Simple regular black hole with logarithmic entropy correction

A simple regular black hole solution satisfying the weak energy condition is obtained within Einstein--non--linear electrodynamics theory. We have computed the thermodynamic properties of this black hole by a careful analysis of the horizons and we have found that the usual Bekenstein--Hawking entropy gets corrected by a logarithmic term. Therefore, in this sense our model realizes some quantum gravity predictions which add this kind of correction to the black hole entropy. In particular, we have established some similitudes between our model and a quadratic generalized uncertainty principle. This similitude has been confirmed by the existence of a remnant, which prevents complete evaporation, in agreement with the quadratic generalized uncertainty principle case

Search for gravitational waves from Scorpius X-1 with a hidden Markov model in O3 LIGO data with a corrected orbital ephemeris

Results are presented for a semi-coherent search for gravitational waves from the low-mass X-ray binary Scorpius X-1 in Observing Run 3 (O3) data from the Laser Interferometer Gravitational Wave Observatory, using an updated orbital parameter ephemeris and a hidden Markov model (HMM) to allow for spin wandering. The new orbital ephemeris corrects errors in previously published orbital measurements and implies a new search domain. This search domain does not overlap with the one used in the original Scorpius X-1 HMM O3 search. The corrected domain is approximately three times smaller by area in the $T_{\rm asc}$--$P$ plane than the original domain, where $T_{\rm asc}$ and $P$ denote the time of passage through the ascending node and the orbital period respectively, reducing the trials factor and computing time. No evidence is found for gravitational radiation in the search band from 60 Hz to 500 Hz. Upper limits are computed for the characteristic gravitational wave strain. They are consistent with the values from the original Scorpius X-1 HMM O3 search.Comment: 8 pages, 2 figure

The Work of Amnesty International and Human Rights Watch: Evidence from Colombia

We process the main written output of Amnesty International and Human Rights Watch on Colombia covering the period 1988-2004, recording all numerical conflict information and accounts of specific conflict events. We check for internal consistency and against a unique Colombian conflict database. We find that both organizations have substantive problems in their handling of quantitative information. Problems include failre to specify sources, unclear definitions, an erratic reporting template and a distorted portrayal of conflict dynamics. Accounts of individual events are fairly representative and much more useful and accurate than the statistical information. We disprove a common accusation that Amnesty International and Human Rights Watch rarely criticize the guerrillas, but do find some evidence of anti-government bias. The quantitative human rights and conflict information produced by these organizations for other countries must be viewed with scepticism along with cross-country and time series human rights data based on Amnesty International reports.

Arquitectura Computacional para la Inferencia deuna CNN Cuantizada para Detectar FibrilaciónAuricular

Atrial Fibrillation is a common cardiac arrhythmia, which is characterized by an abnormal heartbeat rhythm that can be life-threatening. Recently, researchers have proposed several Convolutional Neural Networks (CNNs) to detect Atrial Fibrillation. CNNs have high requirements on computing and memory resources, which usually demand the use of High Performance Computing (eg, GPUs). This high energy demand is a challenge for portable devices. Therefore, efficient hardware implementations are required. We propose a computational architecture for the inference of a Quantized Convolutional Neural Network (Q-CNN) that allows the detection of the Atrial Fibrillation (AF). The architecture exploits data-level parallelism by incorporating SIMD-based vector units, which is optimized in terms of computation and storage and also optimized to perform both the convolutional and fully connected layers. The computational architecture was implemented and tested in a Xilinx Artix-7 FPGA. We present the experimental results regarding the quantization process in a different number of bits, hardware resources, and precision. The results show an accuracy of 94% accuracy for 22-bits. This work aims to be the basis for the future implementation of a portable, low-cost, and high-reliability device for the diagnosis of Atrial Fibrillation.La fibrilación auricular es una arritmia cardíaca común, que se caracte-riza por un ritmo cardíaco anormal que puede poner en peligro la vida.Recientemente, se han propuesto varias Redes Neuronales Convoluciona-les (CNNs, por sus siglas en inglés) para detectar la fibrilación auricular.Las CNN tienen altos requisitos de recursos informáticos y de memoria,lo que generalmente demanda el uso Computación de Altro Rendimientocomo por ejemplo GPUs. Esta alta demanda de energía es un desafío pa-ra los dispositivos portátiles. Por lo tanto, se requieren implementacionesde hardware eficientes. Proponemos una arquitectura computacional pa-ra la inferencia de una Red Neural Convolucional Cuantizada (Q-CNN)que permite la detección de la Fibrilación Auricular (FA). La arquitecturaaprovecha el paralelismo a nivel de datos, incorporando unidades vecto-riales basadas en SIMD, que están optimizadas en términos de cálculoy almacenamiento. El diseño también se optimizó para realizar tanto lascapas convolucionales como las capas completamente conectadas. La ar-quitectura computacional se implementó y probó en una FPGA XilinxArtix-7. Presentamos los resultados experimentales con respecto al proce-so de cuantización en un número diferente de bits, recursos de hardwarey precisión. Los resultados muestran una precisión del 94 % para 22 bits.Este trabajo pretende ser la base para la futura implementación de undispositivo portátil, de bajo costo y alta confiabilidad para el diagnósticode Fibrilación Auricular

