340 research outputs found
Flat rotation curves in Chern-Simons modified gravity
We investigate the spacetime of a slowly rotating black hole in the
Chern-Simons modified gravity. The long range feature of frame-dragging effect
under the Chern-Simon gravity well explains the flat rotation curves of
galaxies which is a central evidence of dark matter. Our solution provides a
different scenario of rotating space from Goedel's solution.Comment: 4 pages, Accepted for publication in Phys. Rev.
Gastro-intestinal parasites of pigs in Sardinia: a copromicroscopical investigation
This paper illustrates a copromicroscopical investigation carried out in Sardinia to update epidemiological data on diffusion of gastro-intestinal parasites in swine. Results obtained lead to suggest the employment of copromicroscopic exam to monitorate parasites diffusion in swine breedings in order to set up correct prophylactic and therapeutically intervents
Apicomplexa diffusion in tissue samples from slaughtered sheep in Sardinia (Italy)
Sheep breeding plays in Sardinia a major role for the economy of the island with over than 3 millions of animals
raised mostly with extensive methods. The results of the present work allow us to conclude that N. caninum did not constitute a health problem for the sheep coming from the monitored districts
Two-dimensional quantum interference contributions to the magnetoresistance of Nd{2-x}Ce{x}CuO{4-d} single crystals
The 2D weak localization effects at low temperatures T = (0.2-4.2)K have been
investigated in nonsuperconducting sample Nd{1.88}Ce{0.12}CuO{4-d} and in the
normal state of the superconducting sample Nd{1.82}Ce{0.18}CuO{4-d} for B>B_c2.
The phase coherence time and the effective thickness of a conducting CuO_2
layer have been estimated by the fitting of 2D weak localization theory
expressions to the magnetoresistivity data for the normal to plane and the
in-plane magnetic fields.Comment: 5 pages, 4 postscript figure
Suppression of 2D superconductivity by the magnetic field: quantum corrections vs superconductor-insulator transition
Magnetotransport of superconducting Nd_{2-x}Ce_xCuO_{4+y} (NdCeCuO) films is
studied in the temperature interval 0.3-30 K. The microscopic theory of the
quantum corrections to conductivity, both in the Cooper and in the diffusion
channels, qualitatively describes the main features of the experiment including
the negative magnetoresistance in the high field limit. Comparison with the
model of the field-induced superconductor-insulator transition (SIT) is
included and a crossover between these two theoretical approaches is discussed.Comment: 5 pages, 4 figures. Submitted to JETP Letter
Evaluation of the efficacy of anthelminthic treatments against sheep gastro-intestinal nematodes in Sardinia
Despite the rising of new methodologies for the controi of endoparasites in animais of zootechnic value, such
as phytotherapy, homeopathy, and genetie selection for screening of resistant individuais (Gruner L, 2002,
Acta SIPAOC, 15: 80-89; Carta A, Scala A, 2004, Parassitologia, 46: 251-255) and hypothetic vaccinations
against NGI (Vercruysse J, 2004, Parassitologia, 46: 261), anthelminthie treatments stilI remains the most
applied measure in the field
Orbital textures and charge density waves in transition metal dichalcogenides
Low-dimensional electron systems, as realized naturally in graphene or
created artificially at the interfaces of heterostructures, exhibit a variety
of fascinating quantum phenomena with great prospects for future applications.
Once electrons are confined to low dimensions, they also tend to spontaneously
break the symmetry of the underlying nuclear lattice by forming so-called
density waves; a state of matter that currently attracts enormous attention
because of its relation to various unconventional electronic properties. In
this study we reveal a remarkable and surprising feature of charge density
waves (CDWs), namely their intimate relation to orbital order. For the
prototypical material 1T-TaS2 we not only show that the CDW within the
two-dimensional TaS2-layers involves previously unidentified orbital textures
of great complexity. We also demonstrate that two metastable stackings of the
orbitally ordered layers allow to manipulate salient features of the electronic
structure. Indeed, these orbital effects enable to switch the properties of
1T-TaS2 nanostructures from metallic to semiconducting with technologically
pertinent gaps of the order of 200 meV. This new type of orbitronics is
especially relevant for the ongoing development of novel, miniaturized and
ultra-fast devices based on layered transition metal dichalcogenides
Hierarchically modelling Kepler dwarfs and subgiants to improve inference of stellar properties with asteroseismology
This work is a part of a project that has received funding from the European Research Council (ERC) under the European Unionâs Horizon 2020 research and innovation programme (CartographY; grant agreement ID 804752). AJL, GRD, and WJC acknowledge the support of the Science and Technology Facilities Council. DH acknowledges support from the Alfred P. Sloan Foundation, the National Aeronautics and Space Administration (80NSSC19K0597), and the National Science Foundation (AST-1717000). MBN acknowledges support from the UK Space Agency. RAG acknowledges the funding from the PLATO CNES grant.With recent advances in modelling stars using high-precision asteroseismology, the systematic effects associated with our assumptions of stellar helium abundance (Y) and the mixing-length theory parameter (αMLT) are becoming more important. We apply a new method to improve the inference of stellar parameters for a sample of Kepler dwarfs and subgiants across a narrow mass range (â 0.8<M<1.2Mâ). In this method, we include a statistical treatment of Y and the αMLT. We develop a hierarchical Bayesian model to encode information about the distribution of Y and αMLT in the population, fitting a linear helium enrichment law including an intrinsic spread around this relation and normal distribution in αMLT. We test various levels of pooling parameters, with and without solar data as a calibrator. When including the Sun as a star, we find the gradient for the enrichment law, ÎY/ÎZ=1.05+0.28â0.25 and the mean αMLT in the population, Όα=1.90+0.10â0.09, Όα=1.90+0.10â0.09â . While accounting for the uncertainty in Y and αMLT, we are still able to report statistical uncertainties of 2.5 per cent in mass, 1.2 per cent in radius, and 12 per cent in age. Our method can also be applied to larger samples that will lead to improved constraints on both the population level inference and the star-by-star fundamental parameters.Publisher PDFPeer reviewe
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