1,323 research outputs found

    Automated Coronal Hole Identification via Multi-Thermal Intensity Segmentation

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    Coronal holes (CH) are regions of open magnetic fields that appear as dark areas in the solar corona due to their low density and temperature compared to the surrounding quiet corona. To date, accurate identification and segmentation of CHs has been a difficult task due to their comparable intensity to local quiet Sun regions. Current segmentation methods typically rely on the use of single EUV passband and magnetogram images to extract CH information. Here, the Coronal Hole Identification via Multi-thermal Emission Recognition Algorithm (CHIMERA) is described, which analyses multi-thermal images from the Atmospheric Image Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) to segment coronal hole boundaries by their intensity ratio across three passbands (171 \AA, 193 \AA, and 211 \AA). The algorithm allows accurate extraction of CH boundaries and many of their properties, such as area, position, latitudinal and longitudinal width, and magnetic polarity of segmented CHs. From these properties, a clear linear relationship was identified between the duration of geomagnetic storms and coronal hole areas. CHIMERA can therefore form the basis of more accurate forecasting of the start and duration of geomagnetic storms

    31P NMR of Backbone Conformation and Dynamics in DNA at Cre Binding Site in Terms of Sequence Context

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    The Cre sequence (ACGT) is a site responsible for the binding of specific transcription factors that determine the activation of genes. Due to its major role in gene transcription, it has become a subject of immense research. The binding of transcription factors to the Cre binding site has been determined to be dependent on DNA conformation. In this study, the effects of flanking sequence around the Cre binding site on the conformation and the dynamics of DNA were investigated. The Cre binding site was studied in its native form with differing flanking sequences to determine the BI/BII profile (conformation) and the magnitude of the energy transition barrier (dynamics) between the BI and BII conformations of each phosphate step of the following three dodecamer sequences: CreACAG, CreGGAG, and CreTATA. In order to obtain the BI/BII profile of each phosphate step, 2D 31P-NMR NOESY and HSQC experiments at various temperatures were utilized. Based of the basic principles of kinetics, the lower the energy barrier between the two conformations, the easier the transition between the BI and BII conformation. Therefore, it was hypothesized that low and high %BII character lead to a large energy barrier (high ∆G‡ values), whereas average %BII character leads to a small energy barrier (low ∆G‡ values). The results of the 2D 31P-NMR experiments of the three dodecamer sequences confirmed this relationship between the %BII character and the magnitude of the energy barrier (∆G‡). However, further conformation and dynamics studies must be conducted to further understand the correlation

    Five minutes with Timothy Garton Ash: “We’re far more European in the UK than we think we are”

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    Is it possible to create a truly European public sphere? In an interview with EUROPP’s editor Stuart Brown, Timothy Garton Ash discusses the failure of efforts to reignite the enthusiasm of citizens for European integration, the importance of European identity, and why the UK is far more European than most people believe

    I Am Always Building Castles In The Air

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    https://digitalcommons.library.umaine.edu/mmb-vp/1633/thumbnail.jp

    I Am Always Building Castles In The Air

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    https://digitalcommons.library.umaine.edu/mmb-vp/1632/thumbnail.jp

    Distance Amplitude Correction Factors for Immersion Ultrasonic Measurements through Curved Surfaces

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    Near net-shaped forgings offer significant advantages for component manufacture, including less material waste and reduced costs for machining to final shape. However, curved entry surfaces on near net shape forgings create complications for ultrasonic inspection methods. In immersion ultrasonic testing, entry surface curvature causes ultrasonic beam focusing or defocusing, which affects the detection sensitivity to interior material flaws, such as voids and inclusions, as compared to inspection through planar surfaces

    Functional characterization of the \u3ci\u3eArabidopsis thaliana\u3c/i\u3e orthologue of Tsc13p, the enoyl reductase of the yeast microsomal fatty acid elongating system

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    The protein encoded by the Arabidopsis At3g55360 gene was selected as a candidate for the enoyl reductase of the microsomal elongase system based on its homology to the Tsc13p protein of S. cerevisiae. The studies presented here demonstrate that heterologous expression of At3g55360 functionally complements the temperature-sensitive phenotype of a yeast tsc13 mutant that is deficient in enoyl reductase activity. Furthermore, AtTSC13 is shown to interact physically with the Elo2p and Elo3p components of the yeast elongase complex. At3g55360 apparently encodes the sole enoyl reductase activity associated with microsomal fatty acid elongation in Arabidopsis. Consistent with this conclusion, AtTSC13 is ubiquitously expressed in Arabidopsis

    A guide to chemokines and their receptors

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    The chemokines (or chemotactic cytokines) are a large family of small, secreted proteins that signal through cell surface G‐protein coupled heptahelical chemokine receptors. They are best known for their ability to stimulate the migration of cells, most notably white blood cells (leukocytes). Consequently, chemokines play a central role in the development and homeostasis of the immune system, and are involved in all protective or destructive immune and inflammatory responses. Classically viewed as inducers of directed chemotactic migration, it is now clear that chemokines can stimulate a variety of other types of directed and undirected migratory behaviour, such as haptotaxis, chemokinesis, and haptokinesis, in addition to inducing cell arrest or adhesion. However, chemokine receptors on leukocytes can do more than just direct migration, and these molecules can also be expressed on, and regulate the biology of, many non‐leukocytic cell types. Chemokines are profoundly affected by post‐translational modification, by interaction with the extracellular matrix (ECM), and by binding to heptahelical ‘atypical’ chemokine receptors that regulate chemokine localisation and abundance. This guide gives a broad overview of the chemokine and chemokine receptor families; summarises the complex physical interactions that occur in the chemokine network; and, using specific examples, discusses general principles of chemokine function, focussing particularly on their ability to direct leukocyte migration
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