Results on stellar occultations by (307261) 2002 MS4

Transneptunian Objects (TNOs) are the remnants of our planetary system and can retain information about the early stages of the Solar System formation. Stellar occultation is a groundbased method used to study these distant bodies which have been presenting exciting results mainly about their physical properties. The big TNO called 2002 MS4 was discovered by Trujillo, C. A., & Brown, M. E., in 2002 using observations made at the Palomar Observatory (EUA). It is classified as a hot classical TNO, with orbital parameters a = 42 AU, e = 0.139, and i = 17.7º. Using thermal measurements with PACS (Herschel) and MIPS (Spitzer Space Telescope) instruments, Vilenius et al. 2012 obtained a radius of 467 +/- 23.5 km and an albedo of 0.051.Predictions of stellar occultations by this body in 2019 were obtained using the Gaia DR2 catalogue and NIMA ephemeris (Desmars et al. 2015) and made available in the Lucky Star web page (https://lesia.obspm.fr/lucky-star/). Four events were observed in South America and Canada. The first stellar occultation was detected on 09 July 2019, resulting in two positives and four negatives chords, including a close one which proven to be helpful to constrain the body’s size. This detection also allowed us to obtain a precise astrometric position that was used to update its ephemeris and improve the predictions of the following events. Two of them were detected on 26 July 2019, separated by eight hours. The first event was observed from South America and resulted in three positive detections, while the second, observed from Canada, resulted in a single chord. Another double chord event was observed on 19 August 2019 also from Canada.Facultad de Ciencias Astronómicas y Geofísica

Estrategias Empresariales

Las empresas se preguntan constantemente hacia dónde deben dirigir su organización, y la respuesta a ello está en las estrategias que cada una formule, implante y evalúe, todo con un propósito en mente: obtener una ventaja competitiva a largo plazo. La obtención de ventajas competitivas sostenibles exige de las empresas la continua transformación y búsqueda de alternativas de mejora tanto de manera externa como interna de la organización. Todas las áreas funcionales de la empresa deben verse involucradas y comprometidas en la obtención de las metas organizacionales. Los resultados de las estrategias deben valorarse siempre desde la perspectiva financiera, por lo que es importante conocer cómo impactan las distintas alternativas estratégicas en los resultados financieros, independientemente que desde la misma función de administración financiera existan acciones que deban llevarse a cabo para la consecución de los resultados deseados. El ambiente empresarial de alta competencia, exige revisar diferentes nuevas teorías administrativas en las que las empresas pueden apoyar su funcionamiento para dar respuesta adecuada a quienes tienen expectativas con respecto a sus resultados. Así también, la globalización crea intercambios comerciales de una forma acelerada, los factores externos de tipo social, económico, ambiental, entre otros, cambian día con día, ello implica que las empresas tengan que actualizarse de manera interna con diferentes tácticas, evolucionando en la mercadotecnia para hacer frente a este proceso

ON THE MINIMUM ABSOLUTE VALUE of THE DISCRIMINANT of ABELIAN FIELDS of DEGREE p(2)

Let p be a prime number. A formula for the minimum absolute value of the discriminant of all Abelian extensions of Q of degree p(2) is given in terms of p

Experimental and computational aspects of green corrosion inhibition for low carbon steel in HCl environment using extract of Chamaerops humilis fruit waste

[EN] The inhibition effect of a methanolic extract of Chamaerops humilis (CHFE) on the corrosion of low-carbon steel in 1 M HCl solution was evaluated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy. The extract was obtained from the fruit seeds by the Soxhlet extraction method. The CHFE demonstrated promising anticorrosive performance, and the inhibition efficiency increased with increasing the concentration of the extract, peaking at 93% at only 500 ppm. Importantly, the inhibitor exhibited a remarkable stability after 48 h of immersion, reaching an efficiency of 94%. The extract revealed a mixed-type inhibitive behavior. In addition, elevating the solution temperature showed a negative influence on the inhibition efficacy. Thermodynamic parameters suggested that the steel dissolution is an endothermic, spontaneous process. In addition, the experimental findings match well with the Langmuir adsorption isotherm and physisorption of the extract prevails. Furthermore, SEM/EDX and UV-Vis analyses demonstrated that the steel surface is protected by the extract molecules, confirming the electrochemical results. Density functional theory (DFT), Fukui function and molecular dynamics (MD) calculations unraveled the nature of inhibitor-metal surface interactions and provided insights into the most favorable electrophilic and nucleophilic active sites of oleic acid, a major constituent of the extract, helping to elucidate the mechanism of corrosion inhibition at the molecular level.M. Boudalia acknowledges the support from Mohammed V University and H.M.A. Amin acknowledges the support from Cairo University.Eddahhaoui, F.; Najem, A.; Elhawary, M.; Boudalia, M.; Campos, OS.; Tabyaoui, M.; Garcia-Anton, J.... (2024). Experimental and computational aspects of green corrosion inhibition for low carbon steel in HCl environment using extract of Chamaerops humilis fruit waste. Journal of Alloys and Compounds. 977. https://doi.org/10.1016/j.jallcom.2023.17330797

