917 research outputs found

    Environment and Rural Affairs Monitoring & Modelling Programme - ERAMMP Technical Annex 1: Soil nutrient management for improved land. Sustainable Farming Scheme. Evidence Review.

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    The Brief: Establish intervention logic for Soil Nutrient Management (SNM) plans across all improved agricultural land. Establish the environmental benefits including GHG emissions reduction, biodiversity, water quality and air quality which will be secured through the universal uptake of SNM plans. Identify the contribution that better SNM will make to the economic resilience and sustainability of Welsh agriculture

    Displaying the Heterogeneity of the SN 2002cx-like Subclass of Type Ia Supernovae with Observations of the Pan-STARRS-1 Discovered SN2009ku

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    SN2009ku, discovered by Pan-STARRS-1, is a Type Ia supernova (SNIa), and a member of the distinct SN2002cx-like class of SNeIa. Its light curves are similar to the prototypical SN2002cx, but are slightly broader and have a later rise to maximum in g. SN2009ku is brighter (~0.6 mag) than other SN2002cx-like objects, peaking at M_V = -18.4 mag - which is still significantly fainter than typical SNeIa. SN2009ku, which had an ejecta velocity of ~2000 kms^-1 at 18 days after maximum brightness is spectroscopically most similar to SN2008ha, which also had extremely low-velocity ejecta. However, SN2008ha had an exceedingly low luminosity, peaking at M_V = -14.2 mag, ~4 mag fainter than SN2009ku. The contrast of high luminosity and low ejecta velocity for SN2009ku is contrary to an emerging trend seen for the SN2002cx class. SN2009ku is a counter-example of a previously held belief that the class was more homogeneous than typical SNeIa, indicating that the class has a diverse progenitor population and/or complicated explosion physics. As the first example of a member of this class of objects from the new generation of transient surveys, SN2009ku is an indication of the potential for these surveys to find rare and interesting objects.Comment: 7 pages, 3 figure

    Isothermal Plasma Wave Properties of the Schwarzschild de-Sitter Black Hole in a Veselago Medium

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    In this paper, we study wave properties of isothermal plasma for the Schwarzschild de-Sitter black hole in a Veselago medium. We use ADM 3+1 formalism to formulate general relativistic magnetohydrodynamical (GRMHD) equations for the Schwarzschild de-Sitter spacetime in Rindler coordinates. Further, Fourier analysis of the linearly perturbed GRMHD equations for the rotating (non-magnetized and magnetized) background is taken whose determinant leads to a dispersion relation. We investigate wave properties by using graphical representation of the wave vector, the refractive index, change in refractive index, phase and group velocities. Also, the modes of wave dispersion are explored. The results indicate the existence of the Veselago medium.Comment: 24 pages, 12 figures, accepted for publication in Astrophys. Space Sci. arXiv admin note: text overlap with arXiv:1101.0884 and arxiv:1007.285

    Frictional drag between non-equilibrium charged gases

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    The frictional drag force between separated but coupled two-dimensional electron gases of different temperatures is studied using the non-equilibrium Green function method based on the separation of center-of-mass and relative dynamics of electrons. As the mechanisms of producing the frictional force we include the direct Coulomb interaction, the interaction mediated via virtual and real TA and LA phonons, optic phonons, plasmons, and TA and LA phonon-electron collective modes. We found that, when the distance between the two electron gases is large, and at intermediate temperature where plasmons and collective modes play the most important role in the frictional drag, the possibility of having a temperature difference between two subsystems modifies greatly the transresistivity.Comment: 8figure

    Transverse Wave Propagation in Relativistic Two-fluid Plasmas in de Sitter Space

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    We investigate transverse electromagnetic waves propagating in a plasma in the de Sitter space. Using the 3+1 formalism we derive the relativistic two-fluid equations to take account of the effects due to the horizon and describe the set of simultaneous linear equations for the perturbations. We use a local approximation to investigate the one-dimensional radial propagation of Alfv\'en and high frequency electromagnetic waves and solve the dispersion relation for these waves numerically.Comment: 19 pages, 12 figure

