Showing 4721 - 4730 of 5831 Items
SU(N) group-theory constraints on color-ordered five-point amplitudes at all loop orders
Date: 2012-05-21
Creator: Alexander C. Edison, Stephen G. Naculich
Access: Open access
- Color-ordered amplitudes for the scattering of n particles in the adjoint representation of SU(N) gauge theory satisfy constraints arising solely from group theory. We derive these constraints for n=.5 at all loop orders using an iterative approach. These constraints generalize well-known tree-level and one-loop group theory relations. © 2012 Elsevier B.V.
Design and Impact of the National Workshop for Early Career Geoscience Faculty
Date: 2020-02-12
Creator: Rachel J. Beane, Ellen R. Altermatt, Ellen R. Iverson, R. Heather Macdonald
Access: Open access
- The National Association of Geoscience Teachers’ Workshop for Early Career Geoscience Faculty: Teaching, Research, and Managing One’s Career has been offered annually since 1999. The five-day workshop with accompanying web resources employs a “whole faculty” approach to support geoscience faculty members during their transition into academic careers. More than 1,000 faculty members (53% female, 47% male) have attended the national workshop; 52% from doctoral-granting institutions, 15% master’s, 28% bachelor’s, and 5% associates. Evidence-based instructional practices are shared and modeled during workshop sessions. Situated learning theory grounds the workshop design and promotes the development of a community of practice. Examination of the 2016 National Geoscience Faculty Survey data using univariate analyses of covariance (ANCOVAs) showed that workshop alumni report spending more class time on student activities, questions, and discussion than faculty members who did not participate in the workshop, particularly on small group discussions or think-pair-share and in-class exercises (for introductory courses p < .05; for majors courses p < .001). Workshop alumni also were more likely than faculty who did not participate to report feeling part of a geoscience community that shares their goals, philosophy, and values for geoscience education (p < .01), more likely to report that interactions with this community help them to become better educators (p < .001), and more likely to attend talks on teaching methods or science education (p < .001). Although causality cannot be established without random assignment, these findings are consistent with the hypothesis that this discipline-based workshop with its holistic approach is effective at promoting evidence-based teaching strategies and a community of practice.
Walking versus breathing: Mechanical differentiation of sea urchin podia corresponds to functional specialization
Date: 2000-01-01
Creator: Holly A. Leddy, Amy S. Johnson
Access: Open access
- The podia of sea urchins function in locomotion, adhesion, feeding, and respiration; but different podia on a single urchin are often specialized to one or more of these tasks. We examined the morphology and material properties of podia of the green sea urchin, Strongylocentrotus droebachiensis, to determine whether, despite apparent similarities, they achieve functional specialization along the oral-aboral axis through the differentiation of distinct mechanical properties. We found that oral podia, which are used primarily for locomotion and adhesion, are stronger and thicker than aboral podia, which are used primarily for capturing drift material and as a respiratory surface. The functional role of ambital podia is more ambiguous; however, they are longer and are extended at a lower strain rate than other podial types. They are also stronger and stiffer than aboral podia. In addition, all podia become stronger and stiffer when extended at faster strain rates, in some cases by nearly an order of magnitude for an order of magnitude change in strain rate. This strain-rate dependence implies that resistance to rapid loading such as that imposed by waves is high compared to resistance to slower, self-imposed loads. Thus, the serially arranged podia of S. droebachiensis are functionally specialized along an oral-aboral axis by differences in their morphology and mechanical properties.
Module structure of cells in unequal-parameter Hecke algebras
Date: 2010-09-06
Creator: Thomas Pietraho
Access: Open access
- A conjecture of Bonnafé, Geck, Iancu, and Lam parametrizes Kazhdan-Lusztig left cells for unequal-parameter Hecke algebras in type Bn by families of standard domino tableaux of arbitrary rank. Relying on a family of properties outlined by Lusztig and the recent work of Bonnafé, we verify the conjecture and describe the structure of each cell as a module for the underlying Weyl group. © 2010 by The Editorial Board of the Nagoya Mathematical Journal.
The spherical Bochner theorem on semisimple Lie groups
Date: 1975-01-01
Creator: William H. Barker
Access: Open access
- Let G be a connected semisimple Lie group with finite center and K a maximal compact subgroup. Denote (i) Harish-Chandra's Schwartz spaces by Cp(G)(0
Telling Toggles: Netsuke in Context
Date: 2002-01-01
Creator: Christine L. Paglia
Access: Open access
- "This brochure accompanies an exhibition of the same name at the Bowdoin College Museum of Art from April 11 through June 9, 2002"--P. [2] of cover
Nonlinear localized modes in two-dimensional hexagonally-packed magnetic lattices
Date: 2021-04-01
Creator: Christopher Chong, Yifan Wang, Donovan Maréchal, Efstathios G. Charalampidis, Miguel, Molerón, Alejandro J. Martínez
Access: Open access
- We conduct an extensive study of nonlinear localized modes (NLMs), which are temporally periodic and spatially localized structures, in a two-dimensional array of repelling magnets. In our experiments, we arrange a lattice in a hexagonal configuration with a light-mass defect, and we harmonically drive the center of the chain with a tunable excitation frequency, amplitude, and angle. We use a damped, driven variant of a vector Fermi-Pasta-Ulam-Tsingou lattice to model our experimental setup. Despite the idealized nature of this model, we obtain good qualitative agreement between theory and experiments for a variety of dynamical behaviors. We find that the spatial decay is direction-dependent and that drive amplitudes along fundamental displacement axes lead to nonlinear resonant peaks in frequency continuations that are similar to those that occur in one-dimensional damped, driven lattices. However, we observe numerically that driving along other directions results in asymmetric NLMs that bifurcate from the main solution branch, which consists of symmetric NLMs. We also demonstrate both experimentally and numerically that solutions that appear to be time-quasiperiodic bifurcate from the branch of symmetric time-periodic NLMs.