Showing 1431 - 1440 of 2039 Items
Discrimination of phytoplankton functional groups using an ocean reflectance inversion model
Date: 2014-08-01
Creator: P. Jeremy Werdell
Collin S. Roesler
Joaquim I. Goes
Access: Open access
- Ocean reflectance inversion models (ORMs) provide a mechanism for inverting the color of the water observed by a satellite into marine inherent optical properties (IOPs), which can then be used to study phytoplankton community structure. Most ORMs effectively separate the total signal of the collective phytoplankton community from other water column constituents; however, few have been shown to effectively identify individual contributions by multiple phytoplankton groups over a large range of environmental conditions. We evaluated the ability of an ORM to discriminate between Noctiluca miliaris and diatoms under conditions typical of the northern Arabian Sea. We: (1) synthesized profiles of IOPs that represent bio-optical conditions for the Arabian Sea; (2) generated remote-sensing reflectances from these profiles using Hydrolight; and (3) applied the ORM to the synthesized reflectances to estimate the relative concentrations of diatoms and N. miliaris. By comparing the estimates from the inversion model with those from synthesized vertical profiles, we identified those conditions under which the ORM performs both well and poorly. Even under perfectly controlled conditions, the absolute accuracy of ORM retrievals degraded when further deconstructing the derived total phytoplankton signal into subcomponents. Although the absolute magnitudes maintained biases, the ORM successfully detected whether or not Noctiluca miliaris appeared in the simulated water column. This quantitatively calls for caution when interpreting the absolute magnitudes of the retrievals, but qualitatively suggests that the ORM provides a robust mechanism for identifying the presence or absence of species.
Carbon credits compete poorly with agricultural commodities in an optimized model of land use in Northern California
Date: 2016-11-01
Creator: Erik Nelson
Virginia Matzek
Access: Open access
- Nascent US carbon markets reward farmers for reforesting agricultural land, with consequent ecological co-benefits. We use a dynamic optimization model to determine the likelihood of an orchard farmer in northern California converting to forest under 90 plausible future scenarios. We find reforestation to be a highly unlikely outcome, occurring only 4.0% of the time under current economic, biophysical, and policy conditions, and only 18.5% of the time under a set of assumptions that make carbon offset production more economically viable. Conversion to "carbon farming" was more sensitive to changes in orchard production costs and yields than to carbon offset policy changes. In the absence of other changes, the price of a carbon offset would have to increase nearly a hundredfold to make reforestation compete economically with orchard agriculture. Our results partly explain low participation in the reforestation sector of US carbon markets. We conclude that farmers will not be interested in forest conversion unless their land has limited agricultural potential or they are motivated by social, rather than economic, rewards.
Political advertising and persuasion in the 2004 and 2008 presidential elections
Date: 2010-03-01
Creator: Michael M. Franz
Travis N. Ridout
Access: Open access
- The 2008 presidential election was historic in many respects. The campaign included the first African American major-party candidate, and neither candidate was an incumbent president or vice president. In addition, one candidate took public funding and the other candidate did not. This latter disparity resulted in an imbalance of resources across the two campaigns, especially in the purchase of political advertising. But did that imbalance matter for who won? Did advertising move voters, and if so, by how much? This article examines patterns of presidential ad buys in 2008 and compares them with presidential ad buys in 2004. It also examines the impact of advertising on county-level vote returns in both years. The results demonstrate some important differences in advertising patterns across years, especially in terms of ad sponsorship and market-level advertising advantages. We also find significant and strong advertising persuasion effects in 2008. © The Author(s) 2010.
