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This paper is one in a series reporting results from small telescope observations of variable young stars. Here, we study the repeating outbursts of three likely Be stars based on long-term optical, near-infrared, and mid-infrared photometry for all three objects, along with follow-up spectra for two of the three. The sources are characterised as rare, truly regularly outbursting Be stars. We interpret the photometric data within a framework for modelling light curve morphology, and find that the models correctly predict the burst shapes, including their larger amplitudes and later peaks towards longer wavelengths. We are thus able to infer the start and end times of mass loading into the circumstellar disks of these stars. The disk sizes are typically 3-6 times the areas of the central star. The disk temperatures are ~40%, and the disk luminosities are ~10% of those of the central Be star, respectively. The available spectroscopy is consistent with inside-out evolution of the disk. Higher excitation lines have larger velocity widths in their double-horned shaped emission profiles. Our observations and analysis support the decretion disk model for outbursting Be stars., Comment: Accepted for publication by MNRAS. 20 pages, 11 figures, 2 tables

OCT4 is a key mediator of induced pluripotent stem cell (iPSC) reprogramming, but the mechanistic insights into the role of exogenous OCT4 and timelines that initiate pluripotency remain to be resolved. Here, using measles reprogramming vectors, we present microRNA (miRNA) targeting of exogenous OCT4 to shut down its expression during the mesenchymal to the epithelial transition phase of reprogramming. We showed that exogenous OCT4 is required only for the initiation of reprogramming and is dispensable for the maturation stage. However, the continuous expression of SOX2, KLF4, and c-MYC is necessary for the maturation stage of the iPSC. Additionally, we demonstrate a novel application of miRNA targeting in a viral vector to contextually control the vector/transgene, ultimately leading to an improved reprogramming efficiency. This novel approach could be applied to other systems for improving the efficiency of vector-induced processes., Graphical abstract, Devaux and colleagues develop a novel miRNA-targeted measles vector that contextually suppress exogenous OCT4 during mesenchymal to epithelial transition (MET) and improve human reprogramming efficiency and kinetics. They show that while SOX2, KLF4, and cMYC are required for both the initiation and maturation stage of reprogramming, OCT4 is essential only for the initiation stage.

Context: Linear Temporal Logic (LTL) has been used widely in verification. Its importance and popularity have only grown with the revival of temporal logic synthesis, and with new uses of LTL in robotics and planning activities. All these uses demand that the user have a clear understanding of what an LTL specification means. Inquiry: Despite the growing use of LTL, no studies have investigated the misconceptions users actually have in understanding LTL formulas. This paper addresses the gap with a first study of LTL misconceptions. Approach: We study researchers' and learners' understanding of LTL in four rounds (three written surveys, one talk-aloud) spread across a two-year timeframe. Concretely, we decompose "understanding LTL" into three questions. A person reading a spec needs to understand what it is saying, so we study the mapping from LTL to English. A person writing a spec needs to go in the other direction, so we study English to LTL. However, misconceptions could arise from two sources: a misunderstanding of LTL's syntax or of its underlying semantics. Therefore, we also study the relationship between formulas and specific traces. Knowledge: We find several misconceptions that have consequences for learners, tool builders, and designers of new property languages. These findings are already resulting in changes to the Alloy modeling language. We also find that the English to LTL direction was the most common source of errors; unfortunately, this is the critical "authoring" direction in which a subtle mistake can lead to a faulty system. We contribute study instruments that are useful for training learners (whether academic or industrial) who are getting acquainted with LTL, and we provide a code book to assist in the analysis of responses to similar-style questions. Grounding: Our findings are grounded in the responses to our survey rounds. Round 1 used Quizius to identify misconceptions among learners in a way that reduces the threat of expert blind spots. Rounds 2 and 3 confirm that both additional learners and researchers (who work in formal methods, robotics, and related fields) make similar errors. Round 4 adds deep support for our misconceptions via talk-aloud surveys. Importance This work provides useful answers to two critical but unexplored questions: in what ways is LTL tricky and what can be done about it? Our survey instruments can serve as a starting point for other studies.

Studying rotational variability of young stars is enabling us to investigate a multitude of properties of young star-disk systems. We utilise high cadence, multi-wavelength optical time series data from the Hunting Outbursting Young Stars citizen science project to identify periodic variables in the Pelican Nebula (IC5070). A double blind study using nine different period-finding algorithms was conducted and a sample of 59 periodic variables was identified. We find that a combination of four period finding algorithms can achieve a completeness of 85% and a contamination of 30% in identifying periods in inhomogeneous data sets. The best performing methods are periodograms that rely on fitting a sine curve. Utilising GaiaEDR3 data, we have identified an unbiased sample of 40 periodic YSOs, without using any colour or magnitude selections. With a 98.9% probability we can exclude a homogeneous YSO period distribution. Instead we find a bi-modal distribution with peaks at three and eight days. The sample has a disk fraction of 50%, and its statistical properties are in agreement with other similarly aged YSOs populations. In particular, we confirm that the presence of the disk is linked to predominantly slow rotation and find a probability of 4.8$\times$10$^{-3}$ that the observed relation between period and presence of a disk has occurred by chance. In our sample of periodic variables, we also find pulsating giants, an eclipsing binary, and potential YSOs in the foreground of IC5070., Comment: 25 pages, 14 figures, 5 tables, accepted for publication in MNRAS

The citizen Continental-America Telescopic Eclipse (CATE) Experiment was a new type of citizen science experiment designed to capture a time sequence of white-light coronal observations during totality from 17:16 to 18:48 UT on 2017 August 21. Using identical instruments the CATE group imaged the inner corona from 1 to 2.1 RSun with 1.″43 pixels at a cadence of 2.1 s. A slow coronal mass ejection (CME) started on the SW limb of the Sun before the total eclipse began. An analysis of CATE data from 17:22 to 17:39 UT maps the spatial distribution of coronal flow velocities from about 1.2 to 2.1 RSun, and shows the CME material accelerates from about 0 to 200 km s−1 across this part of the corona. This CME is observed by LASCO C2 at 3.1–13 RSun with a constant speed of 254 km s−1. The CATE and LASCO observations are not fit by either constant acceleration nor spatially uniform velocity change, and so the CME acceleration mechanism must produce variable acceleration in this region of the corona.

Despite the global aviation industry's strong endorsement of a switch to aviation biofuels, fossil fuel remains the dominant energy source for air travel. Drawing on a multiple case study of 58 organizations in the emerging aviation biofuels industry relevant to Australia, Germany, and the USA, we unpack the lessons learned from this stalling industry. First and foremost, we identify a key difference in industry outlooks and corresponding strategic mindsets. Specifically, the two outlooks—industry optimism and industry pessimism—seem to correspond to specific strategic mindsets. Whereas industry optimists (1) stressed diversification, (2) were demand-driven in their decisions about R&D, and generally (3) had a learning orientation to innovations, industry pessimists emphasized the need for (1) premium pricing, (2) government intervention, and (3) economies of scale as key drivers of industry development and growth. We also found geographic differences in industry outlooks among biofuel entrepreneurs and other stakeholders in Australia, Germany, and the USA. Through our findings, we offer insights for policymakers and other industries seeking to transition to renewables. Refereed/Peer-reviewed