The Cyclical Structure of the Isotopic Diagram of a Lithalsa and Its Radiocarbon Age,Sentsa River Valley,Eastern Sayan     

Vasil’chuk  Yu. K.  Vasil’chuk  J. Yu.  Alexeyev  S. V.  Budantseva  N. A.  Alexeyeva  L. P.  Vasil’chuk  A. C.  Kozyreva  Ye. A.  Svetlakov  A. A. 《Doklady Earth Sciences》2019,489(2):1456-1460

Doklady Earth Sciences - This paper reports on the nature and history of the mineral-rich frost heave mounds—lithalsas—developed on the first terrace of the Sentsa River in Okinsky...  相似文献   

Parameters of the early Universe and primordial black holes     

S. O. Alexeyev  M. V. Sazhin  O. S. Khovanskaya 《Astronomy Letters》2002,28(3):139-142

We consider the possibility of low-mass primordial black holes being formed in terms of the inflationary theory of the early Universe. We found a condition on the reheating temperature under which the relic remnants of primordial black holes had been formed by now. These relic remnants may account for a part of the dark matter in our Universe.  相似文献   

Paradoxical transformation of the equilibrium quartz-water system into an unequilibrated one     

V. A. Alexeyev  L. S. Medvedeva  N. P. Starshinova 《Geochemistry International》2013,51(5):382-404

Our long-lasting (up to 600 days) experiments conducted at 300°C in hermetically sealed gold and platinum ampoules with the application of quenching techniques demonstrate that the equilibrium quartz-water system ceases to be such in 200 days of the experiments: the concentration of dissolved silica decreases below the quartz solubility, and silica is redeposited (in the form of opal) at the bottom and walls of the ampoules above the water meniscus. Upon the passage of 400 days, when initial quartz completely disappears, the concentration of dissolved silica further decreases and becomes hundreds of times lower than the quartz solubility; all silica deposited above the meniscus is then transformed into secondary quartz. Analysis of our and literature experimental data indicates that this paradoxical behavior of silica can not be explained by (1) procedure errors (leakage of the ampoules and the quenching effect), (2) the synthesis of a new mineral of lower solubility, (3) simple recrystallization, and (4) the effect of the small pores of the newly formed silica. This effect is caused by the low temperature gradient (the temperature increases from below upward) of 0.25°C/cm, preferential water evaporation at the margin of the meniscus, and the ensuing local temperature decrease that stimulates water influx from its main volume because of the surface tension effect (Marangoni effect). Silica can be deposited on ampoule walls at water evaporation if the water influx rate to the meniscus is greater than the silica diffusion rate into the opposite direction. This can take place in natural, experimental, and technological systems involving a solution-vapor boundary and some low temperature gradient.  相似文献   

Detection of a neutrino signal from SN 1987A on February 23, 1987 at 7:35 UT: Data from the Baksan Underground Scintillation Telescope     

E. N. Alexeyev  L. N. Alexeyeva 《Astronomy Letters》2008,34(11):745-752

The signal detected by the Baksan Underground Scintillation Telescope comprises five events over a period of 9.1 s. Data from all detectors (Kamiokande II, IMB, Baksan, and LSD) are used to estimate the energy carried away from the stellar core in the form of electron antineutrinos.  相似文献   

A simple model for the evaporation of black holes at final stages     

S. O. Alexeyev  A. Barrow  G. Bowdole  M. V. Sazhin  O. S. Khovanskaya 《Astronomy Letters》2002,28(7):428-433

We present a simple model for the evaporation of primordial black holes at final stages with the formation of a relic remnant with a mass of 1–10³ m _P1. The model takes into account the conservation of energy and the impossibility of passing through the state with the minimum possible mass. These relic remnants may account for a substantial fraction of dark matter in the Universe.  相似文献   

Sectoral approaches to improve regional carbon budgets     

Pete Smith  Gert-Jan Nabuurs  Ivan A. Janssens  Stefan Reis  Gregg Marland  Jean-François Soussana  Torben R. Christensen  Linda Heath  Mike Apps  Vlady Alexeyev  Jingyun Fang  Jean-Pierre Gattuso  Juan Pablo Guerschman  Yao Huang  Esteban Jobbagy  Daniel Murdiyarso  Jian Ni  Antonio Nobre  Changhui Peng  Adrian Walcroft  Shao Qiang Wang  Yude Pan  Guang Sheng Zhou 《Climatic change》2008,88(3-4):209-249

Humans utilise about 40% of the earth’s net primary production (NPP) but the products of this NPP are often managed by different sectors, with timber and forest products managed by the forestry sector and food and fibre products from croplands and grasslands managed by the agricultural sector. Other significant anthropogenic impacts on the global carbon cycle include human utilization of fossil fuels and impacts on less intensively managed systems such as peatlands, wetlands and permafrost. A great deal of knowledge, expertise and data is available within each sector. We describe the contribution of sectoral carbon budgets to our understanding of the global carbon cycle. Whilst many sectors exhibit similarities for carbon budgeting, some key differences arise due to differences in goods and services provided, ecology, management practices used, land-management personnel responsible, policies affecting land management, data types and availability, and the drivers of change. We review the methods and data sources available for assessing sectoral carbon budgets, and describe some of key data limitations and uncertainties for each sector in different regions of the world. We identify the main gaps in our knowledge/data, show that coverage is better for the developed world for most sectors, and suggest how sectoral carbon budgets could be improved in the future. Research priorities include the development of shared protocols through site networks, a move to full carbon accounting within sectors, and the assessment of full greenhouse gas budgets.  相似文献   

Age and provenance of early Precambrian metasedimentary rocks in the Lapland–Kola Belt, Russia: evidence from Pb and Nd isotopic data     

D. Bridgwater  D. J. Scott  V. V. Balagansky  M. J. Timmerman  M. Marker  S. A. Bushmin  N. L. Alexeyev  & J. S. Daly 《地学学报》2001,13(1):32-37

²⁰⁷Pb/²⁰⁶Pb ages are presented for detrital zircons (Laser Ablation Microprobe ICP‐MS) and whole‐rock Nd isotopic determinations (TIMS) from samples of Neoarchean and Palaeoproterozoic metasedimentary rocks from the Umba granulite terrane and the Keivy domain of the Central Kola composite terrane, Kola Peninsula, north‐western Russia. Three are samples of rocks from the Umba granulite terrane that were deposited ≈ 2.20–1.90 Ga; they contain Archaean detritus, much of it older than 3.0 Gyr, as well as abundant 2.20–1.95‐Gyr‐old material. Deposition may have occurred on the margin of an Archaean craton with an exposed Palaeoproterozoic magmatic arc source, possibly during orogenesis. Two samples from the Keivy domain have remarkably similar, dominantly Archaean detrital zircon age spectra. One was deposited pre‐2.4 Ga, whereas the other was probably deposited post‐2.01 Ga. Both had similar sources, compatible with the proximal country rocks, and possible shallow‐water (?) cratonic margin depositional settings.  相似文献   

Some aspects of four-dimensional black hole solutions in gauss-bonnet extended string gravity     

S. O. Alexeyev  M. V. Sazhin 《Journal of Astrophysics and Astronomy》1999,20(3-4):259-268

An internal singularity of a string four-dimensional black hole with second order curvature corrections is investigated. A restriction to a minimal size of a neutral black hole is obtained in the frame of the model considered. Vacuum polarization of the surrounding space-time caused by this minimal-size black hole is also discussed.  相似文献