Universidad Adolfo Ibáñez
  • Viña del Mar, Región Metropolitana, Chile
Recent publications
The work concerns the multiscale modeling of a nerve fascicle of myelinated axons. We present a rigorous derivation of a macroscopic bidomain model describing the behavior of the electric potential in the fascicle based on the FitzHugh–Nagumo membrane dynamics. The approach is based on the two-scale convergence machinery combined with the method of monotone operators.
In 2020 Chile began a constitution-making process that will culminate in writing a new constitution through a 155-member constitutional convention. The Chilean party system is often described as one of the most institutionalised in Latin America, so the election results of the convention’s members were even more surprising. Of the 155 people elected, only 50 (32.2%) are party members, 41 (26.4%) are independents adopted as candidates by a party, 48 (30.9%) are independents outside a party, and 17 (10.9%) are representatives of indigenous peoples, all of them independents. Compared to proximate legislative elections, the number of independent candidates (ICs) and winners was substantially higher. We suggest that this increase was not only due to a political climate of growing distrust of parties but also to an electoral law that allowed ICs to form electoral apparentments with one another, thus combining their votes and increasing their chances of success, especially in low-income municipalities of the capital.
Introduction Maintaining glycemic control during and after physical activity (PA) is a major challenge in type 1 diabetes (T1D). This study compared the glycemic variability and exercise-related diabetic management strategies of adults with T1D achieving higher and lower PA loads in nighttime–daytime and active– sedentary behavior hours in free-living conditions. Research design and methods Active adults (n=28) with T1D (ages: 35±10 years; diabetes duration: 21±11 years; body mass index: 24.8±3.4 kg/m ² ; glycated hemoglobin A1c: 6.9±0.6%) on continuous subcutaneous insulin delivery system with predictive low glucose suspend system and glucose monitoring, performed different types, duration and intensity of PA under free-living conditions, tracked by accelerometer over 14 days. Participants were equally divided into lower load (LL) and higher load (HL) by median of daily counts per minute (61122). Glycemic variability was studied monitoring predefined time in glycemic ranges (time in range (TIR), time above range (TAR) and time below range (TBR)), coefficient of variation (CV) and mean amplitude of glycemic excursions (MAGE). Parameters were studied in defined hours timeframes (nighttime–daytime and active–sedentary behavior). Self-reported diabetes management strategies were analysed during and post-PA. Results Higher glycemic variability (CV) was observed in sedentary hours compared with active hours in the LL group (p≤0.05). HL group showed an increment in glycemic variability (MAGE) during nighttime versus daytime (p≤0.05). There were no differences in TIR and TAR across all timeframes between HL and LL groups. The HL group had significantly more TBR during night hours than the LL group (p≤0.05). Both groups showed TBR above recommended values. All participants used fewer post-PA management strategies than during PA (p≤0.05). Conclusion Active people with T1D are able to maintain glycemic variability, TIR and TAR within recommended values regardless of PA loads. However, the high prevalence of TBR and the less use of post-PA management strategies highlights the potential need to increase awareness on actions to avoid glycemic excursions and hypoglycemia after exercise completion.
Psychedelics have attracted medical interest, but their effects on human brain function are incompletely understood. In a comprehensive, within-subjects, placebo-controlled design, we acquired multimodal neuroimaging [i.e., EEG-fMRI (electroencephalography-functional MRI)] data to assess the effects of intravenous (IV) N,N-Dimethyltryptamine (DMT) on brain function in 20 healthy volunteers. Simultaneous EEG-fMRI was acquired prior to, during, and after a bolus IV administration of 20 mg DMT, and, separately, placebo. At dosages consistent with the present study, DMT, a serotonin 2A receptor (5-HT2AR) agonist, induces a deeply immersive and radically altered state of consciousness. DMT is thus a useful research tool for probing the neural correlates of conscious experience. Here, fMRI results revealed robust increases in global functional connectivity (GFC), network disintegration and desegregation, and a compression of the principal cortical gradient under DMT. GFC × subjective intensity maps correlated with independent positron emission tomography (PET)-derived 5-HT2AR maps, and both overlapped with meta-analytical data implying human-specific psychological functions. Changes in major EEG-measured neurophysiological properties correlated with specific changes in various fMRI metrics, enriching our understanding of the neural basis of DMT's effects. The present findings advance on previous work by confirming a predominant action of DMT-and likely other 5-HT2AR agonist psychedelics-on the brain's transmodal association pole, i.e., the neurodevelopmentally and evolutionarily recent cortex that is associated with species-specific psychological advancements, and high expression of 5-HT2A receptors.
