Showing 2061 - 2070 of 5708 Items
More loops and legs in Higgs-regulated N = 4 SYM amplitudes
Date: 2010-01-01
Creator: Johannes M. Henn, Stephen G. Naculich, Howard J. Schnitzer, Marcus Spradlin
Access: Open access
- We extend the analysis of Higgs-regulated planar amplitudes of N = 4 supersymmetric Yang-Mills theory to four loops for the four-gluon amplitude and to two loops for the five-gluon amplitude. Our calculations are consistent with a proposed all-loop ansatz for planar MHV n-gluon amplitudes that is the analog of the BDS ansatz in dimensional regularization. In all cases considered, we have verified that the IR-finite parts of the logarithm of the amplitudes have the same dependence on kinematic variables as the corresponding functions in dimensionally-regulated amplitudes (up to overall additive constants, which we determine). We also study various Regge limits of N = 4 SYM planar n-gluon amplitudes. Euclidean Regge limits of Higgs-regulated n ≥ 4 amplitudes yield results similar in form to those found using dimensional regularization, but with different expressions for the gluon trajectory and Regge vertices resulting from the different regulator scheme. We also show that the Regge limit of the four-gluon amplitude is dominated at next-to-leading-log order by vertical ladder diagrams together with the class of vertical ladder diagrams with a single H-shaped insertion. © 2010 SISSA, Trieste, Italy.
James Bowdoin: Patriot and Man of The Enlightenment (pamphlet)
Date: 1976-01-01
Creator: Peter R. Mooz
Access: Open access
- Catalog of an exhibition held at the Bowdoin College Museum of Art, May 28-September 12, 1976.
Where to put things? Spatial land management to sustain biodiversity and economic returns
Date: 2008-06-01
Creator: Stephen Polasky, Erik Nelson, Jeff Camm, Blair Csuti, Paul, Fackler, Eric Lonsdorf, Claire Montgomery, Denis White, Jeff Arthur
Access: Open access
- Expanding human population and economic growth have led to large-scale conversion of natural habitat to human-dominated landscapes with consequent large-scale declines in biodiversity. Conserving biodiversity, while at the same time meeting expanding human needs, is an issue of utmost importance. In this paper we develop a spatially explicit landscape-level model for analyzing the biological and economic consequences of alternative land-use patterns. The spatially explicit biological model incorporates habitat preferences, area requirements and dispersal ability between habitat patches for terrestrial vertebrate species to predict the likely number of species that will be sustained on the landscape. The spatially explicit economic model incorporates site characteristics and location to predict economic returns for a variety of potential land uses. We apply the model to search for efficient land-use patterns that maximize biodiversity conservation objectives for given levels of economic returns, and vice versa. We apply the model to the Willamette Basin, Oregon, USA. By thinking carefully about the arrangement of activities, we find land-use patterns that sustain high levels of biodiversity and economic returns. Compared to the 1990 land-use pattern, we show that both biodiversity conservation and the value of economic activity could be increased substantially. © 2008 Elsevier Ltd.
Nonlinear coherent structures in granular crystals
Date: 2017-09-06
Creator: C. Chong, Mason A. Porter, P. G. Kevrekidis, C. Daraio
Access: Open access
- The study of granular crystals, which are nonlinear metamaterials that consist of closely packed arrays of particles that interact elastically, is a vibrant area of research that combines ideas from disciplines such as materials science, nonlinear dynamics, and condensed-matter physics. Granular crystals exploit geometrical nonlinearities in their constitutive microstructure to produce properties (such as tunability and energy localization) that are not conventional to engineering materials and linear devices. In this topical review, we focus on recent experimental, computational, and theoretical results on nonlinear coherent structures in granular crystals. Such structures - which include traveling solitary waves, dispersive shock waves, and discrete breathers - have fascinating dynamics, including a diversity of both transient features and robust, long-lived patterns that emerge from broad classes of initial data. In our review, we primarily discuss phenomena in one-dimensional crystals, as most research to date has focused on such scenarios, but we also present some extensions to two-dimensional settings. Throughout the review, we highlight open problems and discuss a variety of potential engineering applications that arise from the rich dynamic response of granular crystals.
Framing ICT Usage in the Real Estate Industry
Date: 2013-04-12
Creator: Steven Jones
Access: Open access
- The real estate industry, like many, is one based on a competitive consumer culture in which professionals vie for the business and, ultimately, the loyalty of customers. In this case, those customers are purchasing what, for most, is a significant investment, requiring them to navigate various legal and regulatory processes that might be impossible without the assistance of a knowledgeable, seasoned agent. It is the presence of agency that renders real estate unique from retail and other industries where goods and services trade hands. Furthermore, the rise of various information and communication technologies (ICT) over the course of the past 25 years may have led to new challenges for real estate agents and allied professionals. Some scholars surmise that the increased prevalence of ICTs in various industries can become disruptive to those industries, causing individuals and organizations working within them to either adapt accordingly or become obsolete (Bower and Christensen 1995; Markus, et al. 2006).
