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

La hermenéutica y la fenomenología en la investigación en ciencias humanas y sociales

This reflection article problematizes the relations between phenomenology and hermeneutics as epistemic places of research through a documentary approach built in two phases. Firstly, the text reflects on the terminology present in the paradigms, approaches, epistemological perspectives and research methods. Thereby, it is determined that there is no uniqueness of criteria in their references and approaches in the research methodology treaties analyzed. Likewise, methodological proposals that include phenomenology and hermeneutics in a complementary, articulated or isolated way are stressed, without allowing understanding places that situate their application in research. Based on the preceding, the second phase proposes an individual approach to the antecedents and insights of phenomenology and hermeneutics. Moreover, particularities that characterize them, possible theoretical-practical differences and approximations that can be established, given their relevance from the epistemic and methodological framework of research in human and social sciences, are identified.Este artículo de reflexión problematiza las relaciones entre la fenomenología y la hermenéutica como lugares epistémicos del quehacer investigativo por medio de un abordaje documental construido en dos fases. En primer lugar, el texto reflexiona alrededor del uso terminológico presente en los paradigmas, enfoques, perspectivas epistemológicas y métodos investigativos, identificando con ello que no existe unicidad de criterios en sus referencias y aproximaciones en los tratados de metodología de la investigación analizados. De igual manera, se evidencian que hay propuestas metodológicas que comprenden la fenomenología y la hermenéutica de manera complementaria, articulada o aislada sin permitir con ello lugares precisos de comprensión que permitan situar su aplicación en la investigación. En razón de lo anterior, la segunda fase propone una aproximación individual a los antecedentes y comprensiones de la fenomenología y la hermenéutica, identificado particularidades que les caracterizan, posibles diferencias teórico-prácticas y aproximaciones que se pueden establecer de cara a su relevancia desde el marco epistémico y metodológico de la investigación en las ciencias humanas y sociales

Use of cinacalcet for the management of hyperparathyroidism in patients with different degrees of renal failure

Background: The effects of cinacalcet in persistent and/or hypercalcaemia-associated secondary hyperparathyroidism (SHPT) have been described in patients on dialysis. Objectives: To evaluate the efficacy and safety of cinacalcet in SHPT not on dialysis and its effects on bone turnover markers. Methods: Non-randomised, longitudinal, observational, analytical study of patients with chronic kidney disease (CKD) and SHPT (PTH> 80 pg/mL) as well as normo- or hypercalcaemia (≥8.5mg/dL), treated with cinacalcet. Results: Mean cinacalcet dose was 30mg/day in 66.7%. We studied 15 patients (10 women), aged 66.0±17.93years. The aetiology was unknown in 20% of cases. Sociodemographic variables and renal function parameters were recorded. We compared values at baseline as well as after 6 and 12 months. Calcium (10.3±0.55 vs. 9.4±1.04) and iPTH (392.4±317.65 vs. 141.8±59.26) levels decreased. Increased levels of phosphorus (3.7±1.06 vs. 3.9±0.85) and ß-CTX (884.2±797.22 vs. 1053.6±999.00) were detected, although there were no significant changes in GFR, urinary calcium or other bone markers. Two patients withdrew from the study (gastrointestinal intolerance and parathyroidectomy, respectively). Conclusions: Cinacalcet at low doses is effective in the management of SHPT in CKD patients who are not on dialysis. Its use reduces iPTH and calcaemia, without causing serious side effects or significant changes in renal function. Keywords: Bone turnover markers; Calcio; Calcium; Chronic kidney disease; Cinacalcet; Enfermedad renal crónica; Fósforo; Hiperparatiroidismo secundario; Hormona paratiroidea; Marcadores de recambio óseo; Parathyroid hormone; Phosphorus; Secondary hyperparathyroidism

Aportes teóricos de Ignacio Ellacuría para actualizar la praxis pedagógica y eclesial

