Vacuum-polarization contribution to the hyperfine-structure splitting of hydrogenlike atoms

A calculation of the vacuum-polarization contribution to the hyperfine splitting for hydrogenlike atoms is presented. The extended nuclear charge distribution is taken into account. For the experimentally interesting case 209Bi82+ we predict a delta-lambda- -1.6 nm shift for the transition wavelength of the ground-state hyperfine splitting

Formation of heavy quarks in ultrarelativistic heavy-ion collisions

We investigate the production of heavy quarks in continuum and bound states in nuclear collisions. Creation rates for free bb and tt quark pairs and for bottomonium and toponium in the ground state are computed at energies of the BNL Relativistic Heavy Ion Collider, CERN Large Hadron Collider (LHC), and Superconducting Super Collider. Central and peripheral heavy-ion collisions are discussed. For top-quark creation we assumed a mass range of 90≤mt≤250 GeV. The creation rate for top quarks in peripheral collisions is estimated to be by a factor 40 to 130 smaller compared with corresponding central collisions. For mt=130 GeV we calculated a creation rate of about 4760 top-quark pairs per day at the LHC (3.5 TeV/nucleon) for Pb-Pb collisions

Matrix processing peptidase of mitochondria

The mitochondrial processing peptidase (MPP) and the processing enhancing protein (PEP) cooperate in the proteolytic cleavage of matrix targeting sequences from nuclear-encoded mitochondrial precursor proteins. We have determined the cDNA sequence of Neurospora MPP after expression cloning. MPP appears to contain two domains of approximately equal size which are separated by a loop-like sequence. Considerable structural similarity exists to the recently sequenced yeast MPP as well as to Neurospora and yeast PEP. Four cysteine residues are conserved in Neurospora and yeast MPP. Inactivation of MPP can be achieved by using sulfhydryl reagents. MPP (but not PEP) depends on the presence of divalent metal ions for activity. Both MPP and PEP are synthesized as precursors containing matrix targeting signals which are processed during import into mitochondria by the mature forms of MPP and PEP

Brain Imaging and its impact on the development of Cognitive Science

s symposium will address the new data and challenges presented by recent advances in brain imaging methodology. It will include tutorials on the available techniques: Positron Emission Topography (PET), Functional Magnetic Resonance Imaging (fMRJ) and combined fMRI & high density Evoked Response Potentials (ERP). The impact of these techniques on the physiological interpretation of human working memor y will be illustrated

Explicit Bounds for the Distribution Function of the Sum of Dependent Normally Distributed Random Variables

In this paper an analytic expression is given for the bounds of the distribution function of the sum of dependent normally distributed random variables. Using the theory of copulas and the important Frechet bounds the dependence structure is not restricted to any specific type. Numerical illustrations are provided to assess the quality of the derived bounds.Comment: Keywords: Dependent RVs, Copulas, Frechet Bound