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Item The vertical structure of debris disks and the impact of gas.(2022-02-16) Olofsson, Johan; Thébault, Philippe; Kral, Quentin; Bayo, Amelia; Boccaletti, Anthony; Godoy, Nicolás; Henning, Thomas; van Holstein, Rob G.; Maucó, Karina; Milli, Julien; Montesinos, Matías; Rein, Hanno; Sefilian, Antranik A.The vertical structure of debris discs provides clues about their dynamical evolution and the collision rate of the unseen planetesimals. Thanks to the ever-increasing angular resolution of contemporary instruments and facilities, we are beginning to constrain the scale height of a handful of debris discs, either at near-infrared or millimeter wavelengths. None the less, this is often done for individual targets only. We present here the geometric modeling of eight discs close to edge-on, all observed with the same instrument (SPHERE) and using the same mode (dual-beam polarimetric imaging). Motivated by the presence of CO gas in two out of the eight discs, we then investigate the impact that gas can have on the scale height by performing N-body simulations including gas drag and collisions. We show that gas can quickly alter the dynamics of particles (both in the radial and vertical directions), otherwise governed by gravity and radiation pressure. We find that, in the presence of gas, particles smaller than a few tens of microns can efficiently settle toward the midplane at the same time as they migrate outward beyond the birth ring. For second generation gas (Mgas ≤ 0.1 M⊕), the vertical settling should be best observed in scattered light images compared to observations at millimeter wavelengths. But if the gas has a primordial origin (Mgas ≥ 1 M⊕), the disc will appear very flat both at near-infrared and sub-mm wavelengths. Finally, far beyond the birth ring, our results suggest that the surface brightness profile can be as shallow as ∼−2.25.Item Teaching physics in real-life contexts: The Beirut explosion(2023-04-01) Echiburu, Mauricio; Hernández, Carla; Pino, MiguelTeaching physics in real-life contexts continues to be a challenge for teachers at different edu cational levels. In this article, three Context-Rich Problems are proposed to be implemented in the classroom for higher education, using the explosion that occurred in Beirut as a case study. These problems require the search and analysis of real data, integrating technologies as tools to learn physics. In particular, the analysis of images, videos, maps and audio recordings is suggested. The proposed activities are designed to promote active learning of classical mechanics subjects and the development of collaborative skills. The results of each problem allow a discussion based on scientific evidence in the classroom.Item Study of the effect of seismically-induced geoelectric and geomagnetic fields on secondary particle detection at a LAGO site(2022-03-18) Coloma Borja, Diego Alberto; Carrera Jarrin, Edgar; Echiburu, Mauricio; LAGO CollaborationThe LAGO (Latin American Giant Observatory) project is an extended Astroparticle Observatory at global scale. It is mainly oriented to basic research on three branches of Astroparticle physics: the Extreme Universe, Space Weather phenomena, and Atmospheric Radiation at ground level. This work is framed in the latter branch, its aim is to study the potential effects on extensive air showers from changes in geoelectric and geomagnetic fields, induced by the onset of seismic activity. For this purpose, simulations for flux of secondaries are performed with ARTI, a tool developed by LAGO that combines Magnetocosmics, CORSIKA, and Geant4 to account, respectively, for the propagation of a shower by a primary particle, geomagnetic corrections, and detector response. Using ARTI, we have calculated the radiation background at the LAGO Site in Universidad San Francisco de Quito (2200 m.a.s.l). Regular conditions for the Earth's electromagnetic field are taken from the NCEI Geomagnetic Calculator for specific fair-weathered days above the location. Variations from this regularity are introduced based on relevant studies on seismic activity. The results show that there exists an effect on the number of secondary particles at ground level, which could, in principle, be detected by a LAGO WCD detector.Item Glucagon-like peptide 1 receptor activation regulates cocaine actions and dopamine homeostasis in the lateral septum by decreasing arachidonic acid levels(2016) Reddy, IA; Pino, JA; Weikop, P; Osses, N; Sørensen, G; Bering, T; Valle, C; Bluett, RJ; Erreger, K; Wortwein, G; Reyes, JG; Graham, D; Stanwood, GD; Hackett, TA; Fink-Jensen, A; Torres, GE; Galli, A; Patel, SAgonism