The orbits of outer planetary satellites using the Gaia data

Launch of the Gaia space observatory started a new era in astrometry when the accuracy of star coordinates increased by thousands of times. Significant improvement of accuracy was also expected for the coordinates of the Solar system bodies. Gaia DR3 provided us with the data which could be used to test our expectations. In this work, we refine the orbits of a number of outer planetary satellites using both ground-based and Gaia observations. From thirteen outer satellites observed by Gaia, we chose six to obtain their orbits. Some specific moments in using observations of outer satellites made by Gaia are demonstrated. These pecularities stem from scanning motion of Gaia, in particular from the fact that the accuracy of observations is significantly different along and across the scanning direction. As expected, Gaia observations proved to be more precise than those made from Earth, which results in more accurate satellite ephemerides. We estimate accuracy of the ephemerides of considered satellites for the interval between 1996 and 2030. As astrometric positions published in Gaia DR3 were not corrected for the relativistic light deflection by the Sun, we took into account this effect, which slightly diminished the rms residuals. In addition, relativistic light deflection by the giant planets was estimated, which, as it turned out, can be neglected with the given accuracy of Gaia observations.Comment: accepted in MNRAS 28.03.2023, 9 pages, 8 figure

A new zooarchaeological application for geometric morphometric methods: Distinguishing Ovis aries morphotypes to address connectivity and mobility of prehistoric Central Asian pastoralists.

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Geometric morphometric methods (GMM), which were developed to characterize the shape and size of biological organisms, have been applied within zooarchaeology over the past decade to address animal domestication processes and to refine morphological criteria to differentiate between taxa. However, there has been limited utilization of these methods to discriminate between populations of the same taxa to challenge and refine other key archaeological issues, such as migration and connectivity in prehistory. Presented here is a novel application of a three-dimensional landmark based geometric morphometric approach to address the nature of long distance trade and connectivity on the prehistoric Silk Road. The similarity of Bronze and Iron Age archaeological cultures along this steppe route has encouraged characterisations of these people as nomads, with highly mobile, integrated, and connected human and animal populations. However, the interconnectedness of domestic animal populations, in particular sheep (Ovis aries), the foundation of this prehistoric pastoral economy, has never been examined. This study utilized geometric morphometric methods to quantify geometric morphometric variance of O. aries astragali between three geographically disparate settlement sites within a single Final Bronze age cultural and chronological context. Significant differences between morphotypes revealed that protracted mobility patterns were unlikely and that while animal exchange may have occurred, it was not pervasive enough to produce a uniform sheep morphotype across central and southeastern Kazakhstan. The result of this new application of geometric morphometric methods challenges models of uniform and undifferentiated long distance mobility and economic connectivity between the peoples of the Silk Road.Fulbright scholarshipFrances Mary Hazen fellowshi

Admittance of CdS nanowires embedded in porous alumina template

CdSnanowires of 10nm diameter, electrodeposited in porous alumina films, had shown a conductance bistability in the past [Appl. Phys. Lett.76, 460 (2000)]. The conductance has a high (ON) and a low (OFF) state. In the ON state, different sets of nanowires display qualitatively different relation between the conductance and capacitance. We propose a model to explain this anomalous behavior. Based on this model, we predict that the inelastic mean free path of electrons in the nanowires is 3–3.5nm at room temperature. This short mean free path may be a consequence of acoustic phonon confinement

Non-perturbative vacuum-polarization effects in proton-laser collisions

In the collision of a high-energy proton beam and a strong laser field, merging of the laser photons can occur due to the polarization of vacuum. The probability of photon merging is calculated by accounting exactly for the laser field and presents a highly non-perturbative dependence on the laser intensity and frequency. It is shown that the non-perturbative vacuum-polarization effects can be experimentally measured by combining the next-generation of table-top petawatt lasers with presently available proton accelerators.Comment: 5 pages, 2 figure

A new method for the determination of cooperative hydrogen bonding enthalpy of proton acceptors with associated species of alcohols

A calorimetric method for the determination of cooperative hydrogen bonding (HB) enthalpy of proton acceptors (B) with associated species of alcohols is proposed. The average enthalpy of cooperative HB of pyridine with associated species of alcohols was found to be -19.8 ±0.6 kJ mol-1 for all alcohols investigated. This value exceeds the enthalpy of HB in the complex ROH... N5H5 (the average for all alcohols is -15.8 ± 0.2kJ mol-1) by 20-30%. Cooperativity factors (A b, AOx) of hydrogen bonds for (ROH)2... NC 5H5 complexes were determined using the IR-spectroscopic method. The average values for the alcohols under consideration were found to be Ab = 1.41 ±0.04 and AOx = 1.54±0.05. On the basis of IR-spectroscopic and calorimetric data, the enthalpy of cooperative interactions of pyridine with the dimer (ROH)2 was estimated. This value for all the alcohols studied is, on average, -20.9 ±0.1 kJ mol -1. Copyright © 2006 John Wiley & Sons, Ltd

