The statistics of the photometric accuracy based on MASS data and the evaluation of high-altitude wind

The effect of stellar scintillation on the accuracy of photometric measurements is analyzed. We obtain a convenient form of estimaton of this effect in the long exposure regime, when the turbulence shift produced by the wind is much larger than the aperture of the telescope. A simple method is proposed to determine index $S_3$ introduced by perture of the Kenyon et al. (2006), directly from the measurements with the Multi Aperture Scintillation Sensor (MASS) without information on vertical profile of the wind. The statistics $S_3$ resulting from our campaign of 2005 -- 2007 at Maidanak observatory is presented. It is shown that these data can be used to estimate high-altitude winds at pressure level 70 -- 100 mbar. Comparison with the wind speed retrieved from the NCEP/NCAR global models shows a good agreement. Some prospects for retrieval of the wind speed profile from the MASS measurements are outlined.Comment: 11 pages, 9 figures, accepted for publication in Astronomy Letter

Activation and reaction volumes and their correlations with the entropy and enthalpy parameters

© 2015 American Chemical Society. Data for the enthalpies, entropies, and volumes of 271 liquid compounds at standard conditions as well as those for 103 isomerization and decomposition reactions have been collected and compared. It was observed that the values of liquid molar volumes are proportional to the standard molar entropies of these compounds (R = 0.9378, N = 271). For the reactions under consideration, the proportionality ΔVr-n vs ΔSr-n (R = 0.9019, N = 103) was also found. The correlation between the volume and enthalpy changes in these reactions, ΔVr-n vs ΔHr-n, was not established (R = 0.5719, N = 103). The angular coefficient values, namely, 3.8 (eq 7) and 3.8 (eq 11), are close to the value 4.4 (eq 3), observed for the dissociation of acids and bases. The proportionality between the changes of the volume and entropy of activation (ΔV‡ vs ΔS‡) at normal and elevated pressure has been also noted, whereas proportionality with the enthalpy of activation (ΔV‡ vs ΔH‡) under these conditions was not observed

New approach to determine the activation and reaction volumes of low polar molecular processes

© 2015 Wiley Periodicals, Inc. For low polar molecular processes, we found the reliable relationship between the logarithm changes of the rate or equilibrium constants in the pressure range 1-1000 bar, [Ln(KP = 1000/KP = 1)/1000], and tangent modulus at P = 1 bar, ∂Ln(KP)/∂P: ∂Ln(KP)/∂P = 1.15·[Ln(KP = 1000/KP = 1)/1000], R = 0.995, which allows to predict the value of activation and reaction volume at ambient pressure. Therefore, it is sufficient to determine the values of the rate or equilibrium constants only at ambient pressures and at 1000 bar for the reliable estimation of the values of activation or reaction volume

On neoclassical impurity transport in stellarator geometry

The impurity dynamics in stellarators has become an issue of moderate concern due to the inherent tendency of the impurities to accumulate in the core when the neoclassical ambipolar radial electric field points radially inwards (ion root regime). This accumulation can lead to collapse of the plasma due to radiative losses, and thus limit high performance plasma discharges in non-axisymmetric devices.\\ A quantitative description of the neoclassical impurity transport is complicated by the breakdown of the assumption of small $\mathbf{E}\times \mathbf{B}$ drift and trapping due to the electrostatic potential variation on a flux surface $\tilde{\Phi}$ compared to those due to the magnetic field gradient. The present work examines the impact of this potential variation on neoclassical impurity transport in the Large Helical Device (LHD) stellarator. It shows that the neoclassical impurity transport can be strongly affected by $\tilde{\Phi}$. The central numerical tool used is the $\delta f$ particle in cell (PIC) Monte Carlo code EUTERPE. The $\tilde{\Phi}$ used in the calculations is provided by the neoclassical code GSRAKE. The possibility of obtaining a more general $\tilde{\Phi}$ self-consistently with EUTERPE is also addressed and a preliminary calculation is presented.Comment: 11 pages, 15 figures, presented at Joint Varenna-Lausanne International Workshop on Theory of Fusion Plasmas, 2012. Accepted for publication to Plasma Phys. and Control. Fusio

Intracycle interference in ionization of Ar by a laser assisted XUV pulse

Synopsis We present a theoretical and experimental study of the subcycle interference in laser assisted XUV ionization of Ar atoms. Averaging over the focal volume happens to blur the intracycle interference, which thus cannot be measured directly. We show that even at these conditions, the intracycle interference can be obtained through the subtraction of two different angle and energy-resolved distributions at slightly different laser intensities

Cyclic and Acyclic NN Bonds in Reactions with Some Alkenes and Dienes

© 2017 Wiley Periodicals, Inc., A Wiley Company.The kinetics of the Diels-Alder (DA) reactions of 4-phenyl-1,2,4-triazoline-3,5-dione 1, trans-diethyl azodicarboxylate 2, and tetracyanoethene 3 with 1,3-cyclohexadiene 4, cycloheptatriene 5, 1,3-cycloheptadiene 6, cyclooctatetraene 7, and 1,3-cyclooctadiene 8 in a range of temperatures and pressures has been studied. Values of the enthalpy, entropy, and volume of activation, as well as the enthalpy and volume of reaction have been obtained. Observed reaction rates of 5+1 and 7+1 have been compared with the known rate of norcaradiene 17 formation in the equilibrium 5⇌17, and that of bicyclo[4,2,0]-octa-2,4,7-triene 20 in the equilibrium 7⇌20. The kinetic data show that the rate of formation of 17 from 5 is much greater than the loss rate of dienophile 1 in reaction of 5+1. In contrast, the formation rate of tautomer 20 is less than the loss rate of dienophile 1 in reaction of 7+1. This reflects that the consecutive reaction of 5 → 17 (+1) → 15 is possible whereas the consecutive reaction of 7 → 20 (+1) → 22 does not occur as the only way

Changes in permittivity and density of molecular liquids under high pressure

We collected and analyzed the density and permittivity of 57 nonpolar and dipolar molecular liquids at different temperatures (143 sets) and pressures (555 sets). No equation was found that could accurately predict the change to polar liquid permittivity by the change of its density in the range of the pressures and temperatures tested. Consequently, the influence of high hydrostatic pressure and temperature on liquid permittivity may be a more complicated process compared to density changes. The pressure and temperature coefficients of permittivity can be drastically larger than the pressure and temperature coefficients of density, indicating that pressure and particularly temperature significantly affect the structure of molecular liquids. These changes have less influence on the density change but can strongly affect the permittivity change. The clear relationship between the tangent and secant moduli of the permittivity curvatures under pressure for various molecular liquids at different temperatures was obtained, from which one can calculate the Tait equation coefficients from the experimental values of the pressure influence on the permittivity at ambient pressure. © 2014 American Chemical Society

Determination of the reaction acceleration effect at an elevated hydrostatic pressure

© 2017, Springer Science+Business Media, LLC. A method was proposed for the calculation of changes in the rate (k P /k P=0 ) and equilibrium constants (K P /K P=0 ) for chemical reactions under high hydrostatic pressure (10—20 kbar). The calculation based on the activation and reaction volume data makes it possible to select optimum conditions for slow and equilibrium chemical processes