865 research outputs found

    Global polarization measurement in Au+Au collisions

    Full text link
    The system created in non central relativistic nucleus-nucleus collisions carries large angular orbital momentum. Due to spin-orbital coupling, produced particles could be globally polarized along the direction of the system angular momentum. We present results of a measurement of Lambda hyperon global polarization in Au+Au collisions at the center of mass energies 62 and 200 GeV with the STAR detector at RHIC. The observed global polarization of Lambda hyperons in the STAR acceptance is consistent with zero within the precision of the measurement. The obtained upper limit, |P_Lambda| < 0.01, is significantly below the theoretical values discussed recently in the literature.Comment: Talk given at SQM 2006, International Conference on Strangeness in Quark Matter, March 26-31, 2006, Los Angeles CA; 4 pages, 2 figure

    Caudal cervical vertebral morphological variation is not associated with clinical signs in Warmblood horses

    Get PDF
    Background Variation in equine caudal cervical spine morphology at C6 and C7 has high prevalence in Warmblood horses and is suspected to be associated with pain in a large mixed-breed group of horses. At present no data exist on the relationship between radiographic phenotype and clinical presentation in Warmblood horses in a case-control study. Objectives To establish the frequency of radiographically visible morphologic variation in a large group of Warmblood horses with clinical signs and compare this with a group without clinical signs. We hypothesised that occurrence of morphologic variation in the case group would not differ from the control group, indicating there is no association between clinical signs and morphologic variation. Study design Retrospective case-control. Methods Radiographic presence or absence of morphologic variation of cervical vertebrae C6 and C7 was recorded in case (n = 245) and control horses (n = 132). Case and control groups were compared by univariable Pearson's Chi-square and multivariable logistic regression for measurement variables age, sex, breed, degenerative joint disease and morphologic variation at C6 and C7. Odds ratio and confidence intervals were obtained. A P <= 0.05 was considered statistically significant. Results Morphologic variation at C6 and C7 (n = 108/377 = 28.6%; Cases 58/245 = 23.7%; Control 50/132 = 38%) was less frequent in horses with clinical signs in univariable testing (OR 0.48, 95% CI 0.3-0.8, P = 0.001). Age, sex, breed and degenerative joint disease were not retained in the final multivariable logistic regression step whereas morphologic variation remained significantly less present in horses with clinical signs. Main limitations Possible demographic differences between equine clinics. Conclusions Morphologic variation in the caudal cervical spine was detected more frequently in horses without clinical signs. Therefore, radiographic presence of such variation does not necessarily implicate the presence of clinical signs

    Urban Evolution: The Role of Water

    Get PDF
    The structure, function, and services of urban ecosystems evolve over time scales from seconds to centuries as Earth’s population grows, infrastructure ages, and sociopolitical values alter them. In order to systematically study changes over time, the concept of “urban evolution” was proposed. It allows urban planning, management, and restoration to move beyond reactive management to predictive management based on past observations of consistent patterns. Here, we define and review a glossary of core concepts for studying urban evolution, which includes the mechanisms of urban selective pressure and urban adaptation. Urban selective pressure is an environmental or societal driver contributing to urban adaptation. Urban adaptation is thesequential process by which an urban structure, function, or services becomes more fitted to its changing environment or human choices. The role of water is vital to driving urban evolution as demonstrated by historical changes in drainage, sewage flows, hydrologic pulses, and long-term chemistry. In the current paper, we show how hydrologic traits evolve across successive generations of urban ecosystems via shifts in selective pressures and adaptations over time. We explore multiple empirical examples including evolving: (1) urban drainage from stream burial to stormwater management; (2) sewage flows and water quality in response to wastewater treatment; (3) amplification of hydrologic pulses due to the interaction between urbanization and climate variability; and (4) salinization and alkalinization of fresh water due to human inputs and accelerated weathering. Finally, we propose a new conceptual model for the evolution of urban waters from the Industrial Revolution to the present day based on empirical trends and historical information. Ultimately, we propose that water itself is a critical driver of urban evolution that forces urban adaptation, which transforms the structure, function, and services of urban landscapes, waterways, and civilizations over time

    Identification of genes encoding squalestatin S1 biosynthesis and in vitro production of new squalestatin analogues

