The fixing number of a graph G is the minimum cardinality of a set S ⊂ V (G) such that every nonidentity automorphism of G moves at least one member of S, i.e., the automorphism group of the graph obtained from G by fixing every node in S is trivial. We provide a formula for the fixing number of a disconnected graph in terms of the fixing numbers of its components and make some observations abo...

Party brands are central to theories of Congressional action. While previous work assumes that a party’s brand—its long run reputation—is a direct consequence of the content of legislation, in this presentation I show how partisans from both parties use public statements to craft their own party’s reputation and to undermine their opponents party. The incentive to craft and destroy brands varie...

Some of the human embryos generated by in vitro fertilization (IVF) are treasured by the couples whose gametes were fused to create them; they may fulfil the wish of the prospective parents to have a child. We call these ‘wanted embryos’. It would be wrong to destroy such embryos in research; however, not all embryos are wanted. We argue that it is, with the consent of the parents, morally perm...

Continents, especially their Archean cores, are underlain by thick thermal boundary layers that have been largely isolated from the convecting mantle over billion-year timescales, far exceeding the life span of oceanic thermal boundary layers. This longevity is promoted by the fact that continents are underlain by highly melt-depleted peridotites, which result in a chemically distinct boundary ...

The pentoses, xylose and arabinose, have been termed nonfermentable sugars. In a general sense this is true, as the majority of microorganisms, yeasts and bacteria, cannot utilize the pentoses; however, there are certain forms which possess the ability to break down these sugars. Apparently these pentosefermenting bacteria are widely distributed and no doubt play an important role in the econom...