Showing 1901 - 1950 of 5831 Items
Bowdoin Orient, v. 93, no. 7A
Date: 1963-06-28
Access: Open access
- Special Edition: Published by the Office of the Executive Secretary, with thanks to the Bowdoin Publishing Company
Learning cognitive maps: Finding useful structure in an uncertain world
Date: 2008-05-22
Creator: Eric Chown, Byron Boots
Access: Open access
- In this chapter we will describe the central mechanisms that influence how people learn about large-scale space. We will focus particularly on how these mechanisms enable people to effectively cope with both the uncertainty inherent in a constantly changing world and also with the high information content of natural environments. The major lessons are that humans get by with a "less is more" approach to building structure, and that they are able to quickly adapt to environmental changes thanks to a range of general purpose mechanisms. By looking at abstract principles, instead of concrete implementation details, it is shown that the study of human learning can provide valuable lessons for robotics. Finally, these issues are discussed in the context of an implementation on a mobile robot. © 2007 Springer-Verlag Berlin Heidelberg.
The citizens united election? or same as it ever was?
Date: 2010-12-01
Creator: Michael M. Franz
Access: Open access
- In January 2010, the Supreme Court in Citizens United v. FEC overturned long-standing regulations governing the role of unions and corporations in sponsoring pro-candidate advocacy. Many predicted a deleterious effect on the electoral process. In the aftermath of the midterm elections, a number of questions deserve consideration. Was the observed level of outside spending abnormally high in 2010? What can we say about the potential effect of outside spending on the outcomes of House and Senate races? Moreover, what has the decision done to the power of parties and, most especially, their ability to compete with special interests in backing federal candidates? This paper investigates these questions using data from the Wesleyan Media Project, which tracked political ads in 2010. The initial evidence suggests that while interest groups were aggressive players in the air war, their impact may not have been as negative or as large as initially predicted. © 2011 Berkeley Electronic Press.
Reflections questionnaire response by Anonymous on March 22, 2021
Date: 2021-01-01
Creator: Anonymous
Access: Open access
- This is a response to the Documenting Bowdoin & COVID-19 Reflections Questionnaire. The questionnaire was created in March 2021 by staff of Bowdoin's George J. Mitchell Department of Special Collections & Archives. The author is a member of Bowdoin's staff.
Vertical Trade, Exchange Rate Pass-Through, and Exchange Rate Regime
Date: 2012-09-01
Creator: Yao Tang, Ke Pang
Access: Open access
- We compare the welfare of different combinations of monetary and currency policies in an open-economy macroeconomic model that incorporates two important features of many small economies: a high level of vertical international trade and a prevalent use of a large trade partner's currency as the invoicing currency for both imports and exports. In this environment, a small economy prefers a fixed exchange rate regime over a flexible regime, while the larger economy prefers a flexible exchange rate regime. There are two main causes underlying our results. First, in the presence of sticky prices, relative prices adjust through changes in the exchange rate. Multiple stages of production and trade make it more difficult for one exchange rate to balance the whole economy by adjusting several relative prices throughout the vertical chain of production and trade. Namely, there is a trade-off between delivering an efficient relative price between home and foreign final goods and delivering an efficient relative price between home and foreign intermediate goods. Second, because the small economy uses the larger economy's currency in trade, it faces a high degree of exchange rate pass-through under a flexible regime and hence suffers from the lack of efficient relative prices in vertical trade. The larger economy, however, does not face this problem because its level of exchange rate pass-through is low.
The H.C. Carey School of U.S. Currency Doctors: A "Subtle Principle" and its Progeny
Date: 2024-02-20
Creator: Stephen Meardon
Access: Open access
- Henry C. Carey led a school of post-Civil War U.S. currency doctors prescribing an “elastic currency,” expanding and contracting according to commercial needs. The problem for the Careyites was reconciling elasticity, which implied inconvertibility with gold, with the related aim of decentralized financial power. Careyite currency doctors included, among others, Wallace P. Groom, editor of the New York Mercantile Journal, and Henry Carey Baird, Carey’s own nephew and inheritor of his mantle. Their prescribed reform of the banking system featured a financial innovation that would remove superfluous currency from circulation while supplying what was needed. The innovation was an “interconvertible bond,” a debt instrument of the U.S. Treasury that was to be issued upon demand and redeemable for currency at the option of the holder. Its function was supposed to be like the mechanical governor of a steam engine, operating by a “subtle principle” that obviated human governing power and discretion. The Carey school’s prescription and its rationale remained salient up to the advent of the Federal Reserve System.
