A New Spin on Planar Cell Polarity

The generation of planar cell polarity (PCP) and tissue shape during morphogenesis is tightly linked, but it is not clear how. Aigouy et al. (2010) now show in the developing Drosophila wing that PCP initially has a radial orientation that becomes realigned to the proximal-distal axis of organ shape by mechanical forces and cell rearrangements mediated by Dachsous

La disrupción de lo presencial a lo virtual. Percepciones de los directores de docencia sobre el uso de plataformas digitales en contexto de pandemia en una universidad del norte de Chile

As a result of the COVID-19 pandemic, educational practice at different levels of the system was altered and subjected to a contingency situation that forced teachers to use technological tools and strategies for teaching in a virtual context. The purpose of this study is to describe the transition from face-to-face teaching to remote emergency education and the difficulties this presented for academics at the Universidad Arturo Prat (UNAP) in Chile, in terms of the use of available technologies for the development of teaching activities in the context of the pandemic. Qualitative research is developed to characterize the disposition and problems that the academics evidenced regarding remote teaching, through the perceptions of the teaching directors. The results show that academics have transferred the format of their face-to-face classes to virtuality, thus generating the application of a new teaching format in remote modality. Likewise, there is a differentiated use of the available digital technologies according to the age groups of the teachers.Producto de la pandemia de COVID-19, la práctica educativa en los distintos niveles del sistema se vio alterada y sometida a una situación de contingencia que obligó a los docentes a usar herramientas tecnológicas y estrategias para la enseñanza en un contexto de virtualidad. El presente estudio tiene como finalidad describir el paso de una docencia presencial a una educación remota de emergencia y las dificultades que presentó esto para los académicos de la Universidad Arturo Prat (UNAP) de Chile, en cuanto al uso de las tecnologías disponibles para el desarrollo de las actividades lectivas en el contexto de la pandemia. Se desarrolla una investigación de carácter cualitativo, para caracterizar la disposición y problemáticas que evidenciaron los académicos frente a la enseñanza remota, a través de las percepciones de los directores de docencia. Los resultados muestran que los académicos han trasladado el formato de sus clases presenciales a la virtualidad, generando con ello la aplicación de un nuevo formato docente en modalidad remota. Asimismo, se demuestra un uso diferenciado de las tecnologías digitales disponibles según los tramos de edad de los docentes.Como resultado da pandemia global Covid-19, a prática educacional em diferentes níveis do sistema foi alterada e submetida a uma situação de contingência que obrigou os professores a usarem ferramentas e estratégias tecnológicas para o ensino em um contexto virtual. O objetivo deste estudo é descrever a transição do ensino presencial para uma emergência remota e as dificuldades que este apresenta para os acadêmicos da Universidade Arturo Prat, em termos da utilização das tecnologias disponíveis para o desenvolvimento da atividade docente em o contexto da pandemia. Atendendo ao objetivo anterior, optou-se por desenvolver uma pesquisa qualitativa, para caracterizar a disposição e os problemas que os acadêmicos apresentavam diante do ensino a distância. Os resultados mostram que os acadêmicos transferiram o formato de suas aulas presenciais para a virtualidade, o que está impactando no desenvolvimento da aprendizagem e na aquisição de competências dos alunos. Da mesma forma, demonstra-se um uso diferenciado das tecnologias digitais disponíveis em função das faixas etárias dos professores

El Corvo: un caso de discurso xenófobo y nacionalista en un contexto de violencia, Tarapacá, 1919:

El artículo analiza el contenido de El Corvo, periódico pasquín que circuló en la región salitrera de Tarapacá en el norte de Chile en 1919. El contexto es el de la denominada «chilenización», durante la posguerra del Pacífico, en una zona de conflicto y anterior al Tratado de Lima en 1929. Este estudio centra su objetivo en el análisis del discurso presente en las columnas de El Corvo y establece categorías que evidencian la vulgarización y violencia descrita en este medio escrito hacia el habitante peruano de Tarapacá, entendido como un otro por parte de esta editorial. Asimismo, se examinan y describen las estructuras lingüísticas generales (categorías lingüísticas, macroacciones y usos retóricos) y su respectiva correlación con los estereotipos fijados para la población peruana asentada en la región salitrera y específicamente en Iquique (Chile). Se logra establecer la existencia de una cobertura informativa que se basa en la construcción de un habitante tarapaqueño original de estos espacios que es inferiorizado culturalmente a la ocupación chilena de estos territoriosThe article analyzes the content of El Corvo, a pasquín newspaper that circulated in the saltpeter region of Tarapacá in northern Chile in 1919. In a context of the so-called Chileanization, located in the post-war Pacific, in a conflict zone and prior to the Treaty of Lima in 1929. This study focuses its objective on the analysis of the discourse present in the columns of El Corvo and establishes categories that show the vulgarization and violence described in this written medium towards the Peruvian inhabitant of Tarapacá, understood as another by this editorial. Likewise, the general linguistic structures (linguistic categories, macroactions and rhetorical uses) and their respective correlation with the stereotypes set for the Peruvian population settled in the saltpeter region and specifically in Iquique are examined and described. It is possible to establish the existence of an informative coverage that is based on the construction of an original Tarapacan inhabitant of these spaces that is culturally inferior to the Chilean occupation of these territories

