Linking chromospheric activity and magnetic field properties for late-type dwarf stars

ELB is supported by an Australian Postgraduate Award Scholarship. SVJ acknowledges the support of the German Science Foundation (DFG) priority program SPP 1992 ‘Exploring the Diversity of Extrasolar Planets’ (JE 701/5-1). AAV acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 817540, ASTROFLOW). MMJ acknowledges funding from STFC consolidated grant ST/M001296/1. SBS acknowledges the support of the Austrian Science Fund (FWF) Lise Meitner project M2829-N. VS acknowledges funding from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation programme (grant agreement No. 682393 AWESoMeStars) and support from the European Space Agency (ESA) as an ESA Research Fellow.Spectropolarimetric data allow for simultaneous monitoring of stellar chromospheric logR′HK activity and the surface-averaged longitudinal magnetic field, Bl, giving the opportunity to probe the relationship between large-scale stellar magnetic fields and chromospheric manifestations of magnetism. We present logR′HK and/or Bl measurements for 954 mid-F to mid-M stars derived from spectropolarimetric observations contained within the PolarBase database. Our magnetically active sample complements previous stellar activity surveys that focus on inactive planet-search targets. We find a positive correlation between mean logR′HK and mean log |Bl|, but for G stars the relationship may undergo a change between logR′HK∼−4.4 and −4.8. The mean logR′HK shows a similar change with respect to the logR′HK variability amplitude for intermediately-active G stars. We also combine our results with archival chromospheric activity data and published observations of large-scale magnetic field geometries derived using Zeeman Doppler Imaging. The chromospheric activity data indicate a slight under-density of late-F to early-K stars with −4.75≤logR′HK≤−4.5⁠. This is not as prominent as the original Vaughan–Preston gap, and we do not detect similar under-populated regions in the distributions of the mean |Bl|, or the Bl and logR′HK variability amplitudes. Chromospheric activity, activity variability and toroidal field strength decrease on the main sequence as rotation slows. For G stars, the disappearance of dominant toroidal fields occurs at a similar chromospheric activity level as the change in the relationships between chromospheric activity, activity variability and mean field strength.PostprintPeer reviewe

Studying physics during the COVID-19 pandemic: Student assessments of learning achievement, perceived effectiveness of online recitations, and online laboratories

The COVID-19 pandemic has significantly affected the education system worldwide, which was forced to respond with a sudden shift to distance learning. While successful distance teaching requires careful thinking, planning, and the development of technological and human resources, there was no time for preparation in the current situation. Various physics courses, including lectures, tutorials, and laboratory courses, had to be transferred to online formats, resulting in a variety of simultaneous, asynchronous, and mixed activities. To investigate how physics students perceived the sudden shift to online learning, we developed a questionnaire and gathered data from N=578 physics students from five universities in Germany, Austria, and Croatia. In this article, we report how the problem-solving sessions (recitations) and laboratories were adapted, how students judge the different formats of the courses, and how useful and effective they perceived them. The results are correlated with the students’ self-efficacy ratings and other behavioral measures (such as self-regulated learning skills). This study is descriptive in nature, and a survey study design was implemented to examine the relationships among the variables. We found that good communication abilities (r=0.48, p<0.001) and self-organization skills (r=0.63, p<0.001) are positively correlated with perceived learning achievement. Furthermore, the previous duration of studies had a significant impact on several self-reported achievement measures, resulting in consistently lower scores of students in their first academic year compared with students who were further along academically. We draw conclusions and suggest implications for future online classes on the instructor and faculty level. Suggestions include (i) focusing on first-year courses with on-campus teaching when facing limited lecture hall capacities, (ii) offering special courses for promoting self-regulated learning skills, (iii) emphasizing the positive aspects of distance learning, and (iv) installing networking services for supporting student communication

Lab courses for prospective physics teachers: what could we learn from the first COVID-19 lockdown?