Hedgehog signaling regulates dental papilla formation and tooth size during zebrafish odontogenesis
Date: 2015-04-01
Creator: Jeffrey C. Yu, Zachary D. Fox, James L. Crimp, Hana E. Littleford, Andrea L., Jowdry, William R. Jackman
Access: Open access
- Intercellular communication by the hedgehog cell signaling pathway is necessary for tooth development throughout the vertebrates, but it remains unclear which specific developmental signals control cell behavior at different stages of odontogenesis. To address this issue, we have manipulated hedgehog activity during zebrafish tooth development and visualized the results using confocal microscopy. Results: We first established that reporter lines for dlx2b, fli1, NF-κB, and prdm1a are markers for specific subsets of tooth germ tissues. We then blocked hedgehog signaling with cyclopamine and observed a reduction or elimination of the cranial neural crest derived dental papilla, which normally contains the cells that later give rise to dentin-producing odontoblasts. Upon further investigation, we observed that the dental papilla begins to form and then regresses in the absence of hedgehog signaling, through a mechanism unrelated to cell proliferation or apoptosis. We also found evidence of an isometric reduction in tooth size that correlates with the time of earliest hedgehog inhibition. Conclusions: We hypothesize that these results reveal a previously uncharacterized function of hedgehog signaling during tooth morphogenesis, regulating the number of cells in the dental papilla and thereby controlling tooth size.
Reflections questionnaire response by Mary Cote on March 27, 2021
Date: 2021-01-01
Creator: Mary Cote
Access: Open access
- This is a response to the Documenting Bowdoin & COVID-19 Reflections Questionnaire. The questionnaire was created in March 2021 by staff of Bowdoin's George J. Mitchell Department of Special Collections & Archives. The author is a member of Bowdoin's staff.
Reflections questionnaire response by Carey Lee on May 11, 2021
Date: 2021-01-01
Creator: Carey Lee
Access: Open access
- This is a response to the Documenting Bowdoin & COVID-19 Reflections Questionnaire. The questionnaire was created in March 2021 by staff of Bowdoin's George J. Mitchell Department of Special Collections & Archives. Author is class of 2022.
500 Years of Printmaking: Prints and Illustrated Books at Bowdoin College
Date: 1978-01-01
Creator: David P. Becker
Access: Open access
- Exhibition held Oct. 13-Dec. 31, 1978. Preface by Katherine J. Watson.
Evolution of the interaction between Hox genes and a downstream target
Date: 1998-05-07
Creator: Michael F. Palopoli, Nipam H. Patel
Access: Open access
- Segmental identifies along the insect body depend on the activities of Hox genes [1,2]. In Drosophila melanogaster, one well-studied Hox regulatory target is Distal-less (DII), which Is required for the development of distel limb structures [3]. In abdominal segments, DII transcription is prevented when Hox proteins of the Bithorax Complex (BX-C) bind to cis-regulatory elements upstream of the DII transcription start site [4,5]. Previous evolutionary comparisons of gene expression patterns suggest that this direct repression is conserved between Diptera and Lepidoptera, but is absent in the Crustacea [6,7]. We examined gene expression patterns in three orders of hexapods, all of which develop abdominal appendages, in order to determine when the strong repressive interaction between BX-C proteins and DII appeared during evolution. In each of the species examined, DII expression was initiated in abdominal cells despite the presence of high levels of BX-C proteins. It appears that the strong repressive effects of BX-C proteins on DII expression arose relatively late in insect evolution. We suggest that the regulatory interaction between the BX-C genes and DII has evolved within the hexapods in a complex, segment-specific manner.
The Politics of Land Rights in the Transition to Democratic South Africa: The Rise and Fall of the Constitutional Property Clause
Date: 2019-05-01
Creator: Anna Louisa Roosevelt Lennon
Access: Open access
Lipschitzian multifunctions and a Lipschitzian inverse mapping theorem
Date: 2001-01-01
Creator: A.B. Levy
Access: Open access
Interest groups in electoral politics: 2012 in context
Date: 2012-12-01
Creator: Michael M. Franz
Access: Open access
- This paper compares the levels of ad spending from outside groups and traditional party organizations across seven federal election cycles. The data show clearly that outside groups advertised at historic levels in 2012. Such intense efforts send two important signals to students of American campaign finance. The first involves a crisis in the system of limited donations to candidates and party committees moving forward. The second resurrects an old debate in political science about whether parties or candidates should be the center of our electoral process. The paper concludes with a consideration of possible reforms that might help restore parties and candidates to the center of issue debates in competitive federal elections.