Salt-bearing disk candidates around high-mass young stellar objects

Molecular lines tracing the orbital motion of gas in a well-defined disk are valuable tools for inferring both the properties of the disk and the star it surrounds. Lines that arise only from a disk, and not also from the surrounding molecular cloud core that birthed the star or from the outflow it drives, are rare. Several such emission lines have recently been discovered in one example case, those from NaCl and KCl salt molecules. We studied a sample of 23 candidate high-mass young stellar objects (HMYSOs) in 17 high-mass star-forming regions to determine how frequently emission from these species is detected. We present five new detections of water, NaCl, KCl, PN, and SiS from the innermost regions around the objects, bringing the total number of known briny disk candidates to nine. Their kinematic structure is generally disk-like, though we are unable to determine whether they arise from a disk or outflow in the sources with new detections. We demonstrate that these species are spatially coincident in a few resolved cases and show that they are generally detected together, suggesting a common origin or excitation mechanism. We also show that several disks around HMYSOs clearly do not exhibit emission in these species. Salty disks are therefore neither particularly rare in high-mass disks, nor are they ubiquitous.Comment: accepted to Ap

Digging into the Interior of Hot Cores with ALMA (DIHCA). III: The Chemical Link between NH2_{2}CHO, HNCO, and H2_{2}CO

We have analyzed the NH$_{2}$CHO, HNCO, H$_{2}$CO, and CH$_{3}$CN ($^{13}$CH$_{3}$CN) molecular lines at an angular resolution of $\sim 0.3''$ obtained by the Atacama Large Millimeter/submillimeter Array (ALMA) Band 6 toward 30 high-mass star-forming regions. The NH$_{2}$CHO emission has been detected in 23 regions, while the other species have been detected toward 29 regions. A total of 44 hot molecular cores (HMCs) have been identified using the moment 0 maps of the CH$_{3}$CN line. The fractional abundances of the four species have been derived at each HMC. In order to investigate pure chemical relationships, we have conducted a partial correlation test to exclude the effect of temperature. Strong positive correlations between NH$_{2}$CHO and HNCO ($\rho=0.89$) and between NH$_{2}$CHO and H$_{2}$CO (0.84) have been found. These strong correlations indicate their direct chemical links; dual-cyclic hydrogen addition and abstraction reactions between HNCO and NH$_{2}$CHO and gas-phase formation of NH$_{2}$CHO from H$_{2}$CO. Chemical models including these reactions can reproduce the observed abundances in our target sources.Comment: Accepted for The Astrophysical Journal. 27 pages, 10 tables, and 13 figure

Digging into the Interior of Hot Cores with ALMA: Spiral Accretion into the High-mass Protostellar Core G336.01-0.82

We observed the high-mass star-forming core G336.01-0.82 at 1.3 mm and 0.05'' (~150 au) angular resolution with the Atacama Large Millimeter/submillimeter Array (ALMA) as part of the Digging into the Interior of Hot Cores with ALMA (DIHCA) survey. These high-resolution observations reveal two spiral streamers feeding a circumstellar disk at opposite sides in great detail. Molecular line emission from CH$_3$OH shows velocity gradients along the streamers consistent with infall. Similarly, a flattened envelope model with rotation and infall implies a mass larger than 10 M$_\odot$ for the central source and a centrifugal barrier of 300 au. The location of the centrifugal barrier is consistent with local peaks in the continuum emission. We argue that gas brought by the spiral streamers is accumulating at the centrifugal barrier, which can result in future accretion burst events. A total high infall rate of ~$4\times10^{-4}$ M$_\odot$ yr$^{-1}$ is derived by matching models to the observed velocity gradient along the streamers. Their contribution account for 20-50% the global infall rate of the core, indicating streamers play an important role in the formation of high-mass stars.Comment: 11 pages, 5 figures, 2 appendices. Accepted for publication in ApJL. Interactive figure available at https://folguinch.github.io/projects/dihc

Magnetic Fields in Massive Star-forming Regions (MagMaR). II. Tomography through Dust and Molecular Line Polarization in NGC 6334I(N)

