Articles

06/06/2001-- 06/06/2001

Theoretical Considerations of Electrochemical Phase Formation in a Frank-van der Merwe System

Static calculation and preliminary kinetic Monte Carlo simulation studies are undertaken for the nucleation and growth on a model system which follows a Frank-van der Merwe mechanism. In the present case, we consider the deposition of Ag on Au(100) and Au(111) surfaces. The interactions were calculated using the embedded atom model. The process of formation and growth of 2D Ag structures on Au(100) and Au(111) is investigated and the influence of surface steps on this phenomenon is studied. Very different time scales are predicted for Ag diffusion on Au(100) and Au(111), thus rendering very different regimes for the nucleation and growth of the related 2D phases. These observations are drawn from application of a model free of any adjustable parameter.
M. C. Gimenez M. G. Del Popolo E. P. M. Leiva S. G Garcia D. R. Salinas C. E. Mayer W. J. Lorenz
02/03/2003-- 02/03/2003

Kinetic Monte Carlo Study of Electrochemical Growth in a Heteroepitaxial System

Structural and kinetic aspects of 2-D irreversible metal deposition under potentiostatic conditions are analyzed by means of dynamic Monte Carlo simulations employing embedded atom potentials for a model system. Three limiting models, all considering adatom diffusion, were employed to describe adatom deposition.The first model (A) considers adatom deposition on any free substrate site on the surface at the same rate. The second model (B) considers adatom deposition only on substrate sites which exhibit no neighboring sites occupied by adatoms. The third model (C) allows deposition at higher rates on sites presenting neighboring sites occupied by adatoms.
M. Cecilia Gimenez Mario G. Del Popolo Ezequiel P. M. Leiva
06/10/1997-- 06/10/1997

Some theoretical considerations concerning ion hydration in the case of ion transfer between water and 1,2-dichloroethane

Some aspects of direct ion transfer across the water/1,2-dichloroethane are analyzed using a very simple model based on thermodynamic considerations. It was concluded that ion solvation by water molecules may occur in some particular cases in the organic phase, delivering an important contribution to the Gibbs free energy of ion transfer between the aqueous and the organic phase. In general terms, this particular type of transfer should be favored in the case of highly charged small ions at interfaces with a relatively low surface tension and a large difference between the reciprocal of the corresponding dielectric constants.
C. Sanchez S. A. Dassie A. M. Baruzzi E. P. M. Leiva
09/09/1997-- 09/09/1997

Facilitated alkali ion transfer at the water 1,2-dichloroethane interphase: Ab-initio calculations concerning alkaline metal cation - 1,10-phenanthroline complexes

A series of calculations on the energetics of complexation of alkaline metals with 1,10-phenanthroline are presented. It is an experimental fact that the ordering of the free energy of transfer across the water - 1,2-dichloroethane interphase is governed by the charge / size ratio of the diferent cations; the larger cations showing the lower free energy of transfer. This ordering of the free energies of transfer is reverted in the presence of 1,10-phenanthroline in the organic phase. We have devised a thermodynamic cycle for the transfer process and by means of ab-initio calculations have drawn the conclusion that in the presence of phen the free energy of transfer is governed by the stability of the PHEN/M $^{+}$complex, which explains the observed tendency from a theoretical point of view.
C. Sanchez S. A. Dassie A. M. Baruzzi E. P. M. Leiva
06/26/2019-- 06/26/2019

Maximizing LSST Solar System Science: Approaches, Software Tools, and Infrastructure Needs

The Large Synoptic Survey Telescope (LSST) is expected to increase known small solar system object populations by an order of magnitude or more over the next decade, enabling a broad array of transformative solar system science investigations to be performed. In this white paper, we discuss software tools and infrastructure that we anticipate will be needed to conduct these investigations and outline possible approaches for implementing them. Feedback from the community or contributions to future updates of this work are welcome. Our aim is for this white paper to encourage further consideration of the software development needs of the LSST solar system science community, and also to be a call to action for working to meet those needs in advance of the expected start of the survey in late 2022.
Henry H. Hsieh Michele T. Bannister Bryce T. Bolin Josef Durech Siegfried Eggl Wesley C. Fraser Mikael Granvik Michael S. P. Kelley Matthew M. Knight Rodrigo Leiva Marco Micheli Joachim Moeyens Michael Mommert Darin Ragozzine Cristina A. Thomas
12/28/2020-- 12/28/2020

Context-Aware Personality Inference in Dyadic Scenarios: Introducing the UDIVA Dataset

