7,530 research outputs found

    Geophysical study of the structure and processes of the continental convergence zones: Alpine-Himalayan belt

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    Studies of the structure of the continental collision zones using seismic and body waves, theoretical modelling of the thermal regime of the convergence processes, and studies of earthquake mechanisms and deformation aspects of the model are covered

    Inverse Compton scattering in mildly relativistic plasma

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    We investigated the effect of inverse Compton scattering in mildly relativistic static and moving plasmas with low optical depth using Monte Carlo simulations, and calculated the Sunyaev-Zel'dovich effect in the cosmic background radiation. Our semi-analytic method is based on a separation of photon diffusion in frequency and real space. We use Monte Carlo simulation to derive the intensity and frequency of the scattered photons for a monochromatic incoming radiation. The outgoing spectrum is determined by integrating over the spectrum of the incoming radiation using the intensity to determine the correct weight. This method makes it possible to study the emerging radiation as a function of frequency and direction. As a first application we have studied the effects of finite optical depth and gas infall on the Sunyaev-Zel'dovich effect (not possible with the extended Kompaneets equation) and discuss the parameter range in which the Boltzmann equation and its expansions can be used. For high temperature clusters (kBTe15k_B T_e \gtrsim 15 keV) relativistic corrections based on a fifth order expansion of the extended Kompaneets equation seriously underestimate the Sunyaev-Zel'dovich effect at high frequencies. The contribution from plasma infall is less important for reasonable velocities. We give a convenient analytical expression for the dependence of the cross-over frequency on temperature, optical depth, and gas infall speed. Optical depth effects are often more important than relativistic corrections, and should be taken into account for high-precision work, but are smaller than the typical kinematic effect from cluster radial velocities.Comment: LateX, 30 pages and 11 figures. Accepted for publication in the Astrophysical Journa

    THE OPEN BALKAN AS A DEVELOPMENT DETERMINANT OF THE WESTERN BALKAN COUNTRIES

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    The paper starts from the concept of the Open Balkan as a community of countries in the Western Balkans, aimed at strengthening their economic cooperation and development for faster integration in the European Union. Significant attention is paid to the analysis of the interdependence of (in)stability of the state and the economic development of small countries. The position of the Open Balkan and its members is also analysed on the basis of the selected global composite indices. An important subject of the analysis is also the condition of institutional capacities of the members of the Open Balkan and their institutional cooperation from the perspective of faster progress towards the European integration. Two main hypotheses have been tested in the paper: (H1) CEEs countries are not a homogeneous group of countries; and (H2) The Western Balkans is a relatively homogeneous regional integration. To test the convergence hypothesis between 16 Central and Eastern European countries (CEEs), annual data from World Bank’s database on the value of real gross domestic product per capita (in constant dollars 2017, PPP) in the period 2000-2026 were used (projected values for the period until 2026). We employed the method developed by Phillips & Sul (2007) that allows identification of clusters of convergence on the basis of an algorithm that is data-driven and thereby avoids a priori classification of the data into subgroups. Based on the results obtained, it can be concluded that Serbia is the “locomotive” of the Western Balkans and that all countries in this area should join the regional initiative for cooperation, the Open Balkan

    Charm and beauty of the Large Hadron Collider

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    With the acceleration of lead nuclei in the LHC, heavy-ion physics will enter a new energy domain. One of the main novelties introduced by the 30-fold energy-jump from RHIC to the LHC is the abundant heavy-quark production. After discussing a few examples of physics issues that can be addressed using heavy quarks, we present a selection of results on the expected experimental capability of ALICE, the dedicated heavy-ion experiment at the LHC, in the open-heavy-flavour sector.Comment: 10 pages, 5 figures. Invited talk at Strangeness in Quark Matter (SQM) 2004, Cape Town, South Africa, 15-20 September 2004. Submitted to J. Phys.

    Grapevine trunk disease in German viticulture: occurrence of lesser known fungi and first report of Phaeoacremonium viticola and P. fraxinopennsylvanicum

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    Thirteen species of lesser known wood inhabiting fungi living on grapevine (Vitis vinifera) and/or in the vicinity of vineyards are presented with respect to systematics, life strategy and symptoms, host range, geographic distribution, transmission and occurrence on Vitis, identification, and diagnosis. Sampling has been performed during a three-year-survey covering nurseries, vineyards, and neighboring fruit trees in the viticultural area of southern Palatinate, Germany. The possible pathogenic significance and the relation to grapevine trunk diseases are discussed. The following species are reported for the first time in Germany: Cadophora luteo-olivacea, C. fastigiata, Collophora paarla, Coniochaeta hoffmannii, Eucasphaeria capensis, Phomopsis cotoneastri, and the Esca-related Phaeoacremonium viticola and P. fraxinopennsylvannicum. Eucasphaeria capensis and Phomopsis cotoneastri are reported for the first time from Vitis worldwide

    The Genome of the Chicken DT40 Bursal Lymphoma Cell Line

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    The chicken DT40 cell line is a widely used model system in the study of multiple cellular processes due to the efficiency of homologous gene targeting. The cell line was derived from a bursal lymphoma induced by avian leukosis virus infection. In this study we characterized the genome of the cell line using whole genome shotgun sequencing and single nucleotide polymorphism array hybridization. The results indicate that wild type DT40 has a relatively normal karyotype except for whole chromosome copy number gains, and no karyotype variability within stocks. In a comparison to two domestic chicken genomes and the Gallus gallus reference genome we found no unique mutational processes shaping the DT40 genome except for a mild increase in insertion and deletion events, particularly deletions at tandem repeats. We mapped coding sequence mutations that are unique to the DT40 genome; mutations inactivating the PIK3R1 and ATRX genes likely contributed to the oncogenic transformation. In addition to a known avian leukosis virus integration in the MYC gene we detected further integration sites that are likely to de-regulate gene expression. The new findings support the hypothesis that DT40 is a typical transformed cell line with a relatively intact genome, therefore it is well suited to the role of a model system for DNA repair and related processes. The sequence data generated by this study, including a searchable de novo genome assembly and annotated lists of mutated genes, will support future research using this cell line