    Get PDF
    A gene cluster responsible for the biosynthesis of squalestatin S1 (SQS1, 1) was identified by full genome sequencing of two SQS1-producing ascomycetes: Phoma sp. C2932 and unidentified fungus MF5453. A transformation protocol was established and a subsequent knockout of one PKS gene from the cluster led to loss of SQS1 production and enhanced concentration of an SQS1 precursor. An acyltransferase gene from the cluster was expressed in E. coli and the expressed protein MfM4 shown to be responsible for loading acyl groups from CoA onto the squalestatin core as the final step of biosynthesis. MfM4 appears to have a broad substrate selectivity for its acyl CoA substrate, allowing the in vitro synthesis of novel squalestatins

    Radiative capture of protons by deuterons

    Get PDF
    The differential cross section for radiative capture of protons by deuterons is calculated using different realistic NN interactions. We compare our results with the available experimental data below Ex=20MeVE_x = 20 MeV. Excellent agreement is found when taking into account meson exchange currents, dipole and quadrupole contributions, and the full initial state interaction. There is only a small difference between the magnitudes of the cross sections for the different potentials considered. The angular distributions, however, are practically potential independent.Comment: 4 pages (twocolumn), 4 postscript figures included, submitted for publication, revised versio

    Identification of di- and triterpenoid lipid tracers confirms the significant role of autoxidation in the degradation of terrestrial vascular plant material in the Canadian Arctic

    Get PDF
    publisher: Elsevier articletitle: Identification of di- and triterpenoid lipid tracers confirms the significant role of autoxidation in the degradation of terrestrial vascular plant material in the Canadian Arctic journaltitle: Organic Geochemistry articlelink: http://dx.doi.org/10.1016/j.orggeochem.2017.03.011 content_type: article copyright: © 2017 Elsevier Ltd. All rights reserved

    Evidence for Marine Influence on a Low-Gradient Coastal Plain: Ichnology and Invertebrate Paleontology of the Lower Tongue River Member (Fort Union Formation, Middle Paleocene), Western Williston Basin, U.S.A.

    Get PDF
    The Paleocene Tongue River Member of the Fort Union Formation contains trace-fossil associations indicative of marine influence in otherwise freshwater facies. The identified ichnogenera include: Arenicolites, Diplocraterion, Monocraterion, Ophiomorpha, Rhizocorallium, Skolithos linearis, Teichichnus, Thalassinoides, and one form of uncertain affinity. Two species of the marine diatom Coscinodiscus occur a few meters above the base of the member. The burrows occur in at least five discrete, thin, rippled, fine-grained sandstone beds within the lower 85 m of the member west of the Cedar Creek anticline (CCA) in the Signal Butte, Terry Badlands, and Pine Hills areas. Two discrete burrowed beds are found in the lower 10 m of the member east of the CCA in the little Missouri River area. Abundant freshwater ostracodes include Bisulcocypridea arvadensis, Candona, and Cypridopsis. Freshwater bivalves include Plesielliptio and Pachydon mactriformis. We recognize four fossil assemblages that represent fluvio-lacustrine, proximal estuarine, central estuarine, and distal estuarine environments. Biostratal alternations between fresh- and brackish-water assemblages indicate that the Tongue River Member was deposited along a low-gradient coastal plain that was repeatedly inundated from the east by the Cannonball Sea. The existence of marine-influenced beds in the Tongue River Member invalidates the basis for the Slope Formation

    Three-Nucleon Electroweak Capture Reactions

    Get PDF
    Recent advances in the study of the p-d radiative and mu-3he weak capture processes are presented and discussed. The three-nucleon bound and scattering states are obtained using the correlated-hyperspherical-harmonics method, with realistic Hamiltonians consisting of the Argonne v14 or Argonne v18 two-nucleon and Tucson-Melbourne or Urbana IX three-nucleon interactions. The electromagnetic and weak transition operators include one- and two-body contributions. The theoretical accuracy achieved in these calculations allows for interesting comparisons with experimental data.Comment: 12 pages, 4 figures, invited talk at the CFIF Fall Workshop: Nuclear Dynamics, from Quarks to Nuclei, Lisbon, 31st of October - 1st of November 200

    Faddeev Calculations of Proton-Deuteron Radiative Capture with Exchange Currents

    Get PDF
    pd capture processes at various energies have been analyzed based on solutions of 3N-Faddeev equations and using modern NN forces. The application of the Siegert theorem is compared to the explicit use of π\pi- and ρ\rho-like exchange currents connected to the AV18 NN interaction. Overall good agreement with cross sections and spin observables has been obtained but leaving room for improvement in some cases. Feasibility studies for 3NF's consistently included in the 3N continuum and the 3N bound state have been performed as well.Comment: Minor changes in notation, ps files for figure
    • 

    corecore