Illuminating the threat: a decade-long analysis of light pollution in major Colombian urban centres using satellite imagery

La contaminación lumínica es una forma de degradación ambiental que aumenta cada vez más en todo el mundo y afecta el entorno natural, la flora, la fauna y varios aspectos de la vida humana. A pesar de la creciente preocupación por esta problemática, en Colombia su estudio es aún muy limitado. Aquí analizamos de forma exhaustiva la expansión de la luz nocturna artificial en las principales ciudades de Colombia entre el 2012 y el 2022. Se evidenció así un aumento en los niveles de contaminación lumínica en las áreas urbanas de Bogotá, Barranquilla y Cartagena, en tanto que en las de Medellín, Cali y Bucaramanga disminuyó la radiancia promedio. Sin embargo, en todas las ciudades consideradas en el estudio la cobertura de áreas iluminadas aumentó, con un evidente incremento espacial del fenómeno. En el caso de Bogotá, se analizó detalladamente el fenómeno a nivel de localidades y, a partir de datos externos, se verificaron, además, las relaciones del aumento de la contaminación lumínica con la instalación de nuevas luminarias, el cambio a tecnologías LED, y el crecimiento de la densidad poblacional y el producto interno bruto de la ciudad.Light pollution is a form of environmental degradation present throughout the world that affects the natural environment, flora, fauna, and various aspects of human life. Despite the growing concern about this problem, its study in Colombia is still minimal. Here we present a comprehensive analysis of the expansion of artificial nighttime lighting in the main Colombian cities between 2012 and 2022. According to the analysis, light pollution levels in the urban areas of Bogotá, Barranquilla, and Cartagena increased, while in Medellín, Cali, and Bucaramanga, they decreased. However, all the cities evaluated experienced an expansion in the coverage of illuminated areas revealing an evident spatial increase of the problem. In the case of Bogotá, the phenomenon was studied at the locality level. Additionally, we used external data to analyze the relationship between increased light pollution and the installation of new luminaires, the change to LED technologies, and the growing population density and gross domestic product (GDP) in the city. Our results provide valuable information on the threat of light pollution in Colombia and the need to take measures to help control the associated environmental degradation

Cyclic behavior of ultra-high performance fiber reinforced concrete beam-column joint

[EN] Ultra-high performance fiber reinforced concrete (UHPFRC) is a unique class of fiber-reinforced concrete featuring ultra-high compressive strength and ductil e tensile strain hardening behavior, accompanied by multiple narrow cracking. Although many studies have confirmed its superior mechanical and damage tolerance properties under monotonic or blast loading, limited research has been carried out on the cyclic performance of UHPFRC structural members. This paper proposes the use of UHPFRC to improve the cyclic performance of structural elements. An experimental program was carried out on a large number of UHPFRC beam-column joint specimens under a cyclic lateral load. After the cyclic loading test, the following results were obtained: (a) hysterical performance, (b) maximum load, (c) maximum displacement, (d) the maximum energy dissipation (measured by hysteresis cycles), (e) stiffness degradation, (f) the cracking pattern, and (g) the cracking area. The analysis showed that UHPFRC specimens have at least 157% higher energy dissipation than nonfiber conventional reinforced concrete (RC). The initial stiffness of UHPFRC specimens without fibers (NF) was at least 23% higher than the RC specimen. For UHPFRC with fiber, initial stiffness was at least 45% higher than RC specimen.This work was supported by Cementos Argos, Colciencias and the Pontificia Universidad Javeriana, Bogotá (Colombia).Sarmiento, PA.; Torres Górriz, B.; Ruiz, DM.; Alvarado Vargas, YA.; Gasch, I.; Machuca, AF. (2019). Cyclic behavior of ultra-high performance fiber reinforced concrete beam-column joint. Structural Concrete. 20(1):348-360. https://doi.org/10.1002/suco.201800025S34836020

