The Algebra of Grand Unified Theories

The Standard Model of particle physics may seem complicated and arbitrary, but it has hidden patterns that are revealed by the relationship between three "grand unified theories": theories that unify forces and particles by extending the Standard Model symmetry group U(1) x SU(2) x SU(3) to a larger group. These three theories are Georgi and Glashow's SU(5) theory, Georgi's theory based on the group Spin(10), and the Pati-Salam model based on the group SU(2) x SU(2) x SU(4). In this expository account for mathematicians, we explain only the portion of these theories that involves finite-dimensional group representations. This allows us to reduce the prerequisites to a bare minimum while still giving a taste of the profound puzzles that physicists are struggling to solve.Comment: 73 pages, 20 ps figure

Fat Cats and Thin Kittens: Are People Who Make Large Campaign Contributions Different?

Critics of campaign finance in the United States often direct their fire toward contributors who make large donations. Critics charge that large contributions are unfair, unrepresentative, and undemocratic. Accordingly, they push for "reforms" that would favor small contributions over large, and public money over private donations. Survey data on contributors contradict that stereotype of contributors of large amounts and their effects on American politics. Overall, "fat cats" differ less from contributors of smaller amounts than critics have alleged. The differences that do exist are mostly unsurprising and generally small in magnitude. Survey results show that both policy liberalism and Democratic partisanship are well represented among contributors of large sums.The supporters of McCain-Feingold argue that new restrictions on large contributions will profoundly alter American politics for the better. Their claims have no basis in fact. New laws aimed at restricting large donations in favor of smaller ones will have little effect on practical politics

Two Pseudobulges In The "Boxy Bulge" Galaxy NGC 5746

Galaxy formation and growth under the Lambda CDM paradigm is expected to proceed in a hierarchical, bottom-up fashion by which small galaxies grow into large galaxies; this mechanism leaves behind large "classical bulges" kinematically distinct from "pseudobulges" grown by internal, secular processes. We use archival data (Spitzer Space Telescope 3.6 mu m wavelength, Hubble Space Telescope H-band, Two Micron All Sky Survey K-s-band, and Sloan Digital Sky Survey gri-band) to measure composite minor-and major-axis surface brightness profiles of the almost-edge-on spiral galaxy NGC 5746. These light profiles span a large range of radii and surface brightnesses to reveal an inner, high surface brightness stellar component that is distinct from the well-known boxy bulge. It is well fitted by Sersic functions with indices n = 0.99 +/- 0.08 and 1.17 +/- 0.24 along the minor and major axes, respectively. Since n < 2, we conclude that this innermost component is a secularly evolved pseudobulge that is distinct from the boxy pseudobulge. This inner pseudobulge makes up 0.136 +/- 0.019 of the total light of the galaxy. It is therefore considerably less luminous than the boxy structure, which is now understood to be a bar seen nearly end-on. The infrared imagery shows further evidence for secular evolution in the form of a bright inner ring of inner radius 9.1 kpc and width 1.6 kpc. NGC 5746 is therefore a giant, pure-disk SB(r) bc galaxy with no sign of a merger-built bulge. We do not understand how such galaxies form in a Lambda DM universe.NASA NAS 5-26555National Aeronautics and Space AdministrationNational Science Foundation AST-0607490Alfred P. Sloan FoundationU.S. Department of EnergyJapanese MonbukagakushoMax Planck SocietyHigher Education Funding Council for EnglandCentennial Chair in Astronomy at the University of Texas at AustinAstronom

Introduction Post: John Hill

My first two weeks have been busy and exciting. I have trained with several reference librarians during my shifts at the Reference Desk. Each of them has a different perspective on librarianship, and each of them plays a different role in Musselman Library, but all of them are devoted to making useful resources available to students and faculty and to teaching them how to use these resources. I am excited to practice strategies for answering people’s questions, but I am admittedly nervous to staff the desk on my own. I am confident, though, that with a little bit more time and experience, I’ll be okay. [excerpt

Barge Transport of Illinois River Sediment from Peoria to Chicago

A barge load of sediment excavated by clamshell from Lower Peoria Lake was shipped to Chicago, Ill. It was loaded onto trucks with a large excavator and placed at a conservation area and the Paxton I landfill reclamation site (Figures 1 and 2). The material handled well and maintained its consistency in the barge and after placing. It readily dumped from the trucks and formed piles about 2.5 feet high. The demonstration showed that this material can be transported and handled with conventional equipment and placed on fields without the necessity of using engineered containment structures

Degenerate Solutions of General Relativity from Topological Field Theory

Working in the Palatini formalism, we describe a procedure for constructing degenerate solutions of general relativity on 4-manifold M from certain solutions of 2-dimensional BF theory on any framed surface Sigma embedded in M. In these solutions the cotetrad field e (and thus the metric) vanishes outside a neighborhood of Sigma, while inside this neighborhood the connection A and the field E = e ^ e satisfy the equations of 4-dimensional BF theory. Moreover, there is a correspondence between these solutions and certain solutions of 2-dimensional BF theory on Sigma. Our construction works in any signature and with any value of the cosmological constant. If M = R x S for some 3-manifold S, at fixed time our solutions typically describe `flux tubes of area': the 3-metric vanishes outside a collection of thickened links embedded in S, while inside these thickened links it is nondegenerate only in the two transverse directions. We comment on the quantization of the theory of solutions of this form and its relation to the loop representation of quantum gravity.Comment: 16 pages LaTeX, uses diagram.sty and auxdefs.sty macros, 2 encapsulated Postscript figure

Colonialism and Mandates

Daily life in contemporary African countries must be understood as determined by their status as members of an interlocking network of postcolonies, striving to imagine themselves as related through Pan-Africanism but struggling first to realize themselves as fully functioning nations. Even though Ethiopia and Liberia are generally spoken of as the only countries in Africa that were not colonized, this actually suggests the level of subjugation the rest of the continent did experience. After all, if Italy failed in its attempt to take over Ethiopia in the 1880s, Mussolini succeeded in doing so in 1936; Liberia was, in fact, a colony for several decades, created in 1822 by the American Society for Colonization of Free People of Color of the United States as a destination for freed American slaves

Descriptions of Three New Species of Nearctic Ctenopelmatinae (Hymenoptera: Ichneumonidae)

Three new species of Ctenopelmatinae are described from series obtained from rearings of yellowheaded spruce sawfly larvae, Pikonema alaskensis (Rohwer)