6 research outputs found

    Sorption of 137Cs and 60Co on Titanium Oxide Films in Light Water Reactor Primary Circuit Environment

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    This paper discusses the processes of the long-lived 137Cs and 60Co immobilization on titanium surfaces in simulated light water reactor primary circuit environments. This study is prompted by numerous problems in both the maintenance of equipment during reactor operation and the dismantling of the reactor after the completion of the operation, which is associated with contamination of working surfaces with long-lived radionuclides. The composition of the oxide films formed on the surface of commercial titanium alloy ПT-3B has been studied with specimens prepared in autoclave test conditions and surface samples from the pipeline sections to which the primary coolant was applied. These films on the coolant pipeline surface consist of a titanium dioxide layer tightly adhered to the pipeline metal surface and weakly fixed deposits—crystallites comprised of titanium oxides and other corrosion products (oxides and hydrated oxides of iron, nickel, chromium etc.). The radionuclide composition of the samples was studied by gamma-spectrometry. It is shown that the mechanism of titanium-surface contamination with 137Cs is by physisorption, contamination level increases upon the presence of dispersed particles. For 60Co, both sorption and deposition onto surfaces are observed

    The origins and spread of domestic horses from the Western Eurasian steppes

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    This is the final version. Available on open access from Nature Research via the DOI in this recordData availability: All collapsed and paired-end sequence data for samples sequenced in this study are available in compressed fastq format through the European Nucleotide Archive under accession number PRJEB44430, together with rescaled and trimmed bam sequence alignments against both the nuclear and mitochondrial horse reference genomes. Previously published ancient data used in this study are available under accession numbers PRJEB7537, PRJEB10098, PRJEB10854, PRJEB22390 and PRJEB31613, and detailed in Supplementary Table 1. The genomes of ten modern horses, publicly available, were also accessed as indicated in their corresponding original publications57,61,85-87.NOTE: see the published version available via the DOI in this record for the full list of authorsDomestication of horses fundamentally transformed long-range mobility and warfare. However, modern domesticated breeds do not descend from the earliest domestic horse lineage associated with archaeological evidence of bridling, milking and corralling at Botai, Central Asia around 3500 BC. Other longstanding candidate regions for horse domestication, such as Iberia and Anatolia, have also recently been challenged. Thus, the genetic, geographic and temporal origins of modern domestic horses have remained unknown. Here we pinpoint the Western Eurasian steppes, especially the lower Volga-Don region, as the homeland of modern domestic horses. Furthermore, we map the population changes accompanying domestication from 273 ancient horse genomes. This reveals that modern domestic horses ultimately replaced almost all other local populations as they expanded rapidly across Eurasia from about 2000 BC, synchronously with equestrian material culture, including Sintashta spoke-wheeled chariots. We find that equestrianism involved strong selection for critical locomotor and behavioural adaptations at the GSDMC and ZFPM1 genes. Our results reject the commonly held association between horseback riding and the massive expansion of Yamnaya steppe pastoralists into Europe around 3000 BC driving the spread of Indo-European languages. This contrasts with the scenario in Asia where Indo-Iranian languages, chariots and horses spread together, following the early second millennium BC Sintashta culture

    The formation of human populations in South and Central Asia

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    By sequencing 523 ancient humans, we show that the primary source of ancestry in modern South Asians is a prehistoric genetic gradient between people related to early hunter-gatherers of Iran and Southeast Asia. After the Indus Valley Civilization's decline, its people mixed with individuals in the southeast to form one of the two main ancestral populations of South Asia, whose direct descendants live in southern India. Simultaneously, they mixed with descendants of Steppe pastoralists who, starting around 4000 years ago, spread via Central Asia to form the other main ancestral population. The Steppe ancestry in South Asia has the same profile as that in Bronze Age Eastern Europe, tracking a movement of people that affected both regions and that likely spread the distinctive features shared between Indo-Iranian and Balto-Slavic languages.N.P. carried out this work while a fellow at the Radcliffe Institute for Advanced Study at Harvard University. P.M. was supported by a Burroughs Wellcome Fund CASI award. N.N. is supported by a NIGMS (GM007753) fellowship. T.C. and A.D. were supported by the Russian Science Foundation (project 14-50-00036). T.M.S. was supported by the Russian Foundation for Basic Research (grant 18-09-00779) ‚ÄúAnthropological and archaeological aspects of ethnogenesis of the population of the southern part of Western and Central Siberia in the Neolithic and Early Bronze Age.‚ÄĚ D.P., S.S., and D.L. were supported by European Research Council ERC-2011-AdG 295733 grant (Langelin). O.M. was supported by a grant from the Ministry of Education and Sciences of the Russian Federation No. 33.1907, 2017/ő†4 ‚ÄúTraditional and innovational models of a development of ancient Volga population‚ÄĚ. A.E. was supported by a grant from the Ministry of Education and Sciences of the Russian Federation No. 33.5494, 2017/BP ‚ÄúBorderlands of cultural worlds (Southern Urals from Antiquity to Early Modern period).‚ÄĚ Radiocarbon dating work supported by the NSF Archaeometry program BCS-1460369 to D.Ken. and B.J.C. and by the NSF Archaeology program BCS-1725067 to D.Ken. K.Th. was supported by NCP fund (MLP0117) of the Council of Scientific and Industrial Research (CSIR), Government of India, New Delhi. N.Bo., A.N., and M.Z. were supported by the Max Planck Society. D.Re. is an Investigator of the Howard Hughes Medical Institute, and his ancient DNA laboratory work was supported by National Science Foundation HOMINID grant BCS-1032255, by National Institutes of Health grant GM100233, by an Allen Discovery Center grant, and by grant 61220 from the John Templeton Foundation

    Connecting neutrino Astrophysics to Multi-TeV to PeV gamma-ray astronomy with TAIGA

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    Recent evidence for neutrinos in the PeV energy range from IceCube provides additional motivation for the search for the most energetic Galactic accelerators. Gamma-ray astronomy is a sound strategy to reach this goal, providing the energy range beyond 10\,TeV can be covered at a sufficient sensitivity level. The energy spectra of most known gamma-ray emitters only reach up to few 10s of TeV. The HEGRA IACT installation reported evidence for gamma-ray energies from the Crab Nebula as high as 80\,TeV. Uncovering their spectral shape up to few 100s of TeV could answer the question whether some of these objects are cosmic ray Pevatrons, i.e. Galactic PeV accelerators. Extending observations beyond this energy range requires very large effective detector areas, as planned by the TAIGA collaboration

    Simulation of imaging air shower Cherenkov telescopes as part of the TAIGA Project

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    The Tunka Advanced International Gamma-ray and Cosmic ray Astrophysics (TAIGA) project aims at observation of cosmic rays beyond 100 TeV and gamma rays above 1 TeV via observation of the extensive air showers (EAS) caused in the atmosphere. Two common detection techniques are timing arrays and imaging air shower cherenkov telescopes (IACT). Timing arrays yield good directional and energy reconstruction, but provide only mediocre gamma-hadron-separation at their energy threshold. IACTs are good at separation, but since a stereoscopic view of a shower is needed for high reconstruction accuracy, it is difficult to achieve the large effective areas needed for ultra high energy observations. In this work we present the simulations performed to explore and optimize our IACT design and the first steps towards hybrid reconstruction