When hot meets cold: post-flare coronal rain

All solar flares demonstrate a prolonged, hourlong post-flare (or gradual) phase, characterized by arcade-like, post-flare loops (PFLs) visible in many extreme ultraviolet (EUV) passbands. These coronal loops are filled with hot – ~30MK – and dense plasma, evaporated from the chromosphere during the impulsive phase of the flare, and they very gradually recover to normal coronal density and temperature conditions. During this gradual cooling down to ~1MK regimes, much cooler – ~0.01MK – and denser coronal rain is frequently observed inside PFLs. Understanding PFL dynamics in this long-duration, gradual phase is crucial to the entire corona-chromosphere mass and energy cycle. Here we report the first simulation in which a solar flare evolves from pre-flare, over impulsive phase all the way into its gradual phase, which successfully reproduces post-flare coronal rain. This rain results from catastrophic cooling caused by thermal instability, and we analyse the entire mass and energy budget evolution driving this sudden condensation phenomenon. We find that the runaway cooling and rain formation also induces the appearance of dark post-flare loop systems, as observed in EUV channels. We confirm and augment earlier observational findings, suggesting that thermal conduction and radiative losses alternately dominate the cooling of PFLs. Since reconnection-driven flares occur in many astrophysical settings (stellar flares, accretion disks, galactic winds and jets), our study suggests a new and natural pathway to introduce multi-thermal structuring.

An argument for phasing out sales of cigarettes

The successes of tobacco control in some countries and locales have led to discussions of ending the tobacco epidemic, often called the ‘endgame’. In this paper, we recommend articulating the endgame goal as phasing out sales of cigarettes, a goal once called ‘unthinkable’. We develop a logic and argumentation for ending cigarette sales intended to move the discussion beyond the shadow of ‘prohibition’, proposing an approach that appeals to consumer protection standards and suggesting that the effort be led by low-prevalence communities. While phasing out cigarettes will not happen everywhere all at once, and may unfold differently along several lines, we argue that the gradual phase-out approach we propose will reduce the likelihood of the negative consequences often predicted to come with such a policy. To continue permitting widespread sales of the single most deadly consumer product in history is a public health failure that must be addressed.

MACRA 2.5: the legislation moves forward

The Medicare and CHIP Reauthorization Act of 2015 remains the payment policy law of the land. 2017 was the first year in which performance reporting will tangibly impact future physician payments. The Centers for Medicare & Medicaid Services (CMS) considers 2017 and 2018 transitional years before full implementation in 2019. As such, 2018 increases the reporting requirements over 2017 in the form of a gradual phase-in while introducing several key changes and new elements. Indeed, it is the nature of the transition itself that led to the somewhat unique title of this manuscript, i.e., MACRA 2.5. Stakeholder feedback to the CMS regarding the program has ranged widely from the elimination of core components to expanding reporting to non-government payers. This article explores the potential impact on neurointerventional physicians.

Education and Mortality: Evidence from a Social Experiment

We examine the effects on mortality and health due to a major Swedish educational reform that increased the years of compulsory schooling. Using the gradual phase-in of the reform between 1949 and 1962 across municipalities, we estimate insignificant effects of the reform on mortality in the affected cohort. From the confidence intervals, we can rule out effects larger than 1–1.4 months of increased life expectancy. We find no significant impacts on mortality for individuals of low socioeconomic status backgrounds, on deaths that are more likely to be affected by behavior, on hospitalizations, and consumption of prescribed drugs. (JEL H52, I12, I21, I28)

Solar extreme ultraviolet (EUV) flare observations and findings from the Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE)

New solar soft X-ray (SXR) and extreme ultraviolet (EUV) irradiance observations from NASA Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE) provide full coverage from 0.1 to 106 nm and continuously at a cadence of 10 seconds for spectra at 0.1 nm resolution. These observations during flares can usually be decomposed into four distinct characteristics: impulsive phase, gradual phase, coronal dimming, and EUV late phase. Over 6000 flares have been observed during the SDO mission; some flares show all four phases, and some only show the gradual phase. The focus is on the newer results about the EUV late phase and coronal dimming and its relationship to coronal mass ejections (CMEs). These EVE flare measurements are based on observing the sun-as-a-star, so these results could exemplify stellar flares. Of particular interest is that new coronal dimming measurements of stars could be used to estimate mass and velocity of stellar CMEs.