Contemporaneous XMM-Newton investigation of a giant X-ray flare and quiescent state from a cool M-class dwarf in the local cavity

We report the serendipitous detection of a giant X-ray flare from the source 2XMM J043527.2-144301 during an XMM-Newton observation of the high latitude molecular cloud MBM20. The source has not been previously studied at any wavelength. The X-ray flux increases by a factor of more than 52 from quiescent state to peak of flare. A 2MASS counterpart has been identified (2MASS J04352724-1443017), and near-infrared colors reveal a spectral type of M8-M8.5 and a distance of (67\pm 13) pc, placing the source in front of MBM20. Spectral analysis and source luminosity are also consistent with this conclusion. The measured distance makes this object the most distant source (by about a factor of 4) at this spectral type detected in X-rays. The X-ray flare was characterized by peak X-ray luminosity of ~8.2E28 erg s-1 and integrated X-ray energy of ~2.3E32 erg. The flare emission has been characterized with a 2-temperature model with temperatures of ~10 and 46 MK (0.82 and 3.97 keV), and is dominated by the higher temperature component.Comment: 19 pages, 5 figures; Accepted for publication on Ap

Studying Algebraic Structures Using Prover9 and Mace4

In this chapter we present a case study, drawn from our research work, on the application of a fully automated theorem prover together with an automatic counter-example generator in the investigation of a class of algebraic structures. We will see that these tools, when combined with human insight and traditional algebraic methods, help us to explore the problem space quickly and effectively. The counter-example generator rapidly rules out many false conjectures, while the theorem prover is often much more efficient than a human being at verifying algebraic identities. The specific tools in our case study are Prover9 and Mace4; the algebraic structures are generalisations of Heyting algebras known as hoops. We will see how this approach helped us to discover new theorems and to find new or improved proofs of known results. We also make some suggestions for how one might deploy these tools to supplement a more conventional approach to teaching algebra.Comment: 21 pages, to appear as Chapter 5 in "Proof Technology in Mathematics Research and Teaching", Mathematics Education in the Digital Era 14, edited by G. Hanna et al. (eds.), published by Springe

Consensual Assessment in the New Domain of E-Textiles: Comparing Insights from Expert, Quasi-Expert, and Novice Judges

Establishing what constitutes creativity in a domain is something for which we often look to experts—individuals versed in a domain’s history and able to identify timeworn ideas from fresh ones. Such valuations of creative merit are tied to a familiarity with past and present trends and, therefore, opinions of newcomers are often ignored. However, what about domains that build upon new, unexplored practices? This study examines the creativity ratings of judges with varying expertise in the emergent domain of electronic textiles (or e-textiles). E-textiles are fabrics that have programmable electronics such as sensors and actuators embedded in them toward a variety of expressive and functional ends. Judges included domain pioneers (“experts”), individuals with over 20 hr of nonprofessional experience in the domain (“quasi-experts”), and individuals untrained in the domain (“novices”). Each group evaluated the creativity of e-textile artifacts from an online gallery using the Consensual Assessment Technique (CAT). Our analyses found high interjudge reliability within all groups and between quasi-experts and experts, suggesting that quasi-experts could be sufficiently trained to judge the creativity of artifacts on par with experts. Furthermore, larger panels of novice judges may serve as an alternative, but it would be with the caveat that novice scores represent the opinions of general audiences that might not understand technical practices of e-textiles. Findings offer alternative considerations for how creativity is assessed in emergent, technology-rich domains and have implications for judge recruitment. (PsycInfo Database Record (c) 2020 APA, all rights reserved

Performance-based financing contributes to the resilience of health services affected by the Liberian Ebola outbreak.

Setting: The Liberian counties of Bong, with performance-based financing (PBF) for all 36 public primary-care facilities, and Margibi, with no PBF for its 24 public primary-care facilities. Objective: To compare whether specific maternal and child health indicators changed in the two counties during the pre-Ebola (2013), Ebola (2014) and post-Ebola (2015) disease outbreak periods from July to September each year. Design: This was a cross-sectional study. Results: For pregnant women, the numbers of antenatal visits, intermittent preventive malaria treatments, human immunodeficiency virus (HIV) tests and facility-based births with skilled attendants all fell during the Ebola period, with decreases being significantly more marked in Margibi County. Apart from HIV testing, which remained low in both counties, these indicators increased in the post-Ebola period, with increases significantly more marked in Bong than in Margibi. The number of childhood immunisations decreased significantly in Bong in the Ebola period compared with the pre-Ebola period, but increased to above pre-Ebola levels in the post-Ebola period. There were markedly larger decreases in childhood immunisations in Margibi County during the Ebola period, which remained significantly lower in the post-Ebola period compared with Bong County. Conclusion: In a PBF-supported county, selected maternal and childhood health indicators showed less deterioration during Ebola and better recovery post-Ebola than in a non-PBF-supported county

