Discussing the yeast Candida albicans, biochemist Alexander Johnson describes a resident of the human gut that can turn into a fatal pathogen in the immunocompromised. Johnson, a professor of microbiology and immunology at the University of California, San Francisco, appreciates the genetic intricacies of this eukaryote that changed his views on transcriptional regulation and the evolution of m...

Alexander Duncan Langmuir was recruited by the late Joseph Mountin, as I (1. H. S.) was after World War II, with the challenge to explore new areas that related to public health. Mountin was a leader who gained fame by challenging the old order and anticipating future needs (1). He foresaw the need for an agency such as the Communicable Disease Center (now the Centers for Disease Control and Pr...

Let L = 1∪· · ·∪ d+1 be an oriented link in S3, and let L(q) be the d-component link 1 ∪· · ·∪ d regarded in the homology 3-sphere that results from performing 1/q-surgery on d+1. Results about the Alexander polynomial and twisted Alexander polynomials of L(q) corresponding to finite-image representations are obtained. The behavior of the invariants as q increases without bound is described.

Alexander V. Joura,1,2,* J. K. Freericks,3 and Alexander I. Lichtenstein1,2,† 1Institute of Theoretical Physics, University of Hamburg, Jungiusstrasse 9, D-20355 Hamburg, Germany 2European XFEL GmbH, Albert-Einstein-Ring 19, D-22671 Hamburg, Germany 3Department of Physics, Georgetown University, Washington, District of Columbia 20057-0995, USA (Received 16 January 2014; revised manuscript recei...

The extended Alexander group of an oriented virtual link l of d components is defined. From its abelianization a sequence of polynomial invariants ∆i(u1, . . . , ud, v), i = 0, 1, . . . , is obtained. When l is a classical link, ∆i reduces to the well-known ith Alexander polynomial of the link in the d variables u1v, . . . , udv; in particular, ∆0 vanishes.

The extended Alexander group of an oriented virtual link l of d components is defined. From its abelianization a sequence of polynomial invariants ∆i(u1, . . . , ud, v), i = 0, 1, . . . , is obtained. When l is a classical link, ∆i reduces to the well-known ith Alexander polynomial of the link in the d variables u1v, . . . , udv; in particular, ∆0 vanishes.