We introduce Neural Network (NN for short) approximation architectures for the numerical solution of Boundary Integral Equations (BIEs for short). We exemplify the proposed NN approach for the boundary reduction of the potential problem in two spatial dimensions. We adopt a Galerkin formulation-based method, in polygonal domains with a finite number of straight sides. Trial spaces used in the Galerkin discretization of the BIEs are built by using NNs that, in turn, employ the so-called Rectified Linear Units (ReLU) as the underlying activation function. The ReLU-NNs used to approximate the solutions to the BIEs depend nonlinearly on the parameters characterizing the NNs themselves. Consequently, the computation of a numerical solution to a BIE by means of ReLU-NNs boils down to a fine tuning of these parameters, in network training. We argue that ReLU-NNs of fixed depth and with a variable width allow us to recover well-known approximation rate results for the standard Galerkin Boundary Element Method (BEM). This observation hinges on existing well-known properties concerning the regularity of the solution of the BIEs on Lipschitz, polygonal boundaries, i.e. accounting for the effect of corner singularities, and the expressive power of ReLU-NNs over different classes of functions. We prove that shallow ReLU-NNs, i.e. networks having a fixed, moderate depth but with increasing width, can achieve optimal order algebraic convergence rates. We propose novel loss functions for NN training which are obtained using computable, local residual a posteriori error estimators with ReLU-NNs for the numerical approximation of BIEs. We find that weighted residual estimators, which are reliable without further assumptions on the quasi-uniformity of the underlying mesh, can be employed for the construction of computationally efficient loss functions for ReLU-NN training. The proposed framework allows us to leverage on state-of-the-art computational deep learning technologies such as TENSORFLOW and TPUs for the numerical solution of BIEs using ReLU-NNs. Exploratory numerical experiments validate our theoretical findings and indicate the viability of the proposed ReLU-NN Galerkin BEM approach.
This research is framed within the study of automatic recognition of emotions in artworks, proposing a methodology to improve performance in detecting emotions when a network is trained with an image type different from the entry type, which is known as the cross-depiction problem. To achieve this, we used the QuickShift algorithm, which simplifies images’ resources, and applied it to the Open Affective Standardized Image (OASIS) dataset as well as the WikiArt Emotion dataset. Both datasets are also unified under a binary emotional system. Subsequently, a model was trained based on a convolutional neural network using OASIS as a learning base, in order to then be applied on the WikiArt Emotion dataset. The results show an improvement in the general prediction performance when applying QuickShift (73% overall). However, we can observe that artistic style influences the results, with minimalist art being incompatible with the methodology proposed.
Unlabelled: Alzheimer's disease (AD) is a global health issue. Because AD is a condition demanding effective management, its socioeconomic burden is immense and threatens the health systems of both low- and middle-income (LMIC) and high-income (HIC) countries. However, while most of the HICs are increasing their budget for AD research, the situation is different in LMICs, and resources are scarce. In addition, LMIC researchers face significant barriers to publishing in international peer reviewed journals, including funding constraints; language barriers; and in many cases, high article processing charges. In this perspective, we discuss these disparities and propose some actions that could help promote diversity, and ultimately translate into improved AD research capacity in LMICs, especially in Latin American and Caribbean countries. Highlights: Researchers in low- and middle-income countries (LMIC) face increasing difficulties such as financial constraints, language barriers, and article processing charges.Publication fees, in particular, can be a significant barrier in the process of publication and equal access to scientific information.Publication fee equalization initiatives by publishing companies could reduce the scientific inequality that disadvantages researchers in LMICs.
Beta diversity measures the spatial variation in species composition. As it influences several community attributes, studies are increasingly investigating its drivers. Spatial environmental heterogeneity is a major determinant of beta diversity, but canopy-forming foundation species can locally modify environmental properties. We used intertidal communities dominated by the canopy-forming alga Mazzaella laminarioides as a model system to examine how a foundation species affects spatial environmental heterogeneity and the resulting beta diversity. As canopies were found to reduce the spatial variation of temperature and desiccation during low tides, we hypothesized that canopies would decrease understory beta diversity, which we tested through a field experiment that contrasted canopy removal vs. presence treatments over 32 months. The beta diversity of sessile species was always lower under canopies, but canopies never affected the beta diversity of mobile species. The observed responses for sessile species may result from their abundance being more dependent on spatial abiotic variation than for mobile species, which can occur in stressful areas while temporarily foraging or in transit to other areas. These responses may likely apply to other systems exhibiting canopy-forming foundation species hosting sessile and mobile species assemblages.
