f(T1, . . . , Tn) = f(Tσ(1), . . . , Tσ(n)) for all σ ∈ Sn. Example 1. The sum T1 + · · ·+ Tn and product T1 · · ·Tn are symmetric, as are the power sums T r 1 + · · ·+ T r n for any r ≥ 1. As a measure of how symmetric a polynomial is, we introduce an action of Sn on F [T1, . . . , Tn]: (σf)(T1, . . . , Tn) = f(Tσ−1(1), . . . , Tσ−1(n)). We need σ−1 rather than σ on the right side so this is a...

objective(s): the study objective was to assess the diagnostic performance of positron emission tomography (pet) for gliomas using the novel tracer 18f-fluciclovine (anti-[18f]facbc) and to evaluate the safety of this tracer in patients with clinically suspected gliomas.methods: anti-[18f]facbc was administered to 40 patients with clinically suspected high- or low-grade gliomas, followed by pet...