3,692 research outputs found

    SCREENING FOR HEPATITIS C Response from Hepatitis C Trust, BASL, BIA, BVHG, BSG, and BHIVA to article asking whether widespread screening for hepatitis C is justified

    Get PDF
    This is the peer reviewed published version of the following article: Response from Hepatitis C Trust, BASL, BIA, BVHG, BSG, and BHIVA to article asking whether widespread screening for hepatitis C is justified, which has been published in final form at 10.1136/bmj.h998. This article may be used for non-commercial purposes in accordance with BMJ's Terms and Conditions for Self-Archiving.This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/ by/4.0

    Threshold of Singularity Formation in the Semilinear Wave Equation

    Full text link
    Solutions of the semilinear wave equation are found numerically in three spatial dimensions with no assumed symmetry using distributed adaptive mesh refinement. The threshold of singularity formation is studied for the two cases in which the exponent of the nonlinear term is either p=5p=5 or p=7p=7. Near the threshold of singularity formation, numerical solutions suggest an approach to self-similarity for the p=7p=7 case and an approach to a scale evolving static solution for p=5p=5.Comment: 6 pages, 7 figure

    Dark matter: A spin one half fermion field with mass dimension one?

    Full text link
    We report an unexpected theoretical discovery of a spin one half matter field with mass dimension one. It is based on a complete set of eigenspinors of the charge conjugation operator. Due to its unusual properties with respect to charge conjugation and parity it belongs to a non standard Wigner class. Consequently, the theory exhibits non-locality with (CPT)^2 = - I. Its dominant interaction with known forms of matter is via Higgs, and with gravity. This aspect leads us to contemplate it as a first-principle candidate for dark matter.Comment: 5 pages, RevTex, v2: slightly extended discussion, new refs. and note adde

    Cosmological model with non-minimally coupled fermionic field

    Full text link
    A model for the Universe is proposed whose constituents are: (a) a dark energy field modeled by a fermionic field non-minimally coupled with the gravitational field, (b) a matter field which consists of pressureless baryonic and dark matter fields and (c) a field which represents the radiation and the neutrinos. The coupled system of Dirac's equations and Einstein field equations is solved numerically by considering a spatially flat homogeneous and isotropic Universe. It is shown that the proposed model can reproduce the expected red-shift behaviors of the deceleration parameter, of the density parameters of each constituent and of the luminosity distance. Furthermore, for small values of the red-shift the constant which couples the fermionic and gravitational fields has a remarkable influence on the density and deceleration parameters.Comment: Accepted for publication in Europhysics Letter

    Adaptive Optics Discovery of Supernova 2004ip in the Nuclear Regions of the Luminous Infrared Galaxy IRAS 18293-3413

    Full text link
    We report a supernova discovery in Ks-band images from the NAOS CONICA adaptive optics (AO) system on the ESO Very Large Telescope (VLT). The images were obtained as part of a near-infrared search for highly-obscured supernovae in the nuclear regions of luminous and ultraluminous infrared galaxies. SN 2004ip is located within a circumnuclear starburst at 1.4 arcsec (or 500 pc) projected distance from the K-band nucleus of the luminous infrared galaxy IRAS 18293-3413. The supernova luminosity and light curve are consistent with a core-collapse event suffering from a host galaxy extinction of up to about 40 magnitudes in V-band which is as expected for a circumnuclear starburst environment. This is the first supernova to be discovered making use of AO correction and demonstrates the potential of the current 8-meter class telescopes equipped with AO in discovering supernovae from the innermost nuclear regions of luminous and ultraluminous infrared galaxies.Comment: 4 pages, 3 figures, ApJ Letters (accepted

    Treating some solid state problems with the Dirac equation

    Full text link
    The ambiguity involved in the definition of effective-mass Hamiltonians for nonrelativistic models is resolved using the Dirac equation. The multistep approximation is extended for relativistic cases allowing the treatment of arbitrary potential and effective-mass profiles without ordering problems. On the other hand, if the Schrodinger equation is supposed to be used, our relativistic approach demonstrate that both results are coincidents if the BenDaniel and Duke prescription for the kinetic-energy operator is implemented. Applications for semiconductor heterostructures are discussed.Comment: 06 pages, 5 figure

    hnRNP A1 and secondary structure coordinate alternative splicing of Mag

    Get PDF
    Myelin-associated glycoprotein (MAG) is a major component of myelin in the vertebrate central nervous system. MAG is present in the periaxonal region of the myelin structure, where it interacts with neuronal proteins to inhibit axon outgrowth and protect neurons from degeneration. Two alternatively spliced isoforms of Mag mRNA have been identified. The mRNA encoding the shorter isoform, known as S-MAG, contains a termination codon in exon 12, while the mRNA encoding the longer isoform, known as L-MAG, skips exon 12 and produces a protein with a longer C-terminal region. L-MAG is required in the central nervous system. How inclusion of Mag exon 12 is regulated is not clear. In a previous study, we showed that heteronuclear ribonucleoprotein A1 (hnRNP A1) contributes to Mag exon 12 skipping. Here, we show that hnRNP A1 interacts with an element that overlaps the 5\u27 splice site of Mag exon 12. The element has a reduced ability to interact with the U1 snRNP compared with a mutant that improves the splice site consensus. An evolutionarily conserved secondary structure is present surrounding the element. The structure modulates interaction with both hnRNP A1 and U1. Analysis of splice isoforms produced from a series of reporter constructs demonstrates that the hnRNP A1-binding site and the secondary structure both contribute to exclusion of Mag exon 12

    The general-covariant and gauge-invariant theory of quantum particles in classical backgrounds

    Full text link
    A new approach to the concept of particles and their production in quantum field theory is developed. A local operator describing the current of particle density is constructed for scalar and spinor fields in arbitrary gravitational and electromagnetic backgrounds. This enables one to describe particles in a local, general-covariant and gauge-invariant way. However, the current depends on the choice of a 2-point function. There is a choice that leads to the local non-conservation of the current in a gravitational or an electromagnetic background, which describes local particle production consistent with the usual global description based on the Bogoliubov transformation. The most natural choice based on the Green function calculated using the Schwinger-DeWitt method leads to the local conservation of the current, provided that interactions with quantum fields are absent. Interactions with quantum fields lead to the local non-conservation of the current which describes local particle production consistent with the usual global description based on the interaction picture.Comment: 34 pages, revised, to appear in Int. J. Mod. Phys.

    Disclination in Lorentz Space-Time

    Get PDF
    The disclination in Lorentz space-time is studied in detail by means of topological properties of ϕ\phi -mapping. It is found the space-time disclination can be described in term of a Dirac spinor. The size of the disclination, which is proved to be the difference of two sets of su(2)% -like monopoles expressed by two mixed spinors, is quantized topologically in terms of topological invariants−-winding number. The projection of space-time disclination density along an antisymmetric tensor field is characterized by Brouwer degree and Hopf index.Comment: Revtex, 7 page
    • …
    corecore