of the glucagon-like peptide 1 (GLP-1) receptor (GLP-1R) has been effective at treating aspects of addictive behavior for a number of abused substances, including cocaine. However, the molecular mechanisms and brain circuits underlying the therapeutic effects of GLP-1R signaling on cocaine actions remain elusive. Recent evidence has revealed that endogenous signaling at the GLP-1R within the forebrain lateral septum (LS) acts to reduce cocaine-induced locomotion and cocaine conditioned place preference, both considered dopamine (DA)-associated behaviors. DA terminals project from the ventral tegmental area to the LS and express the DA transporter (DAT). Cocaine acts by altering DA bioavailability by targeting the DAT. Therefore, GLP-1R signaling might exert effects on DAT to account for its regulation of cocaine-induced behaviors. We show that the GLP-1R is highly expressed within the LS. GLP-1, in LS slices, significantly enhances DAT surface expression and DAT function. Exenatide (Ex-4), a long-lasting synthetic analog of GLP-1 abolished cocaine-induced elevation of DA. Interestingly, acute administration of Ex-4 reduces septal expression of the retrograde messenger 2-arachidonylglycerol (2-AG), as well as a product of its presynaptic degradation, arachidonic acid (AA). Notably, AA reduces septal DAT function pointing to AA as a novel regulator of central DA homeostasis. We further show that AA oxidation product γ-ketoaldehyde (γ-KA) forms adducts with the DAT and reduces DAT plasma membrane expression and function. These results support a mechanism in which postsynaptic septal GLP-1R activation regulates 2-AG levels to alter presynaptic DA homeostasis and cocaine actions through AA.Item GDAS atmospheric models in astroparticle shower simulations(2021) Grisales-Casadiegos, J.; Sarmiento-Cano, C.; Núñez, Luis A.; LAGO CollaborationAtmospheric conditions affect the development of cascades of secondary particles produced by primary cosmic rays. Global Data Assimilation System, implementing atmospheric models based on meteorological measurements and numerical weather predictions, could significantly improve the outcomes of the simulations for extensive air showers. In this work, we present a methodology to simulate the effect of the atmospheric models in secondary particle flux at the Earth’s surface. The method was implemented for Bucaramanga-Colombia, using ARTI: a complete computational framework developed by the Latin American Giant Observatory Collaboration to estimate the particle spectra on Water Cherenkov Detectors depending on the geographical coordinates. We observe differences in the total flux that varies monthly concerning the subtropical summer atmospheric profile as preliminary results.Item A Hybrid Artificial Intelligence Model for Aeneolamia varia (Hemiptera: Cercopidae) Populations in Sugarcane Crops(2021) Figueredo, Luis; Villa-Murillo, Adriana; Colmenarez, Yelitza; Vásquez, CarlosSugarcane spittlebugs are considered important pests in sugarcane crops ranging from the southeastern United States to northern Argentina. To evaluate the effects of climate variables on adult populations of Aeneolamia varia (Fabricius) (Hemiptera: Cercopidae), a 3-yr monitoring study was carried out in sugarcane fields at weeklong intervals during the rainy season (May to November 2005–2007). The resulting data were analyzed using the univariate Forest-Genetic method. The best predictive model explained 75.8% variability in physiological damage threshold. It predicted that the main climatic factors influencing the adult population would be, in order of importance, evaporation; evapotranspiration by 0.5; evapotranspiration, cloudiness at 2:00 p.m.; average sunshine and relative humidity at 8:00 a.m. The optimization of the predictive model established that the lower and upper limits of the climatic variables produced a threshold in the population development rate of 184 to 267 adult insects under the agroecological conditions of the study area. These results provide a new perspective on decision-making in the preventive management of A. varia adults in sugarcane crops.Item Forbush decrease on September 6-13, 2017 observed by the Tanca water-Cherenkov detector(2021-05-07) de Aguiar, Renan; Campos Fauth, Anderson; LAGO Collaboration; Echiburu, MauricioSolar activity was intense in September 2017 and its effects were observed in different detectors placed at the Earth’s surface. Three halo Coronal Mass Ejections (CME) hit the planet and caused magnetic storms. The effects of the CMEs on the flux of galactic cosmic