Quantum supergroups V. Braid group action

We construct a braid group action on quantum covering groups. We further use this action to construct a PBW basis for the positive half in finite type which is pairwise-orthogonal under the inner product. This braid group action is induced by operators on the integrable modules; however, these operators satisfy spin braid relations.Comment: v1. 31 pages v2. minor revisions, updated references, to appear in CM

Defining 'democracy': Are we staying on topic?

Political scientists' failure to pay careful attention to the content (as opposed to the operationalization) of their chosen definition of 'democracy' can make them liable to draw invalid inferences from their empirical research. With this problem in mind, we argue for the following proposition: if one wishes to conduct empirical research that contributes to an existing conversation about democracy, then one must choose a definition of 'democracy' that picks out the topic of that conversation as opposed to some other (perhaps nearby) topic of conversation. We show that, as a practical matter, one of the most effective methods for preserving "topic continuity" is to choose a definition of `democracy' that concurs with prevailing judgments about how to classify particular regimes, emphasizing the superiority (in this regard) of judgments about stylized hypothetical scenarios as opposed to judgments about the actual regimes we observe in our datasets

Searching for Fast Optical Transients using VERITAS Cherenkov Telescopes

Astronomical transients are intrinsically interesting things to study. Fast optical transients (microsecond timescale) are a largely unexplored field of optical astronomy mainly due to the fact that large optical telescopes are oversubscribed. Furthermore, most optical observations use instruments with integration times on the order of seconds and are thus unable to resolve fast transients. Current-generation atmospheric Cherenkov gamma-ray telescopes, however, have huge collecting areas (e.g., VERITAS, which consists of four 12-m telescopes), larger than any existing optical telescopes, and time is typically available for such studies without interfering with gamma-ray observations. The following outlines the benefits of using a Cherenkov telescope to detect optical transients and the implementation of the VERITAS Transient Detector (TRenDy), a dedicated multi-channel photometer based on field-programmable gate arrays. Data are presented demonstrating the ability of TRenDy to detect transient events such as a star passing through its field of view and the optical light curve of a pulsar