14,093 research outputs found
I am Me and You are You
A collection of fiction short stories about the issue of identity. The stories question the idea of identity on a philosophical level, as well as by what means we frame our identities, and whether is is self-formed or formed by others. A particular tension is related to issues of the Information Age, including social media such as Facebook. Influences include David Foster Wallace, Spalding Gray, Jorge Luis Borges, Tim O\u27Brien, Bruno Schulz, and others
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Dispersal in microbes: fungi in indoor air are dominated by outdoor air and show dispersal limitation at short distances.
The indoor microbiome is a complex system that is thought to depend on dispersal from the outdoor biome and the occupants' microbiome combined with selective pressures imposed by the occupants' behaviors and the building itself. We set out to determine the pattern of fungal diversity and composition in indoor air on a local scale and to identify processes behind that pattern. We surveyed airborne fungal assemblages within 1-month time periods at two seasons, with high replication, indoors and outdoors, within and across standardized residences at a university housing facility. Fungal assemblages indoors were diverse and strongly determined by dispersal from outdoors, and no fungal taxa were found as indicators of indoor air. There was a seasonal effect on the fungi found in both indoor and outdoor air, and quantitatively more fungal biomass was detected outdoors than indoors. A strong signal of isolation by distance existed in both outdoor and indoor airborne fungal assemblages, despite the small geographic scale in which this study was undertaken (<500 m). Moreover, room and occupant behavior had no detectable effect on the fungi found in indoor air. These results show that at the local level, outdoor air fungi dominate the patterning of indoor air. More broadly, they provide additional support for the growing evidence that dispersal limitation, even on small geographic scales, is a key process in structuring the often-observed distance-decay biogeographic pattern in microbial communities
Energy Dependence of Scattering Ground State Polar Molecules
We explore the total cross section of ground state polar molecules in an
electric field at various energies, focusing on RbCs and RbK. An external
electric field polarizes the molecules and induces strong dipolar interactions
leading to non-zero partial waves contributing to the scattering even as the
collision energy goes to zero. This results in the need to compute scattering
problems with many different values of total M to converge the total cross
section. An accurate and efficient approximate total cross section is
introduced and used to study the low field temperature dependence. To
understand the scattering of the polar molecules we compare a semi-classical
cross section with quantum unitarity limit. This comparison leads to the
ability to characterize the scattering based on the value of the electric field
and the collision energy.Comment: Accepted PRA, 10 pages, 5 figure
Biological CO oxidation in the Sargasso Sea and in Vineyard Sound, Massachusetts
Author Posting. © The Author(s), 2005. This is the author's version of the work. It is
posted here by permission of American Society of Limnology and Oceanography for personal use, not for redistribution. The
definitive version was published in Limnology and Oceanography 50 (2005): 1205-1212.In situ dissolved carbon monoxide (CO) in oligotrophic waters follows a diel cycle varying from 0.3 to 0.5 nmol L-1 before dawn to 2.5 to 3 nmol L-1 in early afternoon, when photo-production of CO exceeds biological CO oxidation and other sinks. Coastal waters may contain up to 15 nmol L-1 [CO] in the daytime. Assays to measure the rate of CO bio-oxidation typically involve the addition of labeled CO to sealed samples, resulting in CO concentrations that are above ambient levels during incubation (up to 9 nmol L-1 CO). We find that biological oxidation of CO obeys first-order kinetics when incubated with up to 4 nmol L-1 [CO] in coastal water samples and up to between 4 and 10.8 nmol L-1 in oligotrophic waters. At higher [CO], kinetic behavior transitions to zero-order or saturation kinetics. CO–oxidation rate coefficients obtained in dark incubations were not representative of the entire diurnal period, as others have assumed. Biological CO–oxidation rate coefficients kco measured in dark incubations of Sargasso Sea surface water in summer were 0.020 ± 0.002 h-1 (mean ± standard deviation) and an order of magnitude greater than those measured in situ during daylight hours (0.002 ± 0.001 h-1). Dark and in situ rate coefficients in early spring were 0.006 ± 0.004 h-1 and 0.003 ± 0.001 h-1, respectively. In dark incubations of Vineyard Sound water, kco was 0.127 ± 0.038 h-1. The apparent half-saturation constant Kapp for CO ranged from 2.04 to 5.44 nmol L-1 CO in both environments.This research was supported by National Science Foundation grants OCE-98-11208 and OCE-01-36876, and the Reinhard Coastal Research Center and Coastal Ocean Institute grant BI-10918
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An Assessment of Performance Measures in the Transportation Development Act
"This report examines the performance measures requirements in California’s Transportation Development Act (TDA) of 1971. The TDA is an important source of funding for the state’s public transit agencies, representing approximately 18 percent of their total (2018) revenue between the TDA’s two funds (LTF and STA). Since the TDA’s passage in 1971, the transit operating environment in California has changed, in some cases dramatically. The state has nearly doubled in population (20.4 million in 1971 to 39.8 million in 2019), traffic has worsened considerably, climate change is now a central public policy focus, and many places around the state are investing heavily in making public transit a viable alternative to driving. Our research examined the TDA’s performance requirements and their effects on the state’s transit operators. We also considered alternative approaches to both transit finance and performance requirements, by studying transit funding programs in 13 other states that invest significant amounts of funding in transit. In brief, we find that the TDA’s use of performance measurements to allocate funding is unusual. The states we studied do not for the most part make funding contingent on performance, thereby avoiding the unproductive and difficult-to-implement “death penalty” (Taylor, 1995) of withholding subsidies for a much-needed public service. In several of the cases analyzed, by contrast, states guarantee specific levels or amounts of funding for transit service.To examine how the TDA’s performance measures are working, we conducted a survey of California transit professionals at agencies and at Regional Transportation Planning Agencies (RTPAs). That California’s aspirations for transit have evolved over the years is reflected in the frequent loopholes and exemptions the legislature has added to the TDA to give struggling operators more latitude to receive funding in order to meet multiple goals and objectives while staying in compliance with a single cost-effectiveness goal. The extent and frequency with which these exemptions have occurred suggests that the larger aims for public transit, and indeed the goals for the TDA program itself, have evolved, and need to be re-thought holistically, rather than incrementally.Accordingly we offer six recommendations concerning transit performance assessment in the TDA.
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