Showing 471 - 480 of 5831 Items
All-loop infrared-divergent behavior of most-subleading-color gauge-theory amplitudes
Date: 2013-04-19
Creator: Stephen G. Naculich, Horatiu Nastase, Howard J. Schnitzer
Access: Open access
- The infrared singularities of gravitational amplitudes are one-loop exact, in that higher-loop divergences are characterized by the exponential of the one-loop divergence. We show that the contributions to SU(N) gauge-theory amplitudes that are mostsubleading in the 1/N expansion are also one-loop exact, provided that the dipole conjecture holds. Possible corrections to the dipole conjecture, beginning at three loops, could violate one-loop-exactness, though would still maintain the absence of collinear divergences. We also demonstrate a relation between L-loop four-point N = 8 supergravity and mostsubleading-color N = 4 SYM amplitudes that holds for the two leading IR divergences, (Formula presented.) and (Formula presented.), but breaks down at (Formula presented.).
Color-factor symmetry and BCJ relations for QCD amplitudes
Date: 2016-11-01
Creator: Robert W. Brown, Stephen G. Naculich
Access: Open access
- Tree-level n-point gauge-theory amplitudes with n − 2k gluons and k pairs of (massless or massive) particles in the fundamental (or other) representation of the gauge group are invariant under a set of symmetries that act as momentum-dependent shifts on the color factors in the cubic decomposition of the amplitude. These symmetries lead to gauge-invariant constraints on the kinematic numerators. They also directly imply the BCJ relations among the Melia-basis primitive amplitudes previously obtained by Johansson and Ochirov.
Feasibility and acceptability of an online mindfulness-based group intervention for adults with tic disorders
Date: 2021-12-01
Creator: Hannah E. Reese, W. Alan Brown, Berta J. Summers, Jin Shin, Grace, Wheeler, Sabine Wilhelm
Access: Open access
- Abstract: Background: Preliminary research suggests that a mindfulness-based treatment approach may be beneficial for adults with tic disorders. In the present study, we report on the feasibility, acceptability, safety, and symptomatic effect of a novel online mindfulness-based group intervention for adults with Tourette syndrome or persistent tic disorder. Data from this study will directly inform the conduct of a funded randomized controlled trial comparing the efficacy of this intervention to another active psychological intervention. Methods: One cohort of adults with Tourette syndrome participated in an 8-week online mindfulness-based group intervention. Measures of feasibility, acceptability, and safety were administered throughout and at posttreatment. Self-reported measures of mindfulness and clinician-rated measures of tic severity and impairment were administered at baseline and posttreatment. Results: Data on refusal, dropout rate, attendance, participant satisfaction, and safety suggest that this is a feasible and acceptable intervention. However, participant adherence to home practice was lower than anticipated. Mindfulness, tic severity, and tic-related impairment only modestly improved from baseline to posttreatment. Qualitative analysis of participant feedback revealed aspects of the intervention that were most helpful and also areas for improvement. Conclusions: Data suggest that although this is a feasible and acceptable intervention, it should be modified to enhance participant adherence, more successfully engage the target mechanism, and optimize outcomes. Trial registration: Clinicaltrials.gov registration #NCT03525626. Registered on 24 April 2018
Traveling waves in 2D hexagonal granular crystal lattices
Date: 2014-01-01
Creator: A. Leonard, C. Chong, P. G. Kevrekidis, C. Daraio
Access: Open access
- This study describes the dynamic response of a two-dimensional hexagonal packing of uncompressed stainless steel spheres excited by localized impulsive loadings. The dynamics of the system are modeled using the Hertzian normal contact law. After the initial impact strikes the system, a characteristic wave structure emerges and continuously decays as it propagates through the lattice. Using an extension of the binary collision approximation for one-dimensional chains, we predict its decay rate, which compares well with numerical simulations and experimental data. While the hexagonal lattice does not support constant speed traveling waves, we provide scaling relations that characterize the directional power law decay of the wave velocity for various angles of impact. Lastly, we discuss the effects of weak disorder on the directional amplitude decay rates. © 2014 The Author(s).