This paper introduces UDIVA, a new non-acted dataset of face-to-face dyadic interactions, where interlocutors perform competitive and collaborative tasks with different behavior elicitation and cognitive workload. The dataset consists of 90.5 hours of dyadic interactions among 147 participants distributed in 188 sessions, recorded using multiple audiovisual and physiological sensors. Currently, it includes sociodemographic, self- and peer-reported personality, internal state, and relationship profiling from participants. As an initial analysis on UDIVA, we propose a transformer-based method for self-reported personality inference in dyadic scenarios, which uses audiovisual data and different sources of context from both interlocutors to regress a target person's personality traits. Preliminary results from an incremental study show consistent improvements when using all available context information.
Cristina Palmero Javier Selva Sorina Smeureanu Julio C. S. Jacques Junior Albert Clapés Alexa Moseguí Zejian Zhang David Gallardo Georgina Guilera David Leiva Sergio Escalera
02/23/2024-- 02/23/2024

Artful Path to Healing: Using Machine Learning for Visual Art Recommendation to Prevent and Reduce Post-Intensive Care

Staying in the intensive care unit (ICU) is often traumatic, leading to post-intensive care syndrome (PICS), which encompasses physical, psychological, and cognitive impairments. Currently, there are limited interventions available for PICS. Studies indicate that exposure to visual art may help address the psychological aspects of PICS and be more effective if it is personalized. We develop Machine Learning-based Visual Art Recommendation Systems (VA RecSys) to enable personalized therapeutic visual art experiences for post-ICU patients. We investigate four state-of-the-art VA RecSys engines, evaluating the relevance of their recommendations for therapeutic purposes compared to expert-curated recommendations. We conduct an expert pilot test and a large-scale user study (n=150) to assess the appropriateness and effectiveness of these recommendations. Our results suggest all recommendations enhance temporal affective states. Visual and multimodal VA RecSys engines compare favourably with expert-curated recommendations, indicating their potential to support the delivery of personalized art therapy for PICS prevention and treatment.
Bereket A. Yilma Chan Mi Kim Gerald C. Cupchik Luis A. Leiva
12/09/2002-- 12/03/2002

Algebra of chiral currents on the physical surface

Using a particular structure for the Lagrangian action in a one-dimensional Thirring model and performing the Dirac's procedure, we are able to obtain the algebra for chiral currents which is entirely defied on the constraint surface in the corresponding hamiltonian description of the theory.
Alexis Amezaga Carlos Leiva
02/28/2017-- 07/11/2016

Some features of a Schwarzchild Black Hole from a Snyder perspective

In this paper, the consequences of introducing a deformed Snyder-Kepler potential in the Schwarzchild metric are investigated. After this modification, it is obtained a dynamically depending horizon with different penetration radius for massive particles and light rays in radial orbits. In the case of circular orbits, they all remain untouched.
Carlos Leiva
11/12/2009-- 11/12/2009

Mapping the $ν_\odot$ Secular Resonance for Retrograde Irregular Satellites

Constructing dynamical maps from the filtered output of numerical integrations, we analyze the structure of the $\nu_\odot$ secular resonance for fictitious irregular satellites in retrograde orbits. This commensurability is associated to the secular angle $\theta = \varpi - \varpi_\odot$, where $\varpi$ is the longitude of pericenter of the satellite and $\varpi_\odot$ corresponds to the (fixed) planetocentric orbit of the Sun. Our study is performed in the restricted three-body problem, where the satellites are considered as massless particles around a massive planet and perturbed by the Sun. Depending on the initial conditions, the resonance presents a diversity of possible resonant modes, including librations of $\theta$ around zero (as found for Sinope and Pasiphae) or 180 degrees, as well as asymmetric librations (e.g. Narvi). Symmetric modes are present in all giant planets, although each regime appears restricted to certain values of the satellite inclination. Asymmetric solutions, on the other hand, seem absent around Neptune due to its almost circular heliocentric orbit. Simulating the effects of a smooth orbital migration on the satellite, we find that the resonance lock is preserved as long as the induced change in semimajor axis is much slower compared to the period of the resonant angle (adiabatic limit). However, the librational mode may vary during the process, switching between symmetric and asymmetric oscillations. Finally, we present a simple scaling transformation that allows to estimate the resonant structure around any giant planet from the results calculated around a single primary mass.
J. Correa Otto A. M. Leiva C. A. Giuppone C. Beaugé


with thanks to arxiv.org/