    Impact of solid waste disposal on nutrient dynamics in a sandy catchment

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    Groundwaters impacted by mature landfill leachate are generally enriched in ammonium. In order to assess the dynamics of ammonium exchanges between leachates and the water system inside a sandy permeable catchment we measured ammonium, nitrate and chloride concentrations in the stream and in sediment pore waters of the streambed of a landfill impacted aquifer. Geophysical investigation methods complemented the biogeochemical survey. The studied zone is a 23 km² catchment located in a coastal lagoon area sensitive to eutrophication risk. Ammonium concentrations in the river were up to 800 µmol l−1 during low water period in summer. Three surveys of the river chemistry showed a regular increase in ammonium, nitrate and chloride concentrations along a 1 km section of the watercourse, downstream the landfill, implying that the leachate plume exfiltrates along this section. Sediment cores collected within this section showed all an increase in ammonium concentrations with depth in pore waters as a consequence of the landfill leachate dispersion, as attested by a simultaneous increase in chloride concentrations. Nitrate enrichment in the river water was due to nitrification of ammonium at the interface between groundwater and streamwater. The apparent nitrification rate obtained was within values reported for turbid estuaries, although the river contained very little suspended particulate matter. Actually, pore water chemistry suggests that nitrification occurred for the most part in subsurface permeable sediments, rather than in stream water. The overall topographic, hydrological, geochemical, and geoelectrical data set permit to estimate the extension of the chloride and ammonium plume. The estimation of the apparent ammonium plume velocity is 23 m year−1 whereas the chloride plume velocity should be 50 m year−1. The river is the outlet of the impacted groundwaters. Considering that the input of ammonium from the landfill is balanced by the present day output via the river, the residence time of ammonium in the aquifer is between 7 and 18 years

    Shear viscosity and chemical equilibration of the QGP

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    We have investigated, in the frame work of the transport approach, different aspects of the QGP created in Heavy Ion Collisions at RHIC and LHC energies. The shear viscosity η\eta has been calculated by using the Green-Kubo relation at the cascade level. We have compared the numerical results for η\eta obtained from the Green-Kubo correlator with the analytical formula in both the Relaxation Time Approximation (RTA) and the Chapman-Enskog approximation (CE). From this comparison we show that in the range of temperature explored in a Heavy Ion collision the RTA underestimates the viscosity by about a factor of 2, while a good agreement is found between the CE approximation and Gree-Kubo relation already at first order of approximation. The agreement with the CE approximation supplies an analytical formula that allows to develop kinetic transport theory at fixed shear viscosity to entropy density ratio, η/s\eta/s. We show some results for the build up of anisotropic flows v2v_{2} in a transport approach at fixed shear viscosity to entropy density ratio, η/s\eta/s. We study the impact of a T-dependent η/s(T)\eta/s(T) on the generation of the elliptic flows at both RHIC and LHC. We show that the transport approach provides, in a unified way, a tool able to naturally describe the v2(pT)v_{2}(p_{T}) in a wide range of pTp_{T}, including also the description of the rise and fall and saturation of the v2(pT)v_{2}(p_{T}) observed at LHC. Finally, we have studied the evolution of the quark-gluon composition employing a Boltzmann-Vlasov transport approach that include: the mean fields dynamics, associated to the quasi-particle model, and the elastic and inelastic collisions for massive quarks and gluons. Following the chemical evolution from an initial gluon dominated plasma we predict a quark dominance close to TCT_{C} paving the way to an hadronization via quark coalescence.Comment: 15 pages, 10 figures, Invited Talk given by S. Plumari at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS

    Mechanism of action of VP1-001 in cryAB(R120G)-associated and age-related cataracts

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    PurposeWe previously identified an oxysterol, VP1-001 (also known as compound 29), that partially restores the transparency of lenses with cataracts. To understand the mechanism of VP1-001, we tested the ability of its enantiomer, ent-VP1-001, to bind and stabilize αB-crystallin (cryAB) in vitro and to produce a similar therapeutic effect in cryAB(R120G) mutant and aged wild-type mice with cataracts. VP1-001 and ent-VP1-001 have identical physicochemical properties. These experiments are designed to critically evaluate whether stereoselective binding to cryAB is required for activity.MethodsWe compared the binding of VP1-001 and ent-VP1-001 to cryAB using in silico docking, differential scanning fluorimetry (DSF), and microscale thermophoresis (MST). Compounds were delivered by six topical administrations to mouse eyes over 2 weeks, and the effects on cataracts and lens refractive measures in vivo were examined. Additionally, lens epithelial and fiber cell morphologies were assessed via transmission electron microscopy.ResultsDocking studies suggested greater binding of VP1-001 into a deep groove in the cryAB dimer compared with ent-VP1-001. Consistent with this prediction, DSF and MST experiments showed that VP1-001 bound cryAB, whereas ent-VP1-001 did not. Accordingly, topical treatment of lenses with ent-VP1-001 had no effect, whereas VP1-001 produced a statistically significant improvement in lens clarity and favorable changes in lens morphology.ConclusionsThe ability of VP1-001 to bind native cryAB dimers is important for its ability to reverse lens opacity in mouse models of cataracts
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