Reflection positivity and invertible topological phases

We implement an extended version of reflection positivity (Wick-rotated unitarity) for invertible topological quantum field theories and compute the abelian group of deformation classes using stable homotopy theory. We apply these field theory considerations to lattice systems, assuming the existence and validity of low energy effective field theory approximations, and thereby produce a general formula for the group of Symmetry Protected Topological (SPT) phases in terms of Thom's bordism spectra; the only input is the dimension and symmetry group. We provide computations for fermionic systems in physically relevant dimensions. Other topics include symmetry in quantum field theories, a relativistic 10-fold way, the homotopy theory of relativistic free fermions, and a topological spin-statistics theorem.Comment: 136 pages, 16 figures; minor changes/corrections in version 2; v3 major revision; v4 minor revision: corrected proof of Lemma 9.55, many small changes throughout; v5 version for publication in Geometry & Topolog

Formation of Cosmic Dust Bunnies

Planetary formation is an efficient process now thought to take place on a relatively short astronomical time scale. Recent observations have shown that the dust surrounding a protostar emits more efficiently at longer wavelengths as the protoplanetary disk evolves, suggesting that the dust particles are coagulating into fluffy aggregates, "much as dust bunnies form under a bed." One poorly understood problem in this coagulation process is the manner in which micron-sized, charged grains form the fractal aggregate structures now thought to be the precursors of protoplanetary disk evolution. This study examines the characteristics of such fractal aggregates formed by the collision of spherical monomers and aggregates where the charge is distributed over the aggregate structure. The aggregates are free to rotate due to collisions and dipole-dipole electrostatic interactions. Comparisons are made for different precursor size distributions and like-charged, oppositelycharged, and neutral grains

Teen Depression, Stories of Hope and Health: A Promising Universal School Climate Intervention for Middle School Youth

This study describes the delivery of the Teen Depression: Stories of Health and Healing (TDSHH), a brief school-based depression awareness delivered for middle school students. The main objectives of the proposed evaluation were to examine the effects of TDSHH on middle school health students in the areas of knowledge about depression, willingness to seek help from adults and belief that adults can help. Two Chicago suburban middle schools agreed to be part of the TDSHH intervention study. In both schools, a pre/post-test wait-list control quasi-experimental design was used. Each student in the study (total N=223) completed a questionnaire that incorporated a depression knowledge scale created by the EL team and two additional standardized scales, the Help-Seeking Acceptability at School Scale (Wyman et al., 2008) and the Adult Help for Suicidal Youth Scale (Schmeelk-Cone et al., 2012). Data from the pilot indicates that TDSHH students showed statistically significant gains on understanding depression symptoms; identifying strategies students could use to improve their mental health; and increasing positive attitudes toward help seeking with adults at school