Análisis de la gráfica y acción pública de los movimientos sociales en México

287 páginas : contiene ilustraciones (algunas en color).68-132 Revolución Visual es una publicación que surge de la concurrencia de actores claves, histórica y estéticamente situados, que forman parte del legado vivo de la gráfica visual emanada del convulso 68. Continuada en diversos y persistentes movimientos sociales, esa intensidad de formas y modalidades de la resistencia se extendió a lo largo de varias décadas para ubicarse y prolongarse en los territorios contemporáneos de la relación entre imagen y protesta. En este sentido, los objetivos de la presente publicación colectiva se pueden resumir en los siguientes elementos: 1. Reconocer los procesos de significación generados en los movimientos sociales de protesta en México desde 1968. 2. Mostrar la diversidad de expresiones en contextos de disenso y los efectos políticos e ideológicos de la imagen de protesta. 3. Mantener viva, a cinco décadas del movimiento, la memoria y los imaginarios generacionales de ruptura acompañados por el uso de la imagen como herramienta comunicativa y combativa. 4. Desmitificar la percepción colectiva sobre los actores de la protesta y contextualizar sus manifestaciones pasadas y actuales. Este conjunto de objetivos ha sido abordado en distintos niveles. Por una parte, al periodizar de la imagen de protesta, partiendo por las imágenes del movimiento del 68; en segundo lugar, mediante el reconocimiento de imágenes procedentes de años de protesta social (desde los setentas hasta la primera década del presente siglo) en donde se apuntaló la lucha democrática a varios niveles y escalas territoriales; en tercer lugar, al problematizar el carácter y singularidad de las imágenes de la protesta del movimiento #YoSoy132, así como sus afluentes y proyecciones significativas.Verónica Arroyo Pedroza, Jorge Ortiz Leroux, compilación y coordinación editorialPrefacio -- La gráfica de la protesta. 68-132 Revolución Visual / Jorge Ortiz Leroux y Verónica Arroyo Pedroza. -- CAPITULO 1. La grafica del 68 -- Icónicas combativas: la gráfica política del 68 / Diego Lizarazo Arias -- En el 68, nuestra respuesta estuvo e la imagen critica / Jorge Pérez Vega -- La fotografía y el movimiento estudiantil de 1968 / Alberto del Castillo Troncoso -- Estetización social y contracultura en el movimiento estudiantil de 1968 / José Othón Quiroz. -- CAPITULO 2. Movimientos finiseculares y reproducción de significaciones. Imágenes disidentes en el México contemporáneo. Foro de ideas disidentes / Arnulfo Aquino Casas -- El movimiento estudiantil en México a finales del siglo XX / Sergio Tamayo -- La experiencia gráfica de la revista La Guillotina / Alejandro Moreno Corso -- Del 68 al 132 / Cristina Hijar González. -- CAPITULO 3. La estética de los movimientos emergentes -- Sublevarte colectivo. La persistencia de muchos sueños / Joel Martínez Huerta -- Estéticas callejeras y diseño / Itandehui Franco -- El ruido del fuego / Antonio Ortiz "Gritón" -- Reflexiones sobre la crisis de la enunciación. A propósito del movimiento #yo soy 131+1 / José́ Luis Barrios -- Glosario -- Semblanza de autores

