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

Is there such a Thing called Scientific Waste?

Science is a winner-take-all profession in which only few contributions get excessive attention and the large majority of papers remains receives scant or no attention. This so-called ‘waste’ together with all the competitive strategies of scientists seeking attention is part and parcel of any creative profession and not a worrisome fact as the price society pays for human ingenuity is extremely small: 0.0006 percent of world income goes into the publication of scientific research. The more worrisome features of competition in academic economics reveal themselves not through ordinary citation or publication statistics or competitive attention seeking strategies. The badly designed use of market principles in which citations and publications have become the sol

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

Economic news through the magnifying glass:How the media cover economic boom and bust

One of the normative functions of economic news is surveillance, making monitorial citizens aware of significant economic developments. In this light, it is important to look at the way economic news covers periods of recession and economic boom. Previous studies have focused on how the media cover monthly developments of the economy rather than how coverage varies over the course of the economic cycle. Based on parallels between self-reinforcing news waves or media hypes, on the one hand, and coverage of recession and economic boom, on the other, we argue that the media amplify periods of prolonged economic growth or contraction by making the economy more visible and reporting with an overly positive or negative tone. A time-series analysis of the relation between economic developments and the automatically coded tone and visibility of economic news in Danish newspapers (1996-2012) shows that the media functioned as a magnifying glass. During recession, the economy became more negative and visible than economic developments would predict. During economic boom, economic news became more positive, but not more visible. The media adjusted the tone downwards before the economy entered recession. These results are assessed in light of the surveillance function