Punctuated equilibrium of the surface above subglacial Lake Vostok in antarctica

Progress in understanding the surface dynamics above the subglacial Lake Vostok is achieved owing to use of the ICESat satellite laser elevation measurements, which enabled us to determine surface fluctuations with precision up to 3 cm. A new idea on punctuated equilibrium of the surface above Lake Vostok is elaborated; this idea is concluded in irregular, sharp vertical displacements of the ice surface by up to 40 cm. Deformation of the surface is accompanied with a common raising or lowering, and with local vertical displacements up to 20 cm in amplitude. It has been proved experimentally that snow transport on the surface above the lake causes only redistribution of snow and forms fractal structures that do not have any effect on surface deformation. The form of the surface is not an inclined plane due to many bends that are particularly related to ice flowing on the lake water area.     

Sources of δ18O Concentration Variability in Greenland Ice Cores: Temperature, North Atlantic Oscillation and Solar Activity

This work concerns possible connection between variations of δ¹⁸O in Greenland ice, temperature, precipitation amount, NAO indices and relative sunspot numbers. The relationships between 10-year averaged values of this data were derived making use of regression analysis methods. It was discovered that February temperature yields the main contribution in variability of δ¹⁸O. The multiple correlation coefficient between weighted night temperature of the most important months and δ¹⁸O equals 0.95±0.01. Besides the local source of δ¹⁸O changes, defined by the amount of precipitation and temperature, an additional source correlated with the level of solar activity has been revealed. The relative contribution of this source in the δ¹⁸O variance is about 0.1. It has been shown that the multiple correlation coefficient between δ¹⁸O and NAO indices is equal to 0.85. Therefore the NAO yields more than 2/3 of the variances of climatic change in Greenland. An independent contribution of solar activity in climatic changes is about 1/3.     

Structural and Mineralogical Features of Diamonds from the Lomonosov Deposit (Arkhangelsk Province): New Data and Interpretation

Doklady Earth Sciences - Three groups of diamond crystals that differ in morphology, photoluminescence, infrared absorption, and thermal history were discovered in the Lomonosov deposit. The first...     

<Emphasis Type="Italic">Q</Emphasis>-type bursts in magnetic oscillations of ELF range as a phenomenon reflecting the properties of the global Earth-ionosphere resonator

The observation results of Q-type bursts in the measurements of the horizontal component of the noise magnetic field in the range of the first Schumann resonance in polar regions (Lovozero high-latitude observatory) are presented. Automatic selection of Q-type bursts from the experimental data series is implemented on the basis of a waveform recognition algorithm. The resonant nature of Q-bursts is shown. The possibility of selecting such events in magnetic excitation conditions is highlighted. The global resonator quality upon decreasing the selected waveform amplitudes is estimated. The data obtained by this method are compared with estimates on the basis of Fourier analysis and values known from the world literature. The possible reasons for disagreements of the estimates are analyzed, including the problem of selecting the function approximating the spectrum, the problem of accounting for the background, and the possible irregularity of the spectrum. It is shown that Q-type bursts, besides the quality, allow estimating the resonant frequency of the first oscillation mode; however, the accuracy of such estimation is lower as compared to the results of Fourier analysis methods.     

Collective supernova outbursts and the growth of supershells: Observational manifestations

Numerous supernova outbursts that are correlated in time and space are the main mechanism for the formation of powerful galactic winds and supershells of ionized hydrogen. Information about the dynamics and thermal properties of the gas in shells (bubbles) can be obtained from spectral observations, including those of optical recombination lines. The emission properties of the Hα and Hβ recombination lines and the velocity dispersion of the gas in bubbles formed by numerous supernova outbursts are studied. The appearance of the intensity vs. velocity dispersion (I(H _α)_?σ) diagram depends on the supernova rate and the age of the bubble. The temperature dependence of the I(H_α)/I(H _β) line-intensity ratio (the Balmer decrement) can be used to obtain additional constraints on the evolutionary status of a collective remnant formed by numerous supernova outbursts.     

The formation of the first objects during the virialization of the dark-matter halos

The chemical and thermal evolution of the baryon component in the gravitational field of low-mass primordial dark-matter halos during their virialization is studied. We consider low-mass halos to be those for which the characteristic baryon cooling time can appreciably exceed the comoving Hubble time, so that the cooling process can continue to the current epoch (z～0). The virialization process is described in two scenarios: “quiet” virialization, in which the establishment of the virial state is assumed to be homogeneous over the entire volume considered, and “violent” virialization, in which the establishment of the virial state is assumed to be realized via the action of shock waves. In this second case, the efficiency of the formation of molecular hydrogen grows substantially, and can reach H₂/H～0.01 in some cases, which exceeds current estimates by at least an order of magnitude. This eases the condition for the birth of the first gravitationally bound objects with comparatively low masses (M ? 2 × 10⁵M_⊙), possibly leading to an appreciable increase in the fraction of the mass contained in Population III objects, and also to a shift in the onset of the formation of the first stars toward higher redshifts.     

Growth Pyramids of {110} Faces in Natural Diamonds

Geology of Ore Deposits - The internal structure of two highly dissolved cuboid diamonds from placers of the Krasnovishersk region (the Urals) has been studied. This internal structure has been...