Ethereum is a major blockchain-based platform for smart contracts -Turing complete programs that are executed in a decentralized network and usually manipulate digital units of value. Solidity is the most mature high-level smart contract language. Ethereum is a hostile execution environment, where anonymous attackers exploit bugs for immediate financial gain. Developers have a very limited ability to patch deployed contracts. Hackers steal up to tens of millions of dollars from flawed contracts, a well-known example being "The DAO", broken in June 2016. Advice on secure Ethereum programming practices is spread out across blogs, papers, and tutorials. Many sources are outdated due to a rapid pace of development in this field. Automated vulnerability detection tools, which help detect potentially problematic language constructs, are still underdeveloped in this area.We provide a comprehensive classification of code issues in Solidity and implement SmartCheck -an extensible static analysis tool that detects them 1 . SmartCheck translates Solidity source code into an XML-based intermediate representation and checks it against XPath patterns. We evaluated our tool on a big dataset of real-world contracts and compared the results with manual audit on three contracts. Our tool reflects the current state of knowledge on Solidity vulnerabilities and shows significant improvements over alternatives. SmartCheck has its limitations, as detection of some bugs requires more sophisticated techniques such as taint analysis or even manual audit. We believe though that a static analyzer should be an essential part of contract developers' toolbox, letting them fix simple bugs fast and allocate more effort to complex issues.

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The Middle Palaeolithic site Betovo was discovered in the early 1970s by L.M. Tarasov, who summarized data on paleoecology and habitat conditions on this site in a number of publications. However, the stratigraphic position of the deposits containing the cultural layer remained rather uncertain due to the fact that in the sections of the site it was not possible to identify the reference loess-soil horizons and data on the age of the cultural layer were not obtained. A comprehensive study of the site, renewed since 2007 under the direction of archaeologist A. K. Ocherednoi in the frame of the Verkhnyaya Desna expedition of the Institute for the History of Material Culture RAS, permit to detail the deposition rhythmic during the Late Pleistocene and the stratigraphic position of the cultural layers in different parts of the site. By received 14 C data, the site was inhabited in the range of 28.5–36.0 cal kyr BP (calibrated dates), i.e., belongs to the end of the Valdai megainterstadial (the end of MIS 3). The small mammal fauna found in the 2 cultural layer of the Betovo site includes only the tundra and steppe species. The forest species are absent. The species richness of the Betovo fauna is very low, what also indicates the very severe climate during the end of MIS 3 in the Desna River basin. The received mammalian data clearly indicate the extremely harsh natural-climatic conditions of the time of habitation of the ancient man in the site – the conditions of tundra-steppe (“mammoth steppe”).

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