rays at ground level were observed by the Tanca detector, which is one of the water-Cherenkov detectors (WCD) that make up the Latin American Giant Observatory (LAGO). In this paper we present the detection of Forbush events observed by Tanca during the month of September 2017. This WCD is installed on the campus of the University of Campinas, in Brazil, having three photomultiplier tubes that detect Cherenkov photons produced by cosmic radiation in 11400 liters of ultra pure water. We present the description and performance of the experimental apparatus and the observation on days 6th, 8th and 13th of the Forbush events originated by the CMEs. A decrease in the cosmic rays flux due to a stream inTeraction region was also observed on 14th September. These results were compared with observations made by neutron monitors and indices of the Earth’s magnetic activity.Item Análisis físico del minuto 120 del partido Chile-Brasil en el Mundial de Fútbol 2014(2015-12) Echiburu, MauricioEste trabajo presenta el análisis, desde un punto de vista físico, de la última jugada del alargue del encuentro entre Chile y Brasil, en el Mundial de Fútbol 2014. En dicho partido, el jugador chileno Mauricio Pinilla estrelló el balón en el larguero del arco de Brasil obligando a un alargue a penales. El análisis de la jugada comprende un estudio sobre el movimiento del balón y su posterior rebote en el arco, determinando las velocidades a través de la observación de videos de la jugada, y de estimaciones razonables para la situación. Además, se realiza un análisis de la fuerza de arrastre del aire sobre el balón para la jugada, obteniendo de ello cálculos de la energía cinética del balón antes y después del rebote, para luego estimar la fuerza y deformación que actúa sobre el balón. Todo este análisis se desarrolló con información y tecnología disponible para cualquier persona, de forma que los resultados sean replicables en el aula de clases. Por esto último se sugieren actividades docentes a desarrollar utilizando este análisis como base, para trabajar diferentes fenómenos de la Física, desde una mirada más cercana para los estudiantes.Item The protoplanetary disc around HD 169142: circumstellar or circumbinary?(2021-12) Poblete, P. P.; Cuello, N.; Pérez, S.; Marino, S.; Calcino, J.; Macías, E.; Ribas, Á.; Zurlo, A.; Cuadra, J.; Montesinos, Matías; Zúñiga-Fernández, S.; Bayo, A.; Pinte, C.; Ménard, F.; Price, D. J.Stellar binaries represent a substantial fraction of stellar systems, especially among young stellar objects. Accordingly, binaries play an important role in setting the architecture of a large number of protoplanetary discs. Binaries in coplanar and polar orientations with respect to the circumbinary disc are stable configurations and could induce non-axisymmetric structures in the dust and gas distributions. In this work, we suggest that the structures shown in the central region of the protoplanetary disc HD 169142 are produced by the presence of an inner stellar binary and a circumbinary (P-type) planet. We find that a companion with a mass-ratio of 0:1, semi-major axis of 9:9 au, eccentricity of 0.2, and inclination of 90°, together with a 2 MJ coplanar planet on a circular orbit at 45 au reproduce the structures at the innermost ring observed at 1.3 mm and the shape of spiral features in scattered light observations. The model predicts changes in the disc’s dust structure, and star’s astrometric parameters, which would allow testing its veracity by monitoring this system over the next 20 years.Item Motion analysis of kinetic impact projectiles for physics education in real context(2020-04-16) Hernández, Carla V.; Echiburu, Mauricio A.; Humire, Fernando R.; Mosso, Edward F.The article presents a proposal to contextualize the study of movement in first courses of univer- sity physics, as a contribution to decision-making in situations of a social nature. For this, the case of the use of kinetic impact projectiles and the actual data provided by official sources is considered. This information is used in an object motion model describing the kinematic characteristics of a spherical projectile (a rubber bullet). For these purposes, a number Reynolds Re ≫ 1 was used, which allows applying a nonlinear motion equation to find the velocity and impact energy per unit area of projectile. Results and analysis of this model can generate an interesting discussion in the classroom about the need to build protocols for the use of kinetic impact projectiles, and the importance of using scientific knowledge in social conflicts.
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