Dynamical Cusp Regeneration

After being destroyed by a binary supermassive black hole, a stellar density cusp can regrow at the center of a galaxy via energy exchange between stars moving in the gravitational field of the single, coalesced hole. We illustrate this process via high-accuracy N-body simulations. Regeneration requires roughly one relaxation time and the new cusp extends to a distance of roughly one-fifth the black hole's influence radius, with density rho ~ r^{-7/4}; the mass in the cusp is of order 10% the mass of the black hole. Growth of the cusp is preceded by a stage in which the stellar velocity dispersion evolves toward isotropy and away from the tangentially-anisotropic state induced by the binary. We show that density profiles similar to those observed at the center of the Milky Way and M32 can regenerate themselves in several Gyr following infall of a second black hole; the presence of density cusps at the centers of these galaxies can therefore not be used to infer that no merger has occurred. We argue that Bahcall-Wolf cusps are ubiquitous in stellar spheroids fainter than M_V ~ -18.5 that contain supermassive black holes, but the cusps have not been detected outside of the Local Group since their angular sizes are less than 0.1". We show that the presence of a cusp implies a lower limit of \~10^{-4} per year on the rate of stellar tidal disruptions, and discuss the consequences of the cusps for gravitational lensing and the distribution of dark matter on sub-parsec scales.Comment: Accepted for publication in The Astrophysical Journa

A Key to Container-Breeding Mosquitoes of Michigan (Diptera: Cllllcidae), With Notes on Their Biology

An illustrated key to larvae and notes on the biology of container-breeding mosquitoes of Michigan are presented. Two species included in the key. Aedes aegypti and Aedes albopictus. are not endemic in Michigan, but occasional introductions could occur with commercial shipments of scrap tires or other containers

Larval Ecology of Some Lower Michigan Black Flies (Diptera: Simuliidae) With Keys to the Immature Stages

The species composition, succession, and seasonal abundance of -immature simuliids ocmrrhg in the Rose Lake Wildlife Research Area in lower Michigan are presented. Selected physical and chemical characteristics of streams in the above area were examined and compared in relation to faunal distributions. Comparisons of species differences between permanent and temporary streams were made utilizing the functional group concept based on feeding mechanisms. Keys and illustrations are presented for the identiiication of larvae and pupae of four genera (Prosimulium, Simulium, Stegopterna, Cnephia) and 19 species of Simuliidae known to occur in lower Michigan. Two species, Cnephia ornithophilia and Simulium vemum, were recorded for the first time in Michigan

Cusp Disruption in Minor Mergers

We present 0.55 x 10^6 particle simulations of the accretion of high-density dwarf galaxies by low-density giant galaxies, using models that contain both power-law central density cusps and point masses representing supermassive black holes. The cusp of the dwarf galaxy is disrupted during the merger, producing a remnant with a central density that is only slightly higher than that of the giant galaxy initially. Removing the black hole from the giant galaxy allows the dwarf galaxy to remain intact and leads to a remnant with a high central density, contrary to what is observed. Our results support the hypothesis that the persistence of low-density cores in giant galaxies is a consequence of supermassive black holes.Comment: 5 pages, 2 postscript figures, uses emulateapj.sty. Accepted for publication in The Astrophysical Journal Letter

Redeveloping greyfields : definitions, opportunities and barriers

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2006.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (leaves 61-62).The study of greyfields for this thesis was motivated by the increasing problems of traffic and air pollution associated with sprawling development patterns. Typically located in inner ring suburban areas, greyfields, or failed retail malls, represent sites that can be redeveloped profitably into mixed-use, walkable neighborhoods. Yet, few successful examples of greyfield redevelopment exist, especially when compared to the relative proliferation of brownfield redevelopment. Brownfields, or contaminated urban sites, are very costly to remediate and it is surprising that this type of redevelopment outpaces greyfield redevelopment on such a significant scale. This thesis addresses the disparity between the two redevelopment types and describes differences between brownfields and greyfields through application of an economic model for redevelopment. The variables of the model are then applied to each redevelopment type and considered in the context of several greyfield case studies located on the east coast.(cont.) Where the economic model is incomplete in fully explaining the disparity between the redevelopment types, factors outside of the model have been considered, including the existence of externalities and public subsidies at federal, state and local levels. Lastly, suggestions of how to foster increased implementation of greyfield redevelopment and create an industry around the reuse of greyfield sites are discussed.by Amy W. Merritt.S.M

Constitutional Law—Anti-Miscegenation Statutes Held to Violate Equal Protection and Due Process

Loving v. Virginia, 388 U.S. 1 (1967), rev\u27g 206 Va. 924, 147 S.E.2d 78 (1966)