Results on stellar occultations by (307261) 2002 MS4

Transneptunian Objects (TNOs) are the remnants of our planetary system and can retain information about the early stages of the Solar System formation. Stellar occultation is a ground-based method used to study these distant bodies which have been presenting exciting results mainly about their physical properties. The big TNO called 2002 MS4 was discovered by Trujillo, C. A., & Brown, M. E., in 2002 using observations made at the Palomar Observatory (EUA). It is classified as a hot classical TNO, with orbital parameters a = 42 AU, e = 0.139, and i = 17.7°. Using thermal measurements with PACS (Herschel) and MIPS (Spitzer Space Telescope) instruments, Vilenius et al. 2012 obtained a radius of 467 +/- 23.5 km and an albedo of 0.051.Predictions of stellar occultations by this body in 2019 were obtained using the Gaia DR2 catalogue and NIMA ephemeris (Desmars et al. 2015) and made available in the Lucky Star web page (https://lesia.obspm.fr/lucky-star/). Four events were observed in South America and Canada. The first stellar occultation was detected on 09 July 2019, resulting in two positives and four negatives chords, including a close one which proven to be helpful to constrain the body"s size. This detection also allowed us to obtain a precise astrometric position that was used to update its ephemeris and improve the predictions of the following events. Two of them were detected on 26 July 2019, separated by eight hours. The first event was observed from South America and resulted in three positive detections, while the second, observed from Canada, resulted in a single chord. Another double chord event was observed on 19 August 2019 also from Canada.Due to its size, it is expected that 2002 MS4 is in hydrostatic equilibrium. Thirouin, A. 2013 obtained a rotational light curve of 2002 MS4 and determined two possible periods (7.33 h and 10.44 h) with low amplitude variation (0.05 +/- 0.01 mag). Admitting that it has a Maclaurin shape, the projected limb in the sky plane for Earth-based observers should be the same in the 09 July and 26 July events. The multi-chord detection allows determining an interval of parameters for size and shape. Considering that the same figure should have been observed in the 09 July event, we could use the both chords and the negative observations to constrain its physical parameters. With that, we could determine that 2002 MS4 has an equivalent radius of 385 +/- 1 km (Figure 1). Our results indicate that this TNO is about 100 km smaller in diameter than the value obtained by Vilenius et al. 2012, implying an albedo of 0.076 (Hv = 4.0 +/- 0.6) . The astrometric positions derived from these data were also helpful to improve forthcoming stellar occultations, in special the one crossing Europe on 08 August this year. More data from stellar occultations and observations of rotational light curves will help to confirm these results and assumptions.Acknowledgements: F.L.R is thankful for the support of the CAPES scholarship. The following authors acknowledge the respective CNPq grants: F.B-R 309578/2017-5; R.V-M 304544/2017-5, 401903/2016-8; J.I.B.C. 308150/2016-3; M.A 427700/2018-3, 310683/2017-3, 473002/2013-2. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001 and the National Institute of Science and Technology of the e-Universe project (INCT do e-Universo, CNPq grant 465376/2014-2). G.B-R acknowledges CAPES-FAPERJ/PAPDRJ grant E26/203.173/2016, M.A FAPERJ grant E-26/111.488/2013 and A.R.G-Jr FAPESP grant 2018/11239-8. B.E.M thanks the CAPES/Cofecub-394/2016-05 grant. P.S-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 "LEO-SBNAF" (MCIU/AEI/FEDER, UE). We would like to acknowledge financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award for the Instituto de Astrofı́sica de Andalucı́a (SEV-2017-0709) and the financial support by the Spanish grant AYA-2017-84637-R. Part of the results were based on observations taken at the 1.6 m telescope on Pico dos Dias Observatory of the National Laboratory of Astrophysics (LNA/Brazil). Part of this work was carried out within the "Lucky Star" umbrella that agglomerates the efforts of the Paris, Granada and Rio teams. It is funded by the European Research Council under the European Community"s H2020 (2014-2020/ERC Grant Agreement No. 669416). This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. ReferencesAssafin, M. et al. PRAIA - Platform for Reduction of Astronomical Images Automatically. In: Tanga, P.; Thuillot, W. (Ed.). Gaia follow-up network for the solar system objects : Gaia FUN-SSO workshop proceedings, held at IMCCE -Paris Observatory, France, November 29 - December 1, 2010 / edited by Paolo Tanga, William Thuillot.- ISBN 2-910015-63-7, p. 85-88. [S.l.: s.n.], 2011. p. 85-88.Desmars, J. et al. Orbit determination of trans-Neptunian objects and Centaurs for the prediction of stellar occultations. Astronomy & Astrophysics, v. 584, p. A96, dez. 2015.Thirouin, A. Study of Trans-Neptunian Objects using photometric techniques and numerical simulations. Dissertation. Editorial de la Universidad de Granada. Spain, 2013.Trujillo, C. A., Brown, M. E., Minor Planet Electronic Circulars - MPEC 2002-W27. Disponível em: \url{https://minorplanetcenter.net//iau/mpec/K02/K02W27.html}.Vilenius, E. "TNOs are cool": a survey of the trans-Neptunian region. VI. Herschel/PACS observations and thermal modelling of 19 classical Kuiper belt objects. Astronomy & Astrophysics. v. 541, A94, 2012