Commercial plant production and consumption still follow the latitudinal gradient in species diversity despite economic globalization
Date: 2016-10-01
Creator: Erik J. Nelson
Matthew R. Helmus
Jeannine Cavender-Bares
Stephen Polasky
Jesse R., Lasky
Amy E. Zanne
William D. Pearse
Nathan J.B. Kraft
Daniela A. Miteva
Access: Open access
- Increasing trade between countries and gains in income have given consumers around the world access to a richer and more diverse set of commercial plant products (i.e., foods and fibers produced by farmers). According to the economic theory of comparative advantage, countries open to trade will be able to consume more-in termsof volume and diversity-if they concentrate production on commodities that they can most cost-effectively produce, while importing goods that are expensive to produce, relative to other countries. Here, we performa global analysis of traded commercial plant products and find little evidence that increasing globalization has incentivized agricultural specialization. Instead, a country's plant production and consumption patterns are still largely determined by local evolutionary legacies of plant diversification. Because tropical countries harbor a greater diversity of lineages across the tree of life than temperate countries, tropical countries produce and consume a greater diversity of plant products than do temperate countries. In contrast, the richer and more economically advanced temperate countries have the capacity to produce and consume more plant species than the generally poorer tropical countries, yet this collection of plant species is drawn from fewer branches on the tree of life. Why have countries not increasingly specialized in plant production despite the theoretical financial incentive to do so? Potential explanations include the persistence of domestic agricultural subsidies that distort production decisions, cultural preferences for diverse local food production, and that diverse food production protects rural households in developing countries from food price shocks. Less specialized production patterns will make crop systems more resilient to zonal climatic and social perturbations,but this may come at the expense of global crop production efficiency, an important step in making the transition to a hotter and more crowded world.
The interest group response to campaign finance reform
Date: 2008-04-03
Creator: Michael M. Franz
Access: Open access
- Has the most recent campaign finance reform failed relative to interest groups? More broadly, what's next in the realm of interest group electioneering? This paper explores the role of interest groups in two areas: as contributors to candidates and parties and as candidate and issue advocates. Overall, the numbers reported here show that direct interest group influence with candidates and parties likely declined in the wake of reform. On the other hand, recent uncertainty in the regulatory environment should foster the expansion of interest group advocacy efforts (and has already done so in this year's presidential primary elections). On this score, the attempts of reformers to reduce interest group electioneering have likely failed. Instead of concluding that such a development is bad for American elections, however, this paper argues that such discontent is misplaced. Copyright ©2008 The Berkeley Electronic Press. All rights reserved.
Rachel Carson and the rhetoric of revolution
Date: 2019-07-01
Creator: David K. Hecht
Access: Open access
- Rachel Carson's Silent Spring is justly remembered as a landmark in the history of modern environmentalism. It is, however, a more complicated text than cultural memory tends to acknowledge. Blending conservative and traditional elements with more progressive and pioneering ones, Silent Spring is marked by a complexity that extends to its reception and legacy. This article argues that-in a seeming paradox-it was the more conservative elements of Silent Spring that allowed it to be considered a revolutionary book. Carson carefully constructed her argument in ways that facilitated its initial acceptance. But those same decisions made it easier for supporters to de-emphasize its more radical implications, even as they granted it revolutionary status.
Skin Deep: Analyzing Black Representation in the Teaching of Visual Arts
Date: 2021-01-01
Creator: Destiny Arianna Kearney
Access: Open access
- My honors thesis argues that at Bowdoin College, failure to provide Culturally Relevant Teaching in art studio courses dismisses the representation of Blackness in the Visual Arts Department. Culturally Relevant Teaching (CRT) recognizes the importance of all students' cultural experiences in different aspects of learning. It allows for equitable access to education for students of diverse backgrounds. CRT is crucial to reconstructing Art Education to represent diverse student bodies. My position as a Black-Indigenous artist enables me to reflect on the intersection of these frameworks and to build upon them in order to highlight the need for pedagogical practice in studio art courses, that doesn’t center technical training derived from the Western canon of art production in Bowdoin’s Visual Arts Department. My research lives on a digital format, where you will engage with the history of Art at Bowdoin from 1794 to the present, oral histories from Black identifying alumni who have navigated the department, theoretical frameworks, and an auto ethnography that breaks down my self-taught pedagogical practice in response to the representational gaps in the curriculum. As you navigate this site, I ask you to follow the written instructions and engage with the interactive material. I will virtually guide you through this project chronologically, and through the lens in which I have experienced personally and through observation.