Evaluation method of influence of catalyst precursors on initiation of in-situ combustion and it's dynamics

Copyright 2017, Society of Petroleum Engineers. The growing demand for energy requires alternative technologies for the development of new deposits with tar sands and heavy oil, as well as the rehabilitation of depleted, abandoned deposits. Combining all the advantages of thermal methods, the method of in-situ combustion in the presence of catalyst precursors caused interest in petroleum industry due to the possibility of upgrading or primary refining of heavy oils directly in the reservoir. This article describes an experimental method for studying the effect of catalyst precursors on initiation of in-situ combustion of heavy oils. Thermograms in air atmosphere (combustion curves) for oil-saturated sandstones from Permian deposits in the presence of different precursors were obtained. As a precursor, resinates of copper, cobalt, iron and nickel were used. The possibility of evaluation the catalyst effect on the initiation of in-situ combustion was shown

Laser photon merging in proton-laser collisions

The quantum electrodynamical vacuum polarization effects arising in the collision of a high-energy proton beam and a strong, linearly polarized laser field are investigated. The probability that laser photons merge into one photon by interacting with the proton`s electromagnetic field is calculated taking into account the laser field exactly. Asymptotics of the probability are then derived according to different experimental setups suitable for detecting perturbative and nonperturbative vacuum polarization effects. The experimentally most feasible setup involves the use of a strong optical laser field. It is shown that in this case measurements of the polarization of the outgoing photon and and of its angular distribution provide promising tools to detect these effects for the first time.Comment: 38 pages, 9 figure

Thermodynamic Properties of 1,4-Benzoquinones in Gaseous and Condensed Phases: Experimental and Theoretical Studies

© 2017 American Chemical Society. A complete study of thermodynamic properties of 1,4-benzoquinones in the condensed and gaseous phases was carried out using experimental techniques and theoretical approaches. Enthalpies of combustion and formation of 2-methyl-1,4-benzoquinone were evaluated using combustion calorimetry. The transpiration method was utilized to determine the temperature dependence of the vapor pressures of 1,4-benzoquinone and 2-methyl-1,4-benzoquinone for the sublimation and vaporization enthalpies calculation. The group additivity scheme was used independently for verification of sublimation enthalpy of 2-methyl-1,4-benzoquinone. For this procedure the enthalpy of solution of 2-methyl-1,4-benzoquinone in benzene was measured at 298.15 K. The experimental values obtained were combined with published data and organized to obtain a reliable set of the experimental enthalpies of formation and enthalpies of phase transition of compounds. The methods of quantum chemistry and statistical physics based on the "rigid rotator-anharmonic oscillator" model were used to calculate thermodynamic functions of 1,4-benzoquinones in the ideal gas state in the temperature range 273.15-150 0 K. The strain enthalpy and the enthalpy of π-conjugation were also estimated

A new method for the extraction of specific interaction enthalpy from the enthalpy of solvation

A new, simple method for the extraction of specific interaction enthalpy from the enthalpy of solvation is proposed. It is based on empirical but very general relationships describing the non-specific solvation enthalpy. The specific interaction enthalpy is calculated from the solution enthalpies in the solvent under consideration, cyclohexane and tetrachloromethane. The solution enthalpy of at least one linear alkane in the solvent must also be available. The solution enthalpies of a 'model compound' or homomorph are not required. This method is applicable not only for proton-donor solutes but also for acceptor solutes such as iodine. It can be used also for solvents associated by hydrogen bonding (e.g. alcohols). The enthalpies of specific interaction for 280 solute-solvent systems were calculated. Solution enthalpy data were mainly obtained from the literature and partially measured by the authors. The results were compared with literature data on complexation enthalpy. Copyright © 2004 John Wiley & Sons, Ltd

Calorimetric determination of hydrogen-bonding enthalpy for neat aliphatic alcohols

Hydrogen bonding in pure aliphatic alcohols is investigated using a novel calorimetric approach. Average enthalpies of hydrogen bonding were determined for methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, hexan-1-ol and octan-1-ol. For all the studied alcohols except methanol the average hydrogen-bonding enthalpies fall in the range from -16.9 to -17.7kJ mol -1. A slightly smaller value of -15.1 kJ mol-1 was observed for methanol. From the enthalpies of the specific interactions of the alcohols and chloroform (as proton donors) formed with the alcohols and diethyl ether (as proton acceptors), the dimerization enthalpies were determined for the investigated alcohols: -8.6±0.7 kJ mol-1. The specific interaction and dimerization enthalpies obtained are concurrent with the Badger-Bauer rule and the hydrogen-bond cooperativity effects. The calorimetric data obtained are supported by literature Fourier transform infrared data on dimer and multimer formation for ethanol and octan-1-ol in tetrachloromethane solution. Copyright © 2005 John Wiley & Sons, Ltd