Redeveloping modern housing sites : improving the livability of the ground plane

Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2007.Includes bibliographical references.Le Corbusier's "towers in the park" urban design plan had a profound impact on city form in the United States. Its precepts were used to inform many urban renewal schemes of the 1950s and 1960s that tore down existing urban fabric and replaced it with towers surrounded by undefined open space. Streets were closed off and rerouted to create "superblocks" for these Corbusian tower/park plans but very soon after urban renewal began, people started to decry its effects. Besides the loss of neighborhoods and harm to people forced to move, the new plans often suffered from safety concerns and isolation. The ground planes of Corbusier inspired plans were disconnected from the public. Over time advocates of traditional city form have pushed new ideas to the forefront of urban design to facilitate a pedestrian-friendly environment, such as new urbanism and smart growth. This paper examines the impact of Corbusier's urban designs versus traditional city movements and suggests a middle ground. Towers are not inherently bad and a form-based approach to city design, such as the one used in Vancouver, successfully integrates both towers and pedestrian-scaled environments. Towers and traditional city form can coexist and benefit from each other to address urban design problems shared by both Corbusier and today's planner.by Matthew Brownell.M.C.P

Helios is a key transcriptional regulator of outer hair cell maturation

The sensory cells that are responsible for hearing include the cochlear inner hair cells (IHCs) and outer hair cells (OHCs), with the OHCs being necessary for sound sensitivity and tuning1. Both cell types are thought to arise from common progenitors; however, our understanding of the factors that control the fate of IHCs and OHCs remains limited. Here we identify Ikzf2 (which encodes Helios) as an essential transcription factor in mice that is required for OHC functional maturation and hearing. Helios is expressed in postnatal mouse OHCs, and in the cello mouse model a point mutation in Ikzf2 causes early-onset sensorineural hearing loss. Ikzf2cello/cello OHCs have greatly reduced prestin-dependent electromotile activity, a hallmark of OHC functional maturation, and show reduced levels of crucial OHC-expressed genes such as Slc26a5 (which encodes prestin) and Ocm. Moreover, we show that ectopic expression of Ikzf2 in IHCs: induces the expression of OHC-specific genes; reduces the expression of canonical IHC genes; and confers electromotility to IHCs, demonstrating that Ikzf2 can partially shift the IHC transcriptome towards an OHC-like identity