Showing 301 - 310 of 733 Items
The Issue Focus of Online and Television Advertising in the 2016 Presidential Campaign
Date: 2020-01-01
Creator: Michael M. Franz, Erika Franklin Fowler, Travis Ridout, Meredith Yiran Wang
Access: Open access
- Theories of campaign issue emphasis were developed in a pre-digital era. How well do these theories explain spending in the current era, when digital media allow for targeting of specific types of voters? In this research, we compare how the 2016 campaigns, both primary and general election, deployed television advertising with how they deployed online advertising. We suggest that, because online messages are targeted to specific viewer profiles much more than television messages, television ads should be more likely to discuss highly salient issues and valance issues than online ads. To test these ideas, we rely upon data from the Wesleyan Media Project, which tracked all televised political ads that aired in 2016, and our coding of data from Pathmatics, a company that tracks online advertising. We find, contrary to our expectations, that the predictors of issue discussion online and on television are largely similar.
Multiproxy lake sediment records at the northern and southern boundaries of the Aspen Parkland region of Manitoba, Canada
Date: 2009-09-01
Creator: Rebecca Teed, Charles Umbanhower, Philip Camill
Access: Open access
- Aspen parkland in central Canada may change substantially with increased warming and aridity as prairies replace forests, fire return intervals decrease and lake levels decline. We examined the relationships among vegetation, climate, fire and lake-ecosystem properties using lake sediment cores from the current northern and southern boundaries of the aspen parkland in southwestern Manitoba. We analyzed pollen, charcoal, sediment magnetics, biogenic silica, phosphorus, grain size and LOI, and dated the cores using Pb and C (AMS, calibrated). The Jones Lake record, from the southern edge of the parkland, began considerably earlier (~11 000 cal. BP) than the Mallard Pond record at the northern edge (~8600 cal. BP). These sites were characterized as prairie communities with low fire severity and relatively low lake productivity during the warm, dry period from 9000 to 6000 cal. BP. Beginning around 6500 cal. BP at Jones Lake and 3400 cal. BP at Mallard Pond, conditions appeared to get wetter as indicated by arboreal pollen percentage increases from ~30% to 40-60%, concurrent with a rise in charcoal and proxies for lake productivity (biogenic silica and percent organic phosphorus). Similar to previous studies along the prairie-forest border, we found that charcoal increased during warmer, wetter periods with increased forest cover and fuel loading rather than during warmer, drier periods of prairie dominance. Our results underscore the importance of regional changes in moisture, and its effects on lake levels and forest biomass, as a dominant control of the aspen parkland dynamics. © The Author(s), 2009. 210 14
IR divergences and Regge limits of subleading-color contributions to the four-gluon amplitude in N=4 SYM theory
Date: 2009-11-11
Creator: Stephen G. Naculich, Howard J. Schnitzer
Access: Open access
- We derive a compact all-loop-order expression for the IR-divergent part of the = 4 SYM four-gluon amplitude, which includes both planar and all subleading-color contributions, based on the assumption that the higher-loop soft anomalous dimension matrices are proportional to the one-loop soft anomalous dimension matrix, as has been recently conjectured. We also consider the Regge limit of the four-gluon amplitude, and we present evidence that the leading logarithmic growth of the subleading-color amplitudes is less severe than that of the planar amplitudes. We examine possible 1/N 2 corrections to the gluon Regge trajectory, previously obtained in the planar limit from the BDS ansatz. The double-trace amplitudes have Regge behavior as well, with a nonsense-choosing Regge trajectory and a Regge cut which first emerges at three loops. © SISSA 2009.
Mutation of an Arabidopsis Golgi membrane protein ELMO1 reduces cell adhesion
Date: 2021-05-01
Creator: Bruce D. Kohorn, Frances D.H. Zorensky, Jacob Dexter-Meldrum, Salem Chabout, Gregory, Mouille, Susan Kohorn
Access: Open access
- Plant growth, morphogenesis and development involve cellular adhesion, a process dependent on the composition and structure of the extracellular matrix or cell wall. Pectin in the cell wall is thought to play an essential role in adhesion, and its modification and cleavage are suggested to be highly regulated so as to change adhesive properties. To increase our understanding of plant cell adhesion, a population of ethyl methanesulfonate-mutagenized Arabidopsis were screened for hypocotyl adhesion defects using the pectin binding dye Ruthenium Red that penetrates defective but not wild-type (WT) hypocotyl cell walls. Genomic sequencing was used to identify a mutant allele of ELMO1 which encodes a 20 kDa Golgi membrane protein that has no predicted enzymatic domains. ELMO1 colocalizes with several Golgi markers and elmo1-/- plants can be rescued by an ELMO1-GFP fusion. elmo1-/- exhibits reduced mannose content relative to WT but no other cell wall changes and can be rescued to WT phenotype by mutants in ESMERALDA1, which also suppresses other adhesion mutants. elmo1 describes a previously unidentified role for the ELMO1 protein in plant cell adhesion.
Observation of inclusive B decays to the charmed baryons c++ and c0
Date: 1994-01-01
Creator: M. Procario, R. Balest, K. Cho, M. Daoudi, W. T., Ford, D. R. Johnson, K. Lingel, M. Lohner, P. Rankin, J. G. Smith, J. P. Alexander, C. Bebek, K. Berkelman, K. Bloom, T. E. Browder, D. G. Cassel, H. A. Cho, D. M. Coffman, P. S. Drell, R. Ehrlich, R. S. Galik, M. Garcia-Sciveres, B. Geiser, B. Gittelman, S. W. Gray, D. L. Hartill, B. K. Heltsley, C. D. Jones, S. L. Jones, J. Kandaswamy, N. Katayama
Access: Open access
- Using data collected in the region of the γ(4S) resonance with the CLEO II detector operating at the Cornell Electron Storage Ring, we report on evidence for the production of ++ and c0 baryons in B decays, with c→Λc+π. This observation is based on 77±19 c++ and 76±21 c0 candidates from B decays. We find the product branching fractions B(B̄→cX)B(Λc+→pK-π+) for c=c++, c0, and c+ to be (2.1 ± 0.8 ± 0.7) × 10-4, (2.3 ± 0.8 ± 0.7) × 10-4, and less than 4.8 × 10-4 at 90% confidence level, respectively. A study of the c++ and c0 momentum spectra indicates that B decays to two-body final states with c are suppressed. © 1994 The American Physical Society.
