698 research outputs found

    Predicting the dispersal of SARS-CoV-2 RNA from the wastewater treatment plant to the coast

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    Viral pathogens including SARS-CoV-2 RNA have been detected in wastewater treatment effluent, and untreated sewage overflows, that pose an exposure hazard to humans. We assessed whether SARS-CoV-2 RNA was likely to have been present in detectable quantities in UK rivers and estuaries during the first wave of the Covid-19 pandemic. We simulated realistic viral concentrations parameterised on the Camel and Conwy catchments (UK) and their populations, showing detectable SARS-CoV-2 RNA concentrations for untreated but not for treated loading, but also being contingent on viral decay, hydrology, catchment type/shape, and location. Under mean or low river flow conditions, viral RNA concentrated within the estuaries allowing for viral build-up and caused a lag by up to several weeks between the peak in community infections and the viral peak in the environment. There was an increased hazard posed by SARS-CoV-2 RNA with a T90 decay rate >24 h, as the estuarine build-up effect increased. High discharge events transported the viral RNA downstream and offshore, increasing the exposure risk to coastal bathing waters and shellfisheries – although dilution in this case reduced viral concentrations well below detectable levels. Our results highlight the sensitivity of exposure to viral pathogens downstream of wastewater treatment, across a range of viral loadings and catchment characteristics – with implications to environmental surveillance

    Long Distance Contribution to sdγs \to d\gamma and Implications for ΩΞγ,BsBdγ\Omega^-\to \Xi ^-\gamma, B_s \to B_d^*\gamma and bsγb \to s\gamma

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    We estimate the long distance (LD) contribution to the magnetic part of the sdγs \to d\gamma transition using the Vector Meson Dominance approximation (V=ρ,ω,ψi)(V=\rho,\omega,\psi_i). We find that this contribution may be significantly larger than the short distance (SD) contribution to sdγs \to d\gamma and could possibly saturate the present experimental upper bound on the ΩΞγ\Omega^-\to \Xi^-\gamma decay rate, ΓΩΞγMAX3.7×109\Gamma^{\rm MAX}_{\Omega^-\to \Xi^-\gamma} \simeq 3.7\times10^{-9}eV. For the decay BsBdγB_s \to B^*_d\gamma, which is driven by sdγs \to d\gamma as well, we obtain an upper bound on the branching ratio BR(BsBdγ)<3×108BR(B_s \to B_d^*\gamma)<3\times10^{-8} from ΓΩΞγMAX\Gamma^{\rm MAX}_{\Omega^-\to \Xi^-\gamma}. Barring the possibility that the Quantum Chromodynamics coefficient a2(ms)a_2(m_s) be much smaller than 1, ΓΩΞγMAX\Gamma^{\rm MAX}_{\Omega^-\to \Xi^-\gamma} also implies the approximate relation 23igψi2(0)mψi212gρ2(0)mρ2+16gω2(0)mω2\frac{2}{3} \sum_i \frac{g^2_{\psi_i}(0)}{m^2_{\psi_i}} \simeq \frac{1}{2} \frac{g^2_\rho(0)}{m^2_\rho} + \frac{1}{6}\frac{g^2_\omega(0)}{m^2_\omega}. This relation agrees quantitatively with a recent independent estimate of the l.h.s. by Deshpande et al., confirming that the LD contributions to bsγb \to s\gamma are small. We find that these amount to an increase of (4±2)%(4\pm2)\% in the magnitude of the bsγb \to s \gamma transition amplitude, relative to the SD contribution alone.Comment: 16 pages, LaTeX fil

    ωρ\omega-\rho Mixing and the ωππγ\omega\to\pi\pi\gamma Decay

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    We reexamine the ωπ0π0γ\omega \to \pi^{0} \pi^{0} \gamma decay, adding the effect of ωρ\omega-\rho mixing to the amplitude calculated with the aid of chiral perturbation theory and vector meson dominance. We predict the neutral decay to occur with a width of Γ(\Gamma(\omega \to \pi^{0} \pi^{0} \gamma )=(390±96)eV) =(390\pm96) {\rm eV} and also analyze the effect of the ωρ\omega-\rho mixing on the Γ(\Gamma(\omega \to \pi^{0} \pi^{0} \gamma )/Γ()/ \Gamma(\omega \to \pi^{+} \pi^{-} \gamma )) ratio. Several remarks on the effect of ωρ\omega-\rho mixing on certain radiative decays of vector mesons are presented.Comment: 10 pages, LaTeX, 1 ps-figure. Submitted to Phys. Rev.

    Field-linked States of Ultracold Polar Molecules

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    We explore the character of a novel set of ``field-linked'' states that were predicted in [A. V. Avdeenkov and J. L. Bohn, Phys. Rev. Lett. 90, 043006 (2003)]. These states exist at ultralow temperatures in the presence of an electrostatic field, and their properties are strongly dependent on the field's strength. We clarify the nature of these quasi-bound states by constructing their wave functions and determining their approximate quantum numbers. As the properties of field-linked states are strongly defined by anisotropic dipolar and Stark interactions, we construct adiabatic surfaces as functions of both the intermolecular distance and the angle that the intermolecular axis makes with the electric field. Within an adiabatic approximation we solve the 2-D Schrodinger equation to find bound states, whose energies correlate well with resonance features found in fully-converged multichannel scattering calculations