Recycling of modified asphalt sheets for automotive use

Aldás-Carrasco, MF.; Pavón-Vargas, CP.; Rosa-Ramírez, HDL.; Valle, V.; Ribadeneira, AF. (2021). Recycling of modified asphalt sheets for automotive use. DYNA Ingeniería e Industria (Online). 96(4):351-354. https://doi.org/10.6036/1009735135496

Revalorización de residuos de equipos eléctricos y electrónicos en Colombia: una alternativa para la obtención de metales preciosos y metales para la industria

This article aims to review the global context, and especially the Colombian context, regarding the management of waste electrical and electronic appliances, their use, recovery and the main extraction methods for high added-value base and precious metals. A literature review was carried out to obtain the quantities of residues, their main components and the extraction methods for base and precious metals; for Colombia, a case study was carried out in which, through a hydrometallurgy process applied to cellular phones, the quantities of base and precious metals that can be obtained were calculated. Only 15.5 % of e-waste in the world is recycled, the main recyclable components are iron (Fe), copper (Cu), aluminum (Al), lead (Pb), nickel (Ni), silver (Ag), gold (Au) and palladium (Pd), and that using e-waste as a source of metals could reduce energy consumption by 60-95 %. For the case study in Colombia, it was found that 3.8 t/year of Cu, 3.5 t/year of Fe, 56.5 kg/year of Ag, 6 kg/year of Pd and 10 kg/year of Au could be obtained. The conclusion is that recovering metals from electrical and electronic waste is feasible and that alternatives should be sought to take advantage of them due to their potential added value.El objetivo de este artículo es revisar el contexto mundial, y especialmente el colombiano, respecto al manejo de los residuos de equipos eléctricos y electrónicos, su aprovechamiento, recuperación y los principales métodos para la extracción de metales base y preciosos de alto valor agregado. Para ello, se realizó una revisión bibliográfica para obtener las cantidades de residuos, sus componentes principales y los métodos de extracción de metales base y preciosos; para Colombia, se realizó un estudio de caso, en el que, mediante un proceso de hidrometalurgia aplicado a teléfonos celulares, se calcularon las cantidades de metales base y preciosos que se pueden obtener. Se encontró que solo se aprovecha el 15,5 % de los residuos electrónicos en el mundo, que los principales componentes reciclables son el hierro (Fe), el cobre (Cu), el aluminio (Al), el plomo (Pb), el níquel (Ni), la plata (Ag), el oro (Au) y el paladio (Pd), y que el uso de los residuos electrónicos como fuente de metales podría reducir el consumo de energía entre 60 % y 95 %. Para el estudio de caso en Colombia, se encontró que se podrían obtener 3,8 t/año de Cu, 3,5 t/año de Fe, 56,5 kg/año de Ag, 6 kg/año de Pd y 10 kg/año de Au. Se concluye que es viable la recuperación de metales a partir de residuos eléctricos y electrónicos y que se deben buscar alternativas para aprovecharlos debido a su potencial valor agregado

Cranial nerves anatomy in magnetic resonance

En la actualidad, la Resonancia Magnética (RM) permite evaluar gran parte de la anatomía de los doce pares craneales. Las secuencias empleadas tradicionalmente permiten evaluar los más grandes; sin embargo, los avances en los equipos y el desarrollo de la secuencia steady-state free precession (SSFP) proveen una mejor resolución espacial, submilimétrica y de alta resolución de contraste entre el líquido cefalorraquídeo (LCR) y las estructuras sólidas, que permiten una adecuada evaluación de sus segmentos cisternales y canaliculares con gran detalle anatómico. El objetivo de esta revisión es ilustrar y describir la anatomía normal de los pares craneales en la RM de manera práctica para el uso de los clínicos y radiólogos