Screen-printed electrodes (SPEs) have the advantage of being considered electrochemical cells that can be implemented in portable sensor applications. With the aim to improve the SPE performance, herein, we present different electrochemical surface modifications of carbon-based SPEs by cyclic voltammetry in hydrogen peroxide or sodium peroxide solution. SPEs were characterized using contact angle, Raman spectroscopy, laser-induced breakdown spectroscopy (LIBS), and electrochemical methods, including cyclic voltammetry (CV), electrochemical impedance spectroscopy, and square wave voltammetry (SVW). Main results agree with the observed changes by Raman spectroscopy and the sp²/sp³ ratio (ID/IG) of carbon vibrational bands. The diminishing of C2 Swan signal determined by LIBS suggests that the activation steps produced defects onto the working electrode in the SPE. Considering that the different intermolecular forces of the redox couples are useful to indirectly evaluate the different functional groups, the activated SPEs were studied in the presence of rutin and [Fe(CN)6]³⁻/[Fe(CN)6]⁴⁻ redox couples. Main results show that the electrochemical response of the activated electrode surfaces can be properly used to improve the rutin electrochemical determination. Graphical Abstract
The novel multiferroic flexible films of Dy2NiMnO6 (DNMO) were prepared by incorporating DNMO particles in Polyvinylidene fluoride-based co-polymeric P(VDF-HFP) system. The structural studies validated the crystalline structure of DNMO remains unaffected by the presence of polymer. The scanning electron microscopic image of the composite sample confirms the uniform distribution of DNMO particles in the polymeric matrix. The enhancement in the ferroelectric parameters was observed for the composite sample in comparison with P(VDF-HFP) polymeric film. The composite sample exhibits a large polarization and coercive field at room temperature with enhanced dielectric behavior with reduced dielectric loss. M–H curves of composite show ferromagnetic nature with small increase in coercivity at 5 K. The field- and temperature-dependent magnetic characteristics of DNMO have remained unaltered even though the engagement of P(VDF-HFP) for achieving flexibility. The simultaneous existence of ferroelectric and magnetic order in the flexible DNMO may discover its application in the field of flexible magnetoelectronics.
In this issue of European Journal of Neurology, Robinson et al. present a novel study on primary progressive apraxia of speech. The authors describe different clinicopathological profiles in patients with left-dominant, right-dominant, and bilateral atrophy of the supplementary motor area and lateral premotor cortex. This commentary discusses the importance of this evidence to understand individual differences among these patients, distinguish them from those with nonfluent variant primary progressive aphasia, and reflect on the relations between motor speech deficits and underlying pathology.
Objective: Research on muscularity-oriented disordered eating has grown in recent years. However, the bulk of this research has focused on men and Western populations. Limited research is available in non-Western populations of women (e.g., China) which is likely due to the lack of valid instruments in these populations. Thus, the current study aimed to describe the validity and reliability of the Muscularity-Oriented Eating Test (MOET) in Chinese women. Method: Two online surveys (survey one: n = 599, Mage = 29.49, SD = 7.36; survey two: n = 201, Mage = 28.42, SD = 7.76) were conducted to explore the psychometric properties of the MOET in Chinese women. In survey one, the factor structure of the MOET was examined via exploratory and confirmatory factor analyses (EFA and CFA). Internal consistency reliability and convergent and incremental validity of the MOET were also assessed. In survey two, test-retest reliability across a 2-week interval was examined. Results: EFA and CFA provided support for the unidimensional factor structure of the MOET in Chinese adult women. The MOET presented good internal consistency and test-retest reliability and convergent validity via large, positive associations with theoretically related constructs (e.g., thinness-oriented disordered eating, drive for muscularity, and psychosocial impairment). Finally, muscularity-oriented disordered eating described unique variance in psychosocial impairment, providing support for the incremental validity of the MOET. Discussion: The sound psychometric structure of the MOET was supported in Chinese women. Continued research is needed to describe muscularity-oriented disordered eating in Chinese women to contribute to this significant gap in the literature. Public significance: The Muscularity-Oriented Eating Test (MOET) is a measure specifically developed for assessing muscularity-oriented disordered eating. This study examined the validity and reliability of the MOET in Chinese women. The results showed that the MOET had sound validity and reliability in Chinese women. Thus, the MOET is a valuable tool for advancing the understanding of the muscularity-oriented disordered eating of women from the Chinese context.
Nanobubbles have been applied in many fields, such as environmental cleaning, material production, agriculture, and medicine. However, the measured nanobubble sizes differed among the measurement methods, such as dynamic light scattering, particle trajectory, and resonance mass methods. Additionally, the measurement methods were limited with respect to the bubble concentration, refractive index of liquid, and liquid color. Here, a novel interactive force measurement method for bulk nanobubble size measurement was developed by measuring the force between two electrodes filled with bulk nanobubble-containing liquid under an electric field when the electrode distance was changed in the nm scale with piezoelectric equipment. The nanobubble size was measured with a bubble gas diameter and also an effective water thin film layer covered with a gas bubble that was estimated to be approximately 10 nm based on the difference between the median diameter of the particle trajectory method and this method. This method could also be applied to the solid particle size distribution measurement in a solution.