Laying down the legacy of Ignacio Ellacuría as a criterion for updating Latin-American pedagogical and ecclesial practice implies examining its meaning according to the historical and intellectual dimension that characterizes the author’s life and martyrdom, as well as the historical-conceptual description of the latter. Based on a correlational study, the research is developed from a qualitative approach, from a hermeneutical perspective and according to the documentary-research method. The paper states that the legacy under discussion offers the possibility of updating the return to the anthropological dimension of both the pedagogical and ecclesial agents, rather than a potential conceptual resignification. The impetus of sentient intelligence described by the author, and corroborated in both his historical and intellectual practice, is the aspect that sets the conditions required to account for a re-shaping of pedagogical and ecclesial work in Latin America, which, according to its critical-liberating and emancipatory nature, finds the intellectual, ethical and progressive criteria that underlies Ellacuría's legacy as an indispensable condition to comprehend the historical reality of its structural-dynamic form, with a view to deploying better ways of being therein in, which are articulated in the work of the educational and ecclesial communities lead by their protagonists.Establecer el legado de Ignacio Ellacuría como criterio para actualizar la praxis pedagógica y eclesial latinoamericana, supone indagar su significado según la dimensión histórica e intelectual que caracteriza su vida y martirio, así como también la descripción histórico-conceptual de estas últimas. Según un estudio correlacional, la pesquisa se desarrolla desde el enfoque cualitativo, sobre un carácter hermenéutico y bajo el método de investigación documental. Allí se indica que el legado en discusión ofrece, como posibilidad de actualización, el retorno a la dimensión antropológica de los agentes pedagógicos y eclesiales antes que una eventual resignificación conceptual. El dinamismo de la inteligencia sentiente descrita por el autor, corroborada en su praxis histórica e intelectual, es el aspecto que establece las condiciones para dar cuenta de una reconfiguración de la praxis pedagógica y eclesial en América Latina, la cual, según su carácter crítico-liberador y emancipatorio, encuentra en el dato intelectivo, ético y progresivo que subyace al legado de Ellacuría, una condición de posibilidad para aprehender la realidad histórica en su carácter estructural-dinámico, con miras a desplegar formas mejores de estar en ella que se enuncian en el quehacer de las comunidades educativas y eclesiales en cabeza de sus protagonistas

Desafíos a la divulgación científica del conocimiento en la actualidad

La Editorial del presente número de la revista Civilizar se ha pensado como un preámbulo a la conmemoración del vigésimo año de la publicación del primer número de la revista y a la reflexión acerca de todos los cambios y evoluciones que ha tenido la labor de divulgación científica. Es por esto que, en esta ocasión, este espacio lo pusimos en manos de un equipo de los jóvenes investigadores que se han vinculado en los procesos que se vienen realizando a través de la iniciativa autores 4.0, desde la Universidad Sergio Arboleda; un aporte adicional a la difusión del conocimiento y un reconocimiento al valioso trabajo de nuestros colaboradores. Los investigadores Johan Andrés Nieto-Bravo, John Jairo Pérez-Vargas y Juan Esteban Santamaría-Rodríguez, comparten el texto Desafíos a la divulgación científica del conocimiento en la actualidad como una reflexión a la labor de la divulgación científica y el papel de las revistas en este proceso. &nbsp

Hermeneutics and Phenomenology in Human and Social Sciences Research

This article of reflection problematizes the relationships between phenomenology and hermeneutics as epistemic places of research work through a documentary approach built in two phases. First, the text reflects on the terminological use present in the paradigms, approaches, epistemological perspectives, and research methods, thereby identifying that there is no criteria univocity in its references and approaches about research methodology treaties. Likewise, it is evident that there are methodological proposals that include phenomenology and hermeneutics in a complementary, articulated, or isolated way without allowing precise places of understanding that allow to locate their application in research. Based on the aforementioned, the second phase proposes an individual approach to the background and comprehensions of phenomenology and hermeneutics, identifying particularities that characterize them, possible theoretical-practical differences and approaches that can be established in view of their relevance from the epistemic and methodological framework of research in human and social sciences.This article of reflection problematizes the relationships between phenomenology and hermeneutics as epistemic places of research work through a documentary approach built in two phases. First, the text reflects on the terminological use present in the paradigms, approaches, epistemological perspectives, and research methods, thereby identifying that there is no criteria univocity in its references and approaches about research methodology treaties. Likewise, it is evident that there are methodological proposals that include phenomenology and hermeneutics in a complementary, articulated, or isolated way without allowing precise places of understanding that allow to locate their application in research. Based on the aforementioned, the second phase proposes an individual approach to the background and comprehensions of phenomenology and hermeneutics, identifying particularities that characterize them, possible theoretical-practical differences and approaches that can be established in view of their relevance from the epistemic and methodological framework of research in human and social sciences. This article is a translation from the Spanish version “La hermenéutica y la fenomenología en la investigación en ciencias humanas y sociales”, published in Civilizar, 19(37), 2019. doi: 10.22518/usergioa/jour/ccsh/2019.2/a09. The translation has been authorized and approved by the authors and the Editor

