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

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.

EMBRYONIC BONE DEVELOPMENT AND NFAT EXPRESSION IN THE TS65DN MOUSE MODEL FOR DOWN SYNDROME

poster abstractDown syndrome (DS) is a common genetic disorder that occurs in ap-proximately 1 out of every 750 live births. DS phenotypes include cognitive deficits, altered craniofacial features, muscle hypotonia, heart defects, and abnormal bone structure. The Ts65Dn mouse model is the most common or-ganismal model used to study DS phenotypes. This model exhibits a number of phenotypic traits comparable to those of humans with DS, including bone anomalies. Past studies have shown that Ts65Dn mice exhibit weaker tra-becular bone due to less trabeculae. They have also been shown to have less bone mineral density and bone mineral content at 6 weeks of age when compared to their euploid counterparts, with the severity of these defects lessening by 16 weeks. No studies of bone development have yet decisively identified the origin of these defects. We hypothesized that abnormal endochondral ossification is responsible for the presence of these deficien-cies in bone mineral content and bone mineral density. Aberrant expression of Nfat has been implicated as the molecular cause of many DS-related phe-notypes, and activity of Nfat can be determined based upon its localization. Specifically, Nfat has been shown to control many aspects of bone develop-ment, which makes it of special interest to this research. To test our hypoth-esis of a bone deficit present during embryonic development of Ts65Dn em-bryos, we are comparing cartilaginous template characteristics, progression of the mineralization front, osteoclast activity, percent bone volume, and Nfat localization in euploid and trisomic mouse femurs at embryonic day 17.5. Our preliminary data show lower percent bone volumes in trisomic fe-murs, suggesting that endochondral ossification in Ts65Dn mice lags behind that of their euploid counterparts. These results indicate that DS bone phe-notypes do indeed originate during embryonic development and create a foundation for future work on their treatment. Supported by: National Science Foundation GK-12 Fellowship; Jerome Lejeune Foundatio