108 research outputs found

    Late glacial and holocene palaeovegetation and palaeogeography of Eastern Fennoscandia

    Get PDF
    The monograph is a generalization based on the analysis and synthesis of the voluminous scope of data on the dynamics of palaeovegetation and its mapping, along with aspects of palaeogeography of the Kola Peninsula and Karelia. All the elements of past landscapes are considered against the background of the present state of environments: geology, geomorphology and vegetation. The interval under consideration embraces the Late Glacial Time (12 000-10 300 years BP) and the Holocene (from 10 300 years BP up to the present). The book discusses the methodical and theoretical treatments of the last decade. As a result, the dynamics of past landscapes are shown in the unity of all their components (i.e., relief, hydrology and vegetation), and in comparison with their present-day parameters. Cartographic and textual materials on geology and modern vegetation as well as palaeovegetation maps of model territories used in this book are entirely original. The model territories are rather evenly distributed throughout the Kola Peninsula and Karelia. Seven of them are represented in this work; for each of model territory, a series of maps (for 10 500, 9 500, 8 500, 5 500, 3 000, and 1 000 years BP) are provided, correlated with relief and present-day vegetation. The second stage of data generalization is a comparison of maps related to the same temporal sections. The sequence of the maps from ‘older’ to ‘younger’ characterizes the dynamics of chorological palaeovegetation units. These dynamics readily illustrate shifts of geographical zones in space and time

    Macro- and microelemental composition of the Antarctic fish blood serum

    No full text
    The research materials were selected during the 9-th Ukrainian Antarctic expedition in Academic Vernadsky station region. For analysis the fish samples that related to Nototheniidae, Bathydraconidae and Chaenichthyidae were used. The elemental composition of fish blood serum was estimated by flame atomic absorption spectroscopy and X-ray fluorescence spectroscopy. The elemental analysis of blood serum of the Antarctic fish revealed the species- dependent distribution. The expedience of the fish blood serum use for environmental biotesting is proposed

    Measurements of Dihadron Correlations Relative to the Event Plane in Au+Au Collisions at sNN=200\sqrt{s_{NN}}=200 GeV

    Full text link
    Dihadron azimuthal correlations containing a high transverse momentum (\pt) trigger particle are sensitive to the properties of the nuclear medium created at RHIC through the strong interactions occurring between the traversing parton and the medium, i.e. jet-quenching. Previous measurements revealed a strong modification to dihadron azimuthal correlations in Au+Au collisions with respect to \pp\ and \dAu\ collisions. The modification increases with the collision centrality, suggesting a path-length dependence to the jet-quenching effect. This paper reports STAR measurements of dihadron azimuthal correlations in mid-central (20-60\%) Au+Au collisions at \snn=200~GeV as a function of the trigger particle's azimuthal angle relative to the event plane, \phis=|\phit-\psiEP|. The azimuthal correlation is studied as a function of both the trigger and associated particle \pt. The subtractions of the combinatorial background and anisotropic flow, assuming Zero Yield At Minimum (\zyam), are described. The away-side correlation is strongly modified, and the modification varies with \phis, which is expected to be related to the path-length that the away-side parton traverses. The pseudo-rapidity (\deta) dependence of the near-side correlation, sensitive to long range \deta correlations (the ridge), is also investigated. The ridge and jet-like components of the near-side correlation are studied as a function of \phis. The ridge appears to drop with increasing \phis while the jet-like component remains approximately constant. ...Comment: 50 pages, 39 figures, 6 table

    Studies of di-jet survival and surface emission bias in Au+Au collisions via angular correlations with respect to back-to-back leading hadrons

    Get PDF
    We report first results from an analysis based on a new multi-hadron correlation technique, exploring jet-medium interactions and di-jet surface emission bias at RHIC. Pairs of back-to-back high transverse momentum hadrons are used for triggers to study associated hadron distributions. In contrast with two- and three-particle correlations with a single trigger with similar kinematic selections, the associated hadron distribution of both trigger sides reveals no modification in either relative pseudo-rapidity or relative azimuthal angle from d+Au to central Au+Au collisions. We determine associated hadron yields and spectra as well as production rates for such correlated back-to-back triggers to gain additional insights on medium properties.Comment: By the STAR Collaboration. 6 pages, 2 figure

    System size and energy dependence of near-side di-hadron correlations

    Get PDF
    Two-particle azimuthal (Δϕ\Delta\phi) and pseudorapidity (Δη\Delta\eta) correlations using a trigger particle with large transverse momentum (pTp_T) in dd+Au, Cu+Cu and Au+Au collisions at sNN\sqrt{s_{{NN}}} =\xspace 62.4 GeV and 200~GeV from the STAR experiment at RHIC are presented. The \ns correlation is separated into a jet-like component, narrow in both Δϕ\Delta\phi and Δη\Delta\eta, and the ridge, narrow in Δϕ\Delta\phi but broad in Δη\Delta\eta. Both components are studied as a function of collision centrality, and the jet-like correlation is studied as a function of the trigger and associated pTp_T. The behavior of the jet-like component is remarkably consistent for different collision systems, suggesting it is produced by fragmentation. The width of the jet-like correlation is found to increase with the system size. The ridge, previously observed in Au+Au collisions at sNN\sqrt{s_{{NN}}} = 200 GeV, is also found in Cu+Cu collisions and in collisions at sNN\sqrt{s_{{NN}}} =\xspace 62.4 GeV, but is found to be substantially smaller at sNN\sqrt{s_{{NN}}} =\xspace 62.4 GeV than at sNN\sqrt{s_{{NN}}} = 200 GeV for the same average number of participants (Npart \langle N_{\mathrm{part}}\rangle). Measurements of the ridge are compared to models.Comment: 17 pages, 14 figures, submitted to Phys. Rev.