The Sacralization of Absolute Power: God's Power and Women's Subordination in the Southern Baptist Convention
Date: 2019-05-01
Creator: Sydney Smith
Access: Open access
James Bowdoin: Patriot and Man of The Enlightenment
Date: 1976-01-01
Creator: Gordon EKershaw, Peter R. Mooz
Access: Open access
- "An exhibition held at the Bowdoin College Museum of Art, Brunswick, Maine, May 28 through September 12, 1976."
Civil Society under the Law ‘On Foreign Agents’: NGO Strategies and Network Transformation
Date: 2018-04-21
Creator: Maria Tysiachniouk, Svetlana Tulaeva, Laura A. Henry
Access: Open access
- This essay analyses how the ‘foreign agent’ law has been interpreted and implemented by the Russian authorities and examines diverse NGO survival strategies in response to the ‘foreign agent’ label. The foreign agent law has disrupted and transformed resource mobilisation strategies and transnational NGO networks. Based on qualitative research on environmental NGOs, we offer a typology of NGO responses to the foreign agent law, providing examples to show how the organisations attempt to ensure their survival.
Mechanisms underlying variable responses to isoforms of the neuropeptide C-type allatostatin (AST-C) in the cardiac neuromuscular system of the American lobster, Homarus americanus
Date: 2019-01-01
Creator: Evalyn Mackenzie
Access: Open access
- Central Pattern Generators (CPGs) are neural networks that produce steady, rhythmic patterned outputs that activate particular muscles and consequently create recurrent rhythmic movements. The cardiac ganglion (CG) of the American lobster (Homarus americanus) is a useful model system for the study of CPGs. Neuropeptides modulate cardiac contractions driven by the CG in H. americanus and accordingly elicit a range of effects. Post-translational modifications such as amidation can impact function of a peptide neuromodulator. C-type allatostatins (AST-Cs) are a group of neuropeptides that modulate the cardiac neuromuscular system of H. americanus. The objective of this study was to determine what structural aspects of the peptides were responsible for the similarity in responses elicited by AST-C I and AST-C III and the difference in responses evoked by AST-C II in comparison. AST-C I and AST-C III are not C-terminally amidated, whereas AST-C II is C-terminally amidated. We first hypothesized that amidated AST-C peptides would evoke similar responses to one another in contraction amplitude and frequency. Our second hypothesis was that exchanging the amino acids alanine and tyrosine at a specific location in AST-C II and AST-C III would affect the conformation of the peptide, and consequently impact peptide binding and elicit different effects. In contrast to our predictions, we did not see similar responses evoked by all amidated or all non-amidated peptides among lobsters. In support of our second hypothesis, there was a significant difference in percent change in contraction amplitude elicited among AST-C II Y, AST-C II and AST-C III.
Global divergence of the human follicle mite Demodex folliculorum: Persistent associations between host ancestry and mite lineages
Date: 2015-12-29
Creator: Michael F. Palopoli, Daniel J. Fergus, Samuel Minot, Dorothy T. Pei, W. Brian, Simison, Iria Fernandez-Silva, Megan S. Thoemmes, Robert R. Dunn, Michelle Trautwein
Access: Open access
- Microscopic mites of the genus Demodex live within the hair follicles of mammals and are ubiquitous symbionts of humans, but little molecular work has been done to understand their genetic diversity or transmission. Here we sampled mite DNA from 70 human hosts of diverse geographic ancestries and analyzed 241 sequences from the mitochondrial genome of the species Demodex folliculorum. Phylogenetic analyses recovered multiple deep lineages including a globally distributed lineage common among hosts of European ancestry and three lineages that primarily include hosts of Asian, African, and Latin American ancestry. To a great extent, the ancestral geography of hosts predicted the lineages of mites found on them; 27% of the total molecular variance segregated according to the regional ancestries of hosts. We found that D. folliculorum populations are stable on an individual over the course of years and that some Asian and African American hosts maintain specific mite lineages over the course of years or generations outside their geographic region of birth or ancestry. D. folliculorum haplotypes were much more likely to be shared within families and between spouses than between unrelated individuals, indicating that transmission requires close contact. Dating analyses indicated that D. folliculorum origins may predate modern humans. Overall, D. folliculorum evolution reflects ancient human population divergences, is consistent with an out-of-Africa dispersal hypothesis, and presents an excellent model system for further understanding the history of human movement.