Collecting Privately
Date: 1965-01-01
Access: Open access
- Exhibition catalogue from Bowdoin College Museum of Art.
Peatlands and their role in the global carbon cycle
Date: 2011-04-20
Creator: Zicheng Yu, D. W. Beilman, S. Frolking, G. M. MacDonald, N. T., Roulet, P. Camill, D. J. Charman
Access: Open access
- Global peatlands store a very large carbon (C) pool located within a few meters of the atmosphere. Thus, peatland-atmosphere C exchange should be a major concern to global change scientists: Will large amounts of respired belowground C be released in a warmer climate, causing the climate to further warm (a positive climate feedback)? Will more C be sequestered due to increased plant growth in a warmer climate? How will land use change, fires, and permafrost thaw affect the magnitude and direction of carbon dioxide (CO ) and methane (CH ) exchange with the atmosphere? These questions remain challenging, but some significant progress has been made recently. 2 4
Personally Relevant Indoor Nature Imagery’s Impact on Students’ Well-Being, Connection to Nature, and Eco-Conscious Behaviors
Date: 2019-05-01
Creator: Sarena Sabine
Access: Open access
- Previous research has shown that experiences in nature are predictive of increased connection to nature, well-being, and pro-environmental behavior. The current study investigated whether daily exposure to indoor nature imagery would also improve well-being and eco-conscious behaviors, and whether personally relevant images would enhance this hypothesized effect. Participants completed a test assessing baseline connection to nature and well-being, specifically satisfaction with life, positive and negative emotions, and stress. In the 2 (Nature vs. Built) X 2 (Familiar vs. Unfamiliar) study design, 125 participants either received a poster from a photo that they submitted (a personally-relevant nature scene or personally-relevant built scene) or a poster of an unfamiliar natural or built scene. After four weeks of daily exposure to this new poster in their home, participants completed a post-test which included the same measures of well-being and connection to nature, along with a novel eco-conscious behaviors measure involving environmental petitions. The nature intervention significantly improved participants’ satisfaction with life. The personal relevancy of images did not enhance well-being, either alone nor in interaction with image content. The finding that daily exposure could lead to improved well-being has implications for addressing mental health concerns.
An isochromosome confers drug resistance in vivo by amplification of two genes, ERG11 and TAC1
Date: 2008-05-01
Creator: Anna Selmecki, Maryam Gerami-Nejad, Carsten Paulson, Anja Forche, Judith, Berman
Access: Open access
- Acquired azole resistance is a serious clinical problem that is often associated with the appearance of aneuploidy and, in particular, with the formation of an isochromosome [i(5L)] in the fungal opportunist Candida albicans. Here we exploited a series of isolates from an individual patient during the rapid acquisition of fluconazole resistance (FluR). Comparative genome hybridization arrays revealed that the presence of two extra copies of Chr5L, on the isochromosome, conferred increased FluR and that partial truncation of Chr5L reduced FluR. In vitro analysis of the strains by telomere-mediated truncations and by gene deletion assessed the contribution of all Chr5L genes and of four specific genes. Importantly, ERG11 (encoding the drug target) and a hyperactive allele of TAC1 (encoding a transcriptional regulator of drug efflux pumps) made independent, additive contributions to FluR in a gene copy number-dependent manner that was not different from the contributions of the entire Chr5L arm. Thus, the major mechanism by which i(5L) formation causes increased azole resistance is by amplifying two genes: ERG11 and TAC1. © 2008 The Authors.
Clarifying (Opportunity) Costs
Date: 2015-05-01
Creator: Daniel F. Stone
Access: Open access
- Opportunity cost is widely considered to be a fundamental concept in economics. But the definition of the term continues to be both unclear and controversial. I describe how the term is widely used in two distinct ways, both in academic and non-academic contexts. I propose a practical way for educators to clarify the concept and related terminology.
