Generative adversarial networks for data-scarce spectral applications

Generative adversarial networks (GANs) are one of the most robust and versatile techniques in the field of generative artificial intelligence. In this work, we report on an application of GANs in the domain of synthetic spectral data generation, offering a solution to the scarcity of data found in various scientific contexts. We demonstrate the proposed approach by applying it to an illustrative problem within the realm of near-field radiative heat transfer involving a multilayered hyperbolic metamaterial. We find that a successful generation of spectral data requires two modifications to conventional GANs: (i) the introduction of Wasserstein GANs (WGANs) to avoid mode collapse, and, (ii) the conditioning of WGANs to obtain accurate labels for the generated data. We show that a simple feed-forward neural network (FFNN), when augmented with data generated by a CWGAN, enhances significantly its performance under conditions of limited data availability, demonstrating the intrinsic value of CWGAN data augmentation beyond simply providing larger datasets. In addition, we show that CWGANs can act as a surrogate model with improved performance in the low-data regime with respect to simple FFNNs. Overall, this work highlights the potential of generative machine learning algorithms in scientific applications beyond image generation and optimization

Deep learning for the modeling and inverse design of radiative heat transfer

Deep learning is having a tremendous impact in many areas of computer science and engineering. Motivated by this success, deep neural networks are attracting increasing attention in many other disciplines, including the physical sciences. In this work, we show that artificial neural networks can be successfully used in the theoretical modeling and analysis of a variety of radiative-heat-transfer phenomena and devices. By using a set of custom-designed numerical methods able to efficiently generate the required training data sets, we demonstrate this approach in the context of three very different problems, namely (i) near-field radiative heat transfer between multilayer systems that form hyperbolic metamaterials, (ii) passive radiate cooling in photonic crystal slab structures, and (iii) thermal emission of subwavelength objects. Despite their fundamental differences in nature, in all three cases we show that simple neural-network architectures trained with data sets of moderate size can be used as fast and accurate surrogates for doing numerical simulations, as well as engines for solving inverse design and optimization in the context of radiative heat transfer. Overall, our work shows that deep learning and artificial neural networks provide a valuable and versatile toolkit for advancing the field of thermal radiatio

Tunable Thermal Emission of Subwavelength Silica Ribbons

The thermal properties of individual subwavelength objects, which defy Planck’s law, are attracting significant fundamental and applied interest in different research areas. Special attention has been devoted to anisotropic structures made of polar dielectrics featuring thicknesses smaller than both the thermal wavelength and the skin depth. Recently, a novel experimental technique has enabled the measurement of the thermal emissivity of anisotropic SiO2 nanoribbons (with thicknesses on the order of 100 nm), demonstrating that their emission properties can be largely tuned by adjusting their dimensions. However, despite the great interest aroused by these results, their rigorous theoretical analysis has remained elusive due to the computational challenges arising from the vast difference in the length scales involved in the problem. In this work, we present a systematic theoretical analysis of the thermal emission properties of these dielectric nanoribbons based on simulations within the framework of fluctuational electrodynamics carried out with the boundary element method implemented in the SCUFF-EM code. In agreement with the experiments, we show that the emissivity of these subwavelength structures can be largely tuned and enhanced over the thin-film limit. We elucidate that the peculiar emissivity of these nanoribbons is due to the very anisotropic thermal emission that originates from the phonon polaritons of this material and the properties of the waveguide modes sustained by these dielectric structures. Our work illustrates the rich thermal properties of subwavelength objects, as well as the need for rigorous theoretical methods that are able to unveil the complex thermal emission phenomena emerging in this class of systemsJ.J.G.E. was supported by the Spanish Ministry of Science and Innovation through an FPU grant (FPU19/05281). J.B.A. acknowledges financial support from the Ministerio de Ciencia, Innovacioń y Universidades (RTI2018-098452-B-I00). J.C.C. acknowledges funding from the Spanish Ministry of Science and Innovation (PID2020-114880GB-I00

Challenges for the Adoption of Model-Driven Web Engineering Approaches in Industry

Model-driven web engineering approaches have become an attractive research and technology solution for Web application development. However, after 20 years of development, they have attracted little attention from the Industry due to the mismatch between technical versus research requirements. In this joint work between academia and industry, the authors present the current problems of using these approaches in scale and provide guidelines to convert them into viable industry solutions.Ministerio de ciencia e Innovación TIN2016-76956-C3-2-RMinisterio de Economía y Competitividad TIN2015-71938-RED

Latent Profiles of Burnout, Self-Esteem and Depressive Symptomatology among Teachers

Burnout is a reality in the teaching profession. Specifically, teaching staff usually have higher burnout rates. The present study aims to analyze the different burnout profiles and to verify if there were differences between burnout profiles in depressive symptomatology and in the self-esteem of the teachers at school. The total number of participants was 210 teachers from 30 to 65 years. The first scale was the Maslach burnout inventory, the second scale was the Self-Rating depression scale and the third scale was the Rosenberg Self-Esteem Scale . The latent class analysis identified three burnout profiles: the first group with a high level of emotional exhaustion, low personal accomplishment and depersonalization (high burnout); the second group with low emotional exhaustion, low depersonalization and high personal accomplishment (low burnout) and the third group with low depersonalization, low emotional exhaustion and low personal accomplishment (moderate burnout). The results revealed that there were differences in depressive symptomatology (group 1 obtained higher scores than group 2 and group 3) and self-esteem (group 2 obtained higher scores than group 1). The psychological balance and health of teachers depend on preventing the factors that have been associated with this syndrome

