89 research outputs found

    Water Quality Sampling, Analysis and Annual Load Determinations for TSS, Nitrogen and Phosphorus at the Ballard Creek Near Arkansas/Oklahoma Line

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    The Illinois River Basin has experienced water quality impairment from non-point source pollution for many years. This fact was well documented in the State of Arkansas\u27 Water Quality Assessment report, the Soil Conservation Service River Basin Study, and several University of Arkansas studies. Thirty-seven sub-watersheds have been identified by the SCS in the Arkansas portion of the Illinois River basin. In the Arkansas portion of the Basin, the Illinois River, Evansville Creek, Baron Fork, Cincinnati Creek, Muddy Fork, Moores Creek, Clear Creek, Osage Creek and Flint Creek were all classified as not supporting their designated use as primary contact recreation streams. The identified causes of the impairment were: sediment, bacteria and nutrients. In 1997, the University of Arkansas completed a project that estimated the phosphorus loading from each of the thirty-seven sub-watersheds. This project also prioritized watersheds for implementation work based on phosphorus loads, nitrogen loads and total suspended solids loads per unit area. The thirty-seven sub-watersheds were grouped into Low (16), Medium (10) and High (11) categories based on phosphorus loadings. The selection of a sub-watershed for targeted intensive voluntary Best Management Practices (BMP) implementation was based on the following criteria: a) the sub-watershed had to be above the current median value for phosphorus loading, b) there would be no sewage treatment plant in the sub-watershed, and c) land user interest. The Upper Ballard Creek watershed met all these requirements. The watershed covers 6700 hectares. The creek is listed in the High category with a unit area loading of 1.75 kg. per hectare per year. The median value for the thirty-seven watersheds was 0.73 kg. per hectare per year

    Water Quality Sampling, Analysis and Annual Load Determinations for TSS, Nitrogen and Phosphorus at the L\u27Anguille River Near Palestine 2005 Annual Report

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    A water quality sampling station was installed at the L’Anguille River near Palestine in 2003. This station is coordinated with a USGS gauging station at the same location. This station is instrumented to collect samples at sufficient intervals across the hydrograph to accurately estimate the flux of total suspended solids, nitrogen and phosphorus in the River. The L’Anguille River was listed on Arkansas\u27 1998 (listed in later reports?) 303d list as impaired from sediment (turbidity). The L’Anguille River was the second stream to have total maximum daily loads (TMDL) determined in Arkansas. Accurate determination of stream nutrients and sediment is critical for future determinations of TMDLs, effectiveness of best management practices and trends in water quality

    Spectroscopy of resonance decays in high-energy heavy-ion collisions

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    Invariant mass distributions of the hadronic decay products from resonances formed in relativistic heavy ion collision (RHIC) experiments are investigated with a view to disentangle the effects of thermal motion and the phase space of decay products from those of intrinsic changes in the structure of resonances at the freeze-out conditions. Analytic results of peak mass shifts for the cases of both equal and unequal mass decay products are derived. The shift is expressed in terms of the peak mass and width of the vacuum or medium-modified spectral functions and temperature. Examples of expected shifts in meson (e.g., rho, omega, and sigma) and baryon (e.g., Delta) resonances that are helpful to interpret recent RHIC measurements at BNL are provided. Although significant downward mass shifts are caused by widened widths of the ρ\rho-meson in medium, a downward shift of at least 50 MeV in its intrinsic mass is required to account for the reported downward shift of 60-70 MeV in the peak of the rho-invariant mass distribution. An observed downward shift from the vacuum peak value of the Delta distinctively signals a significant downward shift in its intrinsic peak mass, since unlike for the rho-meson, phase space functions produce an upward shift for the Delta isobar.Comment: published version with slight change of title and some typos corrected, 12 pages, 5 figure

    Photon and dilepton emission rates from high density quark matter

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    We compute the rates of real and virtual photon (dilepton) emission from dense QCD matter in the color-flavor locked (CFL) phase, focusing on results at moderate densities (3-5 times the nuclear saturation density) and temperatures T80T\simeq80 MeV. We pursue two approaches to evaluate the electromagnetic (e.m.) response of the CFL ground state: (i) a direct evaluation of the photon self energy using quark particle/-hole degrees of freedom, and (ii) a Hidden Local Symmetry (HLS) framework based on generalized mesonic excitations where the ρ\rho meson is introduced as a gauge boson of a local SU(3) color-flavor group. The ρ\rho coupling to generalized two-pion states induces a finite width and allows to address the issue of vector meson dominance (VMD) in the CFL phase. We compare the calculated emissivities (dilepton rates) to those arising from standard hadronic approaches including in-medium effects. For rather large superconducting gaps (several tens of MeV at moderate densities), as suggested by both perturbative and nonperturbative estimates, the dilepton rates from CFL quark matter turn out to be very similar to those obtained in hadronic many-body calculations, especially for invariant masses above M0.3M\simeq0.3 GeV. A similar observation holds for (real) photon production.Comment: 18 pages, 12 figure

    Fermion Condensates of massless QED2QED_2 at Finite Density in non-trivial Topological Sectors

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    Vacuum expectation values of products of local bilinears ψˉψ\bar\psi\psi are computed in massless QED2QED_2 at finite density. It is shown that chiral condensates exhibit an oscillatory inhomogeneous behaviour depending on the chemical potential. The use of a path-integral approach clarifies the connection of this phenomenon with the topological structure of the theory.Comment: 16 pages, no figures, To be published in Phys.Rev.

