The almost constant-speed two-body problem with resistance

The almost constant-speed motion of a mass acted upon by a Newtonian attraction and a resisting force is treated. The equation of orbit is derived for a specific type of resistance which covers the familiar case of Danby's drag(=r ^–2) whilst the vector invariants are obtained by direct operation on the vector form of the equation of motion.     

Powder- and single crystal Mössbauer spectroscopy on synthetic fayalite

Mössbauer measurements on synthetic iron orthosilicate Fe₂SiO₄ (fayalite) were carried out in the antiferromagnetic spin state below T _N 65 K. The Mössbauer parameters isomer shift , inner magnetic field H(0), angle between H(0) and the z-component of the electric field gradient (efg), quadrupole splitting QS and asymmetry parameter were determined as a function of temperature. These parameters could be attributed to the two crystallographic sites M1 and M2.The smaller isomer shift on M1 with respect to M2 displays the more covalent character of the Fe-O bond on M1, which is supported by previous neutron diffraction experiments. H(0) shows a Brillouin-type behaviour with different fields on the two crystallographic sites (stronger on M1) and a small discontinuity at T = 23 K which corresponds with previous magnetic measurements. The quadrupole splitting is equal on both sites within error bars, in agreement with previous theoretical results and in contradiction to previous Mössbauer refinements published elsewhere.     

Carbon and Noble Gas Isotopes in the Tengchong Volcanic Geothermal Area, Yunnan, Southwestern China

Carbon and noble gas isotope analyses are reported for bubbling gas samples from the Tengchong volcanic geothermal area near the Indo-Eurasian suture zone. All samples contain a resolvable component of mantle-derived 3He. Occurrence of mantle-derived 3He coincides with surface volcanism. However, 3He occurs over a larger geographic areathan do surface volcanics. δ13C values for CO2 and CH4 vary from -33.4‰ to 1.6 ‰ and from -52.8‰ to -2.8‰, respectively. He and C isotope systematics indicate that CO2 and CH4 in the CO2-rich gases originated predominantly from magmatic component mixed with crustal CO2 produced from carbonate. However, breakdown of organic matter and near-surface processes accounts for the CH4 and CO2 in N2-rich gases. 3He/4He ratio distribution pattern suggests that mantle-derived He and heat sources of high-temperature system in central Tengchong originate from a hidden magma reservoir at subsurface. CO2-rich gases with the highest 3He/4He ratio (5.2 Ra) may be representative of the     

Concentration and Diffusion of Nutrients in the Interpore–Bottom Water System of the Ob River Estuary

Oceanology - On cruise 76 in 2019, the R/V Akademik Mstislav Keldysh completed the Gulf of Ob–Kara Sea slope transect. Samples of bottom water and two sediment layers 1 cm thick were obtained...     

In memory of I. K. Korolyuk

Chronicle

In memory of I. K. Korolyuk     

Dust-acoustic soliton in a plasma with multi-species ions and kappa-distributed electrons

In this work, we consider the formation of electrostatic, dust-acoustic solitary structure in a unmagnetized plasma with Lorentzian electrons (kappa-distributed) and more than one species of thermal ions (Maxwellian). The work is inspired by results of different space-based observations of electrostatic solitary waves (ESW) in the near-earth and magnetospheric plasmas and recent experimental realization of existence of superthermal electron component in various space plasmas. We have, in this work, shown that existence of compressive potential structure is possible only with more than one species of thermal ions. Besides, formation of compressive double layers is also possible which depends on the amount of deviation of the electron thermal velocities from a Maxwellian distribution. We show that both dust-temperature and super-thermal electrons lead to a decrease in the soliton amplitude.     

Tropospheric Ozone in a Global-Scale Three-Dimensional Lagrangian Model and Its Response to NOX Emission Controls

A three-dimensional Lagrangian tropospheric chemistry modelis used toinvestigate the impact of human activities on the tropospheric distributionofozone and hydroxyl radicals. The model describes the behaviour of 50 speciesincluding methane, carbon monoxide, oxides of nitrogen, sulphur dioxide andnineorganic compounds emitted from human activities and a range of other sources.Thechemical mechanism involves about 100 chemical reactions of which 16 arephotochemical reactions whose diurnal dependence is treated in full. The modelutilises a five minute chemistry time step and a three hour advection timestepfor the 50,000 air parcels. Meteorological data for the winds, temperatures,clouds and so on are taken from the UK Meteorological Office global model for1994 onwards. The impacts of a 50% reduction in European NO_Xemissions onglobal ozone concentrations are assessed. Surface ozoneconcentrations decrease in summertime and rise in wintertime, but to differentextents.     

A NEW APPROACH TO THE INVERSION OF SEISMIC DATA*

A new inversion method for seismic reflection data is based on impedance concepts and uses transformations to reduce the essentially non-linear problem to a linear eigenvalue formulation without approximation. A set of reflection data has been inverted using this method. The characteristic impedances of the layers so determined are compared with log data from a reference borehole.     

Variations in exospheric density at heights near 1100km, derived from satellite orbits

In an earlier paper, values of exospheric density were obtained from the orbit of Echo 2 for the years 1964–1965. The results indicated a semi-annual variation in density by a factor of between 2 and 3, considerably larger than predicted by existing atmospheric models.

These studies have now been extended to the beginning of 1967, using both Echo 2 and Calsphere 1, to show how the density is responding to increasing solar activity. Variations in density during 1964 have been analysed in more detail. The long-term variation associated with the solar cycle and the short-term variations associated with magnetic and solar disturbances agree with the variations expected on the basis of current models. The semi-annual variation is persisting to higher levels of solar activity, and although its amplitude is diminishing the factor of variation was still 1.6 in 1966.