Momentum, Density, and Isospin dependence of the Symmetric and Asymmetric Nuclear Matter Properties

Properties of symmetric and asymmetric nuclear matter have been investigated in the relativistic Dirac-Brueckner-Hartree-Fock approach based on projection techniques using the Bonn A potential. The momentum, density, and isospin dependence of the optical potentials and nucleon effective masses are studied. It turns out that the isovector optical potential depends sensitively on density and momentum, but is almost insensitive to the isospin asymmetry. Furthermore, the Dirac mass $m^*_D$ and the nonrelativistic mass $m^*_{NR}$ which parametrizes the energy dependence of the single particle spectrum, are both determined from relativistic Dirac-Brueckner-Hartree-Fock calculations. The nonrelativistic mass shows a characteristic peak structure at momenta slightly above the Fermi momentum \kf. The relativistic Dirac mass shows a proton-neutron mass splitting of $m^*_{D,n} <m^*_{D,p}$ in isospin asymmetric nuclear matter. However, the nonrelativistic mass has a reversed mass splitting $m^*_{NR,n} >m^*_{NR,p}$ which is in agreement with the results from nonrelativistic calculations.Comment: 25 pages, 12 figures, to appear in Physical Review

An Index of Authors to A Survey of the Scientific Manuscripts in the Egyptian National Library

In 1986, David A. King published an English survey of his Arabic catalogue of the scientific manuscripts in the Egyptian National Library in Cairo, which had appeared in two large volumes in 1981 and 1986. This survey is arranged chronologically by author within a number of geographical regions. Although a list of all authors is found at the beginning of thework, no alphabetical index of authors is included. On the occasion of King’s retirement, and with an eye on the recent renewed interest in the bio-bibliography of Islamic scholars, this article presents such an index, generated from a computer database by Benno van Dalen

Toxoplasmosis of the Domestic Feline

This article will review toxoplasmosis in the domestic feline from a practical, clinical standpoint. Aspects of transmission of infection, the life cycle of the organism, clinical signs and lesions will be discussed along with diagnosis, treatment and prevention of the disease

Bulk Viscosity in Neutron Stars from Hyperons

The contribution from hyperons to the bulk viscosity of neutron star matter is calculated. Compared to previous works we use for the weak interaction the one-pion exchange model rather than a current-current interaction, and include the neutral current $nn \leftrightarrow n\Lambda$ process. Also the sensitivity to details of the equation of state is examined. Compared to previous works we find that the contribution from hyperons to the bulk viscosity is about two orders of magnitude smaller.Comment: 18 pages, to appear in Physical Review

Attention and the Art of Scientific Publishing

Attention is the coordination device, which makes modern science work the way it does. A typical characteristic of attention in the scientific world is that those who seek attention are the same people who are giving it. Another important feature within groups is the skewed distribution of attention. We discuss the effect these characteristics have on scientific institutions. An important thesis is that scientists converge in clusters of likeminded scientists. Given the character of scientific organisation and communication we expect that the digitalisation of scientific communication will not affect the basic scientific institutions as the principles upon which the Internet and open source code projects function coincide more or less with the way science functions