Here, we report ALMA detections of polarized emission from dust, CS(J = 5 → 4), and C33S(J = 5 → 4) toward the high-mass star-forming region NGC 6334I(N). A clear “hourglass” magnetic field morphology was inferred from the polarized dust emission, which is also directly seen from the polarized CS emission across velocity, where the polarization appears to be parallel to the field. By considering previous findings, the field retains a pinched shape that can be traced to clump length scales from the envelope scales traced by ALMA, suggesting that the field is dynamically important across multiple length scales in this region. The CS total intensity emission is found to be optically thick (τ CS = 32 ± 12) while the C33S emission appears to be optically thin (). This suggests that sources of anisotropy other than large velocity gradients, i.e., anisotropies in the radiation field, are required to explain the polarized emission from CS seen by ALMA. By using four variants of the Davis–Chandrasekhar–Fermi technique and the angle dispersion function methods (ADF), we obtain an average of the estimates for the magnetic field strength on the plane of the sky of mG from the dust and mG from the CS emission, where each emission traces different molecular hydrogen number densities. This effectively enables a tomographic view of the magnetic field within a single ALMA observation.Fil: Cortés, Paulo C.. National Radio Astronomy Observatory; Estados UnidosFil: Sanhueza, Patricio. No especifíca;Fil: Houde, Martin. Western University; CanadáFil: Martín, Sergio. No especifíca;Fil: Hull, Charles L. H.. No especifíca;Fil: Girart, Josep M.. Consejo Superior de Investigaciones Científicas; EspañaFil: Zhang, Qizhou. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Fernandez Lopez, Manuel. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Zapata, Luis A.. Universidad Nacional Autónoma de México; MéxicoFil: Stephens, Ian W.. No especifíca;Fil: Li, Hua Bai. No especifíca;Fil: Wu, Benjamin. No especifíca;Fil: Olguin, Fernando. No especifíca;Fil: Lu, Xing. No especifíca;Fil: Guzmán, Andres E.. No especifíca;Fil: Nakamura, Fumitaka. No especifíca

Gravity-driven Magnetic Field at ∼1000 au Scales in High-mass Star Formation

A full understanding of high-mass star formation requires the study of one of the most elusive components of the energy balance in the interstellar medium: magnetic fields. We report Atacama Large Millimeter/submillimeter Array (ALMA) 1.2 mm, high-resolution (700 au) dust polarization and molecular line observations of the rotating hot molecular core embedded in the high-mass star-forming region IRAS 18089-1732. The dust continuum emission and magnetic field morphology present spiral-like features resembling a whirlpool. The velocity field traced by the H13CO+ (J = 3-2) transition line reveals a complex structure with spiral filaments that are likely infalling and rotating, dragging the field with them. We have modeled the magnetic field and find that the best model corresponds to a weakly magnetized core with a mass-to-magnetic-flux ratio (λ) of 8.38. The modeled magnetic field is dominated by a poloidal component, but with an important contribution from the toroidal component that has a magnitude of 30% of the poloidal component. Using the Davis-Chandrasekhar-Fermi method, we estimate a magnetic field strength of 3.5 mG. At the spatial scales accessible to ALMA, an analysis of the energy balance of the system indicates that gravity overwhelms turbulence, rotation, and the magnetic field. We show that high-mass star formation can occur in weakly magnetized environments, with gravity taking the dominant role.Fil: Sanhueza, Patricio. National Astronomical Observatory Of Japan; JapónFil: Girart, Josep Miquel. Instituto de Estudios Espaciales de Cataluña; EspañaFil: Padovani, Marco. Osservatorio Astrofisico Di Arcetri; ItaliaFil: Galli, Daniele. Osservatorio Astrofisico Di Arcetri; ItaliaFil: Hull, Charles L. H.. Atacama Large Millimeter-submillimeter Array; ChileFil: Zhang, Qizhou. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Cortes, Paulo. National Radio Astronomy Observatory; Estados UnidosFil: Stephens, Ian. Worcester State University; Estados UnidosFil: Fernandez Lopez, Manuel. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Jackson, James M.. NASA Ames Research Center; Estados UnidosFil: Frau, Pau. Csic. Instituto de Ciencias del Espacio; EspañaFil: Kock, Patrick M.. Academia Sinica; ChinaFil: Wu, Benjamin. National Astronomical Observatory Of Japan; JapónFil: Zapata, Luis A.. Instituto de Radioastronomía y Astrofísica; MéxicoFil: Olguin, Fernando. National Tsing Hua University; ChinaFil: Lu, Xing. National Astronomical Observatory Of Japan; JapónFil: Silva, Andrea. National Astronomical Observatory Of Japan; JapónFil: Tang, Ya Wen. Academia Sinica; ChinaFil: Sakai, Takeshi. The University Of Electro-communications; JapónFil: Guzmán, Andrés E.. National Astronomical Observatory Of Japan; JapónFil: Tatematsu, Ken'Ichi. National Astronomical Observatory Of Japan; JapónFil: Nakamura, Fumitaka. National Astronomical Observatory Of Japan; JapónFil: Chen, Huei Ru Vivien. National Tsing Hua University; Chin