Showing 4551 - 4560 of 5831 Items
US Household Demand for Organic Fruit
Date: 2017-08-31
Creator: Erik Nelson, John M Fitzgerald, Nathan Tefft, John L. Anderson
Access: Open access
- We estimate US household monthly elasticities of demand for some of the more popular organic fruits. To our knowledge, this is the first US-wide, multi-year analysis of price and income elasticities for various organic fruits. We calculate elasticities of demand for low-income, middle class, and rich income bracket households using three estimation techniques: two econometric methods and one machine learning method (least absolute shrinkage and selection operator (LASSO)). Demand estimates are based on Nielsen scanner data from approximately 60,000 households collected from 2011 to 2013. Generally, we find that own-price conditional and unconditional elasticities of demand for organic fruits are negative. Unconditional elasticity magnitudes tend to be largest in the representative middle-class household. Income elasticities of demand measurements are inconsistent and often statistically insignificant. This finding is consistent with the survey literature finding that many consumers buy organic food for mostly moral or ethical reasons. We run two policy experiments: a 10% subsidy of organic fruits, and a 10% tax on conventional fruits. Our hypothetical policies engender a stronger reaction among the general public than habitual buyers of organic fruit; unconditional purchase and expenditure elasticities are generally larger than conditional purchase and expenditure elasticities. Finally, we find that elasticities measured with the LASSO technique are not radically different than those measured with econometric methods. The most noticeable difference between the two analytical techniques is that LASSO is more likely to find price and income elasticities of demand that indistinguishable from zero, both substantively and statistically.
African Extensions: A Photographic Search for African Survivals in the Americas
Date: 1981-01-01
Creator: Reginald L. Jackson
Access: Open access
- Catalog for an exhibition co-sponsored by the Afro-American Studies Program, held at the Bowdoin College Museum of Art, John A. and Helen P. Becker Gallery, 7-22 March, 1991.
Erratum: Stochastic boolean satisfiability (Journal of Automated Reasoning (2001) 27 (251-296))
Date: 2002-01-01
Creator: Michael L. Littman, Stephen M. Majercik, Toniann Pitassi
Access: Open access
James Bowdoin III: Pursuing Style in the Age of Independence
Date: 2008-01-01
Creator: Vernon Scott
Access: Open access
- Catalog of an exhibition held at the Bowdoin College Museum of Art from Sept. 9, 2008, through June 7, 2009. Essay by V. Scott Dimond
On Kindleberger and Hegemony: From Berlin to M.I.T. and Back
Date: 2013-09-29
Creator: Stephen Meardon
Access: Open access
- The most notable idea of Charles P. Kindleberger’s later career is the value of a single country acting as stabilizer of an international economy prone to instability. It runs through his widely read books, The World in Depression, 1929-1939 (1973), Manias, Crises, and Panics (1978), A Financial History of Western Europe (1984), and kindred works. “Hegemonic stability,” the idea is called in the literature it inspired. This essay traces Kindleberger’s attachment to the idea back to his tenure as chief of the State Department’s Division of German and Austrian Economic Affairs from 1945 to 1947 and adviser to the European Recovery Program from 1947 to 1948. In both capacities Kindleberger observed and participated indirectly in the 1948 monetary reform in Western Germany. In the 1990s, during his octogenary decade, he revisited the German monetary reform with a fellow participant, economist, and longtime friend, F. Taylor Ostrander. Their collaborative essay marked Kindleberger’s effort to reclaim hegemonic stability theory from the scholars who developed it following his works of the 1970s and 1980s.