    Observation of the antimatter helium-4 nucleus

    Get PDF
    High-energy nuclear collisions create an energy density similar to that of the universe microseconds after the Big Bang, and in both cases, matter and antimatter are formed with comparable abundance. However, the relatively short-lived expansion in nuclear collisions allows antimatter to decouple quickly from matter, and avoid annihilation. Thus, a high energy accelerator of heavy nuclei is an efficient means of producing and studying antimatter. The antimatter helium-4 nucleus (4Heˉ^4\bar{He}), also known as the anti-{\alpha} (αˉ\bar{\alpha}), consists of two antiprotons and two antineutrons (baryon number B=-4). It has not been observed previously, although the {\alpha} particle was identified a century ago by Rutherford and is present in cosmic radiation at the 10% level. Antimatter nuclei with B < -1 have been observed only as rare products of interactions at particle accelerators, where the rate of antinucleus production in high-energy collisions decreases by about 1000 with each additional antinucleon. We present the observation of the antimatter helium-4 nucleus, the heaviest observed antinucleus. In total 18 4Heˉ^4\bar{He} counts were detected at the STAR experiment at RHIC in 109^9 recorded Au+Au collisions at center-of-mass energies of 200 GeV and 62 GeV per nucleon-nucleon pair. The yield is consistent with expectations from thermodynamic and coalescent nucleosynthesis models, which has implications beyond nuclear physics.Comment: 19 pages, 4 figures. Submitted to Nature. Under media embarg

    Identified hadron compositions in p+p and Au+Au collisions at high transverse momenta at sNN=200\sqrt{s_{_{NN}}} = 200 GeV

    Get PDF
    We report transverse momentum (pT15p_{T} \leq15 GeV/cc) spectra of π±\pi^{\pm}, K±K^{\pm}, pp, pˉ\bar{p}, KS0K_{S}^{0}, and ρ0\rho^{0} at mid-rapidity in p+p and Au+Au collisions at sNN\sqrt{s_{_{NN}}} = 200 GeV. Perturbative QCD calculations are consistent with π±\pi^{\pm} spectra in p+p collisions but do not reproduce KK and p(pˉ)p(\bar{p}) spectra. The observed decreasing antiparticle-to-particle ratios with increasing pTp_T provide experimental evidence for varying quark and gluon jet contributions to high-pTp_T hadron yields. The relative hadron abundances in Au+Au at pT>8p_{T}{}^{>}_{\sim}8 GeV/cc are measured to be similar to the p+p results, despite the expected Casimir effect for parton energy loss.Comment: 6 pages, 3 figures, published at PR

    Strangeness Enhancement in Cu+Cu and Au+Au Collisions at \sqrt{s_{NN}} = 200 GeV

    Get PDF
    We report new STAR measurements of mid-rapidity yields for the Λ\Lambda, Λˉ\bar{\Lambda}, KS0K^{0}_{S}, Ξ\Xi^{-}, Ξˉ+\bar{\Xi}^{+}, Ω\Omega^{-}, Ωˉ+\bar{\Omega}^{+} particles in Cu+Cu collisions at \sNN{200}, and mid-rapidity yields for the Λ\Lambda, Λˉ\bar{\Lambda}, KS0K^{0}_{S} particles in Au+Au at \sNN{200}. We show that at a given number of participating nucleons, the production of strange hadrons is higher in Cu+Cu collisions than in Au+Au collisions at the same center-of-mass energy. We find that aspects of the enhancement factors for all particles can be described by a parameterization based on the fraction of participants that undergo multiple collisions

    Variation in RNA expression and genomic DNA content acquired during cell culture

    Get PDF
    Specific chromosomal abnormalities are increasingly recognised to be associated with particular tumour subtypes. These cytogenetic abnormalities define the sites of specific genes, the alteration of which is implicated in the neoplastic process. We used comparative genomic hybridisation (CGH) to examine DNA from different breast and ovarian cancer cell lines for variations in DNA sequence copy number compared with the same normal control. We also compared different sources of the MCF7 breast line by both CGH and cDNA expression arrays. Some of the differences between the subcultures were extensive and involved large regions of the chromosome. Differences between the four subcultures were observed for gains of 2q, 5p, 5q, 6q, 7p, 7q, 9q, 10p, 11q, 13q, 14c, 16q, 18p and 20p, and losses of 4q, 5p, 5q, 6q, 7q, 8p, 11p, 11q, 12q, 13q, 15q, 19p, 19q, 20p, 21q, 22q and Xp. However, few variations were found between two subcultures examined, 5 months apart, from the same initial source. The RNA arrays also demonstrated considerable variation between the three different subcultures, with only 43% of genes expressed at the same levels in all three. Moreover, the patterns of the expressed genes did not always reflect our observed CGH aberrations. These results demonstrate extensive genomic instability and variation in RNA expression during subculture and provide supportive data for evidence that cell lines do evolve in culture, thereby weakening the direct relevance of such cultures as models of human cancer. This work also reinforces the concern that comparisons of published analyses of cultures of the same name may be dangerous
    corecore