Expert assessment of vulnerability of permafrost carbon to climate change
Date: 2013-07-01
Creator: E. A.G. Schuur, B. W. Abbott, W. B. Bowden, V. Brovkin, P., Camill, J. G. Canadell, J. P. Chanton, F. S. Chapin, T. R. Christensen, P. Ciais, B. T. Crosby, C. I. Czimczik, G. Grosse, J. Harden, D. J. Hayes, G. Hugelius
Access: Open access
- Approximately 1700 Pg of soil carbon (C) are stored in the northern circumpolar permafrost zone, more than twice as much C than in the atmosphere. The overall amount, rate, and form of C released to the atmosphere in a warmer world will influence the strength of the permafrost C feedback to climate change. We used a survey to quantify variability in the perception of the vulnerability of permafrost C to climate change. Experts were asked to provide quantitative estimates of permafrost change in response to four scenarios of warming. For the highest warming scenario (RCP 8.5), experts hypothesized that C release from permafrost zone soils could be 19-45 Pg C by 2040, 162-288 Pg C by 2100, and 381-616 Pg C by 2300 in CO equivalent using 100-year CH global warming potential (GWP). These values become 50 % larger using 20-year CH GWP, with a third to a half of expected climate forcing coming from CH even though CH was only 2.3 % of the expected C release. Experts projected that two-thirds of this release could be avoided under the lowest warming scenario (RCP 2.6). These results highlight the potential risk from permafrost thaw and serve to frame a hypothesis about the magnitude of this feedback to climate change. However, the level of emissions proposed here are unlikely to overshadow the impact of fossil fuel burning, which will continue to be the main source of C emissions and climate forcing. © 2013 The Author(s). 2 4 4 4 4
Two databases derived from BGC-Argo float measurements for marine biogeochemical and bio-optical applications
Date: 2017-11-22
Creator: Emanuele Organelli, Marie Barbieux, Hervé Claustre, Catherine Schmechtig, Antoine, Poteau, Annick Bricaud, Emmanuel Boss, Nathan Briggs, Giorgio Dall'Olmo, Fabrizio D'Ortenzio, Edouard Leymarie, Antoine Mangin, Grigor Obolensky, Christophe Penkerc'H, Louis Prieur, Collin Roesler, Romain Serra, Julia Uitz, Xiaogang Xing
Access: Open access
- Since 2012, an array of 105 Biogeochemical-Argo (BGC-Argo) floats has been deployed across the world's oceans to assist in filling observational gaps that are required for characterizing open-ocean environments. Profiles of biogeochemical (chlorophyll and dissolved organic matter) and optical (single-wavelength particulate optical backscattering, downward irradiance at three wavelengths, and photosynthetically available radiation) variables are collected in the upper 1000 m every 1 to 10 days. The database of 9837 vertical profiles collected up to January 2016 is presented and its spatial and temporal coverage is discussed. Each variable is quality controlled with specifically developed procedures and its time series is quality-assessed to identify issues related to biofouling and/or instrument drift. A second database of 5748 profile-derived products within the first optical depth (i.e., the layer of interest for satellite remote sensing) is also presented and its spatiotemporal distribution discussed. This database, devoted to field and remote ocean color applications, includes diffuse attenuation coefficients for downward irradiance at three narrow wavebands and one broad waveband (photosynthetically available radiation), calibrated chlorophyll and fluorescent dissolved organic matter concentrations, and single-wavelength particulate optical backscattering. To demonstrate the applicability of these databases, data within the first optical depth are compared with previously established bio-optical models and used to validate remotely derived bio-optical products. The quality-controlled databases are publicly available from the SEANOE (SEA scieNtific Open data Edition) publisher at https://doi.org/10.17882/49388 and https://doi.org/10.17882/47142 for vertical profiles and products within the first optical depth, respectively.
Are melanized feather barbs stronger?
