Contribution to the knowledge of Crataego-Prunetea Tüxen 1962 class in Bulgaria

Mantle vegetation includes plant communities dominated mostly by shrubs and occurs in habitats where the typical tree layers meet difficulties to evolve. This study was conducted in three areas of Bulgaria – Western Balkan Range, Western Sredna Gora Mt. and the Fore-Balkan. Numerical classification and ordination were performed by PC-ORD and JUICE software packages. Diagnostic species were determined by calculating the Phi-coefficient. Two associations and one plant community of the Berberidion alliance were recognized – Corno-Ligustretum Horvat ex Trinajstić & Z. Pavletić 1991, Pruno spinosae-Ligustretum vulgaris Tüxen 1952 and Elytrigia repens-Crataegus monogyna community. The latter considered as a successional stage of shrub encroachment into the grasslands. Its species composition is very close to that of the ass. Corno-Ligustretum. The species composition of ass. Pruno-Ligustretum represents a mixture of species characteristic for dry and mesic grasslands, fringe and forest vegetation.The Crataego-Prunetea class is still poorly studied in Bulgaria and much more data from all regions in the country have to be collected

Revisiting the time of the last mass straightening bends on the upper Kama

The scientists investigating channels and palaeographers still do not have a clear answer to the question when the last mass channel directional change processes started on the upper Kama and its tributaries. Distinct morphometrical parameters of numerous ox-bows, now located along relatively straight channel parts and at the same time absence of imperforation (ageing) signs do not allow to makes unambiguous conclusions about the duration of directional straightening of the river and major restructuring of the floodplain-channel complexes. Finding the answer to this question included: a) the analysis of historical documents and local folklore that mention change in the location (removal) of the Kama channel; b) comparison of the degree of the Kama ox-bows imperforation and peat overgrowing with the standard peat accumulation rates under the conditions of taiga landscapes. According to the results of complex analysis the following suggestion has been made – the beginning of the last mass straightening bends of the upper Kama was in the second half the Subatlantic period.The scientists investigating channels and palaeographers still do not have a clear answer to the question when the last mass channel directional change processes started on the upper Kama and its tributaries. Distinct morphometrical parameters of numerous ox-bows, now located along relatively straight channel parts and at the same time absence of imperforation (ageing) signs do not allow to makes unambiguous conclusions about the duration of directional straightening of the river and major restructuring of the floodplain-channel complexes. Finding the answer to this question included: a) the analysis of historical documents and local folklore that mention change in the location (removal) of the Kama channel; b) comparison of the degree of the Kama ox-bows imperforation and peat overgrowing with the standard peat accumulation rates under the conditions of taiga landscapes. According to the results of complex analysis the following suggestion has been made – the beginning of the last mass straightening bends of the upper Kama was in the second half the Subatlantic period

Groundwater compatibility with formation water and pay zone rocks in Pervomaysk oil-gas-condensate field to maintain formation pressure

The paper describes the research results in determining the compatibility of groundwater from Aptain-Albian-Cenomanian aquifer with formation water and pay zone rocks in U1 layer sediments, Pervomaysk oil field

Subjective Sleepiness Dynamics Dataset (SSDD) Presentation: the Study of Two Scales Consistency

While the first references to the system of sleepiness assessment are associated with medical re-search and the study of the effects of drugs on sleep, currently subjective sleepiness assessment is widely used across fundamental and practically oriented studies. The Stanford Sleepiness Scale (SSS) and the Karolinska Sleepiness Scale (KSS) are often used as ground truth in sleepiness re-search. Only a few studies applied both scales and practically none aimed at studying their con-sistency and specific features. The present study is devoted to analyzing the dynamics and con-sistency of subjective sleepiness as measured by the KSS and the SSS in the adult population. A particular task of the paper is to present the Subjective Sleepiness Dynamics Dataset (SSDD) with the evening and morning dynamics of situational subjective sleepiness. A total of 208 adults took part in the experiment. The results of the study revealed that sleepiness generally increased from evening till night and was maximal at early morning. The SSS score appeared to be more sensitive to some factors (e.g., the presence of sleep problems). The SSS and KSS scores were strongly consistent with each other. The KSS showed a generally more even distribution than the SSS. SSDD continues to be collected, we are going to equalize the sample by sex, we are actively adding older people. We plan to collect a sample of 1,000 people. Currently SSDD contains a lot of in-formation that can be used for scientific research.Comment: 18 pages, 6 figures, 3 table

RADIOCARBON DATING CALIBRATION IN ARCHEOLOGICAL STUDIES

This volume of the Baltic Pontic Studies focuses on the results of the research carried out so far into the absolute (radiocarbon) chronology of the area lying between the Vistula and Dnieper or the bio-cultural borderland between the West and East of Europe. Absolute chronology is treated here both as a research goal and fundamental premise in the broader studies of the chronometrie and development synchronization of "borderland" cultural systems. In a series of articles devoted to individual taxa a considerable number of new 14C dates have been compared. The dates concern source materials that have been chosen from the point of view of their representativeness and chronometrie value ("short-lived" materials were preferred to minimize a potential error). The vast majority of analyses were purposefully made in the same 14C laboratory of the State Scientific Center of Environmental Radiogeochemistry of Ukrainian Academy of Sciences in Kiev taking advantage of funds generously provided by the Polish Committee for Scientific Research. The volume devoted to the "dark" section of the "borderland" history (3150-1850 BC) is the first but not the last publication on the broader issues mentioned above that we intend to present in the near future

Contribution to the knowledge of Crataego-Prunetea Tüxen 1962 class in Bulgaria

Mantle vegetation includes plant communities dominated mostly by shrubs and occurs in habitats where the typical tree layers meet difficulties to evolve. This study was conducted in three areas of Bulgaria – Western Balkan Range, Western Sredna Gora Mt. and the Fore-Balkan. Numerical classification and ordination were performed by PC-ORD and JUICE software packages. Diagnostic species were determined by calculating the Phi-coefficient. Two associations and one plant community of the Berberidion alliance were recognized – Corno-Ligustretum Horvat ex Trinajstić ---amp--- Z. Pavletić 1991, Pruno spinosae-Ligustretum vulgaris Tüxen 1952 and Elytrigia repens-Crataegus monogyna community. The latter considered as a successional stage of shrub encroachment into the grasslands. Its species composition is very close to that of the ass. Corno-Ligustretum. The species composition of ass. Pruno-Ligustretum represents a mixture of species characteristic for dry and mesic grasslands, fringe and forest vegetation. The Crataego-Prunetea class is still poorly studied in Bulgaria and much more data from all regions in the country have to be collected

Resistance force pulsations of annular flow in the Couette-Taylor system with counter-rotating cylinders

The paper presents the results of an experimental study of the Couette-Taylor flow fluctuations in a ring channel with oppositely rotating multicylinder rotors. Experiments were carried out using water-glycerine solutions as a working fluid. The rotation resistance moment and its pulsations were investigated, using the system for measuring the torque resistance of rotation of rotors, made in the form of a digital dynamometer based on a tension sensor. The investigations made it possible to establish that the classic dependence of the appearance of Taylor vortices is observed in the slit flow of a multicylinder system rotating oppositely. It was shown that in the range of Reynolds numbers Re = (100 – 500), pulsations of dissipative processes with variable frequency and amplitude up to 10% of the mean value of rotation resistance are observed