Anomaly constraints and string/F-theory geometry in 6D quantum gravity

Quantum anomalies, determined by the Atiyah-Singer index theorem, place strong constraints on the space of quantum gravity theories in six dimensions with minimal supersymmetry. The conjecture of "string universality" states that all such theories which do not have anomalies or other quantum inconsistencies are realized in string theory. This paper describes this conjecture and recent work by Kumar, Morrison, and the author towards developing a global picture of the space of consistent 6D supergravities and their realization in string theory via F-theory constructions. We focus on the discrete data for each model associated with the gauge symmetry group and the representation of this group on matter fields. The 6D anomaly structure determines an integral lattice for each gravity theory, which is related to the geometry of an elliptically fibered Calabi-Yau three-fold in an F-theory construction. Possible exceptions to the string universality conjecture suggest novel constraints on low-energy gravity theories which may be identified from the structure of F-theory geometry.Comment: 22 pages, LaTeX; Contribution to proceedings of "Perspectives in Mathematics and Physics," conference in honor of I. M. Singe

How Black Candidates Affect Voter Turnout

Both Black and White voter turnout increases 2-3 percentage points with each Black Democrat on the ballot. Given the groups' representations in the population, the White response is numerically greater. Whites of both parties are less likely to vote for their parties' candidate when s/he is Black. The turnout findings are not explained away by voter, election, or politician characteristics. However the fact that there is no turnout response to Black Republicans suggests that a perception of Blacks' ideology may be a factor.

Epidemiology of Gun Violence in Pennsylvania

Raynard Washington, PhD, MPH, is the Chief Epidemiologist at the Philadelphia Department of Public Health. In this role, Dr. Washington is responsible for collecting, analyzing, and interpreting data that provides actionable information on the health status of Philadelphia residents. Dr. Washington coordinates and provides guidance to epidemiologic activities across department divisions and works internally and externally to enhance existing and establish new health surveillance systems He also leads the Community Health Assessment and other strategic initiatives. Dr. Washington earned his undergraduate and graduate degrees at the University of Pittsburgh