Influence of liquid properties on ultrasonic atomization

[EN] Ultrasonic atomization is very convenient because it can generate droplets with diameters of a few microns and with very narrow size distribution. Besides, opposite to twin fluid nozzles, in ultrasonic atomization, droplet generation and transport are decoupled processes. Droplets are ejected from the liquid surface with very low velocities, so driving them is relatively simple. Although this atomization method is now common in some specific applications, for example in household humidifiers, there are still some details about the physics of this process that are not completely understood. Up to date, most of the published results have been limited to experiments with water. However, it has been demonstrated that atomization rates quickly decrease as liquid viscosity increases. This work analyzes the characteristics of ultrasonic atomization of some alternative fluids to determine if there is any influence of other physical properties such as surface tension or vapor pressure. Experiments are performed using a commercial piezoceramic disk with a resonance frequency of 1.65 MHz. The disk is excited with a sinusoidal signal with voltage amplitudes that go up to 60 V. Sprays are visually characterized analyzing instantaneous images and high speed video sequences. Besides atomization rates are calculated by measuring the weight loss in a fixed time.This work has been partially funded by the Secretariat of State for Research of the Spanish Ministry of Economy and Competitiveness under project DPI2013-45814-P. Support of the RegionaLozano, A.; García, JA.; Alconchel, J.; Barreras, F.; Calvo, E.; Santolaya, JL. (2017). Influence of liquid properties on ultrasonic atomization. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 35-42. https://doi.org/10.4995/ILASS2017.2017.4588OCS354

Quartet Tomography in Multiterminal Josephson Junctions

We investigate the detection of quartets in hybrid multiterminal Josephson junctions. Using simple models of quantum dots coupled to superconducting leads, we find that quartets are ubiquitous and show how to rigorously extract their contribution to the current-phase relation (CPR). We also demonstrate that quartets are closely related to the hybridization of Andreev bound states (ABSs) in these systems and propose a method to identify quartets directly in ABS spectra. We illustrate our method by analyzing the spectroscopic measurements of the ABS spectrum in a three-terminal Josephson junction realized in an InAs/Al heterostructure. Our analysis strongly suggests the existence of quartets in the studied hybrid system.Comment: 6 pages, 2 figure

Learning style and academic achievement in medical students: Case-control study

Características de los estilos de aprendizaje y su relación con el rendimiento académico en los estudiantes del programa Medicina de una Universidad privada del suroccidente colombiano en el periodo académico 2015-2: Un estudio de casos y controles. Universidad IcesiIntroducción: el bajo rendimiento y la consecuente deserción académica son problemas crecientes que pueden afectar la situación socio-económica de un país. Objetivos: Relacionar el estilo de aprendizaje y variables sociodemográficas con el rendimiento académico en estudiantes de medicina de una universidad privada colombiana. Métodos: Se incluyeron los estudiantes que cumplían los criterios de inclusión como caso por bajo rendimiento y su respectivo control, a quienes se les analizó variables sociodemográficas, académicas y estilos de aprendizaje. Para el análisis se usaron técnicas de estadística descriptiva e inferencial por medio del software SPSS 19.0. Resultados: del total de la población (n=340 estudiantes), 35 cumplieron los criterios de elegibilidad como casos, a quienes se les asignó el respectivo control. No se encontró relación estadísticamente significativa entre el estilo de aprendizaje y el rendimiento académico general, ni con el rendimiento específico de las materias profesionales evaluadas. Tampoco se encontró relación entre el rendimiento académico y las variables sociodemográficas de la población a estudio. Conclusiones: el rendimiento académico en nuestra población, puede estar influenciado por otras variables diferentes al estilo de aprendizaje. Sin embargo, se deben tener en cuenta las diversas limitaciones técnicas que este estudio pudo haber tenidoIntroduction: low academic performance and dropout rates are consistently growing problems that can affect the socio-economic situation of a country. Objectives: To describe whether there is a relationship between the learning style and academic performance in medical students of a private Colombian university. Methods: The study included students which met the criteria for inclusion as a case for underperformance and its respective control. Socio-demographic, academic and learning style variables were analysed. For the analysis, descriptive and inferential statistics techniques were used through SPSS 19.0 software. Results: of the total population (n = 340 students), 35 met the criteria for eligibility and were assigned to their respective control. No statistically significant relationships between learning style and the general performance or the specific performance of professionalizing subjects were found. Conclusions: academic performance in medical students in our population may be influenced by other different learning style variables. However, the technical limitations of the study should have been considere

Age differences in selected measures of physical fitness in young handball players

[EN] Objective: The aims of the present study were: 1) to calculate the change of direction (COD) deficit (using a modified version of the 505 test and 10 m sprint time), and (2) to examine the differences in linear sprint, jump and COD performances, as well as COD deficit, between under-13 (U13) and under-15 (U15) male handball players. Methods: One hundred and nineteen young male handball players (under-13 [U13; n = 82] and under-15 [U15; n = 37]). Tests included anthropometric measurements, countermovement jump (CMJ), triple leg-hop for distance, linear sprint test (5, 10 and 20 m), and a modified version of the 505 COD test. Results: Results showed moderate to very large differences (P 0.05). Conclusions: Our results suggest that during the transition from pre- to post-puberty, young handball players should focus on transferring their progressive improvements in strength, speed, and power capacities to COD performance.S