Investigagation of vibrations of variable cross-section linking elements

The applicability of analytical models for vibrations of variable cross-section two- layered cylindrical structural elements is investigated. Natural frequencies of longitudinal and lateral vibrations are calculated and validated experimentally. Natural frequency )( 0 n ? dependence on material properties (?, E) and geometric parameters (l, R, r, S) of structural element provide means for optimization of vibration amplitude characteristic

Vegetation responses to climatic changes during the late glacial according to palaeobotanical data in western Lithuania : a preliminary results

The organic-rich material has been studied from the bottom part of lacustrine sediments of the Lake Kasuciai, western Lithuania. Radiocarbon dates and palaeobotanical data showed that these sediments accumulated between 13,500 and 9000 14C yr BP. The Late Glacial interstadial is defined by the dominance of Characeae and accumulation of carbonate. The Bolling is characterized by the pioneer taxa and the communities of open habitats. During the Allerod pine replaced the light demanding taxa that show development of a closer woodland habitat and dryness of climate. The short period between Bolling and Allerod with increasing representation of Betula and plants typical for the highly eroded habitats could be correlated with Older Dryas. The onset of the Younger Dryas is marked by degradation of the forest cover and expansion of heliophytic grasses. Entire vegetation cover with birch and pine forest was settled during the Preborial. Formation of calcareous sediments and appearance of thermophilous taxa confirm the climatic amelioration

Population genomics of Bronze Age Eurasia

© 2015 Macmillan Publishers Limited. All rights reserved.The Bronze Age of Eurasia (around 3000-1000 BC) was a period of major cultural changes. However, there is debate about whether these changes resulted from the circulation of ideas or from human migrations, potentially also facilitating the spread of languages and certain phenotypic traits. We investigated this by using new, improved methods to sequence low-coverage genomes from 101 ancient humans from across Eurasia. We show that the Bronze Age was a highly dynamic period involving large-scale population migrations and replacements, responsible for shaping major parts of present-day demographic structure in both Europe and Asia. Our findings are consistent with the hypothesized spread of Indo-European languages during the Early Bronze Age. We also demonstrate that light skin pigmentation in Europeans was already present at high frequency in the Bronze Age, but not lactose tolerance, indicating a more recent onset of positive selection on lactose tolerance than previously thought

Population genomics of Bronze Age Eurasia

© 2015 Macmillan Publishers Limited. All rights reserved.The Bronze Age of Eurasia (around 3000-1000 BC) was a period of major cultural changes. However, there is debate about whether these changes resulted from the circulation of ideas or from human migrations, potentially also facilitating the spread of languages and certain phenotypic traits. We investigated this by using new, improved methods to sequence low-coverage genomes from 101 ancient humans from across Eurasia. We show that the Bronze Age was a highly dynamic period involving large-scale population migrations and replacements, responsible for shaping major parts of present-day demographic structure in both Europe and Asia. Our findings are consistent with the hypothesized spread of Indo-European languages during the Early Bronze Age. We also demonstrate that light skin pigmentation in Europeans was already present at high frequency in the Bronze Age, but not lactose tolerance, indicating a more recent onset of positive selection on lactose tolerance than previously thought

Population genomics of Bronze Age Eurasia

The Bronze Age of Eurasia (around 3000–1000 BC) was a period of major cultural changes. However, there is debate about whether these changes resulted from the circulation of ideas or from human migrations, potentially also facilitating the spread of languages and certain phenotypic traits. We investigated this by using new, improved methods to sequence low-coverage genomes from 101 ancient humans from across Eurasia. We show that the Bronze Age was a highly dynamic period involving large-scale population migrations and replacements, responsible for shaping major parts of present-day demographic structure in both Europe and Asia. Our findings are consistent with the hypothesized spread of Indo-European languages during the Early Bronze Age. We also demonstrate that light skin pigmentation in Europeans was already present at high frequency in the Bronze Age, but not lactose tolerance, indicating a more recent onset of positive selection on lactose tolerance than previously thought