Unique properties of humic substances from sapropel

Doklady Earth Sciences - Sapropel from inland Russian water reservoirs is becoming a popular raw material for medicinal purposes, production of sorbents, organomineral fertilizers, and food...     

Results of detecting thermal neutrons at Tien Shan high altitude station

The unit for detecting thermal neutrons, which makes it possible to study variations in cosmic rays of the interplanetary and geophysical origin, has been created at the high altitude cosmic ray station (3340 m above sea level) near the Earth’s crust fault. It has been established that variations in thermal neutrons are of the same nature as high-energy variations registered with a neutron supermonitor in the absence of seismic activity. The flux of thermal neutrons from the Earth’s crust during seismic activity in December 2006 has been registered for the first time. The flux value is higher than the background level by 5–6%. The method for detecting the flux of thermal neutrons from the Earth’s crust with the simultaneous registration of high-energy neutrons has been proposed.     

Difference between the spectra of acoustic gravity waves in daytime and nighttime hours due to nonequilibrium effects in the atmosphere

The singularities of the wave disturbance spectra of the nonequilibrium atmosphere in the range of acoustic gravity waves (AGWs) have been analyzed. Using the dispersion ratio for AGWs in the nonequilibrium atmosphere, it has been established that the spectra in the daytime and nighttime hours are different and this difference, caused by a nonequilibrium spectrum sensitivity to atmospheric temperature, can reach several percent in certain atmospheric regions. For the spectrum of the equilibrium model of the atmosphere, the difference between the daytime and nighttime spectra makes up several fractions of percent. As a result of the spectral treatment of variations in pressure and intensity of cosmic rays (CRs), it has been found out that the daytime AGW spectrum is higher-frequency than the nighttime spectrum. A comparison of the theoretical calculations of the AGW spectrum with observations has made it possible to distinguish the effect of nonequilibrium in the AGW spectral composition.     

Influence of water suspension dispersibility on the toxicity of Lake Ladoga blooming

Doklady Earth Sciences -     

The significance of identification of nano-size particles in freshwater bodies: Case study of Lake Ladoga

The effect of abiotic and biotic factors on the properties of nano-size particles in freshwater bodies is considered. Field studies of the aquatic environments of Lake Ladoga ecosystem provided an experimental confirmation of the total water mineralization and organic matter content in the formation of nano-size particle properties under natural conditions.     

Methods of Laser,Non-Linear,and Fiber Optics in Studying Fundamental Problems of Astrophysics

Precise measurements of Doppler shifts of lines in stellar spectra allowing the radial velocity to be measured are an important field of astrophysical studies. A remarkable feature of the Doppler spectroscopy is the possibility to reliably measure quite small variations of the radial velocities (its acceleration, in fact) during long periods of time. Influence of a planet on a star is an example of such a variation. Under the influence of a planet rotating around a star, the latter demonstrates periodic motion manifested in the Doppler shift of the stellar spectrum. Precise measurements of this shift made it possible to indirectly discover planets outside the Solar system (exoplanets). Along with this, searching for Earth-type exoplanets within the habitable zone is an important challenge. For this purpose, accuracy of spectral measurements has to allow one to determine radial velocity variations at the level of centimeters per second during the timespans of about a year. Suchmeasurements on the periods of 10–15 years also would serve as a directmethod for determination of assumed acceleration of the Universe expansion. However, the required accuracy of spectroscopic measurements for this exceeds the possibilities of the traditional spectroscopy (an iodine cell, spectral lamps). Methods of radical improvement of possibilities of astronomical Doppler spectroscopy allowing one to attain the required measurement accuracy of Doppler shifts are considered. The issue of precise calibration can be solved through creating a system of a laser optical frequency generator of an exceptionally high accuracy and stability.     

Accretion Flows: Aspects of Gas Dynamic Modeling

We present our view on the application of numerical models to accretion flows in astrophysics. Special attention is paid to the problem of existence of steady-state solutions in time-dependent calculations and to origin of numerically induced instabilities. The problem is considered of the supersonic wind accretion onto gravitating objects. We also present the results of the gas dynamic simulation of accretion on a body imitating the shape of the star magnetosphere with holes in its polar regions. This shape can occur as a result of the cusp disintegration owing to theRayleigh–Taylor instability in the equatorial region of the magnetosphere. This revised version was published online in July 2006 with corrections to the Cover Date.     

High-resolution fiber-fed echelle spectrograph for the 6-m telescope. I. Optical scheme,arrangement, and control system

We propose a project of a high-resolution (R = 100 000) fiber-fed spectrograph for comprehensive studies of stellar atmospheres, exoplanet searches, asteroseismological studies, studies of stellar magnetism, active nuclei of bright galaxies, interstellar medium, etc. We present the optical scheme of the instrument. The operating wavelength region spans from 4000 to 7500 Å. We also present the optical scheme of the pre-fiber optic unit of the spectrograph. The unit supports four main modes of spectroscopic observations: the mode of traditional spectroscopy with the spectrum of the studied object taken along with the background spectrum in the immediate vicinity of the object; the mode of the simultaneous recording of the spectrum of the object and that of the wavelength standard; the mode of high-precision spectroscopy with an iodine cell, and the mode of spectropolarimetric observations with the measurement of all the Stokes parameters.     

Finds of economic platinum in ores from the South Khingan Mn deposit

Platinum is revealed by the authors in the Mn ores from the South Khingan deposit of Malyi Khingan. Its quality (grain size, aggregates) and amount are of economic interest. Platinum has higher contents of Fe, Cu, Mn, Ni, Os, and other metals. The Pt potential is related to carbonaceous metasomatites, which replaced fluidolites.