427 research outputs found

    A Review of Neogene and Quaternary Pikes of Southeastern Europe and a New Species from the Early Pleistocene of Nogaisk, Ukraine

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    The fish genus Esox (Teleostei, Esocidae) has been recorded from thirty late Miocene, Pliocene, and Pleistocene localities where forty-one bone-bearing strata are exposed in the territory of Ukraine, Russian Federation, and Republic of Moldova. From eight localities the genus is reported or described for the first time. A detailed description and morphological analysis of the currently available osteological material demonstrates the presence of four species in the studied area: (i) Esox sibiricus (late Miocene–early Pliocene); (ii) Esox moldavicus (early Pliocene–early Pleistocene); (iii) Esox nogaicus sp. nov. (early Pleistocene, Calabrian); (iv) Esox lucius (early–middle Pleistocene). The Northern Pike (Esox lucius) is recorded for the first time in the early Pleistocene fossil record of southeastern Europe. The new species E. nogaicus is characterized by a massive dentary with deep symphysis and the possible presence of a pair of fixed canine-like teeth near the anterior end of the vomer. Such canine teeth are seen also in certain species known only from North America, the extant Esox masquinongy, the fossil species E. columbianus, and an unnamed Miocene form. However, unlike in E. nogaicus, in the three North American species fixed canines also occur anteriorly on the palatines. The Miocene, Pliocene, and Pleistocene pikes from southeastern Europe document a greater diversity of morphologies in the past than exists today in the pike species of Europe. Changes in the predominant species of Esox in southeastern Europe are hypothesized to be driven by changing global and regional climates

    Ukrainian Iconography of the Late XX–Early XXI Century: Trends and Leading Schools

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    The article deals with the development of modern Ukrainian iconography, the formation of the main centers and regional schools, traces artistic and stylistic features and trends. The article analyzes the activities of the Kyiv and Lviv Art Schools in the field of sacred art. The main features of the development of modern iconography are identified, the creativity of leading specialists and iconographers, genres and technological specifics of iconography are studied. The scientific novelty of this research consists in a comprehensive study of modern Ukrainian iconography, taking into account artistic and stylistic, regional, technological, and canonical aspects. Features of formation of art schools and associations of sacred art in Ukraine are traced. The aim of the study is to determine the main trends in the development of modern Ukrainian iconography, to identify the influence of leading schools in the field of sacred art. The methodological basis is a comprehensive approach to the analysis of cultural and artistic phenomena in the chronological and theoretical aspects of the development of modern sacred art in Ukraine

    Dielectric and electrical properties of nematic liquid crystals 6CB doped with iron oxide nanoparticles. The combined effect of nanodopant concentration and cell thickness

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    Dispersing nanomaterials in liquid crystals has emerged as a very promising non-synthetic way to produce advanced multifunctional and tunable materials. As a rule, dielectric and electrical characterization of such materials is performed using cells of single thickness. As a result, the published reports vary even for similar systems. Confusion still exists as to the effects of nanodopants and cell thickness on the dielectric and electrical properties of liquid crystals. This factor hinders a widespread use of liquid crystals – nanoparticles systems in modern tech products. In this paper, we report systematic experimental studies of the combined effect of the cell thickness and iron oxide nanoparticle concentration on the electrical and dielectric properties of nematic liquid crystals 6CB. The measured dielectric spectra can be divided into three distinct regions corresponding to a low frequency (<10 Hz) dispersion, dispersion free range (102 - 104 Hz (electrical conductivity) and 102 - 105 (dielectric permittivity)), and high frequency dispersion (104 - 106 Hz (electrical conductivity) and 105 - 106 Hz (dielectric permittivity)). The real part of the dielectric permittivity is not affected by the cell thickness and its value can be tuned by changing the concentration of nanoparticles. At the same time, the electrical conductivity depends on both cell thickness and nanoparticle concentration. At intermediate frequencies (102 - 104 Hz) the electrical conductivity obeys the Jonscher power law and is dependent on the cell thickness because of ion-releasing and ioncapturing effects caused by nanoparticles and substrates of the cell. In addition, its value is affected by the electronic conductivity due to iron oxide nanoparticles and their nanoclusters. At higher frequencies (104 - 106 Hz) the electrical conductivity follows a super linear power law and is nearly independent of the cell thickness and nanoparticle concentration

    Browsers, grazers or mix-feeders? Study of the diet of extinct Pleistocene Eurasian forest rhinoceros Stephanorhinus kirchbergensis (Jšager, 1839) and woolly rhinoceros Coelodonta antiquitatis (Blumenbach, 1799)

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    The wooly rhinoceros (Coelodonta antiquitatis) and forest rhinoceros (Stephanorhinus kirchbergensis) were prominent representatives of the Middle and Late Pleistocene glacial and interglacial faunas of Eurasia. Their diet has traditionally been inferred on functional morphology of the dentition and skull. In rare cases, food remains are preserved in the fossas of the teeth or as gut content. New approaches to infer diet include the study of isotopes and mesowear. Here we apply all four methods to infer the diet of these emblematic rhinoceros’ species and compare the food actually taken with the food available, as indicated by independent botanical data from the localities where the rhinoceros’ fossils were found: Gorz®ow Wielkopolski (Eemian) and Starunia (Middle Vistulian) as well as analysis of literature data. We also made inferences on the season of death of these individuals. Our results indicate that the woolly rhino in both Europe and Asia (Siberia) was mainly a grazer, although at different times of the year and depending on the region its diet was also supplemented by leaves of shrubs and trees. According to the results of isotope studies, there were important individual variations. The data show a clear seasonal variation in the isotope composition of this rhino’s diet. In contrast, Stephanorhinus kirchbergensis was a browser, though its diet included low-growing vegetation. Its habitat consisted of various types of forests, from riparian to deciduous and mixed forests, and open areas. The diet of this species consisted of selected items of vegetation, also including plants growing near both flowing and standing waters. The food remains from the fossae of the teeth indicated flexible browsing, confirming the previous interpretations based on functional morphology and stable isotopes. Long-term data from mesowear and microwear across a wider range of S. kirchbergensis fossils indicate a more mixed diet with a browsing component. The different diets of both of rhinoceros reflect not only the different habitats, but also climate changes that occurred during the Late Pleistocene

