5,075 research outputs found

    D=5 Einstein-Maxwell-Chern-Simons Black Holes

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    5-dimensional Einstein-Maxwell-Chern-Simons theory with Chern-Simons coefficient λ=1\lambda=1 has supersymmetric black holes with vanishing horizon angular velocity, but finite angular momentum. Here supersymmetry is associated with a borderline between stability and instability, since for λ>1\lambda>1 a rotational instability arises, where counterrotating black holes appear, whose horizon rotates in the opposite sense to the angular momentum. For λ>2\lambda>2 black holes are no longer uniquely characterized by their global charges, and rotating black holes with vanishing angular momentum appear.Comment: 4 pages, 4 figures, RevTeX styl

    Pairing of 1-hexyl-3-methylimidazolium and tetrafluoroborate ions in n-pentanol

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    Molecular dynamics simulations are obtained and analyzed to study pairing of 1-hexyl-3-methylimidazolium and tetrafluoroborate ions in n-pentanol, in particular by evaluating the potential-of-mean-force between counter ions. The present molecular model and simulation accurately predicts the dissociation constant Kd in comparison to experiment, and thus the behavior and magnitudes for the ion-pair pmf at molecular distances, even though the dielectric constant of the simulated solvent differs from the experimental value by about 30%. A naive dielectric model does not capture molecule structural effects such as multiple conformations and binding geometries of the Hmim+ and BF4- ion-pairs. Mobilities identify multiple time-scale effects in the autocorrelation of the random forces on the ions, and specifically a slow, exponential time-decay of those long-ranged forces associated here with dielectric friction effects.Comment: 5 pages, 7 figures. V2: Figs. 4 & 7 redrawn for better visual clarity with log-scales. No change in results. In press J. Chem. Phys. 201

    Orbits in the Field of a Gravitating Magnetic Monopole

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    Orbits of test particles and light rays are an important tool to study the properties of space-time metrics. Here we systematically study the properties of the gravitational field of a globally regular magnetic monopole in terms of the geodesics of test particles and light. The gravitational field depends on two dimensionless parameters, defined as ratios of the characteristic mass scales present. For critical values of these parameters the resulting metric coefficients develop a singular behavior, which has profound influence on the properties of the resulting space-time and which is clearly reflected in the orbits of the test particles and light rays.Comment: 24 pages, 15 figures. Accepted for publication in GR

    Mixed neutron-star-plus-wormhole systems: Equilibrium configurations

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    We study gravitationally bound, spherically symmetric equilibrium configurations consisting of ordinary (neutron-star) matter and of a phantom/ghost scalar field which provides the nontrivial topology in the system. For such mixed configurations, we show the existence of static, regular, asymptotically flat general relativistic solutions. Based on the energy approach, we discuss the stability as a function of the core density of the neutron matter for various sizes of the wormhole throat.Comment: 18 pages, 3 figures, minor corrections to content, references added, version published in PR

    Thyroid hormones, blood plasma metabolites and haematological parameters in relationship to milk yield in dairy cows

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    To study their relationship to milk yield, the concentrations, in jugular venous blood, of thyroxine iodine (T4I), thyroxine (T4), 3,5,3'-tri-iodothyronine (T3), glucose, non-esterified fatty acids (NEFA), triglycerides, phospholipids, cholesterol, total protein, albumin, urea, haemoglobin and packed cell volume (PCV) have been measured in 36 cows (Simmental, Swiss Brown, Holstein and Simmental × Holstein) of different ages during a full lactation, pregnancy, dry period, parturition and 150 days of the ensuing lactation. Thyroid hormones and triglycerides were negatively, and total protein, globulin, cholesterol and phospholipids were positively, correlated with uncorrected or corrected milk yield during several periods of lactation, whereas glucose, NEFA, albumin, urea, haemoglobin and packed cell volume were not correlated with milk yield. The 10 animals with the highest milk yield (18·9 to 23·5 kg/day) exhibited significantly lower values of T4I, T4, T3 and glucose, significantly higher levels of total protein and globulin and tended to have higher levels of NEFA than the 10 cows with the lowest milk yield (10·9 to 14·3 kg/day) throughout or during certain periods of lactation, whereas concentrations of triglycerides, phospholipids, cholesterol, albumin, haemoglobin and PCV did not differ. Changes in T4I, T4, T3, glucose and total protein during lactation were also influenced by age, presumably associated with an increase in milk production with age. T3 was consistently lowest and cholesterol and phospholipids, during later stages of lactation, were highest in Holsteins, which had the highest milk yields of all breeds. Changes of blood parameters were mainly caused by shifts in energy and protein metabolism in association with level of milk productio

    Comparison between two methods of solution of coupled equations for low-energy scattering

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    Cross sections from low-energy neutron-nucleus scattering have been evaluated using a coupled channel theory of scattering. Both a coordinate-space and a momentum-space formalism of that coupled-channel theory are considered.A simple rotational model of the channel interaction potentials is used to find results using two relevant codes, ECIS97 and MCAS, so that they may be compared. The very same model is then used in the MCAS approach to quantify the changes that occur when allowance is made for effects of the Pauli principle.Comment: 6 pages, 3 figure