A deep reinforcement learning (DRL) approach is applied, for the frst time, to solve the routing, modulation, spectrum, and core allocation (RMSCA) problem in dynamic multicore fber elastic optical networks (MCF-EONs). To do so, a new environment was designed and implemented to emulate the operation of MCF-EONs-taking into account the modulation format-dependent reach and intercore crosstalk (XT)-and four DRL agents were trained to solve the RMSCA problem. Te blocking performance of the trained agents was compared through simulation to 3 baselines RMSCA heuristics. Results obtained for the NSFNet and COST239 network topologies under diferent trafc loads show that the best-performing agent achieves, on average, up to a four-times decrease in blocking probability with respect to the best-performing baseline heuristic method.
Positive affect is often considered the “hallmark of well-being,” associated with better health, longevity, and success. Self-determination theory (SDT) proposes that satisfying three basic psychological needs for autonomy, competence and relatedness (BNS) fosters optimal functioning, thriving, and positive affect. Meanwhile, broaden-and-build theory suggests that positive emotions predict future psychosocial resources such as need satisfaction. Previous research on the BNS–positive affect link has not sufficiently established to what extent changes in BNS precede changes in positive affect or vice versa. We tested this in two 3-wave longitudinal studies, conducted over 2 years in the UK (Study 1: N = 958) and over 2 months in Latin America (Study 2: N = 1200). Bivariate latent trait-state-occasion models revealed that within-person fluctuations in BNS significantly predicted subsequent fluctuations in positive affect in both studies, but fluctuations in positive affect predicted subsequent fluctuations in BNS only in Study 2. These findings consistently support SDT predictions, whereas they only partially support broaden-and-build theory predictions, helping to clarify the likely causal relations between BNS and positive affect.
This article considers a homogeneous platoon with vehicles that communicate through channels prone to data loss. The vehicles use a predecessor-following topology, where each vehicle sends relevant data to the next, and data loss is modeled through a Bernoulli process. To address the lossy communication, we propose a strategy to estimate the missing data based on the Kalman filter with intermittent observations combined with a linear extrapolation stage. This strategy enables the followers to better deal with data dropouts. We compare this approach to one purely based on the linear extrapolation of previous data. The performance of both strategies is analyzed through Monte Carlo simulations and experiments in an ad hoc testbed, considering various data loss and transmission loss probabilities depending on the inter-vehicle distance. The results show that for the considered cases, the proposed strategy outperforms the linear extrapolation approach in terms of tracking and estimation error variances. Our results also show that the proposed strategy can achieve string stability for the mean and variance for both the tracking and estimation errors in scenarios where the basic extrapolation strategy cannot.
This paper proposes a framework to calculate the bounds on failure probability of linear structural systems whose performance is affected by both random variables and interval variables. This kind of problems is known to be very challenging, as it demands coping with aleatoric and epistemic uncertainty explicitly. Inspired by the framework of the operator norm theorem, it is proposed to consider the maximum standard deviation of the structural response as a proxy for detecting the crisp values of the interval parameters, which yield the bounds of the failure probability. The scope of application of the proposed approach comprises linear structural systems, whose properties may be affected by both aleatoric and epistemic uncertainty and that are subjected to (possibly imprecise) Gaussian loading. Numerical examples indicate that the application of such proxy leads to substantial numerical advantages when compared to a traditional double-loop approach for coping with imprecise failure probabilities. In fact, the proposed framework allows to decouple the propagation of aleatoric and epistemic uncertainty.
Resumen: El presente texto busca introducir una interrogante referida al lugar que ocupa la filosofía dentro de la escena contemporánea, abriendo así una problematización respecto a si esta es capaz de responder a las demandas y exigencias que le impone el presente. En esta medida proponemos repensar la noción de filosofía desde un encuadre que rescata sus dimensiones prácticas, materiales y afectivas, visibilizando el impulso transformador que esta puede tener respecto de los sentidos habituales asociados a la producción disciplinar, vinculada a la división tradicional entre teoría y práctica, abriéndola así hacia una dimensión que reconozca el rol implicante - creativo e interventivo - que la filosofía posee en la producción de la realidad.
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2,613 members
Agustin Ibanez
  • Latin American Brain Health Institute (BrainLat)
Marcela Drien
  • History and Social Sciences
Akira Otsuki
  • Facultad de Ingeniería y Ciencias
Daniela Figueroa
  • Facultad de Artes Liberales
Gonzalo Bustamante Kuschel
  • Escuela de Gobierno
Av. Diagonal Las Torres 2700, 7941169, Viña del Mar, Región Metropolitana, Chile