Simultaneous multiwavelength observations of V404 Cygni during its 2015 June outburst decay strengthen the case for an extremely energetic jet-base

We present results of multiband optical photometry of the black hole X-ray binary system V404 Cygni obtained using Wheaton College Observatory's 0.3m telescope, along with strictly simultaneous INTEGRAL and Swift observations during 2015 June 25.15--26.33 UT, and 2015 June 27.10--27.34 UT. These observations were made during the 2015 June outburst of the source when it was going through an epoch of violent activity in all wavelengths ranging from radio to $\gamma$-rays. The multiwavelength variability timescale favors a compact emission region, most likely originating in a jet outflow, for both observing epochs presented in this work. The simultaneous INTEGRAL/Imager on Board the Integral Satellite (IBIS) 20--40 keV light curve obtained during the June 27 observing run correlates very strongly with the optical light curve, with no detectable delay between the optical bands as well as between the optical and hard X-rays. The average slope of the dereddened spectral energy distribution was roughly flat between the $I_C$- and $V$-bands during the June 27 run, even though the optical and X-ray flux varied by $>$25$\times$ during the run, ruling out an irradiation origin for the optical and suggesting that the optically thick to optically thin jet synchrotron break during the observations was at a frequency larger than that of $V$-band, which is quite extreme for X-ray binaries. These observations suggest that the optical emission originated very close to the base of the jet. A strong H$\alpha$ emission line, probably originating in a quasi-spherical nebula around the source, also contributes significantly in the $R_C$-band. Our data, in conjunction with contemporaneous data at other wavelengths presented by other groups, strongly suggest that the jet-base was extremely compact and energetic during this phase of the outburst.Comment: 15 pages, 2 tables, 5 figures. Accepted for publication in Ap

Đe se završava južnoslovenski areal? Napomene o panonskom narječju poznoga praslovenskog

U izlaganju se prikazuju refleksi praslovenskih akcenatskih opreka i osobita pažnja se dijeli praslovenskome starom akutu u kontekstu panonske prelazne zone pozne praslovenskoga jezika. U pitanju je relativno dugi opstanak uzlaznosti akuta u zahodnom arealu južnoslovenskih kao i dijela zapadnoslovenskih dijalekata te mogućih razloga za taj opstanak

You’re Making Me Sick: A Systematic Review of How Virtual Reality Research Considers Gender & Cybersickness

© {Owner/Author | ACM} 2021. This is the author's version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in Proceedings of the 2021 CHI Conference on Human Factors in Computing Systems, http://dx.doi.org/10.1145/3411764.3445701.While multiple studies suggest that female-identified participants are more likely to experience cybersickness in virtual reality (VR), our systematic review of 71 eligible VR publications (59 studies and 12 surveys) pertaining to gender and cybersickness reveals a number of confounding factors in study design (e.g., a variety of technical specifications, tasks, content), a lack of demographic data, and a bias in participant recruitment. Our review shows an ongoing need within VR research to more consistently include and report on women’s experiences in VR to better understand the gendered possibility of cybersickness. Based on the gaps identified in our systematic review, we contribute study design recommendations for future work, arguing that gender considerations are necessary at every stage of VR study design, even when the study is not ‘about’ gender.Funder 1, NSERC Discovery Grant 2016-04422 || Funder 2, NSERC Discovery Accelerator Grant 492970-2016 || Funder 3, NSERC CREATE Saskatchewan-Waterloo Games User Research (SWaGUR) Grant 479724-2016 || Funder 4, Ontario Early Researcher Award ER15-11-18

Multimedia Showdown: A Comparative Analysis of Audio, Video and Avatar-Based Communication

