Showing 161 - 170 of 2040 Items
Voluntary sustainability standards could significantly reduce detrimental impacts of global agriculture
Date: 2019-02-05
Creator: W. K. Smith
E. Nelson
J. A. Johnson
S. Polasky
J. C., Milder
J. S. Gerber
P. C. West
S. Siebert
K. A. Brauman
Access: Open access
- Voluntary sustainability standards (VSS) are stakeholder-derived principles with measurable and enforceable criteria to promote sustainable production outcomes. While institutional commitments to use VSS to meet sustainable procurement policies have grown rapidly over the past decade, we still have relatively little understanding of the (i) direct environmental benefits of large-scale VSS adoption; (ii) potential perverse indirect impacts of adoption; and (iii) implementation pathways. Here, we illustrate and address these knowledge gaps using an ecosystem service modeling and scenario analysis of Bonsucro, the leading VSS for sugarcane. We find that global compliance with the Bonsucro environmental standards would reduce current sugarcane production area (−24%), net tonnage (−11%), irrigation water use (−65%), nutrient loading (−34%), and greenhouse gas emissions from cultivation (−51%). Under a scenario of doubled global sugarcane production, Bonsucro adoption would further limit water use and greenhouse gas emissions by preventing sugarcane expansion into water-stressed and high-carbon stock ecosystems. This outcome was achieved via expansion largely on existing agricultural lands. However, displacement of other crops could drive detrimental impacts from indirect land use. We find that over half of the potential direct environmental benefits of Bonsucro standards under the doubling scenario could be achieved by targeting adoption in just 10% of global sugarcane production areas. However, designing policy that generates the most environmentally beneficial Bonsucro adoption pathway requires a better understanding of the economic and social costs of VSS adoption. Finally, we suggest research directions to advance sustainable consumption and production.
Promoting the "Public Welfare" in Wartime: Stanford University during World War II
Date: 2005-11-01
Creator: Charles Dorn
Access: Open access
- As with many U.S. colleges and universities during World War II, Stanford University responded to the demands of mobilization by increasing its commitment to technical training and adopting a defense research agenda. In a striking departure from this national trend, however, Stanford also established its School of Humanities in 1942. By examining such seemingly disparate pursuits, this study reveals the complexity of the challenges that confronted institutions of higher education throughout the war era. Stanford University's simultaneous embrace of these programs illuminates broad concerns regarding the role of higher education in fostering civic-mindedness in a society denned by rapid technological advance and the perception of an ever-increasing threat to national security. © 2005 by The University of Chicago. All rights reserved.
DC-SSAT: A divide-and-conquer approach to solving stochastic satisfiability problems efficiently
Date: 2005-12-01
Creator: Stephen M. Majercik
Byron Boots
Access: Open access
- We present DC-SSAT, a sound and complete divide-and-conquer algorithm for solving stochastic satisfiability (SSAT) problems that outperforms the best existing algorithm for solving such problems (ZANDER) by several orders of magnitude with respect to both time and space. DC-SSAT achieves this performance by dividing the SSAT problem into subproblems based on the structure of the original instance, caching the viable partial assignments (VPAs) generated by solving these subproblems, and using these VPAs to construct the solution to the original problem. DC-SSAT does not save redundant VPAs and each VPA saved is necessary to construct the solution. Furthermore, DC-SSAT builds a solution that is already human-comprehensible, allowing it to avoid the costly solution rebuilding phase in ZANDER. As a result, DC-SSAT is able to solve problems using, typically, 1-2 orders of magnitude less space than ZANDER, allowing DC-SSAT to solve problems ZANDER cannot solve due to space constraints. And, in spite of its more parsimonious use of space, DC-SSAT is typically 1-2 orders of magnitude faster than ZANDER. We describe the DC-SSAT algorithm and present empirical results comparing its performance to that of ZANDER on a set of SSAT problems. Copyright © 2005, American Association for Artificial Intelligence (www.aaai.org). All rights reserved.
Evaluating democracy: The 1946 U.S. education mission to Germany
Date: 2005-06-01
Creator: Charles Dorn
Access: Open access
- Following World War II, a group of American educators was assigned the task of evaluating the U.S. military government's program for reconstructing Germany's educational system. Although issuing a generally positive report, this education mission identified a number of persistent tensions that ultimately undermined America's efforts to rehabilitate and reform German schooling. As with the American occupation of Germany during the postwar era, current U.S. foreign policy directives include establishing educational institutions in the "broader Middle East" as a primary mechanism for inculcating democratic values and ideals. Determining America's success with these efforts, especially in ideologically conservative nations, poses a significant challenge to evaluators. Through an analysis of the 1946 Report of the United States Education Mission to Germany, this article presents a historical case study of the stumbling blocks, failings, and successes of one attempt to evaluate efforts in infusing democratic values into educational institutions in a fallen totalitarian state. © 2005 American Evaluation Association.