    DD-dimensions Dirac fermions BEC-BCS cross-over thermodynamics

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    An effective Proca Lagrangian action is used to address the vector condensation Lorentz violation effects on the equation of state of the strongly interacting fermions system. The interior quantum fluctuation effects are incorporated as an external field approximation indirectly through a fictive generalized Thomson Problem counterterm background. The general analytical formulas for the dd-dimensions thermodynamics are given near the unitary limit region. In the non-relativistic limit for d=3d=3, the universal dimensionless coefficient ξ=4/9\xi ={4}/{9} and energy gap Δ/ϵf=5/18\Delta/\epsilon_f ={5}/{18} are reasonably consistent with the existed theoretical and experimental results. In the unitary limit for d=2d=2 and T=0, the universal coefficient can even approach the extreme occasion ξ=0\xi=0 corresponding to the infinite effective fermion mass m=m^*=\infty which can be mapped to the strongly coupled two-dimensions electrons and is quite similar to the three-dimensions Bose-Einstein Condensation of ideal boson gas. Instead, for d=1d=1, the universal coefficient ξ\xi is negative, implying the non-existence of phase transition from superfluidity to normal state. The solutions manifest the quantum Ising universal class characteristic of the strongly coupled unitary fermions gas.Comment: Improved versio

    Hadronic observables from SIS to SPS energies - anything strange with strangeness ?

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    We calculate p,π±,K±p, \pi^\pm, K^\pm and Λ\Lambda(+Σ0\Sigma^0) rapidity distributions and compare to experimental data from SIS to SPS energies within the UrQMD and HSD transport approaches that are both based on string, quark, diquark (q,qˉ,qq,qˉqˉq, \bar{q}, qq, \bar{q}\bar{q}) and hadronic degrees of freedom. The two transport models do not include any explicit phase transition to a quark-gluon plasma (QGP). It is found that both approaches agree rather well with each other and with the experimental rapidity distributions for protons, Λ\Lambda's, π±\pi^\pm and K±K^\pm. Inspite of this apparent agreement both transport models fail to reproduce the maximum in the excitation function for the ratio K+/π+K^+/\pi^+ found experimentally between 11 and 40 A\cdotGeV. A comparison to the various experimental data shows that this 'failure' is dominantly due to an insufficient description of pion rapidity distributions rather than missing 'strangeness'. The modest differences in the transport model results -- on the other hand -- can be attributed to different implementations of string formation and fragmentation, that are not sufficiently controlled by experimental data for the 'elementary' reactions in vacuum.Comment: 46 pages, including 15 eps figures, to be published in Phys. Rev.

    A renormalisation group approach to two-body scattering in the presence of long-range forces

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    We apply renormalisation-group methods to two-body scattering by a combination of known long-range and unknown short-range potentials. We impose a cut-off in the basis of distorted waves of the long-range potential and identify possible fixed points of the short-range potential as this cut-off is lowered to zero. The expansions around these fixed points define the power countings for the corresponding effective field theories. Expansions around nontrivial fixed points are shown to correspond to distorted-wave versions of the effective-range expansion. These methods are applied to scattering in the presence of Coulomb, Yukawa and repulsive inverse-square potentials.Comment: 22 pages (RevTeX), 4 figure

    Deconstructing 1S0 nucleon-nucleon scattering

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    A distorted-wave method is used to analyse nucleon-nucleon scattering in the 1S0 channel. Effects of one-pion exchange are removed from the empirical phase shift to all orders by using a modified effective-range expansion. Two-pion exchange is then subtracted in the distorted-wave Born approximation, with matrix elements taken between scattering waves for the one-pion exchange potential. The residual short-range interaction shows a very rapid energy dependence for kinetic energies above about 100 MeV, suggesting that the breakdown scale of the corresponding effective theory is only 270MeV. This may signal the need to include the Delta resonance as an explicit degree of freedom in order to describe scattering at these energies. An alternative strategy of keeping the cutoff finite to reduce large, but finite, contributions from the long-range forces is also discussed.Comment: 10 pages, 2 figures (introduction revised, references added; version to appear in EPJA
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