How Did Exchange Rates Affect Employment in US Cities?
Date: 2013-05-07
Creator: Yao Tang, Haifang Huang
Access: Open access
- We estimate the effects of real exchange rate movements on employment in US cities between 2003 and 2010. We explore the differences in the composition of local industries to construct city-specific changes in exchange rates and estimate their effects on local employment in manufacturing industries and in nonmanufacturing industries. Controlling for year and city fixed effects, we find that a depreciation of the US dollar increased local employment in the manufacturing industries, our proxy for the tradable sector. The depreciation also increased employment in the nonmanufacturing industries, the nontradable sector. Furthermore, the effects on nonmanufacturing employment were stronger in cities that had a higher fraction of manufacturing employment, indicating the exchange rate movements’ indirect effects through the manufacturing industries. We also consider an alternative definition of the tradable sector that is broadened to include five service industries. The findings are similar.
The organization (re)invented by its blogs
Date: 2013-04-12
Creator: Alex Primo
Access: Open access
- This article discusses how interactions in organizational blogs participate in the emergence of the organization itself. Based on the principles of The Montreal School of organizational communication, the paper reflects on how the recursive relationship between texts and conversations in blogs, according to their affordances, mobilizes the organization and contributes to its continuing creation. In order to conduct this argument, the concept of social media, uses of organizational blogs and the main contributions of The Montreal School are analyzed. Finally, this article demonstrates how blogs contribute to the definition of the organization. Beyond their promotional potential, the blog’ role as co-creator of the organization is highlighted.
Partner choice in spontaneous mitotic recombination in wild type and homologous recombination mutants of Candida albicans
Date: 2019-11-01
Creator: Alberto Bellido, Toni Ciudad, Belén Hermosa, Encarnación Andaluz, Anja, Forche, Germán Larriba
Access: Open access
- Candida albicans, the most common fungal pathogen, is a diploid with a genome that is rich in repeats and has high levels of heterozygosity. To study the role of different recombination pathways on direct-repeat recombination, we replaced either allele of the RAD52 gene (Chr6) with the URA-blaster cassette (hisG-URA3-hisG), measured rates of URA3 loss as resistance to 5-fluoroorotic acid (5FOAR) and used CHEF Southern hybridization and SNP-RFLP analysis to identify recombination mechanisms and their frequency in wildtype and recombination mutants. FOAR rates varied little across different strain backgrounds. In contrast, the type and frequency of mechanisms underlying direct repeat recombination varied greatly. For example, wildtype, rad59 and lig4 strains all displayed a bias for URA3 loss via pop-out/deletion vs. inter-homolog recombination and this bias was reduced in rad51 mutants. In addition, in rad51-derived 5FOAR strains direct repeat recombination was associated with ectopic translocation (5%), chromosome loss/truncation (14%) and inter-homolog recombination (6%). In the absence of RAD52, URA3 loss was mostly due to chromosome loss and truncation (80–90%), and the bias of retained allele frequency points to the presence of a recessive lethal allele on Chr6B. However, a few single-strand annealing (SSA)-like events were identified and these were independent of either Rad59 or Lig4. Finally, the specific sizes of Chr6 truncations suggest that the inserted URA-blaster could represent a fragile site.
Development of Rare Bacterial Monosaccharide Analogs for Metabolic Glycan Labeling in Pathogenic Bacteria
Date: 2016-12-16
Creator: Emily L. Clark, Madhu Emmadi, Katharine L. Krupp, Ananda R. Podilapu, Jennifer D., Helble, Suvarn S. Kulkarni, Danielle H. Dube
Access: Open access
- Bacterial glycans contain rare, exclusively bacterial monosaccharides that are frequently linked to pathogenesis and essentially absent from human cells. Therefore, bacterial glycans are intriguing molecular targets. However, systematic discovery of bacterial glycoproteins is hampered by the presence of rare deoxy amino sugars, which are refractory to traditional glycan-binding reagents. Thus, the development of chemical tools that label bacterial glycans is a crucial step toward discovering and targeting these biomolecules. Here, we explore the extent to which metabolic glycan labeling facilitates the studying and targeting of glycoproteins in a range of pathogenic and symbiotic bacterial strains. We began with an azide-containing analog of the naturally abundant monosaccharide N-acetylglucosamine and discovered that it is not broadly incorporated into bacterial glycans, thus revealing a need for additional azidosugar substrates to broaden the utility of metabolic glycan labeling in bacteria. Therefore, we designed and synthesized analogs of the rare deoxy amino d-sugars N-acetylfucosamine, bacillosamine, and 2,4-diacetamido-2,4,6-trideoxygalactose and established that these analogs are differentially incorporated into glycan-containing structures in a range of pathogenic and symbiotic bacterial species. Further application of these analogs will refine our knowledge of the glycan repertoire in diverse bacteria and may find utility in treating a variety of infectious diseases with selectivity.