R;

Publication
HEALTHCARE

Abstract
Background: The role of mindful eating (ME) and intuitive eating (IE) in improving eating behavior, diet quality, and health is an area of increasing interest. Objective: The objective of this review was to identify the instruments used to assess ME and IE among higher education students and outcomes related to these dimensions. Methods: This review was carried out according to the PRISMA statement, through systematic searches in PubMed, Web of Science, PsycInfo, and Scopus. The inclusion criteria selected for higher education students, levels of ME and/or IE reported, and observational and clinical studies. The exclusion criteria selected against reviews, qualitative studies, and case studies. Quality was assessed using the Academy of Nutrition and Dietetics Quality Criteria Checklist. Results: A total of 516 initial records were identified, from which 75 were included. Cross-sectional studies were the most common research design (86.7%). Most studies were conducted with samples that were predominantly female (90.7%), White (76.0%), aged 18 to 22 years (88.4%), with BMI < 25 kg/m(2) (83.0%), and in the United States (61.3%). The Intuitive Eating Scale (IES), the Mindful Eating Questionnaire (MEQ), and their different versions were the most used instruments. The outcomes most studies included were eating behavior and disorders (77.3%), anthropometric assessments (47.8%), mental health (42.0%), and body image (40.6%). Regarding the quality of studies, 34.7% of studies were assigned a positive, 1.3% a negative, and 64.0% a neutral rate. Conclusions: IES and MEQ were the most used instruments. RCT and cohort studies are scarce, and future research with a higher level of quality is needed, especially on the topics of food consumption, diet quality, and biochemical markers.

2024

X-Wing: The Hybrid KEM You've Been Looking For

Authors
Barbosa, M; Connolly, D; Duarte, JD; Kaiser, A; Schwabe, P; Varner, K; Westerbaan, B;

Publication
IACR Cryptol. ePrint Arch.

Abstract

2024

"Viewing puzzles as two-faced: theoretical and practical implications for Puzzle-based Learning"

Authors
Fontes, MM; Morgado, LC; Pestana, P; Pedrosa, D; Cravino, JP;

Publication
THINKING SKILLS AND CREATIVITY

Abstract
The Puzzle -based Learning approach has been applied to several fields of knowledge. In education research papers, the instructional usage of puzzles is considered to improve learners' motivation and engagement and help them to develop critical skills but difficulties concerning learners' interaction with puzzles have also been pointed out. Our paper investigates the dynamics of the concept of a puzzle and its interface to provide a better understanding of its form and functions, and help learners interact with puzzles. We consider Puzzle -based Learning tenets as well as their educational impacts on both critical thinking and learner engagement and provide an original proposal concerning the understanding of puzzles. Our proposal centered on the dynamics of puzzles bears conceptual and educational facets. Conceptually, puzzle dynamics is viewed as composed of two elements: a mechanism, the Puzzle Trigger, and a process, the Puzzle -Solving. From an educational point of view, the rationale for integrating Puzzle Triggers in Puzzle -based Learning is meant to help learners interact with puzzles and consequently become motivated and engaged in the Puzzle -Solving process. This way, learners' critical thinking skills are reinforced and focused on finding solutions to challenges. We illustrate the implementation of Puzzle Triggers and Puzzle -Solving by considering two instructional activities in a Software Development undergraduate course of an online learning Informatics Engineering Program.

2024

Impact of gaseous interferents on palladium expansion for hydrogen optical sensing: A time stability study

Authors
Almeida, MAS; Almeida, JMMMD; Coelho, LCC;

Publication
OPTICS AND LASER TECHNOLOGY

Abstract
Continuous monitoring of hydrogen (H2) concentration is critical for safer use, which can be done using optical sensors. Palladium (Pd) is the most commonly used transducer material for this monitoring. This material absorbs H2 leading to an isotropic expansion. This process is reversible but is affected by the interaction with interferents, and the lifetime of Pd thin films is a recurring issue. Fiber Bragg Grating (FBG) sensors are used to follow the strain induced by H2 on Pd thin films. In this work, it is studied the stability of Pd-coated FBGs, protected with a thin Polytetrafluoroethylene (PTFE) layer, 10 years after their deposition to assess their viability to be used as H2 sensors for long periods of time. It was found that Pd coatings that were PTFE-protected after deposition had a longer lifetime than unprotected films, with the same sensitivities that they had immediately after their deposition, namely 23 and 10 pm/vol% for the sensors with 150 and 100 nm of Pd, respectively, and a saturation point around 2 kPa. Furthermore, the Pd expansion was analyzed in the presence of H2, nitrogen (N2), carbon dioxide (CO2), methane (CH4) and water vapor (H2O), finding that H2O is the main interferent. Finally, an exhaustive test for 90 h is also done to analyze the long-term stability of Pd films in dry and humid environments, with only the protected sensor maintaining the long-term response. As a result, this study emphasizes the importance of using protective polymeric layers in Pd films to achieve the five-year lifetime required for a real H2 monitoring application.

2024

Cues to fast-forward collaboration: A Survey of Workspace Awareness and Visual Cues in XR Collaborative Systems

Authors
Assaf, R; Mendes, D; Rodrigues, R;

Publication
COMPUTER GRAPHICS FORUM

Abstract
Collaboration in extended reality (XR) environments presents complex challenges that revolve around how users perceive the presence, intentions, and actions of their collaborators. This paper delves into the intricate realm of group awareness, focusing specifically on workspace awareness and the innovative visual cues designed to enhance user comprehension. The research begins by identifying a spectrum of collaborative situations drawn from an analysis of XR prototypes in the existing literature. Then, we describe and introduce a novel classification for workspace awareness, along with an exploration of visual cues recently employed in research endeavors. Lastly, we present the key findings and shine a spotlight on promising yet unexplored topics. This work not only serves as a reference for experienced researchers seeking to inform the design of their own collaborative XR applications but also extends a welcoming hand to newcomers in this dynamic field.

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