Showing 3421 - 3430 of 5708 Items
MnNiO3 revisited with modern theoretical and experimental methods
Date: 2017-11-07
Creator: Allison L. Dzubak, Chandrima Mitra, Michael Chance, Stephen Kuhn, Gerald E., Jellison, Athena S. Sefat, Jaron T. Krogel, Fernando A. Reboredo
Access: Open access
- MnNiO3 is a strongly correlated transition metal oxide that has recently been investigated theoretically for its potential application as an oxygen-evolution photocatalyst. However, there is no experimental report on critical quantities such as the band gap or bulk modulus. Recent theoretical predictions with standard functionals such as LDA+U and HSE show large discrepancies in the band gaps (about 1.23 eV), depending on the nature of the functional used. Hence there is clearly a need for an accurate quantitative prediction of the band gap to gauge its utility as a photocatalyst. In this work, we present a diffusion quantum Monte Carlo study of the bulk properties of MnNiO3 and revisit the synthesis and experimental properties of the compound. We predict quasiparticle band gaps of 2.0(5) eV and 3.8(6) eV for the majority and minority spin channels, respectively, and an equilibrium volume of 92.8 Å3, which compares well to the experimental value of 94.4 Å3. A bulk modulus of 217 GPa is predicted for MnNiO3. We rationalize the difficulty for the formation of ordered ilmenite-type structure with specific sites for Ni and Mn to be potentially due to the formation of antisite defects that form during synthesis, which ultimately affects the physical properties of MnNiO3.
The power of context in networks: Ideal point models with social interactions
Date: 2019-01-01
Creator: Mohammad T. Irfan, Tucker Gordon
Access: Open access
- Game theory has been widely used for modeling strategic behaviors in networked multiagent systems. However, the context within which these strategic behaviors take place has received limited attention. We present a model of strategic behavior in networks that incorporates the behavioral context, focusing on the contextual aspects of congressional voting. One salient predictive model in political science is the ideal point model, which assigns each senator and each bill a number on the real line of political spectrum. We extend the classical ideal point model with network-structured interactions among senators. In contrast to the ideal point model's prediction of individual voting behavior, we predict joint voting behaviors in a game-theoretic fashion. The consideration of context allows our model to outperform previous models that solely focus on the networked interactions with no contextual parameters. We focus on two fundamental problems: learning the model using real-world data and computing stable outcomes of the model with a view to predicting joint voting behaviors and identifying most influential senators. We demonstrate the effectiveness of our model through experiments using data from the 114th U.S. Congress.
Walter K. Gutman Collection
Date: 1966-01-01
Access: Open access
- Exhibition catalogue from Bowdoin College Museum of Art. Includes and essay by Walter Gutman.
Human protein Sam68 relocalization and interaction with poliovirus RNA polymerase in infected cells
Date: 1996-03-19
Creator: A. E. Mcbride, A. Schlegel, K. Kirkegaard
Access: Open access
- A HeLa cDNA expression library was screened for human polypeptides that interacted with the poliovirus RNA-dependent RNA polymerase, 3D, using the two-hybrid system in the yeast Saccharomyces cerevisiae. Sam68 (Src- associated in mitosis, 68 kDa) emerged as the human cDNA that, when fused to a transcriptional activation domain, gave the strongest 3D interaction signal with a LexA-3D hybrid protein. 3D polymerase and Sam68 coimmunoprecipitated from infected human cell lysates with antibodies that recognized either protein. Upon poliovirus infection. Sam68 relocalized from the nucleus to the cytoplasm, where poliovirus replication occurs. Sam68 was isolated from infected cell lysates with an antibody that recognizes poliovirus protein 2C, suggesting that it is found on poliovirus-induced membranes upon which viral RNA synthesis occurs. These data, in combination with the known RNA- and protein-binding properties of Sam68, make Sam68 a strong candidate for a host protein with a functional role in poliovirus replication.
Virtual Communities Don’t Exist: Avoiding Digital Dualism in Studying Collaboration
Date: 2013-04-12
Creator: PJ Rey, Nathan Jurgenson
Access: Open access
- Effective collaboration in communities requires information sharing. Though digital media may have certain affordances that encourage us to communicate differently than in the past, the communities these media facilitate are no less real than communities bound together by voice or text. In this paper, we argue that idea of “virtual communities” is misleading. Communities and collaboration occur not in some virtual world or a new, cyber, space, but instead they are part of one reality influenced simultaneously by materiality and the various flows of information—digital included. In light of this argument, we implore researchers to take serious the influence of digitality, and, specific to this conference, those looking primarily at digitality to take seriously the materiality, bodies, history, and politics not separate from but deeply interpenetrating the digital. The changes in community organization brought about by digital media should not be thought of or called “virtual” (e.g., “virtual teams” as opposed to real ones), but instead part of one augmented community. Presented at the Collaborative Organizations & Social Media Conference at Bowdoin College on April 12, 2013.
As Maine Goes
Date: 1966-01-01
Access: Open access
- Catalogue of an exhibition held at the Bowdoin College Museum of Art.
Projected land-use change impacts on ecosystem services in the United States
Date: 2014-05-20
Creator: Joshua J. Lawler, David J. Lewis, Erik Nelson, Andrew J. Plantinga, Stephen, Polasky, John C. Withey, David P. Helmers, Sebastián Martinuzzi, Derric Penningtonh
Access: Open access
- Providing food, timber, energy, housing, and other goods and services, while maintaining ecosystem functions and biodiversity that underpin their sustainable supply, is one of the great challenges of our time. Understanding the drivers of land-use change and how policies can alter land-use change will be critical to meeting this challenge. Here we project land-use change in the contiguous United States to 2051 under two plausible baseline trajectories of economic conditions to illustrate how differences in underlying market forces can have large impacts on land-use with cascading effects on ecosystem services and wildlife habitat. We project a large increase in croplands (28.2 million ha) under a scenario with high crop demand mirroring conditions starting in 2007, compared with a loss of cropland (11.2 million ha) mirroring conditions in the 1990s. Projected land-use changes result in increases in carbon storage, timber production, food production from increased yields, and >10% decreases in habitat for 25% of modeled species. We also analyze policy alternatives designed to encourage forest cover and natural landscapes and reduce urban expansion. Although these policy scenarios modify baseline land-use patterns, they do not reverse powerful underlying trends. Policy interventions need to be aggressive to significantly alter underlying land-use change trends and shift the trajectory of ecosystem service provision.