Probing phase-separation in Bose-Fermi mixtures by the critical superfluid velocity

We investigate the effect exerted by spin-polarized fermions on the interaction between superfluid bosons for a Bose-Fermi mixture residing on an optical lattice, with particular emphasis on the possibility of an induced phase-separation. Using a set of microscopic parameters relevant to a $^{40}$K-$^{87}$Rb mixture, we show how the phase-separation criterion may be directly probed by means of the critical superfluid velocity of the bosonic condensate. We report quantitative results for the magnitude of the superfluid velocity and its dependence on the trap depth, the boson-fermion interaction, and the fermionic filling fraction. All of these parameters can be controlled experimentally in a well-defined manner. We propose an experimental setup for probing the critical superfluid velocity.Comment: 7 pages, 5 figure

Strong Gravitational Lensing and Dark Energy Complementarity

In the search for the nature of dark energy most cosmological probes measure simple functions of the expansion rate. While powerful, these all involve roughly the same dependence on the dark energy equation of state parameters, with anticorrelation between its present value w_0 and time variation w_a. Quantities that have instead positive correlation and so a sensitivity direction largely orthogonal to, e.g., distance probes offer the hope of achieving tight constraints through complementarity. Such quantities are found in strong gravitational lensing observations of image separations and time delays. While degeneracy between cosmological parameters prevents full complementarity, strong lensing measurements to 1% accuracy can improve equation of state characterization by 15-50%. Next generation surveys should provide data on roughly 10^5 lens systems, though systematic errors will remain challenging.Comment: 7 pages, 5 figure

Exposure to Sexualized Images of Athletes Negatively Affects Adolescent Male Athletes’ Appraisals of Self and Others

This study used a between-subjects experimental design to examine the effects of viewing sexualized versus performance images of male athletes on male adolescent athletes perceptions of self and other. Participants (n = 83, mean age = 15.4) viewed sexualized or performance images (n = 5) of male celebrity athletes and then completed explicit and implicit measures of self-perceptions. They also judged the athletic competence and respectability of the athletes in the images. Results indicated that viewing sexualized images resulted in lower self-esteem and lower ratings of the athletic competence and respectability of the athletes in the photos compared to viewing performance images. These findings are among the first to demonstrate the negative effects of viewing sexualized images of male athletes on adolescent males