Our new work culture relies heavily on online meetings and computer-mediated communication (CMC). However, making an online meeting engaging while keeping communication productive is a major challenge. We collected quantitative data from the user engagement scale (UES) and qualitative data from semi-structured interviews to investigate how user engagement differed. Using the gamified web-conferencing platform Gather, we compared four communication channels: (1) audio-only, (2) audio and video (no avatar), (3) audio and avatar (no video), and (4) audio and video and avatar. We began qualitative data analysis using reflexive thematic analysis. Although the UES results did not reveal significant differences, the preliminary results from the thematic analysis such as people prefer communication platforms designed for specific use cases because video makes them feel more self-conscious, while avatars make them feel more represented. Lastly, we provide a work-in-progress applied definition of user engagement in communication channels with their perspective on individual engagement constructs.This work was made possible by the NSERC CREATE SWaGUR grant, the Social Sciences and Humanities Research Council, Lennart Nacke’s NSERC Discovery Grant, the Canada Foundation for Innovation John R. Evans Leaders Fund “The seamless user-centered conscious experience study system (SUCCESS)”.Joseph Tu, Arielle Grinberg, Mark Hancock, Lennart E. Nacke | ACM (2023). This is the author's version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in Companion Proceedings of the Annual Symposium on Computer-Human Interaction in Play (CHI PLAY Companion ’23), https://doi.org/10.1145/3573382.3616081

The carbon footprint of large astronomy meetings

The annual meeting of the European Astronomical Society took place in Lyon, France, in 2019, but in 2020 it was held online only due the COVID-19 pandemic. The carbon footprint of the virtual meeting was roughly 3,000 times smaller than the face-to-face one, providing encouragement for more ecologically minded conferencing.Comment: Originated in a Twitter discussion (https://twitter.com/sarahkendrew/status/1144186571538739202) at EWASS 2019; followed up at the EAS 2020 conference sustainability session by https://astronomersforplanet.earth - published in Nature Astronomy, September 202

Three years of Fermi GBM Earth Occultation Monitoring: Observations of Hard X-ray/Soft Gamma-Ray Sources

The Gamma ray Burst Monitor (GBM) on board Fermi has been providing continuous data to the astronomical community since 2008 August 12. In this paper we present the results of the analysis of the first three years of these continuous data using the Earth occultation technique to monitor a catalog of 209 sources. From this catalog, we detect 99 sources, including 40 low-mass X-ray binary/neutron star systems, 31 high-mass X-ray binary neutron star systems, 12 black hole binaries, 12 active galaxies, 2 other sources, plus the Crab Nebula, and the Sun. Nine of these sources are detected in the 100-300 keV band, including seven black-hole binaries, the active galaxy Cen A, and the Crab. The Crab and Cyg X-1 are also detected in the 300-500 keV band. GBM provides complementary data to other sky-monitors below 100 keV and is the only all-sky monitor above 100 keV. Up-to-date light curves for all of the catalog sources can be found at http://heastro.phys.lsu.edu/gbm/.Comment: 24 pages, 12 figures, accepted for publication in ApJ

Atomistic origins of high-performance in hybrid halide perovskite solar cells

The performance of organometallic perovskite solar cells has rapidly surpassed that of both conventional dye-sensitised and organic photovoltaics. High power conversion efficiency can be realised in both mesoporous and thin-film device architectures. We address the origin of this success in the context of the materials chemistry and physics of the bulk perovskite as described by electronic structure calculations. In addition to the basic optoelectronic properties essential for an efficient photovoltaic device (spectrally suitable band gap, high optical absorption, low carrier effective masses), the materials are structurally and compositionally flexible. As we show, hybrid perovskites exhibit spontaneous electric polarisation; we also suggest ways in which this can be tuned through judicious choice of the organic cation. The presence of ferroelectric domains will result in internal junctions that may aid separation of photoexcited electron and hole pairs, and reduction of recombination through segregation of charge carriers. The combination of high dielectric constant and low effective mass promotes both Wannier-Mott exciton separation and effective ionisation of donor and acceptor defects. The photoferroic effect could be exploited in nanostructured films to generate a higher open circuit voltage and may contribute to the current-voltage hysteresis observed in perovskite solar cells.Comment: 6 pages, 5 figure