    A comparison of precipitation and filtration-based SARS-CoV-2 recovery methods and the influence of temperature, turbidity, and surfactant load in urban wastewater

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    Wastewater-based epidemiology (WBE) has become a complimentary surveillance tool during the SARS-CoV-2 pandemic. Viral concentration methods from wastewater are still being optimised and compared, whilst viral recovery under different wastewater characteristics and storage temperatures remains poorly understood. Using urban wastewater samples, we tested three viral concentration methods; polyethylene glycol precipitation (PEG), ammonium sulphate precipitation (AS), and CP select™ InnovaPrep® (IP) ultrafiltration. We found no major difference in SARS-CoV-2 and faecal indicator virus (crAssphage) recovery from wastewater samples (n = 46) using these methods, PEG slightly (albeit non-significantly), outperformed AS and IP for SARS-CoV-2 detection, as a higher genome copies per litre (gc/l) was recorded for a larger proportion of samples. Next generation sequencing of 8 paired samples revealed non-significant differences in the quality of data between AS and IP, though IP data quality was slightly better and less variable. A controlled experiment assessed the impact of wastewater suspended solids (turbidity; 0–400 NTU), surfactant load (0–200 mg/l), and storage temperature (5–20 °C) on viral recovery using the AS and IP methods. SARS-CoV-2 recoveries were >20% with AS and  0.05), whilst surfactant and storage temperature combined were significant negative correlates (p < 0.001 and p < 0.05, respectively). In conclusion, our results show that choice of methodology had small effect on viral recovery of SARS-CoV-2 and crAssphage in wastewater samples within this study. In contrast, sample turbidity, storage temperature, and surfactant load did affect viral recovery, highlighting the need for careful consideration of the viral concentration methodology used when working with wastewater samples

    Gauge equivalence in QCD: the Weyl and Coulomb gauges

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    The Weyl-gauge (A0a=0)A_0^a=0) QCD Hamiltonian is unitarily transformed to a representation in which it is expressed entirely in terms of gauge-invariant quark and gluon fields. In a subspace of gauge-invariant states we have constructed that implement the non-Abelian Gauss's law, this unitarily transformed Weyl-gauge Hamiltonian can be further transformed and, under appropriate circumstances, can be identified with the QCD Hamiltonian in the Coulomb gauge. We demonstrate an isomorphism that materially facilitates the application of this Hamiltonian to a variety of physical processes, including the evaluation of SS-matrix elements. This isomorphism relates the gauge-invariant representation of the Hamiltonian and the required set of gauge-invariant states to a Hamiltonian of the same functional form but dependent on ordinary unconstrained Weyl-gauge fields operating within a space of ``standard'' perturbative states. The fact that the gauge-invariant chromoelectric field is not hermitian has important implications for the functional form of the Hamiltonian finally obtained. When this nonhermiticity is taken into account, the ``extra'' vertices in Christ and Lee's Coulomb-gauge Hamiltonian are natural outgrowths of the formalism. When this nonhermiticity is neglected, the Hamiltonian used in the earlier work of Gribov and others results.Comment: 25 page

    Accounting for International War: The State of the Discipline

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    In studies of war it is important to observe that the processes leading to so frequent an event as conflict are not necessarily those that lead to so infrequent an event as war. Also, many models fail to recognize that a phenomenon irregularly distributed in time and space, such as war, cannot be explained on the basis of relatively invariant phenomena. Much research on periodicity in the occurrence of war has yielded little result, suggesting that the direction should now be to focus on such variables as diffusion and contagion. Structural variables, such as bipolarity, show contradictory results with some clear inter-century differences. Bipolarity, some results suggest, might have different effects on different social entities. A considerable number of studies analysing dyadic variables show a clear connection between equal capabilities among contending nations and escalation of conflict into war. Finally, research into national attributes often points to strength and geographical location as important variables. In general, the article concludes, there is room for modest optimism, as research into the question of war is no longer moving in non-cumulative circles. Systematic research is producing results and there is even a discernible tendency of convergence, in spite of a great diversity in theoretical orientations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69148/2/10.1177_002234338101800101.pd

    First lattice QCD estimate of the g_{D^* D pi} coupling

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    We present the results of the first lattice QCD study of the strong coupling g_{D^* D pi}. From our simulations in the quenched approximation, we obtain g_{D^* D pi} = 18.8 +/- 2.3^{+1.1}_{-2.0} and hat(g)_c = 0.67 +/- 0.08^{+0.04}_{-0.06}. Whereas previous theoretical studies gave different predictions, our result favours a large value for hat(g)_c. It agrees very well with the recent experimental value by CLEO. hat(g) varies very little with the heavy mass and we find in the infinite mass limit hat(g)_infinity = 0.69(18).Comment: 24 pages, 7 figures; references added, corrected typos, Comments added about the continuum limi

    Metabolic and nutritional support of critically ill patients: consensus and controversies.

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    The results of recent large-scale clinical trials have led us to review our understanding of the metabolic response to stress and the most appropriate means of managing nutrition in critically ill patients. This review presents an update in this field, identifying and discussing a number of areas for which consensus has been reached and others where controversy remains and presenting areas for future research. We discuss optimal calorie and protein intake, the incidence and management of re-feeding syndrome, the role of gastric residual volume monitoring, the place of supplemental parenteral nutrition when enteral feeding is deemed insufficient, the role of indirect calorimetry, and potential indications for several pharmaconutrients
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