On Non-tachyonic Z_N x Z_M Orientifolds of Type 0B String Theory

We study open descendants of four dimensional Z_N x Z_M orbifolds of the non-supersymmetric type 0B string theory. An exhaustive analysis shows, that using the crosscap constraint the only model for which one can project out the tachyon is the Z_2 x Z_2 orbifold. For this case we explicitly construct the open string amplitudes. The gauge group corresponding to the various inequivalent Klein bottle projections turns out to be either symplectic or unitary.Comment: 15 pages, harvma

Simple Calculation of Instanton Corrections in Massive N=2 SU(3) SYM

We give an explicit derivation of the Picard-Fuchs equations for N=2 supersymmetric SU(3) Yang-Mills theory with $N_f<6$ massive hypermultiplets in the fundamental representation. We determine the instanton corrections to the prepotential in the weak coupling region using the relation between \tr and the prepotential. This method can be generalized to other gauge groups.Comment: 16 pages, Late

Autoimmune rheumatische Erkrankungen in der Schwangerschaft

Zusammenfassung: Eine erfolgreiche Schwangerschaft beruht auf der Modulation des mütterlichen Immunsystems, um eine Abstoßung des Föten zu verhindern. Die Toleranzmechanismen der Schwangerschaft können den Verlauf einer rheumatischen Autoimmunerkrankung positiv oder negativ beeinflussen. So bewirkt die Schwangerschaft bei der rheumatoiden Arthritis oft eine eindrucksvolle Besserung, während bei der ankylosierenden Spondylitis die entzündlichen Rückenschmerzen meist unverändert persistieren. Bei Kollagenosen oder Vaskulitis, insbesondere bei hoher Krankheitsaktivität, bestehen in der Schwangerschaft Risiken für Mutter und Kind. Im Vorfeld einer Schwangerschaft sollte einerseits eine inaktive Krankheitsphase abgewartet werden und andererseits eine "schwangerschaftsverträgliche" Therapie zur Krankheitskontrolle zum Einsatz kommen. Eine engmaschige interdisziplinäre Betreuung dieser Patienten ist der Schlüssel für eine erfolgreiche Schwangerschaf

Is IgG galactosylation the relevant factor for pregnancy-induced remission of rheumatoid arthritis?

During pregnancy, most patients with rheumatoid arthritis (RA) experience spontaneous improvement of their disease activity. Among the soluble candidates that have been investigated in search for the most relevant disease-remitting factor are the galactosylation levels of immunoglobulin G (IgG). In RA, a higher percentage of IgG lacking the terminal galactose residues, thought to play a pro-inflammatory role, is found. During pregnancy, however, IgG galactosylation levels increase and correlate with improved disease activity. The question remains whether the increase in IgG galactosylation during pregnancy is a mere epiphenomenon or a true remission-inducing factor

Higher-Derivative Gravity in String Theory

We explicitly extract the structure of higher-derivative curvature-squared terms at genus 0 and 1 in the d=4 heterotic string effective action compactified on symmetric orbifolds by computing on-shell S-matrix superstring amplitudes. In particular, this is done within the context of calculating the graviton 4-point amplitude. We also discuss the moduli-dependent gravitational threshold corrections to the coupling associated with the CP even quadratic curvature terms.Comment: 14 pages, 6 Postscript figures, latex and psfi

String Amplitudes and N=2, d=4 Prepotential in Heterotic K3 x T^2 Compactifications

For the gauge couplings, which arise after toroidal compactification of six-dimensional heterotic N=1 string theories from the T^2 torus, we calculate their one-loop corrections. This is performed by considering string amplitudes involving two gauge fields and moduli fields. We compare our results with the equations following from N=2 special geometry and the underlying prepotential of the theory. Moreover we find relations between derivatives of the N=2, d=4 prepotential and world-sheet tau-integrals which appear in various string amplitudes of any T^2-compactification.Comment: 28 TeX pages, uses harvmac, Final Version to appear in NP