    Pathway for the Biosynthesis of the Pigment Chrysogine by Penicillium chrysogenum

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    Chrysogine is a yellow pigment produced by Penicillium chrysogenum and other filamentous fungi. Although the pigment was first isolated in 1973, its biosynthetic pathway has so far not been resolved. Here, we show that deletion of the highly expressed nonribosomal peptide synthetase (NRPS) gene Pc21g12630 (chyA) resulted in a decrease in the production of chrysogine and 13 related compounds in the culture broth of P. chrysogenum. Each of the genes of the chyAcontaining gene cluster was individually deleted, and corresponding mutants were examined by metabolic profiling in order to elucidate their function. The data suggest that the NRPS ChyA mediates the condensation of anthranilic acid and alanine into the intermediate 2-(2-aminopropanamido) benzoic acid, which was verified by feeding experiments of a Delta chyA strain with the chemically synthesized product. The remainder of the pathway is highly branched, yielding at least 13 chrysogine-related compounds. IMPORTANCE Penicillium chrysogenum is used in industry for the production of Delta-lactams, but also produces several other secondary metabolites. The yellow pigment chrysogine is one of the most abundant metabolites in the culture broth, next to Delta-lactams. Here, we have characterized the biosynthetic gene cluster involved in chrysogine production and elucidated a complex and highly branched biosynthetic pathway, assigning each of the chrysogine cluster genes to biosynthetic steps and metabolic intermediates. The work further unlocks the metabolic potential of filamentous fungi and the complexity of secondary metabolite pathways

    Diversity of muskox Ovibos moschatus (Zimmerman, 1780) (Bovidae, Mammalia) in time and space based on cranial morphometry

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    Muskox Ovibos moschatus is a Pleistocene relic, which has survived only in North America and Greenland. During the Pleistocene, it was widely distributed in Eurasia and North America. To evaluate its morphological variability through time and space, we conducted an extensive morphometric study of 217 Praeovibos and Ovibos skull remains. The analyses showed that the skulls grew progressively wider from Praeovibos sp. to the Pleistocene O. moschatus, while from the Pleistocene to the recent O. moschatus, the facial regions of the skull turned narrower and shorter. We also noticed significant geographic differences between the various Pleistocene Ovibos crania. Siberian skulls were usually larger than those from Western and Central Europe. Eastern Europeanmuskoxen also exceeded in size those from the other regions of Europe. The large size of Late Pleistocene muskoxen from regions located in more continental climatic regimes was probably associated with the presence of more suitable food resources in steppe-tundra settings. Consistently, radiocarbon-dated records of this species are more numerous in colder periods, when the steppe-tundra was widely spread, and less abundant in warmer periods

    ĐșĐŸĐ»Đ”ĐșтоĐČĐœĐ° ĐŒĐŸĐœĐŸĐłŃ€Đ°Ń„Ń–Ń

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    ĐšŃ€ĐžĐŒŃ–ĐœĐ°Đ»ŃŒĐœĐžĐč ĐżŃ€ĐŸŃ†Đ”ŃŃƒĐ°Đ»ŃŒĐœĐžĐč ĐșĐŸĐŽĐ”Đșс 2012 Ń€ĐŸĐșу: Ń–ĐŽĐ”ĐŸĐ»ĐŸĐłŃ–Ń та праĐșтоĐșĐ° праĐČĐŸĐ·Đ°ŃŃ‚ĐŸŃŃƒĐČĐ°ĐœĐœŃ: ĐșĐŸĐ»Đ”ĐșтоĐČĐœĐ° ĐŒĐŸĐœĐŸĐłŃ€Đ°Ń„Ń–Ń / Đ·Đ° Đ·Đ°Đł. рДЎ. Đź. П. ĐĐ»Đ”ĐœŃ–ĐœĐ° ; ĐČŃ–ĐŽĐżĐŸĐČ. Đ·Đ° ĐČОп. І. В. Đ“Đ»ĐŸĐČюĐș. - ОЎДса : ВоЮаĐČĐœĐžŃ‡ĐžĐč ĐŽŃ–ĐŒ Â«Đ“Đ”Đ»ŃŒĐČДтОĐșа», 2018. - 1148 с

    Measurement of the Splitting Function in &ITpp &ITand Pb-Pb Collisions at root&ITsNN&IT=5.02 TeV

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    Data from heavy ion collisions suggest that the evolution of a parton shower is modified by interactions with the color charges in the dense partonic medium created in these collisions, but it is not known where in the shower evolution the modifications occur. The momentum ratio of the two leading partons, resolved as subjets, provides information about the parton shower evolution. This substructure observable, known as the splitting function, reflects the process of a parton splitting into two other partons and has been measured for jets with transverse momentum between 140 and 500 GeV, in pp and PbPb collisions at a center-of-mass energy of 5.02 TeV per nucleon pair. In central PbPb collisions, the splitting function indicates a more unbalanced momentum ratio, compared to peripheral PbPb and pp collisions.. The measurements are compared to various predictions from event generators and analytical calculations.Peer reviewe

    Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

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    Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (Ό̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ÂŻ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ÂŻ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),Ό̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| &lt; 0.03 at 95% confidence level. [Figure not available: see fulltext.

    Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

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