Hermeneutics and Phenomenology in Human and Social Sciences Research

This article of reflection problematizes the relationships between phenomenology and hermeneutics as epistemic places of research work through a documentary approach built in two phases. First, the text reflects on the terminological use present in the paradigms, approaches, epistemological perspectives, and research methods, thereby identifying that there is no criteria univocity in its references and approaches about research methodology treaties. Likewise, it is evident that there are methodological proposals that include phenomenology and hermeneutics in a complementary, articulated, or isolated way without allowing precise places of understanding that allow to locate their application in research. Based on the aforementioned, the second phase proposes an individual approach to the background and comprehensions of phenomenology and hermeneutics, identifying particularities that characterize them, possible theoretical-practical differences and approaches that can be established in view of their relevance from the epistemic and methodological framework of research in human and social sciences.This article of reflection problematizes the relationships between phenomenology and hermeneutics as epistemic places of research work through a documentary approach built in two phases. First, the text reflects on the terminological use present in the paradigms, approaches, epistemological perspectives, and research methods, thereby identifying that there is no criteria univocity in its references and approaches about research methodology treaties. Likewise, it is evident that there are methodological proposals that include phenomenology and hermeneutics in a complementary, articulated, or isolated way without allowing precise places of understanding that allow to locate their application in research. Based on the aforementioned, the second phase proposes an individual approach to the background and comprehensions of phenomenology and hermeneutics, identifying particularities that characterize them, possible theoretical-practical differences and approaches that can be established in view of their relevance from the epistemic and methodological framework of research in human and social sciences. This article is a translation from the Spanish version “La hermenéutica y la fenomenología en la investigación en ciencias humanas y sociales”, published in Civilizar, 19(37), 2019. doi: 10.22518/usergioa/jour/ccsh/2019.2/a09. The translation has been authorized and approved by the authors and the Editor

Chemical imaging of phase separated polymer blends by fluorescence microscopy

Blends of poly(vinylacetate) (PVAc) and poly(cyclohexylmethacrylate) (PCHMA) labeled by copolymerization with 4-methacryloylamine-48-nitrostilbene (Sb), with (1-pyrenylmethyl)methacrylate (Py), or with 3-(methacryloylamine)propyl-N-carbazole (Cbz) were prepared by casting dilute solutions in tetrahydrofurane (THF) or chloroform. Films about 10 mm thick were formed. Phase separation in two types of domains is observed by transmission optical microscopy (TOM) and epifluorescence microscopy (EFM): small craters of 1 to 10 mm placed at the polymer–air interface and larger domains, on the scale of 100 mm. The morphology of samples depends on the composition of the polymer blend and on solvent. The green fluorescence of Sb, the violet of Py, or the blue of Cbz provides imaging of the distribution of PCHMA in the different domains and in the matrix. It is thus observed that (i) superficial craters and large domains are formed mainly by PCHMA and (ii) the matrix is composed of PVAc in films cast from THF and it is a blend of the two polymers, homogeneous at the submicrometric scale, for chloroform. The emission intensity of Py, recorded by microfluorescence spectroscopy (MFS), yields a mapping similar to imaging detection. It is remarkable that in films cast from chloroform, the smaller domains are distributed with a 2D hexatic order disrupted by dislocations and disclinations, whereas in films cast from THF, a larger heterogeneity is found, denoting different mechanisms of solvent evaporation.This work was supported by CICYT (Spain) and Brite-Euran (EU) under Grants PB95-0247 and BE-97-4672, respectively