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Deriving the coronal hole electron temperature: electron density dependent ionization / recombination considerations

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Research in Astronomy and Astrophysics 2010年第1期10卷 91-95页

作者： John Gerard Doyle Steven Chapman Paul Bryans David Pérez-Suárez Avninda Singh Hugh summers daniel w.lf Savin Armagh Observatory College HillArmagh BT61 9DGN.Ireland Centre for Astrophysics University of Central LancashirePrestonUK Space Science Division Naval Research LaboratoryWashingtonDC 20375USA George Mason University 4400 University DriveFairfaxVA 22020USA Department of Physics & Electronics Deen Dayal Upadhyaya CollegeUniversity of DelhiIndia Department of Physics University of Strathclyde107 RottenrowGlasgowG4 0NGScotland Columbia Astrophysics Laboratory 550 W 120th StNew YorkNY 10027USA

Comparison of appropriate theoretically derived line ratios w.th observational data can yield estimates of a plasma＇s physical parameters, such as electron density or temperature. The usual practice in the calculation of the line ratio is the assumption of excitation by electrons/protons follow.d by radiative decay. Furthermore, it is normal to use the so-called coronal approximation, i.e. one only considers ionization and recombination to and from the ground-state. A more accurate treatment is to include ionization/recombination to and from metastable levels. Here, w. apply this to tw. lines from adjacent ionization stages, Mg IX 368A and Mg × 625A, w.ich has been show. to be a very useful temperature diagnostic. At densities typical of coronal hole conditions, the difference betw.en the electron temperature derived assuming the zero density limit compared w.th the electron density dependent ionization/recombination is small. This, how.ver, is not the case for flares w.ere the electron density is orders of magnitude larger. The derived temperature for the coronal hole at solar maximum is around 1.04MK compared to just below.0.82MK at solar minimum.

关键词： atomic processes - line formation - Sun activity

Thermodynamic contributions of 5’- and 3’-single strand dangling-ends to the stability of short duplex DNAs

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Journal of Biophysical Chemistry 2012年第1期3卷 1-15页

作者： Rebekah Dickman Fidelis Manyanga Greg P. Brew.od daniel J. Fish Cameron A. Fish Charlie summers M. Todd Horne Albert S. Benight Portland Bioscience Inc. Portland USA

Differential scanning calorimetry (DSC) melting analysis w.s performed on 27 short double stranded DNA duplexes containing 15 to 25 base pairs. Experimental duplexes w.re divided into tw. categories containing either tw. 5’ dangling-ends or one 5’ and one 3’ dangling-end. Duplex regions w.re incrementally reduced from 25 to 15 base pairs w.th a concurrent increase in length of dangling-ends from 1 to 10 bases. Blunt-ended duplexes from 15 to 25 base pairs served as controls. An additional set of molecules containing 21 base pair duplexes and a single four base dangling-end w.re also examined. DSC melting curves w.re measured in varying concentrations of sodium ion (Na+). From these measurements, thermodynamic parameters for 5’ and 3’ dangling-ends w.re evaluated as a function of dangling end length. 5’ ends w.re found to be slightly stabilizing but essentially constant w.ile the 3’ ends w.re destabilizing w.th increasing length of the dangling-end. 3’ ends also display a stronger dependence on Na+ concentration. In low.r Na+ environment, the 3’ ends w.re more destabilizing than in higher salt environment suggesting a more significant electrostatic component of the destabilizing interactions. Analysis of thermodynamic parameters of dangling ended duplexes as a function of Na+ concentration indicated the 3' dangling ends behave differently than 5' dangling ended and blunt-ended duplexes. Molecules w.th one 5' and one 3' dangling end show.d variation in excess specific heat capacity (ΔCp) w.en compared to the blunt-ended molecule, w.ile the molecules w.th tw. 5’ ends had ΔCp values that w.re essentially the same as blunt-ended duplexes. These observations suggested differences exist in duplexes w.th 3’ and 5’ dangling ends, w.ich are interpreted in terms of composite differences in interactions w.th Na+, solvent, and terminal base pairs of the duplex.

关键词： DNA Thermodynamics Dangling-Ends DNA Stability

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拉里·芬克首席执行官黑石公司

商业周刊（中文版） 2013年第17期 89-89页

作者： Nick summers daniel Shea(摄影)

这位全球规模最大的资产管理公司的创始人拉里-芬克（LarryFink）谈到了如何解决退休危机。

关键词：资产管理公司首席执行官投资组合政府官员创始人

Realizing Attosecond Core-Level X-ray Spectroscopy for the Investigation of Condensed Matter Systems

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Ultrafast Science 2023年第4期3卷 1-13页

作者： Adam M.summers Stefano Severino Maurizio Reduzzi Themistoklis P.H.Sidiropoulos daniel E.Rivas Nicola Di Palo Hung-w.i Sun Ying-Hao Chien Iker Leon Barbara Buades Seth L.Cousin Stephan M.Teichmann Tobias Mey Klaus Mann Barbara Keitel Elke Plonjes Dmitri K.Efetov Heinrich Schw.erere Jens Biegert ICFO-Institut de Ciencies Fotoniques The Barcelona Institute of Science and Technology08860 CastelldefelsBarcelonaSpain Linac Coherent Light Source SLAC National Accelerator LaboratoryMenlo ParkCA 94025USA European XFEL Holzkoppel 422869 SchenefeldGermany Institut für Nanophotonik Göttingen e.V. Hans-Adolf-Krebs-Weg 137077 GöttingenGermany Deutsches Elektronen-Synchrotron Notkestraße 8522607 HamburgGermany Max-Planck-Institut für Struktur und Dynamik der Materie 22761 HamburgGermany ICREA Pg.Lluís Companys 2308010 BarcelonaSpain

Unraveling the exact nature of nonequilibrium and correlated interactions is paramount for continued progress in many areas of condensed matter science. Such insight is a prerequisite to develop an engineered approach for smart materials w.th targeted properties designed to address standing needs such as efficient light harvesting, energy storage, or information processing. For this goal, it is critical to unravel the dynamics of the energy conversion processes betw.en carriers in the earliest time scales of the excitation dynamics. w. discuss the implementation and benefits of attosecond soft x-ray core-level spectroscopy up to photon energies of 600 eV for measurements in solid-state systems. In particular, w. examine how.the pairing betw.en coherent spectral coverage and temporal resolution provides a pow.rful new.insight into the quantum dynamic interactions that determine the macroscopic electronic and optical response. w. highlight the different building blocks of the methodology and point out the important aspects for its application from condensed matter studies to materials as thin as 25 nm. Furthermore, w. discuss the technological developments in the field of tabletop attosecond soft x-ray sources w.th time-resolved measurements at the near and extended edge simultaneously and investigate the exciting prospective of extending such technique to the study of 2-dimensional materials.

关键词： Attosecond Science Core-level x-ray Spectroscopy High Harmonic Generation X-ray Absorption Ultrafast solid-state dynamics

Thermodynamic contributions of 5’- and 3’-single strand dangling-ends to the stability of short duplex DNAs

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