Context-dependent protein stabilization by methionine-to-leucine substitution shown in T4 lysozyme
Date: 1998-01-01
Creator: Leigh Ann Lipscomb, Nadine C. Gassner, Sheila D. Snow, Aimee M. Eldridge, Walter A., Baase, Devin L. Drew, Brian W. Matthews
Access: Open access
- The substitution of methionines with leucines within the interior of a protein is expected to increase stability both because of a more favorable solvent transfer team as well as the reduced entropic cost of holding a leucine side chain in a defined position. Together, these two terms are expected to contribute about 1.4 kcal/mol to protein stability for each Met → Leu substitution when fully buried. At the same time, this expected beneficial effect may be offset by steric factors due to differences in the shape of leucine and methionine. To investigate the interplay between these factors, all methionines in T4 lysozyme except at the amino-terminus were individually replaced with leucine. Of these mutants, M106L and M120L have stabilities 0.5 kcal/mol higher than wild-type T4 lysozyme, while M6L is significantly destabilized (-2.8 kcal/mol). M102L, described previously, is also destabilized (-0.9 kcal/mol). Based on this limited sample it appears that methionine-to-leucine substitutions can increase protein stability but only in a situation where the methionine side chain is fully or partially buried, yet allows the introduction of the leucine without concomitant steric interference. The variants, together with methionine-to-lysine substitutions at the same sites, follow the general pattern that substitutions at rigid, internal sites tend to be most destabilizing, whereas replacements at more solvent-exposed sites are better tolerated.
Environmental issues in russia
Date: 2008-12-01
Creator: Laura A. Henry, Vladimir Douhovnikoff
Access: Open access
- This review examines the literature available on the state of the environment and environmental protection in the Russian Federation. As the largest country on Earth, rich in natural resources and biodiversity, Russia's problems and policies have global consequences. Environmental quality and management are influenced by the legacy of Soviet economic planning and authoritarian governance, as well as by Russia's post-Soviet economic recession and current strategies of economic development. Russia achieved a reduction in some pollutants owing to the collapse of industrial production in the 1990s, but many environmental indicators suggest growing degradation. Russia has signed on to a number of international environmental agreements, but its record on implementation is mixed, and it discourages environmental activism. Scholarship on the Russian environment is a limited, but growing, field, constrained by challenges of data availability, yet it offers great potential for testing scientific and social scientific hypotheses. ©2008 by Annual Reviews.
Destabilization of cortical dendrites and spines by BDNF
Date: 1999-01-01
Creator: Hadley Wilson Horch, Alex Krüttgen, Stuart D. Portbury, Lawrence C. Katz
Access: Open access
- Particle-mediated gene transfer and two-photon microscopy were used to monitor the behavior of dendrites of individual cortical pyramidal neurons coexpressing green fluorescent protein (GFP) and brain-derived neurotrophic factor (BDNF). While the dendrites and spines of neurons expressing GFP alone grew modestly over 24-48 hr, coexpressing BDNF elicited dramatic sprouting of basal dendrites, accompanied by a regression of dendritic spines. Compared to GFP-transfected controls, the newly formed dendrites and spines were highly unstable. Experiments utilizing Trk receptor bodies, K252a, and overexpression of nerve growth factor (NGF) demonstrated that these effects were mediated by secreted BDNF interacting with extracellular TrkB receptors. Thus, BDNF induces structural instability in dendrites and spines, which, when restricted to particular portions of a dendritic arbor, may help translate activity patterns into specific morphological changes.
Deciphering the bacterial glycocode: Recent advances in bacterial glycoproteomics
Date: 2013-02-01
Creator: Scott A. Longwell, Danielle H. Dube
Access: Open access
- Bacterial glycoproteins represent an attractive target for new antibacterial treatments, as they are frequently linked to pathogenesis and contain distinctive glycans that are absent in humans. Despite their potential therapeutic importance, many bacterial glycoproteins remain uncharacterized. This review focuses on recent advances in deciphering the bacterial glycocode, including metabolic glycan labeling to discover and characterize bacterial glycoproteins, lectin-based microarrays to monitor bacterial glycoprotein dynamics, crosslinking sugars to assess the roles of bacterial glycoproteins, and harnessing bacterial glycosylation systems for the efficient production of industrially important glycoproteins. © 2012 Elsevier Ltd.
Approximate initial data for binary black holes
Date: 2006-09-21
Creator: Kenneth A. Dennison, Thomas W. Baumgarte, Harald P. Pfeiffer
Access: Open access
- We construct approximate analytical solutions to the constraint equations of general relativity for binary black holes of arbitrary mass ratio in quasicircular orbit. We adopt the puncture method to solve the constraint equations in the transverse-traceless decomposition and consider perturbations of Schwarzschild black holes caused by boosts and the presence of a binary companion. A superposition of these two perturbations then yields approximate, but fully analytic binary black hole initial data that are accurate to first order in the inverse of the binary separation and the square of the black holes' momenta. © 2006 The American Physical Society.