    The Trispectrum of the 4 Year COBE-DMR data

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    We propose an estimator for the trispectrum of a scalar random field on a sphere, discuss its geometrical and statistical properties, and outline its implementation. By estimating the trispectrum of the 4 year COBE-DMR data (in HEALPix pixelization) we find new evidence of a non-Gaussian signal associated with a known systematic effect. We find that by removing data from the sky maps for those periods of time perturbed by this effect, the amplitudes of the trispectrum coefficients become completely consistent with predictions for a Gaussian sky. These results reinforce the importance of statistical methods based in harmonic space for quantifying non-Gaussianity.Comment: 4 pages, 2 figures, emulateapj style. Updated to match published versio

    UV induces resistance in Arabidopsis Thaliana to the Oomycete Pathogen Hyaloperonospora Parasitica

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    Owing to their sessile nature, plants have evolved mechanisms to minimise the damaging effects of abiotic and biotic stresses. Attack by pathogenic fungi, viruses and bacterium is a major type of biotic stress. To resist infection, plants recognise invading pathogens and induce disease resistance through multiple signal transduction pathways. In addition, appropriate stimulation can cause plants to increase their resistance to future pathogen attack. We have found that exposure to non-lethal doses of UV-C (254 nm) renders a normally susceptible ecotype of Arabidopsis thaliana resistant to the biotrophic Oomycete pathogen Hyaloperonospora parasitica. The UV treatment induces an incompatible response in a dose-dependent fashion, and is still effective upon pathogen inoculation up to seven days after UV exposure. The degree of resistance diminishes with time but higher doses result in greater levels of resistance, even after seven days. Furthermore, the effect is systemic, occurring in parts of the plant that have not been irradiated. Incubation in the dark post?irradiation and prior to infection reduces the UV dose required to generate a specific level of pathogen resistance without affecting the duration of resistance. These observations, plus the inability of plants to photoreactivate UV photoproducts in the dark, strongly suggest that DNA damage induces the resistance phenotype. Currently, we are assessing the influence of DNA repair defects on UV-induced resistance, following the expression of a number of defence?related genes post-UV-C irradiation, and assessing the effect of UV in plant mutants deficient in specific signalling molecules involved in resistance.<br /

    Effects of graded levels of dietary pomegranate peel on methane and nitrogen losses, and metabolic and health indicators in dairy cows

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    This study aimed to quantify the effects of dietary inclusion of tannin-rich pomegranate peel (PP) on intake, methane and nitrogen (N) losses, and metabolic and health indicators in dairy cows. Four multiparous, late-lactating Brown Swiss dairy cows (796 kg body weight; 29 kg/d of energy corrected milk yield) were randomly allocated to 3 treatments in a randomized cyclic change-over design with 3 periods, each comprising 14 d of adaptation, 7 d of milk, urine, and feces collection, and 2 d of methane measurements. Treatments were formulated using PP that replaced on a dry matter (DM) basis 0% (control), 5%, and 10% of the basal mixed ration (BMR) consisting of corn and grass silage, alfalfa, and concentrate. Gaseous exchange of the cows was determined in open-circuit respiration chambers. Blood samples were collected on d 15 of each period. Individual feed intake as well as feces and urine excretion were quantified, and representative samples were collected for analyses of nutrients and phenol composition. Milk was analyzed for concentrations of fat, protein, lactose, milk urea N, and fatty acids. Total phenols and antioxidant capacity in milk and plasma were determined. In serum, the concentrations of urea and bilirubin as well as the activities of alanine aminotransferase (ALT), aspartate aminotransferase, glutamate dehydrogenase, alkaline phosphatase, and γ-glutamyl transferase were measured. The data was subjected to ANOVA with the Mixed procedure of SAS, with treatment and period as fixed and animal as random effects. The PP and BMR contained 218 and 3.5 g total extractable tannins per kg DM, respectively, and thereof 203 and 3.3 g hydrolyzable tannins. Total DM intake, energy corrected milk, and methane emission (total, yield, and intensity) were not affected by PP supplementation. The proportions of C18:2 n-6 and C18:3 n-3 in milk increased linearly as the amount of PP increased in the diet. Milk urea N, blood urea N, and urinary N excretion decreased linearly with the increase in dietary PP content. Total phenols and antioxidant capacity in milk and plasma were not affected by the inclusion of PP. The activity of ALT increased in a linear manner with the inclusion of PP. In conclusion, replacing up to 10% of BMR with PP improved milk fatty acid composition and alleviated metabolic and environmental N load. However, the elevated serum ALT activity indicates an onset of liver stress even at 5% PP, requiring the development of adaptation protocols for safe inclusion of PP in ruminant diets

    Calculations of 8^{8}He+p Elastic Cross Sections Using Microscopic Optical Potential

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    An approach to calculate microscopic optical potential (OP) with the real part obtained by a folding procedure and with the imaginary part inherent in the high-energy approximation (HEA) is applied to study the 8^8He+p elastic scattering data at energies of tens of MeV/nucleon (MeV/N). The neutron and proton density distributions obtained in different models for 8^{8}He are utilized in the calculations of the differential cross sections. The role of the spin-orbit potential is studied. Comparison of the calculations with the available experimental data on the elastic scattering differential cross sections at beam energies of 15.7, 26.25, 32, 66 and 73 MeV/N is performed. The problem of the ambiguities of the depths of each component of the optical potential is considered by means of the imposed physical criterion related to the known behavior of the volume integrals as functions of the incident energy. It is shown also that the role of the surface absorption is rather important, in particular for the lowest incident energies (e.g., 15.7 and 26.25 MeV/nucleon).Comment: 11 pages, 7 figures, accepted for publication in Physical Review
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