George A. Willis

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We study contraction groups for automorphisms of totally disconnected locally compact groups using the scale of the automorphism as a tool. The contraction group is shown to be unbounded when the inverse automorphism has non-trivial scale and this scale is shown to be the inverse value of the modular function on the closure of the contraction group at the(More)
Let α be an automorphism of the totally disconnected group G. The compact open subgroup, V , of G is tidy for α if [α(V ) : α(V ) ∩ V ] is minimised at V , where V ′ ranges over all compact open subgroups of G. Identifying a subgroup tidy for α is analogous to identifying a basis which puts a linear transformation into Jordan canonical form. This analogy is(More)
Chemical deterioration of teeth is common among modern humans, and has been suggested for some extinct primates. Dental erosion caused by acidic foods may also obscure microwear signals of mechanical food properties. Ring-tailed lemurs at the Beza Mahafaly Special Reserve (BMSR), Madagascar, display frequent severe tooth wear and subsequent tooth loss. In(More)
The Margulis-Zimmer conjecture. The subject of this paper is a well known question advertised by Gregory Margulis and Robert Zimmer since the late 1970’s, which seeks refinement of the celebrated Normal Subgroup Theorem of Margulis (hereafter abbreviated NST). Although Margulis’ NST is stated and proved in the context of (higher rank) irreducible lattices(More)
We consider locally compact groups G admitting a topologically transitive Z -action by automorphisms. It is shown that such a group G has a compact normal subgroupK ofG, invariant under the action, such thatG/K is a product of (finitely many) locally compact fields of characteristic zero; moreover, the totally disconnected fields in the decomposition can be(More)
INTRODUCTION Linking educational objectives and clinical learning during clerkships can be difficult. Clinical shifts during emergency medicine (EM) clerkships provide a wide variety of experiences, some of which may not be relevant to recommended educational objectives. Students can be directed to standardize their clinical experiences, and this improves(More)