Emergence of classicality for primordial fluctuations: Concepts and analogies

We clarify the way in which cosmological perturbations of quantum origin, produced during inflation, assume classical properties. Two features play an important role in this process: First, the dynamics of fluctuations which are presently on large cosmological scales leads to a very peculiar state (highly squeezed) that is indistinguishable, in a precise sense, from a classical stochastic process. This holds for almost all initial quantum states. Second, the process of decoherence by interaction with the environment distinguishes the field amplitude basis as the robust pointer basis. We discuss in detail the interplay between these features and use simple analogies such as the free quantum particle to illustrate the main conceptual issues.     

Chemical composition and reaction analysis of single aerosol particles

In situ measurements of gas-liquid surface reactions of single aerosol microdroplets are presented. By means of optical levitation in combination with elastic (Mie) and inelastic (Raman) light scattering it is possible to get information on the chemistry of e.g. acid/base reactions as well as the physical behavior of single microparticles.     

The UV-laser excited resonance raman spectrum of the I3 ion

Solutions of cesium tri-iodide and potassium iodide and iodine in water show a strong resonance Raman effect of the I⁻₃ ion when excited by the ultraviolet lines at 3638 and 3511 Å of an argon ion laser, High intensity overtone progressions of the “symmetric” vibration ν_i were observed. This progression allows the confirmation of the presence of the I⁻₃ ion in iodine-methanol solutions.     

WAVELENGTH DEPENDENCE OF INACTIVATION and MUTAGENESIS IN HAPLOID YEAST CELLS OF DIFFERENT SENSITIVITIES

The wavelength dependence of inactivation and mutagenesis in the range between 254 and 313 nm was investigated in haploid cells of the yeast Saccharomyces cerevisiae. The action spectra for a wild type and an excision deficient mutant essentially corresponded to those for bacteria and mammalian cells. There were, however, minor differences. The ratio of mutagenic to lethal action decreased with increasing wavelength in the wild type, but remained constant in the excision deficient mutant. This is discussed in terms of error-prone and erro-free repair. For both inactivation and mutagensis, photorcactivability was lower with longer wavelengths in the wild type, but did not change in the excision deficient mutant. Implications for the role of pyrimidine dimers are considered.     

INACTIVATION AND MUTATION INDUCTION TO 6-THIOGUANINE RESISTANCE IN V79 HAMSTER FIBROBLASTS BY SIMULATED SUNLIGHT

Abstract— Risk estimates for an enhancement of ultraviolet radiation are frequently based on action spectra, in which case it is assumed that the different components of natural or artificial sunlight act independently and the overall effect can be derived by a simple summation procedure. Such an approach, however, may not always be justified and-as shown earlier-lead to a considerable underestimation of inactivation and mutation induction to 6-thioguanine resistance by filtered 'sunlamp'-radiation. Here we report on experiments employing different kinds of simulated sunlight. A good agreement between theoretical and experimental results was found. The apparent contradiction can be resolved by an analysis for the spectral regions primarily responsible for the overall effect.