RHESSI and SDO/AIA observations of the chromospheric and coronal plasma parameters during a solar flare

X-ray and EUV observations are an important diagnostic of various plasma parameters of the solar atmosphere during solar flares. Soft X-ray and EUV observations often show coronal sources near the top of flaring loops, while hard X-ray emission is mostly observed from chromospheric footpoints. Combining RHESSI with simultaneous SDO/AIA observations, it is possible for the first time to determine the density, temperature, and emission profile of the solar atmosphere over a wide range of heights during a flare, using two independent methods. Here we analyze a near limb event during the first of three hard X-ray peaks. The emission measure, temperature, and density of the coronal source is found using soft X-ray RHESSI images while the chromospheric density is determined using RHESSI visibility analysis of the hard X-ray footpoints. A regularized inversion technique is applied to AIA images of the flare to find the differential emission measure (DEM). Using DEM maps we determine the emission and temperature structure of the loop, as well as the density, and compare it with RHESSI results. The soft X-ray and hard X-ray sources are spatially coincident with the top and bottom of the EUV loop, but the bulk of the EUV emission originates from a region without co-spatial RHESSI emission. The temperature analysis along the loop indicates that the hottest plasma is found near the coronal loop top source. The EUV observations suggest that the density in the loop legs increases with increasing height while the temperature remains constant within uncertainties.Comment: 23 pages, 6 figures, accepted for publication in Ap

Electron distribution and energy release in magnetic reconnection outflow regions during the pre-impulsive phase of a solar flare

We present observations of electron energization in magnetic reconnection outflows during the pre-impulsive phase of solar flare SOL2012-07-19T05:58. During a time-interval of about 20 minutes, starting 40 minutes before the onset of the impulsive phase, two X-ray sources were observed in the corona, one above the presumed reconnection region and one below. For both of these sources, the mean electron distribution function as a function of time is determined over an energy range from 0.1~keV up to several tens of keV, for the first time. This is done by simultaneous forward fitting of X-ray and EUV data. Imaging spectroscopy with RHESSI provides information on the high-energy tail of the electron distribution in these sources while EUV images from SDO/AIA are used to constrain the low specific electron energies. The measured electron distribution spectrum in the magnetic reconnection outflows is consistent with a time-evolving kappa-distribution with $\kappa =3.5-5.5$. The spectral evolution suggests that electrons are accelerated to progressively higher energies in the source above the reconnection region, while in the source below, the spectral shape does not change but an overall increase of the emission measure is observed, suggesting density increase due to evaporation. The main mechanisms by which energy is transported away from the source regions are conduction and free-streaming electrons. The latter dominates by more than one order of magnitude and is comparable to typical non-thermal energies during the hard X-ray peak of solar flares, suggesting efficient acceleration even during this early phase of the event.Comment: 9 pages, 5 figures, accepted for publication in Ap

Association between high school students’ cigarette smoking, asthma and related beliefs: a population-based study

Background Smoking has a detrimental effect on the symptoms and severity of asthma, a common chronic disease among adolescents. The purpose of this study was to examine the association between asthma and smoking among high school students and assess provider-patient communication with asthmatic adolescents regarding smoking and adolescents’ beliefs about the harms of smoking. Methods In fall 2014, data from high school students, ages 14–18 years, completing the 2009-2010 Virginia Youth Tobacco Survey (N = 1796) were used in descriptive analyses and multivariable logistic regression models adjusting for model-specific confounders as appropriate. Results Overall, an estimated 19 % of high school students in Virginia smoked and 16 % had asthma. Odds of smoking did not differ by asthma status; however, asthmatics had 1.5 times higher odds of being asked if they smoke (95 % CI 1.06–2.13) and being advised not to smoke by a health professional (95 % CI 1.10–2.14) compared to non-asthmatics. Asthmatics who believed second-hand smoke or smoking 1–5 cigarettes/day was not harmful had respectively 4.2 and 2.8 times higher odds of smoking than those who thought each was harmful. Further, asthmatics who thought smoking 1−2 years is safe had 3.4 times higher odds of smoking than those who did not (95 % CI 1.57–10.1). Conclusions While asthmatic adolescents are just as likely to smoke as non-asthmatics, less healthy beliefs about the risks of smoking increase the odds of smoking among asthmatics. Thus, targeted asthma-specific smoking prevention and education to change attitudes and beliefs could be an effective tool for adolescents

Female Scent Signals Enhances Male Resistance to Influenza

Scent of receptive females as signal to reproduction stimulate male mice to olfactory search of a potential breeding partner^1, 2^. This searching behavior is coupled with infection risk due to bacterial contamination of the fecal and urine scent marks^4^. The theoretical consideration of host evolution under inevitable parasitic pressures, including helminthes, bacteria, virus etc., predicts adaptations that help protect against parasites associated with breeding^7^. In this study, we propose that acceptation of female signals by male mice leads to adaptive redistribution of immune defense directed to protection against respiratory infection risks. Our results reveal migration of macrophages and neutrophils to upper airways upon exposure to female odor stimulus resulting in increased resistance to influenza virus in male mice. Contrary to widely accepted immunosuppressive function of female sexual signals, our data provide the first demonstration of the adaptive immunological response to female odor stimulus through induction of nonspecific immune response in upper airways

Unusual products of the aqueous chlorination of atenolol

The reaction of the drug atenolol with hypochlorite under conditions that simulate wastewater disinfection was investigated. The pharmaceutical reacted in 1 h yielding three products that were separated by chromatographic techniques and characterized by spectroscopic features. Two unusual products 2-(4-(3-(chloro(2-chloropropan- 2-yl)amino)-2-hydroxypropoxy) phenyl) acetamide and 2-(4- (3-formamido- 2-hydroxypropoxy) phenyl) acetamide were obtained along with 2-(4-hydroxyphenyl) acetamide. When the reaction was stopped at shorter times only 2-(4-(3-amino-2-hydroxypropoxy) phenyl) acetamide and the dichlorinated product were detected. Tests performed on the seeds of Lactuca sativa show that chlorinated products have phytotoxic activity