We study numerically the inhomogeneous pre-big-bang inflation in a spherically symmetric space-time. We find that a large initial inhomogeneity suppresses the onset of the pre-big-bang inflation. We also find that even if the pre-big-bang inflationary stage is realized, the initial inhomogeneities are not homogenized. Namely, during the pre-big-bang inflation “hairs”(irregularities) do not fall...

We examine the effect of credit default swaps (CDSs) on the restructuring of distressed firms. Theoretically, we show that if bondholders are insured with CDSs, the participation rate in a restructuring decreases. Using a sample of distressed exchange offers, we estimate that the participation rate is 29% lower if the firm has CDSs traded on its debt, compared to an unconditional mean of 54%. W...

We generalize previous work on inhomogeneous pre-big bang cosmology by including the effect of non-trivial moduli and antisymmetric-tensor/axion fields. The general quasi-homogeneous asymptotic solution—as one approaches the big bang singularity from perturbative initial data—is given and its range of validity is discussed, allowing us to give a general quantitative estimate of the amount of in...

The recent search for a stochastic background of gravitational waves with LIGO interferometers has produced a new upper bound on the amplitude of this background in the 100 Hz region. We investigate the implications of the current and future LIGO results on pre-Big-Bang models of the early Universe, determining the exclusion regions in the parameter space of the minimal pre-Big Bang scenario. A...

investment plays a vital role on economic growth. one of the main objectives of all countries is to achieve sustainable economic growth and development. nowadays, a considerable amount of activities performed by the managers and investors in general is to make a portfolio of assets effectively meeting demand goals. in this study, mean-variance markowitz model by cardinality constraints and also...