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We present light curves and flares from a 7 day, multiwavelength observational campaign of AU Mic, a young and active dM1e star with exoplanets and a debris disk. We report on 73 unique flares between the X-ray to optical data. We use high-time-resolution near-UV (NUV) photometry and soft X-ray (SXR) data from the X-ray Multi-Mirror Mission to study the empirical Neupert effect, which correlates the gradual and impulsive phase flaring emissions. We find that 65% (30 of 46) flares do not follow the Neupert effect, which is 3 times more excursions than seen in solar flares, and propose a four-part Neupert effect classification (Neupert, quasi-Neupert, non-Neupert types I and II) to explain the multiwavelength responses. While the SXR emission generally lags behind the NUV as expected from the chromospheric evaporation flare models, the Neupert effect is more prevalent in larger, more impulsive flares. Preliminary flaring rate analysis with X-ray and U -band data suggests that previously estimated energy ratios hold for a collection of flares observed over the same time period, but not necessarily for an individual, multiwavelength flare. These results imply that one model cannot explain all stellar flares and care should be taken when extrapolating between wavelength regimes. Future work will expand wavelength coverage using radio data to constrain the nonthermal empirical and theoretical Neupert effects to better refine models and bridge the gap between stellar and solar flare physics.

Purpose: To present a case of inadvertent retinal toxicity induced by a standard dose of subconjunctival cefuroxime after epiretinal membrane surgery. Narrative review of cefuroxime overdose or toxicity after intraocular surgery was carried out to describe characteristics of cefuroxime toxicity and their relationship to visual outcome. Observations: A 64-year-old man underwent pars plana vitrectomy (PPV) with epiretinal membrane peel and received a standard dose of subconjunctival cefuroxime as endophthalmitis prophylaxis. At two weeks, visual acuity measured counting fingers, and fundus examination showed haemorrhages and cotton wool spots. Fluorescein angiography confirmed widespread ischaemia involving the macula. Subsequent litigation ruled that inadvertent cefuroxime toxicity after an accidental penetration of sclera was the likely aetiology. Conclusions and importance: In addition to inadvertent overdose due to dilution errors, accidental scleral penetration is another mechanism for drug toxicity following subconjunctival cefuroxime injection. Literature review revealed broadly different manifestations of cefuroxime retinal toxicity. This case highlights the need to consider severe cefuroxime toxicity in patients presenting with unexplained post-PPV visual loss.

Abstract The following is a response to the recent review article by Girsang and colleagues (Int J Retina Vitreous. 2020;6:46), who describe concept and application of relaxing radial retinectomy for retinal detachment with advanced proliferative vitreoretinopathy. We discuss the distribution of the retinal nerve fiber layer, an aspect not touched on by the authors, and the importance of its consideration in determining visual field outcomes when performing retinectomy. Moreover, we share our clinical experience with both radial and circumferential retinectomy and discuss scenarios where the combination of both is more effective.

Isolated Swift gamma-ray burst (GRB) pulses, like their higher-energy BATSE counterparts, emit the bulk of their pulsed emission as a hard-to-soft component that can be fitted by the Norris et al. empirical pulse model. This signal is overlaid by a fainter, three-peaked signal that can be modeled by the residual fit of Hakkila & Preece: the two fits combine to reproduce GRB pulses with distinctive three-peaked shapes. The precursor peak appears on or before the pulse rise and is often the hardest component, the central peak is the brightest, and the decay peak converts exponentially decaying emission into a long, soft, power-law tail. Accounting for systematic instrumental differences, the general characteristics of the fitted pulses are remarkably similar. Isolated GRB pulses are dominated by hard-to-soft evolution; this is more pronounced for asymmetric pulses than for symmetric ones. Isolated GRB pulses can also exhibit intensity tracking behaviors that, when observed, are tied to the timing of the three peaks: pulses with the largest maximum hardnesses are hardest during the precursor, those with smaller maximum hardnesses are hardest during the central peak, and all pulses can re-harden during the central peak and/or during the decay peak. Since these behaviors are essentially seen in all isolated pulses, the distinction between “hard-to-soft and “intensity-tracking” pulses really no longer applies. Additionally, the triple-peaked nature of isolated GRB pulses seems to indicate that energy is injected on three separate occasions during the pulse duration: theoretical pulse models need to account for this. [ABSTRACT FROM AUTHOR]