Time evolution of intrinsic alignments of galaxies

Intrinsic alignments (IA), correlations between the intrinsic shapes and orientations of galaxies on the sky, are both a significant systematic in weak lensing and a probe of the effect of large-scale structure on galactic structure and angular momentum. In the era of precision cosmology, it is thus especially important to model IA with high accuracy. Efforts to use cosmological perturbation theory to model the dependence of IA on the large-scale structure have thus far been relatively successful; however, extant models do not consistently account for time evolution. In particular, advection of galaxies due to peculiar velocities alters the impact of IA, because galaxy positions when observed are generally different from their positions at the epoch when IA is believed to be set. In this work, we evolve the galaxy IA from the time of galaxy formation to the time at which they are observed, including the effects of this advection, and show how this process naturally leads to a dependence of IA on the velocity shear. We calculate the galaxy-galaxy-IA bispectrum to tree level (in the linear matter density) in terms of the evolved IA coefficients. We then discuss the implications for weak lensing systematics as well as for studies of galaxy formation and evolution. We find that considering advection introduces nonlocality into the bispectrum, and that the degree of nonlocality represents the memory of a galaxy's path from the time of its formation to the time of observation. We discuss how this result can be used to constrain the redshift at which IA is determined and provide Fisher estimation for the relevant measurements using the example of SDSS-BOSS.Comment: 30 pages, 5 figures, 2 table

Migration, vulnerability and the complexity of violence: Experiences of documented non-EU migrants in Slovakia

Migration to East and Central Europe (ECE) remains under-researched, not least because of the relatively small number of migrants in the region. Exploring experiences of documented non-EU migrants in Slovakia with various forms of violence – including violence motivated by hate and associated with work exploitation – the paper uncovers patterns of violence and vulnerability across the migrant cohort. As a broader contribution to studies of migration, the research alerts scholars to the need for a greater attention to the experiences of smaller cohorts of migrants, which often remain under the radar because of their size. The second line of the argument highlights the complexity and relations between different kinds of violence. Several risk factors are identified as contributing to the risk of migrants’ exposure to various forms of abuse at the same time, providing with implications for preventive and supportive policies and practices. The analysis particularly emphasises the importance of ties between migrant communities and formal institutions for mitigating violence

High energy density fluctuations in terms of factorial moments and associated frequency moments

We propose to verify relations between quantities which characterize scaling properties of high energy density fluctuations in terms of factorial moments and newly introduced associated frequency moments. Typical examples are presented in frame of systematics developed in the present paper. It involves also several sorts of moments applied so far in the search for intermittency and multifractality. Our approach takes the advantage of relations in which a linear combination of associated frequency moments reduces statistical fluctuations to the same extent as it is done by corresponding factorial moments.Comment: 20 page

Assessment of Human Hemodynamics under Hyper- and Microgravity: Results of two Aachen University Parabolic Flight Experiments

Astronauts complain about fluid shifts from their lower extremities to their head caused by weightlessness during their flight into space. For a study of this phenomenon, RWTH Aachen University and Charité University Berlin participated in a joint project on two parabolic flight campaigns of the German Aerospace Centre (DLR) in September 2005 and June 2006. During these campaigns, the characteristics of the rapid fluid shifts during hyper- and micro gravity were measured by a combination of PPG and PPGI optoelectronic sensor concepts.