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 Introduction to Pure Spinor Superstring Theory

In these lecture notes presented at the 2015 Villa de Leyva Summer School, we give an introduction to superstring theory. We begin by studying the particle and superparticle in order to get a better understanding on the superstring side. Afterwards, we review the pure spinor formalism and end by computing the scattering amplitude for three gravitons at tree-level.Comment: Villa de Leyva Summer School 2015 proceedings, 28 pages, 2 figure

Phrasal Alternation in the Pondok Tinggi Dialect of Kerinci; an Intergenerational Analysis

This paper examines the implications of language contact in a Malay sub-variety known as Pondok Tinggi, spoken in Sumatra. My focus is on the grammatical phenomenon of phrasal alternation. Phrasal alternation is characterized by the presence of two distinct forms for nearly all lexical items, whose final syllables differ in shape. These are termed absolute and oblique (Steinhauer and Usman 1978: 485). The intergenerational transmission of this uncommon feature offers a way to measure the degree of contact-induced language change in Pondok Tinggi. An experiment was conducted to elicit the USAge of the absolute and the oblique forms in order to find out how the distribution of phrasal alternation has changed within the last two generations. I reveal a grammatical simplification caused by contact between Pondok Tinggi and Bahasa Indonesia, a related Malayic variety serving as Indonesia's prestigious official language. This adds a dimension of loss of local linguistic diversity to more familiar tropes of the national success of Bahasa Indonesia

Three Applications of Instanton Numbers

We use instanton numbers to: (i) stratify moduli of vector bundles, (ii) calculate relative homology of moduli spaces and (iii) distinguish curve singularities.Comment: To appear in Communications in Mathematical Physic

Simultaneous processing of vibration test data

Data from record tracks of all accelerometers is injected simultaneously into electronic circuits which convert inputs into single, composite graphical representation. Three adequate methods of processing data: peak acceleration at a frequency, average of all channels, and quad-mean of all channels