58 research outputs found

    Propagation of an Earth-directed coronal mass ejection in three dimensions

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    Solar coronal mass ejections (CMEs) are the most significant drivers of adverse space weather at Earth, but the physics governing their propagation through the heliosphere is not well understood. While stereoscopic imaging of CMEs with the Solar Terrestrial Relations Observatory (STEREO) has provided some insight into their three-dimensional (3D) propagation, the mechanisms governing their evolution remain unclear due to difficulties in reconstructing their true 3D structure. Here we use a new elliptical tie-pointing technique to reconstruct a full CME front in 3D, enabling us to quantify its deflected trajectory from high latitudes along the ecliptic, and measure its increasing angular width and propagation from 2-46 solar radii (approximately 0.2 AU). Beyond 7 solar radii, we show that its motion is determined by an aerodynamic drag in the solar wind and, using our reconstruction as input for a 3D magnetohydrodynamic simulation, we determine an accurate arrival time at the Lagrangian L1 point near Earth.Comment: 5 figures, 2 supplementary movie

    Population-Specific Responses to Interspecific Competition in the Gut Microbiota of Two Atlantic Salmon (Salmo salar) Populations

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    The gut microbial community in vertebrates plays a role in nutrient digestion and absorption, development of intestine and immune systems, resistance to infection, regulation of bone mass and even host behavior and can thus impact host fitness. Atlantic salmon (Salmo salar) reintroduction efforts into Lake Ontario, Canada, have been unsuccessful, likely due to competition with non-native salmonids. In this study, we explored interspecific competition effects on the gut microbiota of two Atlantic salmon populations (LaHave and Sebago) resulting from four non-native salmonids. After 10 months of rearing in semi-natural stream tanks under six interspecific competition treatments, we characterized the gut microbiota of 178 Atlantic salmon by parallel sequencing the 16S rRNA gene. We found 3978 bacterial OTUs across all samples. Microbiota alpha diversity and abundance of 27 OTUs significantly differed between the two populations. Interspecific competition reduced relative abundance of potential beneficial bacteria (six genera of lactic acid bacteria) as well as 13 OTUs, but only in the LaHave population, indicating population-specific competition effects. The pattern of gut microbiota response to interspecific competition may reflect local adaptation of the host-microbiota interactions and can be used to select candidate populations for improved species reintroduction success

    Eculizumab improves fatigue in refractory generalized myasthenia gravis

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    Gas-phase Base-induced Elimination-reactions In Onium Intermediates .1. Competitive Substitution and Elimination Mechanisms In the Attack of Amines On Diethylmethyloxonium Ions

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    The elimination/substitution branching ratio assocd. with the attack of amines on diethylmethyloxonium ions has been studied in the gas phase by using the method of Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Increasing the base strength causes enhancement of the efficiency of the elimination process relative to substitution. The same trend is obsd. upon increasing the excitation energy of the encounter between the oxonium ion and the base. At low encounter excitation energies, nucleophilic displacement is flanked by an entropically favored E2 elimination mechanism. At high encounter excitation energies, these reactions are superseded by alternative entropically favored processes, characterized by an initial one-electron transfer from the amine to the oxonium ion leading to a long-lived electrostatically bound adduct involving the amine radical ion and an alkyl radical loosely bound to an ether mol. Collapse of this adduct may involve an alkyl radical-amine ion-radical recombination (an SRN1-like mechanism) or, alternatively, a hydrogen transfer from the present neutrals to the mol. ion of the base (an ER1 mechanism). These proposed mechanisms are unprecedented in the field of gas-phase pos. ion-mol. chem

    Epidemiological and cost analysis of burn injuries admitted to the emergency department of a tertiary burn center

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    Background: Burn injury is an emergency medical condition that rapidly develops as a result of tissue exposure to electrical, chemical or thermal energy. Therefore, its treatment usually begins at the emergency department. In this study we aimed to perform an epidemiological analysis of burn injuries presenting to the emergency department of a tertiary burn center, and factors affecting the cost of their medical care. Methods: Patients who presented to Baskent University Ankara Hospital Adult Emergency Department with burn injuries between January 2012 and December 2014 were studied for age, sex, time of admission, type of burn injury, clinical prognosis, mortality rate, percent burn area, and total cost of care. A total of 264 patients were enrolled. Chi square test was used for the comparison of categorical variables. Non-parametric tests were used for the comparison of continuous variables. Results: This study included 179 (67.8 %) women and 85 (32.2 %) men. The most common types of burn injuries were hot water burns and scalding. Eleven point seven percent of the patients sustained burn injuries in occupational accidents. 95.1 % of the patients were discharged from the emergency and 4.5 % of them were hospitalized. Only 1 (0.4 %) patient died. There was no significant difference between patient outcomes (discharge vs. hospital admission) with respect to the cost of care (p = 0.846) No significant difference was found between the cost of care of surgical and non-surgical management of burn injuries (p = 0.206). No significant difference was found between the costs of care of different types of burn injuries (p = 0.053). There was a significant difference between burn degrees with respect to the cost of care (p = 0.038). A significant difference was found between the costs of care of patients with a percent burn area of less than 10 % and those with a percent burn area of more than 10 % (p < 0.001), indicating that as percent burn area increased, a proportional increase occurred in the cost of care. Conclusions: Burn degree and percent burn area were the main determinants of the cost of care of burn injuries. In conclusion, burn injuries are preventable by taking occupational measures and raising public awareness about domestic accidents

    Molecular-Cloning of a Gene Involved in Glucose Sensing in the Yeast Saccharomyces-Cerevisiae

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    Cells of the yeast Saccharomyces cerevisiae display a wide range of glucose-induced regulatory phenomena, including glucose-induced activation of the RAS-adenylate cyclase pathway and phosphatidylinositol turnover, rapid post-translational effects on the activity of different enzymes as well as long-term effects at the transcriptional level. A gene called GGS1 (for General Glucose Sensor) that is apparently required for the glucose-induced regulatory effects and several ggs1 alleles (fdp1, byp1 and cif1) has been cloned and characterized. A GGS1 homologue is present in Methanobacterium thermoautotrophicum. Yeast ggs1 mutants are unable to grow on glucose or related readily fermentable sugars, apparently owing to unrestricted influx of sugar into glycolysis, resulting in its rapid deregulation. Levels of intracellular free glucose and metabolites measured over a period of a few minutes after addition of glucose to cells of a ggs1DELTA strain are consistent with our previous suggestion of a functional interaction between a sugar transporter, a sugar kinase and the GGS1 gene product. Such a glucose-sensing system might both restrict the influx of glucose and activate several signal transduction pathways, leading to the wide range of glucose-induced regulatory phenomena. Deregulation of these pathways in ggs1 mutants might explain phenotypic defects observed in the absence of glucose, e.g. the inability of ggs1 diploids to sporulate
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