    QCD Corrections to QED Vacuum Polarization

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    We compute QCD corrections to QED calculations for vacuum polarization in background magnetic fields. Formally, the diagram for virtual eeˉe\bar{e} loops is identical to the one for virtual qqˉq\bar{q} loops. However due to confinement, or to the growth of αs\alpha_s as p2p^2 decreases, a direct calculation of the diagram is not allowed. At large p2p^2 we consider the virtual qqˉq\bar{q} diagram, in the intermediate region we discuss the role of the contribution of quark condensates \left and at the low-energy limit we consider the π0\pi^0, as well as charged pion π+π−\pi^+\pi^- loops. Although these effects seem to be out of the measurement accuracy of photon-photon laboratory experiments they may be relevant for γ\gamma-ray burst propagation. In particular, for emissions from the center of the galaxy (8.5 kpc), we show that the mixing between the neutral pseudo-scalar pion π0\pi_0 and photons renders a deviation from the power-law spectrum in the TeVTeV range. As for scalar quark condensates \left and virtual qqˉq\bar{q} loops are relevant only for very high radiation density ∼300MeV/fm3\sim 300 MeV/fm^3 and very strong magnetic fields of order ∼1014T\sim 10^{14} T.Comment: 15 pages, 4 figures; Final versio

    Gravitational radiation from a particle in circular orbit around a black hole. V. Black-hole absorption and tail corrections

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    A particle of mass μ\mu moves on a circular orbit of a nonrotating black hole of mass MM. Under the restrictions μ/M≪1\mu/M \ll 1 and v≪1v \ll 1, where vv is the orbital velocity, we consider the gravitational waves emitted by such a binary system. We calculate E˙\dot{E}, the rate at which the gravitational waves remove energy from the system. The total energy loss is given by E˙=E˙∞+E˙H\dot{E} = \dot{E}^\infty + \dot{E}^H, where E˙∞\dot{E}^\infty denotes that part of the gravitational-wave energy which is carried off to infinity, while E˙H\dot{E}^H denotes the part which is absorbed by the black hole. We show that the black-hole absorption is a small effect: E˙H/E˙≃v8\dot{E}^H/\dot{E} \simeq v^8. We also compare the wave generation formalism which derives from perturbation theory to the post-Newtonian formalism of Blanchet and Damour. Among other things we consider the corrections to the asymptotic gravitational-wave field which are due to wave-propagation (tail) effects.Comment: ReVTeX, 17 page

    Genetic and Phenotypic Features of Schizophrenia in the UK Biobank

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    IMPORTANCE Large-scale biobanks provide important opportunities for mental health research, but selection biases raise questions regarding the comparability of individuals with those in clinical research settings. OBJECTIVE To compare the genetic liability to psychiatric disorders in individuals with schizophrenia in the UK Biobank with individuals in the Psychiatric Genomics Consortium (PGC) and to compare genetic liability and phenotypic features with participants recruited from clinical settings. DESIGN, SETTING, AND PARTICIPANTS This cross-sectional study included participants from the population-based UK Biobank and schizophrenia samples recruited from clinical settings (CLOZUK, CardiffCOGS, Cardiff F-Series, and Cardiff Affected Sib-Pairs). Data were collected between January 1993 and July 2021. Data analysis was conducted between July 2021 and June 2023. MAIN OUTCOMES AND MEASURES A genome-wide association study of UK Biobank schizophrenia case-control status was conducted, and the results were compared with those from the PGC via genetic correlations. To test for differences with the clinical samples, polygenic risk scores (PRS) were calculated for schizophrenia, bipolar disorder, depression, and intelligence using PRS-CS. PRS and phenotypic comparisons were conducted using pairwise logistic regressions. The proportions of individuals with copy number variants associated with schizophrenia were compared using Firth logistic regression. RESULTS The sample of 517 375 participants included 1438 UK Biobank participants with schizophrenia (550 [38.2%] female; mean [SD] age, 54.7 [8.3] years), 499 475 UK Biobank controls (271 884 [54.4%] female; mean [SD] age, 56.5 [8.1] years), and 4 schizophrenia research samples (4758 [28.9%] female; mean [SD] age, 38.2 [21.0] years). Liability to schizophrenia in UK Biobank was highly correlated with the latest genome-wide association study from the PGC (genetic correlation, 0.98; SE, 0.18) and showed the expected patterns of correlations with other psychiatric disorders. The schizophrenia PRS explained 6.8% of the variance in liability for schizophrenia case status in UK Biobank. UK Biobank participants with schizophrenia had significantly lower schizophrenia PRS than 3 of the clinically ascertained samples and significantly lower rates of schizophrenia-associated copy number variants than the CLOZUK sample. UK Biobank participants with schizophrenia had higher educational attainment and employment rates than the clinically ascertained schizophrenia samples, lower rates of smoking, and a later age of onset of psychosis. CONCLUSIONS AND RELEVANCE Individuals with schizophrenia in the UK Biobank, and likely other volunteer-based biobanks, represent those less severely affected. Their inclusion in wider studies should enhance the representation of the full spectrum of illness severity
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