Date: 2004-01-01
Creator: Michael Butler, Amy S. Johnson
Access: Open access
- Melanin has been associated with increased resistance to abrasion, decreased wear and lowered barb breakage in feathers. But, this association was inferred without considering barb position along the rachis as a potentially confounding variable. We examined the cross-sectional area, breaking force, breaking stress, breaking strain and toughness of melanized and unmelanized barbs along the entire rachis of a primary feather from an osprey (Pandion haliaetus). Although breaking force was higher for melanized barbs, breaking stress (force divided by cross-sectional area) was greater for unmelanized barbs. But when position was considered, all mechanical differences between melanized and unmelanized barbs disappeared. Barb breaking stress, breaking strain and toughness decreased, and breaking stiffness increased, distally along the rachis. These proximal-distal material property changes are small and seem unlikely to affect flight performance of barbs. Our observations of barb bending, breaking and morphology, however, lead us to propose a design principle for barbs. We propose that, by being thicker-walled dorso-ventrally, the barb's flexural stiffness is increased during flight; but, by allowing for twisting when loaded with dangerously high forces, barbs firstly avoid failure by bending and secondly avoid complete failure by buckling rather than rupturing.
James Bowdoin: Patriot and Man of The Enlightenment (pamphlet)
Date: 1976-01-01
Creator: Peter R. Mooz
Access: Open access
- Catalog of an exhibition held at the Bowdoin College Museum of Art, May 28-September 12, 1976.
Where to put things? Spatial land management to sustain biodiversity and economic returns
Date: 2008-06-01
Creator: Stephen Polasky, Erik Nelson, Jeff Camm, Blair Csuti, Paul, Fackler, Eric Lonsdorf, Claire Montgomery, Denis White, Jeff Arthur
Access: Open access
- Expanding human population and economic growth have led to large-scale conversion of natural habitat to human-dominated landscapes with consequent large-scale declines in biodiversity. Conserving biodiversity, while at the same time meeting expanding human needs, is an issue of utmost importance. In this paper we develop a spatially explicit landscape-level model for analyzing the biological and economic consequences of alternative land-use patterns. The spatially explicit biological model incorporates habitat preferences, area requirements and dispersal ability between habitat patches for terrestrial vertebrate species to predict the likely number of species that will be sustained on the landscape. The spatially explicit economic model incorporates site characteristics and location to predict economic returns for a variety of potential land uses. We apply the model to search for efficient land-use patterns that maximize biodiversity conservation objectives for given levels of economic returns, and vice versa. We apply the model to the Willamette Basin, Oregon, USA. By thinking carefully about the arrangement of activities, we find land-use patterns that sustain high levels of biodiversity and economic returns. Compared to the 1990 land-use pattern, we show that both biodiversity conservation and the value of economic activity could be increased substantially. © 2008 Elsevier Ltd.
Nonlinear coherent structures in granular crystals
Date: 2017-09-06
Creator: C. Chong, Mason A. Porter, P. G. Kevrekidis, C. Daraio
Access: Open access
- The study of granular crystals, which are nonlinear metamaterials that consist of closely packed arrays of particles that interact elastically, is a vibrant area of research that combines ideas from disciplines such as materials science, nonlinear dynamics, and condensed-matter physics. Granular crystals exploit geometrical nonlinearities in their constitutive microstructure to produce properties (such as tunability and energy localization) that are not conventional to engineering materials and linear devices. In this topical review, we focus on recent experimental, computational, and theoretical results on nonlinear coherent structures in granular crystals. Such structures - which include traveling solitary waves, dispersive shock waves, and discrete breathers - have fascinating dynamics, including a diversity of both transient features and robust, long-lived patterns that emerge from broad classes of initial data. In our review, we primarily discuss phenomena in one-dimensional crystals, as most research to date has focused on such scenarios, but we also present some extensions to two-dimensional settings. Throughout the review, we highlight open problems and discuss a variety of potential engineering applications that arise from the rich dynamic response of granular crystals.
Framing ICT Usage in the Real Estate Industry
Date: 2013-04-12
Creator: Steven Jones
Access: Open access
- The real estate industry, like many, is one based on a competitive consumer culture in which professionals vie for the business and, ultimately, the loyalty of customers. In this case, those customers are purchasing what, for most, is a significant investment, requiring them to navigate various legal and regulatory processes that might be impossible without the assistance of a knowledgeable, seasoned agent. It is the presence of agency that renders real estate unique from retail and other industries where goods and services trade hands. Furthermore, the rise of various information and communication technologies (ICT) over the course of the past 25 years may have led to new challenges for real estate agents and allied professionals. Some scholars surmise that the increased prevalence of ICTs in various industries can become disruptive to those industries, causing individuals and organizations working within them to either adapt accordingly or become obsolete (Bower and Christensen 1995; Markus, et al. 2006).