2MASS J03105986+1648155AB - A new binary at the L/T transition

The transition from the L to the T spectral type of brown dwarfs is marked by a very rapid transition phase, remarkable brightening in the J-band and a higher binary frequency. Despite being an active area of inquiry, this transition regime still remains one of the most poorly understood phases of brown dwarf evolution. We resolved the L dwarf 2MASS J03105986+1648155 for the first time into two almost equally bright components straddling the L/T transition. Since such a co-eval system with common age and composition provides crucial information of this special transition phase, we monitored the system over 3 years to derive first orbital parameters and dynamical mass estimates, as well as a spectral type determination. We obtained resolved high angular resolution, near-IR images with HST and the adaptive optics instrument NACO at the VLT including the laser guide star system PARSEC. Based on two epochs of astrometric data we derive a minimum semi-major axis of 5.2 +- 0.8 AU. The assumption of a face-on circular orbit yields an orbital period of 72 +- 4 years and a total system mass of 30-60 Mjup. This places the masses of the individual components of the system at the lower end of the mass regime of brown dwarfs. The achieved photometry allowed a first spectral type determination of L9 +- 1 for each component. In addition, this seems to be only the fifth resolved L/T transition binary with a flux reversal. While ultimate explanations for this effect are still owing, the 2MASS J03105986+1648155 system adds an important benchmark object for improving our understanding of this remarkable evolutionary phase of brown dwarfs. Additionally, the observational results of 2MASS J03105986+1648155 AB derived with the new PARSEC AO system at the VLT show the importance of this technical capability. The updated AO system allows us to significantly extend the sample of brown dwarfs observable with high-resolution from the ground and hence to reveal more of their physical properties.Comment: 6 pages, 2 figures, 3 tables, accepted for publication by A&

Epsilon Indi B: a new benchmark T dwarf

We have identified a new early T dwarf only 3.6pc from the Sun, as a common proper motion companion (separation 1459AU) to the K5V star Epsilon Indi (HD209100). As such, Epsilon Indi B is one of the highest proper motion sources outside the solar system (~4.7 arcsec/yr), part of one of the twenty nearest stellar systems, and the nearest brown dwarf to the Sun. Optical photometry obtained from the SuperCOSMOS Sky Survey was combined with approximate infrared photometry from the 2MASS Quicklook survey data release, yielding colours for the source typical of early T dwarfs. Follow up infrared spectroscopy using the ESO NTT and SOFI confirmed its spectral type to be T2.5+/-0.5. With Ks=11.2, Epsilon Indi B is 1.7 magnitudes brighter than any previously known T dwarf and 4 magnitudes brighter than the typical object in its class, making it highly amenable to detailed study. Also, as a companion to a bright nearby star, it has a precisely known distance (3.626pc) and relatively well-known age (0.8-2Gyr), allowing us to estimate its luminosity as logL/Lsun=-4.67, its effective temperature as 1260K, and its mass as ~40-60Mjup. Epsilon Indi B represents an important addition to the census of the Solar neighbourhood and, equally importantly, a new benchmark object in our understanding of substellar objects.Comment: Accepted by A&A (Letters); 5 pages, 3 figure

Binarity at the L/T brown dwarf transition

Current atmospheric models cannot reproduce some of the characteristics of the transition between the L dwarfs with cloudy atmospheres and the T dwarfs with dust-depleted photospheres. It has been proposed that a majority of the L/T transition brown dwarfs could actually be a combinaison of a cloudy L dwarf and a clear T dwarf. Indeed binarity seems to occur more frequently among L/T transition brown dwarfs. We aim to refine the statistical significance of the seemingly higher frequency of binaries. Co-eval binaries would also be interesting test-beds for evolutionary models. We obtained high-resolution imaging for six mid-L to late-T dwarfs, with photometric distances between 8 and 33pc, using the adaptive optics systems NACO at the VLT, and the Lick system, both with the laser guide star. We resolve none of our targets. Combining our data with published results, we obtain a frequency of resolved L/T transition brown dwarfs of (31+21-15)%, compared to (21+10-7)% and (14+14-7)% for mid-L and T dwarfs (90% of confidence level). These fractions do not significantly support, nor contradict, the hypothesis of a larger binary fraction in the L/T transition. None of our targets has companions with effective temperatures as low as 360-1000K at separations larger than 0.5".Comment: 6 pages, 4 figures, accepted by A&