At the universities of Dresden, Vienna, and Zagreb, a laboratory course for prospective physics teachers was transferred to an online environment because of the lockdown in March 2020 due to the COVID-19 pandemic. The aim of this paper is to present and compare students’ and instructors’ considerations about the experiences with this laboratory course at these three universities and to formulate guidelines for organizing lab courses for prospective physics teachers. The research was conducted in three steps: first, interviews were conducted with prospective physics teachers (N = 10) ; second, an online questionnaire was administered to course participants (N = 99) ; and third, lab course instructors completed an online questionnaire (N = 8). The results show that an increase in creativity and confidence was expressed when conducting home experiments. Students who received support and guidance benefited more from the online lab course, but some students also experienced a greater time commitment. On a positive note, all participants thought outside- the-box during this lab experience and found solutions that led to new ways of conducting labs. Our study suggests that in future online or regular lab courses, students should have the chance to make decisions about experiments and be creative, with an emphasis on peer discussions and support from instructors

The Dabbing Dilemma: A Call for Research on Butane Hash Oil and Other Alternate Forms of Cannabis Use

Abstract not available

Aspectos radiológicos e epidemiológicos do granuloma central de células gigantes Radiological and epidemiological aspects of central giant cell granuloma

OBJETIVO: Este estudo teve como objetivo avaliar os principais aspectos radiográficos e epidemiológicos das lesões de células gigantes (granulomas centrais de células gigantes e tumores marrons do hiperparatireoidismo). MATERIAIS E MÉTODOS: A amostra consistiu de 26 lesões de células gigantes diagnosticadas em 22 pacientes divididos em dois grupos, um deles composto por 17 pacientes que não tinham hiperparatireoidismo (grupo A) e o outro formado por cinco pacientes portadores de tal distúrbio (grupo B). RESULTADOS: O sexo feminino (72,7%) foi o mais acometido. As lesões ocorreram mais freqüentemente na segunda década de vida, com média de idade de 27 anos. A mandíbula (61,5%) foi o arco mais envolvido. Radiograficamente, 57,7% das lesões eram multiloculares e 42,3% eram uniloculares com limites definidos. Todas as 26 lesões provocaram expansão óssea, 15,4% produziram reabsorção radicular, 50% causaram deslocamento dentário e 11,5% produziram dor. Na mandíbula, 18,7% das lesões cruzavam a linha média. O grupo A apresentou 66,7% das lesões na mandíbula e o grupo B mostrou igualdade na distribuição das lesões entre os arcos. O grupo A apresentou 66,7% das lesões multiloculares e 33,3%, uniloculares. O grupo B apresentou 62,5% das lesões uniloculares e 37,5%, multiloculares. CONCLUSÃO: As lesões de células gigantes podem manifestar-se, radiograficamente, com um amplo espectro, desde pequenas lesões uniloculares de crescimento lento até extensas lesões multiloculares. Elas apresentam características de benignidade, embora algumas lesões possam demonstrar um comportamento localmente agressivo.<br>OBJECTIVE: The present study was aimed at evaluating main radiological and epidemiological aspects of giant cell lesions (central giant cell granuloma and brown tumors of hyperparathyroidism). MATERIALS AND METHODS: The sample consisted of 26 giant cell lesions diagnosed in 22 patients divided into two groups, one of them including 17 patients who were not affected by hyperparathyroidism (group A) and another including five patients with such a disorder (group B). RESULTS: Prevalence was higher in female patients (72.7%). Most frequently, lesions occurred more in the second decade of life (mean age, 27 years). The mandible arc was most frequently involved (61.5%). Radiographically, 57.7% of lesions were multilocular and 42.3% were unilocular with defined limits. All of the 26 lesions caused expansion of bone, 15.4% radicular resorption, 50% dental displacement, and 11.5% produced pain. In the mandible 18.7% of the lesions crossed the midline. Group A showed 66.7% of lesions in the mandible and group B showed an even distribution of lesions between arches. In group A 66.7% of lesions were multilocular, and 33.3% unilocular; in group B 62.5% were unilocular, and 37.5% multilocular. CONCLUSION: Giant cells lesions may present themselves with a wide spectrum, from small, slow-growing unilocular lesions to extensive multilocular lesions. They present features of benignity, though some lesions may demonstrate a locally aggressive behavior