Showing 5251 - 5260 of 5713 Items
Beyond Thirst: The Dimensions of Drink
Date: 2003-01-01
Creator: Caitlin M. Nelson, Christine L. Paglia
Access: Open access
- "This brochure accompanies an exhibition of the same name at the Bowdoin College Museum of Art from April 17 through June 15, 2003"--Page 2 of cover
Que vivan los estudiantes: Cycles of Contention and the Chilean Student Movement (1906-present)
Date: 2018-01-01
Creator: Jonah Watt
Access: Open access
- [No abstract]
Hedgehog signaling is required at multiple stages of zebrafish tooth development
Date: 2010-12-02
Creator: William R. Jackman, James J. Yoo, David W. Stock
Access: Open access
- Background. The accessibility of the developing zebrafish pharyngeal dentition makes it an advantageous system in which to study many aspects of tooth development from early initiation to late morphogenesis. In mammals, hedgehog signaling is known to be essential for multiple stages of odontogenesis; however, potential roles for the pathway during initiation of tooth development or in later morphogenesis are incompletely understood. Results. We have identified mRNA expression of the hedgehog ligands shha and the receptors ptc1 and ptc2 during zebrafish pharyngeal tooth development. We looked for, but did not detect, tooth germ expression of the other known zebrafish hedgehog ligands shhb, dhh, ihha, or ihhb, suggesting that as in mammals, only Shh participates in zebrafish tooth development. Supporting this idea, we found that morphological and gene expression evidence of tooth initiation is eliminated in shha mutant embryos, and that morpholino antisense oligonucleotide knockdown of shha, but not shhb, function prevents mature tooth formation. Hedgehog pathway inhibition with the antagonist compound cyclopamine affected tooth formation at each stage in which we applied it: arresting development at early stages and disrupting mature tooth morphology when applied later. These results suggest that hedgehog signaling is required continuously during odontogenesis. In contrast, over-expression of shha had no effect on the developing dentition, possibly because shha is normally extensively expressed in the zebrafish pharyngeal region. Conclusion. We have identified previously unknown requirements for hedgehog signaling for early tooth initiation and later morphogenesis. The similarity of our results with data from mouse and other vertebrates suggests that despite gene duplication and changes in the location of where teeth form, the roles of hedgehog signaling in tooth development have been largely conserved during evolution. © 2010 Jackman et al; licensee BioMed Central Ltd.
The Role of Competition and Patient Travel in Hospital Profits: Why Health Insurers Should Subsidize Patient Travel
Date: 2013-05-01
Creator: Joseph S Durgin
Access: Open access
- This paper explores the effects of patient travel distance on hospital profit margins, with consideration to the effects of travel subsidies on hospital pricing. We develop a model in which hospital agglomeration leads to a negative relationship between profit margins and patient travel distance, challenging the standard IO theory that profit margins are higher for firms with greater distances of customer travel. Using data on patient visits and hospital finances from the California Office of Statewide Health Planning and Development (OSHPD), we test our theory and confirm that a hospital tends to have less pricing power if it draws patients from beyond its local cluster. We then consider how our results might justify the subsidizing of patient travel by insurers and government payers. Lastly, we present an argument for why the ubiquitous Hirschman-Herfindahl index of market concentration can be robust to owner and system-level hospital cooperation.
The first formed tooth serves as a signalling centre to induce the formation of the dental row in zebrafish
Date: 2019-06-12
Creator: Yann Gibert, Eric Samarut, Megan K. Ellis, William R. Jackman, Vincent, Laudet
Access: Open access
- The diversity of teeth patterns in actinopterygians is impressive with tooth rows in many locations in the oral and pharyngeal regions. The first-formed tooth has been hypothesized to serve as an initiator controlling the formation of the subsequent teeth. In zebrafish, the existence of the first tooth (named 4 V1) is puzzling as its replacement is induced before the opening of the mouth. Functionally, it has been shown that 4 V1 formation requires fibroblast growth factor (FGF) and retinoic acid (RA) signalling. Here, we show that the ablation of 4 V1 prevents the development of the dental row demonstrating its dependency over it. If endogenous levels of FGF and RA are restored after 4 V1 ablation, embryonic dentition starts again by de novo formation of a first tooth, followed by the dental row. Similarly, induction of anterior ectopic teeth induces subsequent tooth formation, demonstrating that the initiator tooth is necessary and sufficient for dental row formation, probably via FGF ligands released by 4 V1 to induce the formation of subsequent teeth. Our results show that by modifying the formation of the initiator tooth it is possible to control the formation of a dental row. This could help to explain the diversity of tooth patterns observed in actinopterygians and more broadly, how diverse traits evolved through molecular fine-tuning.
Pandemic as method
Date: 2019-10-01
Creator: Belinda Kong
Access: Open access
- This essay deploys the concept of pandemic as a set of discursive relations rather than a neutral description of a natural phenomenon, arguing that pandemic discourse is a product of layered histories of power that in turn reproduces myriad forms of imperial and racial power in the new millennium. The essay aims to denaturalize the idea of infectious disease by reframing it as an assemblage of multiple histories of American geopower and biopower from the Cold War to the War on Terror. In particular, Asia and Asian bodies have been targeted by US discourses of infection and biosecurity as frontiers of bioterrorism and the diseased other. A contemporary example of this bioorientalism can be seen around the 2003 SARS epidemic, in which global discourses projected the source of contagion onto Asia and Asians. Pandemic as method can thus serve as a theoretical pathway for examining cultural concatenations of orientalism and biopower.
Images of New World Natives
Date: 1974-01-01
Creator: Jim Nicholson
Access: Open access
- Catalog ; with an introducton by James E. Nicholson : "Post-contact art of the northwest coast"
Does Productivity Respond to Exchange Rate Appreciations? A Theoretical and Empirical Investigation
Date: 2010-12-15
Creator: Yao Tang
Access: Open access
- Although real currency appreciations pose direct difficulties for exporters and import-competing firms as they will face more intense competition, is it possible that such competition spurs firms to improve productivity? To answer this question, the paper first constructs a theoretical model to show how the competitive pressures of currency appreciations induce firms to improve productivity by adopting new technologies. In addition, the model predicts that during appreciations there will be a positive relation between market concentration and improvements in productivity for industries highly exposed to trade, because the marginal benefits of productivity improvement will be bigger for firms with a larger market share. The paper then examines Canadian manufacturing data from 1997 to 2006, and finds evidence consistent with model predictions. I find that growth rates of labor productivity were on average higher during the Canadian dollar appreciation between 2002 and 2006, after controlling for industry characteristics. Within the group of highly traded Canadian industries, the more concentrated ones experienced larger growth in labor productivity.
Picturing Creativity: Portraits of Artists, 1860-1960
Date: 1998-01-01
Creator: Laura B. Groves
Access: Open access
- Exhibit organized by Laura B. Groves.