BEC Collapse and Dynamical Squeezing of Vacuum Fluctuations

We analyze the phenomena of Bose Novae, as described by Donley et al [Nature 412, 295 (2001)], by focusing on the behavior of excitations or fluctuations above the condensate, as driven by the dynamics of the condensate (rather than the dynamics of the condensate alone or the kinetics of the atoms). The dynamics of the condensate squeezes and amplifies the quantum excitations, mixing the positive and negative frequency components of their wave functions thereby creating particles which appear as bursts and jets. By analyzing the changing amplitude and particle content of these excitations, our simple physical picture (based on a test field approximation) explains well the overall features of the Bose Novae phenomena and provide excellent quantitative fits with experimental data on several aspects, such as the scaling behavior of the collapse time and the amount of particles in the jet. The predictions of the bursts at this level of approximation is less than satisfactory but may be improved on by including the backreaction of the excitations on the condensate. The mechanism behind the dominant effect -- parametric amplification of vacuum fluctuations and freezing of modes outside of horizon -- is similar to that of cosmological particle creation and structure formation in a rapid quench (which is fundamentally different from Hawking radiation in black holes). This shows that BEC dynamics is a promising venue for doing `laboratory cosmology'.Comment: Latex 36 pages, 6 figure

Mapping the Quality of Life and Unmet Needs of Urban Women with Metastatic Breast Cancer.

Enhancing quality of life and reducing the unmet needs of women are central to the successful management of advanced breast cancer. The objective of this study was to investigate the quality of life and support and information needs of urban women with advanced breast cancer. This study was conducted at four large urban hospitals in Melbourne, Australia. A consecutive sample of 105 women with advanced breast cancer completed a questionnaire that contained the European Organization of Research and Treatment of Cancer Quality of Life Q-C30 and the Supportive Care Needs Survey. Between one quarter and a third of the women reported difficulties with their physical, role and social functioning, and a little over a quarter of the women reported poor global health status. Fatigue was a problem for most women. The highest unmet needs were in the psychological and health information domains. Almost no differences in unmet needs were detected when comparing different demographic and disease characteristics of women. Health care providers should routinely monitor the quality of life and needs of women with advanced breast cancer to ensure that appropriate treatment, information or supportive services are made available