Showing 4881 - 4890 of 5713 Items
Investigating enhancer regulation through chromatin conformation in Drosophila Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2020-01-01
Creator: Hannah D. Konkel
Access: Access restricted to the Bowdoin Community
Interview with Paul Brountas (1) by Mike Hastings
Date: 2009-02-20
Creator: Paul P. Brountas
Access: Audio recording permanently restricted
- Biographical NotePaul Peter Brountas was born on March 19, 1932, in Bangor, Maine. He and George Mitchell were classmates at Bowdoin College, where he was graduated with a bachelor’s degree in 1954; he took bachelor’s and master’s degrees from the University of Oxford in 1956 and his law degree from Harvard Law School in 1960. That same year, he joined Hale and Dorr, the predecessor of WilmerHale. He became a partner in 1968 and served as senior counsel to the firm from 2003 until his retirement in 2005. In 1987 and 1988, he served as national chairman of the Committee to Elect Michael S. Dukakis President of the United States, and in 1968 he served as a campaign aide to Senator Edmund Muskie during the Humphrey-Muskie presidential campaign. SummaryInterview includes discussion of: growing up in Bangor, Maine, influenced by Greek ethnicity; attending Bowdoin College in the early 1950s. Remainder of interview permanently restricted.
Maximal stomatal conductance to water and plasticity in stomatal traits differ between native and invasive introduced lineages of Phragmites australis in North America
Date: 2016-01-27
Creator: V. Douhovnikoff, S. H. Taylor, E. L.G. Hazelton, C. M. Smith, J., O'Brien
Access: Open access
- The fitness costs of reproduction by clonal growth can include a limited ability to adapt to environmental and temporal heterogeneity. Paradoxically, some facultatively clonal species are not only able to survive, but colonize, thrive and expand in heterogeneous environments. This is likely due to the capacity for acclimation (sensu stricto) that compensates for the fitness costs and complements the ecological advantages of clonality. Introduced Phragmites australis demonstrates great phenotypic plasticity in response to temperature, nutrient availability, geographic gradient, water depths, habitat fertility, atmospheric CO2, interspecific competition and intraspecific competition for light. However, no in situ comparative subspecies studies have explored the difference in plasticity between the non-invasive native lineage and the highly invasive introduced lineage. Clonality of the native and introduced lineages makes it possible to control for genetic variation, making P. australis a unique system for the comparative study of plasticity. Using previously identified clonal genotypes, we investigated differences in their phenotypic plasticity through measurements of the lengths and densities of stomata on both the abaxial (lower) and adaxial (upper) surfaces of leaves, and synthesized these measurements to estimate impacts on maximum stomatal conductance to water (gwmax). Results demonstrated that at three marsh sites, invasive lineages have consistently greater gwmax than their native congeners, as a result of greater stomatal densities and smaller stomata. Our analysis also suggests that phenotypic plasticity, determined as within-genotype variation in gwmax, of the invasive lineage is similar to, or exceeds, that shown by the native lineage.
Applying IsoTaG to understand Helicobacter pylori’s glycoprotein biosynthesis Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2021-01-01
Creator: Chiamaka Doris Okoye
Access: Access restricted to the Bowdoin Community
Can AFLP genome scans detect small islands of differentiation? The case of shell sculpture variation in the periwinkle Echinolittorina hawaiiensis
Date: 2011-08-01
Creator: Kimberly A. Tice, D. B. Carlon
Access: Open access
- Genome scans have identified candidate regions of the genome undergoing selection in a wide variety of organisms, yet have rarely been applied to broadly dispersing marine organisms experiencing divergent selection pressures, where high recombination rates can reduce the extent of linkage disequilibrium (LD) and the ability to detect genomic regions under selection. The broadly dispersing periwinkle Echinolittorina hawaiiensis exhibits a heritable shell sculpture polymorphism that is correlated with environmental variation. To elucidate the genetic basis of phenotypic variation, a genome scan using over 1000 AFLP loci was conducted on smooth and sculptured snails from divergent habitats at four replicate sites. Approximately 5% of loci were identified as outliers with Dfdist, whereas no outliers were identified by BayeScan. Closer examination of the Dfdist outliers supported the conclusion that these loci were false positives. These results highlight the importance of controlling for Type I error using multiple outlier detection approaches, multitest corrections and replicate population comparisons. Assuming shell phenotypes have a genetic basis, our failure to detect outliers suggests that the life history of the target species needs to be considered when designing a genome scan. © 2011 The Authors. Journal of Evolutionary Biology © 2011 European Society For Evolutionary Biology.
Schwarzschild-de Sitter spacetimes, McVittie coordinates, and trumpet geometries
Date: 2017-12-15
Creator: Kenneth A. Dennison, Thomas W. Baumgarte
Access: Open access
- Trumpet geometries play an important role in numerical simulations of black hole spacetimes, which are usually performed under the assumption of asymptotic flatness. Our Universe is not asymptotically flat, however, which has motivated numerical studies of black holes in asymptotically de Sitter spacetimes. We derive analytical expressions for trumpet geometries in Schwarzschild-de Sitter spacetimes by first generalizing the static maximal trumpet slicing of the Schwarzschild spacetime to static constant mean curvature trumpet slicings of Schwarzschild-de Sitter spacetimes. We then switch to a comoving isotropic radial coordinate which results in a coordinate system analogous to McVittie coordinates. At large distances from the black hole the resulting metric asymptotes to a Friedmann-Lemaître-Robertson-Walker metric with an exponentially-expanding scale factor. While McVittie coordinates have another asymptotically de Sitter end as the radial coordinate goes to zero, so that they generalize the notion of a "wormhole" geometry, our new coordinates approach a horizon-penetrating trumpet geometry in the same limit. Our analytical expressions clarify the role of time-dependence, boundary conditions and coordinate conditions for trumpet slices in a cosmological context, and provide a useful test for black hole simulations in asymptotically de Sitter spacetimes.
Promises Unfulfilled: Integration and Segregation in Metropolitan Philadelphia Public Schools, 1954-2009
Date: 2021-01-01
Creator: Nina Nayiri McKay
Access: Open access
- Even though Brown v. Board of Education outlawed segregation in public schools in 1954, many American children still attend schools that are racially and, increasingly, socioeconomically segregated. Philadelphia, a northern city that did not have an explicit policy of segregating children on the basis of race when Brown was decided, nevertheless still has entrenched residential segregation that replicates in public schools. The metropolitan area became a segregated space in the years around World War II, when housing discrimination, employment discrimination, lending discrimination, suburbanization, and urban renewal started the years-long trajectory of growing white suburbs surrounding an increasingly non-white and under-resourced urban core. These patterns had profound implications for school segregation, which city organizers began trying to fight shortly after Brown v. Board. However, the first court case to take on segregation in Philadelphia schools—Chisholm v. The Board of Education—was largely unsuccessful, with overburdened NAACP and ally lawyers struggling to meet the judge’s expectations of concrete proof of an intent to segregate on the School District of Philadelphia’s part. In the early 1960s, though, the state’s Human Relations Commission obtained a legislative mandate to take on school desegregation. It won its first integration victory in the Pennsylvania port city of Chester before moving to Philadelphia, where it pushed for school integration from 1968 to 2009. The city’s political and ideological battles over those decades reflect national trends around the rise of conservatism and neoliberalism in suburban politics and school reform, limiting the possibilities for change.