Waterfowl habitat change over five decades in a freshwater tidal ecosystem in mid-coast maine
Date: 2011-01-01
Creator: J. Lichter
M.E.H. Burton
S.L. Close
J.M. Grinvalsky
J., Reblin
Access: Open access
Under the hood of satellite empirical chlorophyll a algorithms: Revealing the dependencies of maximum band ratio algorithms on inherent optical properties
Date: 2012-09-10
Creator: Michael J. Sauer
C. S. Roesler
P. J. Werdell
A. Barnard
Access: Open access
- Empirically-based satellite estimates of chlorophyll a [Chl] (e.g. OC3) are an important indicator of phytoplankton biomass. To correctly interpret [Chl] variability, estimates must be accurate and sources of algorithm errors known. While the underlying assumptions of band ratio algorithms such as OC3 have been tacitly hypothesized (i.e. CDOM and phytoplankton absorption covary), the influence of component absorption and scattering on the shape of the algorithm and estimated [Chl] error has yet to be explicitly revealed. We utilized the NOMAD bio-optical data set to examine variations between satellite estimated [Chl] and in situ values. We partitioned the variability into (a) signal contamination and (b) natural phytoplankton variability (variability in chlorophyll-specific phytoplankton absorption). Not surprisingly, the OC3 best-fit curve resulted from a balance between these two different sources of variation confirming the bias by detrital absorption on global scale. Unlike previous descriptions of empirical [Chl] algorithms, our study (a) quantified the mean detrital:phytoplankton absorption as ~1:1in the global NOMAD data set, and (b) removed detrital (CDOM + non-algal particle) absorption in radiative transfer models directly showing that the scale of the remaining variability in the band ratio algorithm was dominated by phytoplankton absorption cross section. © 2012 Optical Society of America.
The Future of Social Movement Organizations: The Waning Dominance of SMOs Online
Creator: Jennifer Earl
Access: Open access
- For scholars interested in the role of information communication technologies (ICTs) in protest and social movements, the importance of organizations doesn’t appear to be as axiomatic. Work over the past decade researching “Internet activism” has raised fundamental questions about SMOs and their continuing importance to protest: Do organizations play the same role in online protest as they have played in offline protest? Are SMOs as necessary for online movements and protest organizing? What role or functions do SMOs play in online protest? In this article, I address these questions by first surveying social movement research on pre-Internet protest to establish how traditional social movement scholarship understands the role and impact of SMOs. I then compare these expectations to existing work on online protest. In the end, I argue that there are a variety of factors that contribute to the declining necessity of SMOs. Nonetheless, I point to some advantages that SMOs still seem to offer over other forms of organizing. Finally, I discuss the differences between a movement ecology devoid of SMOs versus one that has some level of SMO presence as well as reasons why SMOs might persist, separate and apart from the advantages the organizational form imparts.
Underway and moored methods for improving accuracy in measurement of spectral particulate absorption and attenuation
Date: 2010-10-01
Creator: Wayne H. Slade
Emmanuel Boss
Giorgio Dall'olmo
M. Rois Langner
James, Loftin
Michael J. Behrenfeld
Collin Roesler
Toby K. Westberry
Access: Open access
- Optical sensors have distinct advantages when used in ocean observatories, autonomous platforms, and on vessels of opportunity, because of their high-frequency measurements, low power consumption, and the numerous established relationships between optical measurements and biogeochemical variables. However, the issues of biofouling and instrument stability over time remain complicating factors when optical instruments are used over periods longer than several days. Here, a method for obtaining calibration-independent measurements of spectral particle absorption and attenuation is presented. Flow-through optical instrumentation is routinely diverted through a large-surface area 0.2-μm cartridge filter, allowing for the calculation of particle optical properties by differencing temporally adjacent filtered and whole water samples. This approach yields measurements that are independent of drift in instrument calibration. The method has advantages not only for coastally moored deployments, but also for applications in optically clear waters where uncertainties in instrument calibration can be a significant part of the signal measured. The differencing technique is demonstrated using WET Labs (Philomath, Oregon) ac-9 and ac-s multi- and hyperspectral absorption and attenuation meters. For the ac-s sensor, a correction scheme is discussed that utilizes the spectral shape of water absorption in the near-infrared to improve the accuracy of temperature and scattering-corrected spectra. Flow-through particulate absorption measurements are compared with discrete filter-pad measurements and are found to agree well (R = 0.77; rmse = 0.0174 m ). © 2010 American Meteorological Society. 2 -1
Understanding the effect of political advertising on voter turnout: A response to Krasno and Green
Date: 2008-01-01
Creator: Michael M. Franz
Paul Freedman
Ken Goldstein
Travis N. Ridout
Access: Open access
- Krasno and Green have argued that political advertising has no impact on voter turnout. We remain unconvinced by their evidence, given concerns about how they measure the advertising environment, how they measure advertising tone, their choice of modeling techniques and the generalizability of their findings. These differences aside, we strongly agree that political advertising does little to undermine voter participation. © 2008 Southern Political Science Association.
Climate change's impact on key ecosystem services and the human well-being they support in the US
Date: 2013-11-01
Creator: Erik J. Nelson
Peter Kareiva
Mary Ruckelshaus
Katie Arkema
Gary, Geller
Evan Girvetz
Dave Goodrich
Virginia Matzek
Malin Pinsky
Access: Open access
- Climate change alters the functions of ecological systems. As a result, the provision of ecosystem services and the well-being of people that rely on these services are being modified. Climate models portend continued warming and more frequent extreme weather events across the US. Such weather-related disturbances will place a premium on the ecosystem services that people rely on. We discuss some of the observed and anticipated impacts of climate change on ecosystem service provision and livelihoods in the US. We also highlight promising adaptive measures. The challenge will be choosing which adaptive strategies to implement, given limited resources and time. We suggest using dynamic balance sheets or accounts of natural capital and natural assets to prioritize and evaluate national and regional adaptation strategies that involve ecosystem services. © The Ecological Society of America.