4,947 research outputs found
The Study of the Water Table and the Classification of the Overlying Strata
A study, based on ten holes on the University of North Dakota Campus, indicated that the water table in general is nine to ten feet below the surface and three distinct lithologic units lie above the water table
Opportunities, Race, and Urban Location: The Influence of John Kain
Today, no economist studying the spatial economy of urban areas would ignore the effects of race on housing markets and labor market opportunities, but this was not always the case. Through what can be seen as a consistent and integrated research plan, John Kain developed many central ideas of urban economics but, more importantly, legitimized and encouraged scholarly consideration of the geography of racial opportunities. His provocative (and prescient) study of the linkage between housing segregation and the labor market opportunities of Blacks was a natural outgrowth of his prior work on employment decentralization and housing constraints on Black households. His more recent program of research on school outcomes employing detailed administrative data was an extension of the same empirical interest in how the economic opportunities of minority households vary with location. This paper identifies the influence of John Kain’s ideas on different areas of research and suggests that his scientific work was thoroughly interrelated.
Optimal Rebuilding of Fish Stocks in Different Nations: Bioeconomic Lessons for Regulators
Under the rubric of sustainable fisheries, nations are mandated to rebuild overfished stocks. Although rebuilding strategies are almost universally directed by the available biological information, approaches vary depending on fishery laws, management objectives, and technical guidelines. For example, rebuilding schedules in the United States are primarily designed to achieve rapid rebuilding of biomass and spawning stocks consistent with the biological characteristics of the resource. In contrast, New Zealand has greater flexibility in rebuilding stocks in order to consider economic, social, and cultural needs. In this paper we investigate potential economic costs to the fishery that result by limiting the US manager’s flexibility in choosing a recovery trajectory. Using numerical models for moderate- and long-lived stocks, the analysis reveals that depending on productivity of the stock and the discount rate, extending the rebuilding timeframe can substantially increase annual harvests and economic benefits. The results underscore the importance of economic analysis in crafting flexible rebuilding schedules that account for the unique characteristics of the fisheries, including economic and social needs.Fisheries economics, fisheries management, K-selective species, rebuilding., Resource /Energy Economics and Policy, Q22, C61,
Ruthenium-catalysed Z-selective cross metathesis of allylic-substituted olefins
The Z-selective cross metathesis of allylic-substituted olefins is explored with recently developed ruthenium-based metathesis catalysts. The reaction proceeds with excellent stereoselectivity for the Z-isomer (typically >95%) and yields of up to 88% for a variety of allylic substituents. This includes the first synthesis of Z-α,β-unsaturated acetals by cross metathesis and their elaboration to Z-α,β-unsaturated aldehydes. In addition, the reaction is tolerant of a variety of cross partners, varying in functionality and steric profile
Transgenerational inheritance of shuffled symbiont communities in the coral Montipora digitata
Adult organisms may "prime" their offspring for environmental change through a number of genetic and non-genetic mechanisms, termed parental effects. Some coral species may shuffle the proportions of Symbiodiniaceae within their endosymbiotic communities, subsequently altering their thermal tolerance, but it is unclear if shuffled communities are transferred to offspring. We evaluated Symbiodiniaceae community composition in tagged colonies of Montipora digitata over two successive annual spawning seasons and the 2016 bleaching event on the Great Barrier Reef. ITS2 amplicon sequencing was applied to four families (four maternal colonies and 10-12 eggs per family) previously sampled and sequenced the year before to characterize shuffling potential in these M. digitata colonies and determine if shuffled abundances were preserved in gametes. Symbiont densities and photochemical efficiencies differed significantly among adults in 2016, suggesting differential responses to increased temperatures. Low-abundance ("background") sequence variants differed more among years than between maternal colonies and offspring. Results indicate that shuffling can occur in a canonically 'stable' symbiosis, and that the shuffled community is heritable. Hence, acclimatory changes like shuffling of the Symbiodiniaceae community are not limited to the lifetime of an adult coral and that shuffled communities are inherited across generations in a species with vertical symbiont transmission. Although previously hypothesized, to our knowledge, this is the first evidence that shuffled Symbiodiniaceae communities (at both the inter- and intra- genera level) can be inherited by offspring and supports the hypothesis that shuffling in microbial communities may serve as a mechanism of rapid coral acclimation to changing environmental conditions
Graduate Teaching Assistant Training: Preparing Instructors to Assist ESL Students in the Introductory Public Speaking Course
Much research identifies the need to assist English as a Second Language (ESL) students in our classrooms. Some communication educators have addressed this need by enrolling students in special sections of introductory courses for ESL students only. With a focus specifically on graduate teaching assistant (GTA) training, this paper suggests ways to assist ESL students, along with native speaking students, enrolled in regular sections of the introductory public speaking course. We first identify steps for assessing whether an ESL student is appropriately enrolled in a course. We then focus on ways instructors can assist ESL students with: 1) pronunciation, comprehensibility, and listening, 2) thinking rhetorically, and 3) delivery skills
- …