Identification, physiological actions, and distribution of TPSGFLGMRamide: A novel tachykinin-related peptide from the midgut and stomatogastric nervous system of Cancer crabs
Date: 2007-06-01
Creator: Elizabeth A. Stemmler, Braulio Peguero, Emily A. Bruns, Patsy S. Dickinson, Andrew E., Christie
Access: Open access
- In most invertebrates, multiple species-specific isoforms of tachykinin-related peptide (TRP) are common. In contrast, only a single conserved TRP isoform, APSGFLGMRamide, has been documented in decapod crustaceans, leading to the hypothesis that it is the sole TRP present in this arthropod order. Previous studies of crustacean TRPs have focused on neuronal tissue, but the recent demonstration of TRPs in midgut epithelial cells in Cancer species led us to question whether other TRPs are present in the gut, as is the case in insects. Using direct tissue matrix assisted laser desorption/ionization Fourier transform mass spectrometry, in combination with sustained off-resonance irradiation collision-induced dissociation, we found that at least one additional TRP is present in Cancer irroratus, Cancer borealis, Cancer magister, and Cancer productus. The novel TRP isoform, TPSGFLGMRamide, was present not only in the midgut, but also in the stomatogastric nervous system (STNS). In addition, we identified an unprocessed TRP precursor APSGFLGMRG, which was detected in midgut tissues only. TRP immunohistochemistry, in combination with preadsorption studies, suggests that APSGFLGMRamide and TPSGFLGMRamide are co-localized in the stomatogastric ganglion (STG), which is contained within the STNS. Exogenous application of TPSGFLGMRamide to the STG elicited a pyloric motor pattern that was identical to that elicited by APSGFLGMRamide, whereas APSGFLGMRG did not alter the pyloric motor pattern. © 2007 The Authors.
Retinoic acid expands the evolutionarily reduced dentition of zebrafish
Date: 2012-12-01
Creator: Pawat Seritrakul, Eric Samarut, Tenzing T.S. Lama, Yann Gibert, Vincent, Laudet, William R. Jackman
Access: Open access
- Zebrafish lost anterior teeth during evolution but retain a posterior pharyngeal dentition that requires retinoic acid (RA) cell-cell signaling for its development. The purposes of this study were to test the sufficiency of RA to induce tooth development and to assess its role in evolution. We found that exposure of embryos to exogenous RA induces a dramatic anterior expansion of the number of pharyngeal teeth that later form and shifts anteriorly the expression patterns of genes normally expressed in the posterior tooth-forming region, such as pitx2 and dlx2b. After RA exposure, we also observed a correlation between cartilage malformations and ectopic tooth induction, as well as abnormal cranial neural crest marker gene expression. Additionally, we observed that the RA-induced zebrafish anterior teeth resemble in pattern and number the dentition of fish species that retain anterior pharyngeal teeth such as medaka but that medaka do not express the aldh1a2 RA-synthesizing enzyme in tooth-forming regions. We conclude that RA is sufficient to induce anterior ectopic tooth development in zebrafish where teeth were lost in evolution, potentially by altering neural crest cell development, and that changes in the location of RA synthesis correlate with evolutionary changes in vertebrate dentitions. © FASEB.
GEM-PSO: Particle Swarm Optimization Guided by Enhanced Memory
Date: 2019-05-01
Creator: Kevin Fakai Chen
Access: Open access
- Particle Swarm Optimization (PSO) is a widely-used nature-inspired optimization technique in which a swarm of virtual particles work together with limited communication to find a global minimum or optimum. PSO has has been successfully applied to a wide variety of practical problems, such as optimization in engineering fields, hybridization with other nature-inspired algorithms, or even general optimization problems. However, PSO suffers from a phenomenon known as premature convergence, in which the algorithm's particles all converge on a local optimum instead of the global optimum, and cannot improve their solution any further. We seek to improve upon the standard Particle Swarm PSO algorithm by fixing this premature convergence behavior. We do so by storing and exploiting increased information in the form of past bests, which we deem enhanced memory. We introduce three types of modifications to each new algorithm (which we call a GEM-PSO: Particle Swarm Optimization, Guided by Enhanced Memory, because our modifications all deal with enhancing the memory of each particle). These are procedures for saving a found best, for removing a best from memory when a new one is to be added, and for selecting one (or more) bests to be used from those saved in memory. By using different combinations of these modifications, we can create many different variants of GEM-PSO that have a wide variety of behaviors and qualities. We analyze the performance of GEM-PSO, discuss the impact of PSO's parameters on the algorithms' performances, isolate different modifications in order to closely study their impact on the performance of any given GEM-PSO variant, and finally look at how multiple modifications perform. Finally, we draw conclusions about the efficacy and potential of GEM-PSO variants, and provide ideas for further exploration in this area of study. Many GEM-PSO variants are able to consistently outperform standard PSO on specific functions, and GEM-PSO variants can be shown to be promising, with both general and specific use cases.
Social Media as Technologies of Accountability: Explaining Resistance to Implementation Within Organizations
Date: 2013-04-12
Creator: Jeffrey Treem
Access: Open access