Location, orbit and energy of a meteoroid impacting the moon during the Lunar Eclipse of January 21, 2019

During lunar eclipse of January 21, 2019 a meteoroid impacted the Moon producing a visible light flash. The impact was witnessed by casual observers offering an opportunity to study the phenomenon from multiple geographical locations. We use images and videos collected by observers in 7 countries to estimate the location, impact parameters (speed and incoming direction) and energy of the meteoroid. Using parallax, we achieve determining the impact location at lat. $-29.43^{+0.30}_{-0.21}$, lon. $-67.89^{+0.07}_{-0.09}$ and geocentric distance as 356553 km. After devising and applying a photo-metric procedure for measuring flash standard magnitudes in multiple RGB images having different exposure times, we found that the flash, had an average G-magnitude $\langle G\rangle = 6.7\pm0.3$. We use gravitational ray tracing (GRT) to estimate the orbital properties and likely radiant of the impactor. We find that the meteoroid impacted the moon with a speed of $14^{+7}_{-6}$ km/s (70% C.L.) and at a shallow angle, $\theta < 38.2$ degrees. Assuming a normal error for our estimated flash brightness, educated priors for the luminous efficiency and object density, and using the GRT-computed probability distributions of impact speed and incoming directions, we calculate posterior probability distributions for the kinetic energy (median $K_{\rm med}$ = 0.8 kton), body mass ($M_{\rm med}$ = 27 kg) and diameter ($d_{\rm med}$ = 29 cm), and crater size ($D_{\rm med}$ = 9 m). If our assumptions are correct, the crater left by the impact could be detectable by prospecting lunar probes. These results arose from a timely collaboration between professional and amateur astronomers which highlight the potential importance of citizen science in astronomy.Comment: 19 pages, 11 figures, 4 tables. Data and scripts available in https://github.com/seap-udea/MoonFlashes. Accepted for publication in MNRA

Knowledge and organizational performance in franchised restaurants in Colombia

Purpose: The aim of this study is to analyze the importance of knowledge in reaching organizational objectives (long-term organizational goals) and in constructing competitive advantage (value-added) and identifying the impact of this knowledge on organizational performance of franchised restaurants in an emerging market. Design/methodology/approach: Likert-scale surveys were applied to 50 managers representing 80% of the franchised restaurant business in Bogotá, Colombia. Data processing was performed through descriptive statistics, multiple correspondences analysis (MCA) and logit regression (LR). Findings: Results indicate that 1) of the set of factors that contribute to the achievement of franchise objectives, personnel motivation and continuous environmental scanning are the most important; 2) the primary sources of knowledge for construction of competitive advantage are clients and providers; and 3) the most significant impact of knowledge occurs in human resource and organizational development and in increased earnings. Practical implications: The study provides evidence of the role and the impact of knowledge in the performance of franchised restaurants and thereby contributes to academic analysis and managerial decision-making. Originality: This study provides aggregated and disaggregated analysis of empirical data on the role of knowledge in franchised restaurants, a sector with limited extant research in the context of emerging markets. © 2020, Emerald Publishing Limited

Un enfoque de bajo costo para monitorear la salud estructural de los puentes peatonales

Changes in dynamic properties of structures, such as damping ratios and natural frequencies can be detected by periodic monitoring (e.g. one time by year). These changes are often indications of structural damage thereby, the maintenance or demolition of the structure can be doing in due time. In the case of pedestrian bridges, people’s movements may produce a resonance state, which leads to excessive deflection that accelerates the deterioration of these structures. Typically, these dynamic properties are detected by using high-cost vibration measurement equipment to achieve high levels of precision (i.e. a very low noise levels). This article studies the measurement of dynamic properties in pedestrian bridges using a tri-axial accelerometer integrated into a mobile phone as a low-cost and alternative practice. Accelerations were recorded on a steel pedestrian bridge (flexible) and on a post-tensioned concrete pedestrian bridge (rigid) located in Barranquilla City (Colombia). Vibrations were induced by a person (e.g., by jumping). Previous studies based on traditional measuring techniques show that two dominant frequencies in both types of bridges can be identified. However, in this study a reliable damping ratio could only be established for the steel bridge that it is associated with the flexibility and the low amplitude of the induced vibrations by a single pedestrian use

Mundo de la vida, espacios pedagógicos, espacios escolares y ex-centricidad humana: reflexiones antropológico-pedagógicas y socio-fenomenológicas

El presente texto pretende problematizar, a la luz del diálogo de saberes de la antropología pedagógica y la socio-fenomenología, el tema de los espacios pedagógicos. Para tal fin, se traen a colación las categorías de mundo de la vida,excentricidad humana y espacio escolar, con el interés final de poner en cuestión la clásica idea de considerar por antonomasia la escuela como espacio pedagógico privilegiado.-I. A modo de introducción y contextualización. -II. Sociología fenomenológica y el mundo de la vida. -III. Aspectos del mundo de la vida y espacio vital. -IV. Espacios pedagógicos. -V. Espacios escolares. -VI. A modo de conclusión: la tensión entre espacios escolares y ex-centricidad. -Bibliografía

Alberto Ginastera and the Guitar Chord: An Analytical Study

The guitar chord (a sonority based on the open strings of the guitar) is one of Alberto Ginastera's compositional trademarks. The use of the guitar chord expands throughout forty years, creating a common link between different compositional stages and techniques. Chapters I and II provide the historical and technical background on Ginastera's life, oeuvre and scholar research. Chapter IV explores the origins of the guitar chord and compares it to similar specific sonorities used by different composers to express extra-musical ideas. Chapter V discusses Ginastera's initial uses and modifications of the guitar chord. Chapter VI explores the use of the guitar chord as a referential sonority based on Variaciones Concertantes, Op. 23: I-II, examining vertical (subsets) and horizontal (derivation of motives) aspects. Chapter VII explores uses of trichords and hexachords derived from the guitar chord in the Sonata for Guitar Op. 47

Dualidad en optimización multi-objetivo bajo incertidumbre

Existen varias teorías de optimización en relación con la palabra incertidumbre: Optimización difusa, optimización estocástica u optimización intervalo-valuada, entre otras. Cada una de éstas teorías de la optimización se diferencian en las características que asumen los parámetros utilizados tanto en la función objetivo como en las restricciones que determinan el conjunto factible.72 p.Contenido parcial: Optimización bajo incertidumbre -- Optimización estocástica -- Optimización intervalo valuada -- Formulación del problema de optimización y conceptos de solución -- Condiciones KKT intervalo valuada

Safety of vaginal erbium laser: A review of 113,000 patients treated in the past 8 years.

Background: Energy-based devices are becoming a popular option for minimally invasive vaginal procedures. The aim of this study was to obtain information on the frequency of occurrence of adverse effects (AEs) related to vaginal erbium laser (VEL™) treatment.Materials and methods: The global survey was conducted among practitioners using the non-ablative VEL™ (Fotona, Ljubljana, Slovenia). Users were invited to provide the number of patients treated with VEL™ and the number of observed laser-related AEs.Results: The survey was conducted from August 2018 to April 2019. Responses from 535 practitioners were collected, with a total of 113,174 patients treated in the period from 2012 to 2019. Out of 535 respondents, 160 (30%) shared detailed information about the indications they treated in a population of 62,727 patients, whereas 188 (35%) respondents provided information on the frequency of AEs observed in their treated population of 43,095 patients. All observed AEs were mild to moderate, transient and appeared with low frequencies.Conclusions: Minimally invasive thermal-only laser treatment using the non-ablative VEL™ procedures appears to be safe and the incidence of AEs is low