Graduate Recital:David S. Leigh, Trombonist

Centennial Lecture Hall July 25, 1967 8:15p.m

Dynamics of the DBI Spike Soliton

We compare oscillations of a fundamental string ending on a D3-brane in two different settings: (1) a test-string radially threading the horizon of an extremal black D3-brane and (2) the spike soliton of the DBI effective action for a D3-brane. Previous work has shown that overall transverse modes of the test-string appear as l=0 modes of the transverse scalar fields of the DBI system. We identify DBI world-volume degrees of freedom that have dynamics matching those of the test-string relative transverse modes. We show that there is a map, resembling T-duality, between relative and overall transverse modes for the test-string that interchanges Neumann and Dirichlet boundary conditions and implies equality of the absorption coefficients for both modes. We give general solutions to the overall and relative transverse parts of the DBI coupled gauge and scalar system and calculate absorption coefficients for the higher angular momentum modes in the low frequency limit. We find that there is a nonzero amplitude for l>0 modes to travel out to infinity along the spike, demonstrating that the spike remains effectively 3+1-dimensional.Comment: 15 pages, 1 figur

Connecting the Greenland Ice Sheet and the ocean : a case study of Helheim Glacier and Sermilik Fjord

Author Posting. © The Oceanography Society, 2016. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 29, no. 4 (2016): 34–45, doi:10.5670/oceanog.2016.97.The rapid ice loss from the Greenland Ice Sheet that began in the late 1990s sparked an interest in glacier/ocean exchanges both because an increase in submarine melting of the glacier is a potential trigger of glacier retreat and because the increasing freshwater discharge can affect the regional ocean’s circulation and ecosystems. An interdisciplinary field project focused on the Helheim Glacier-Sermilik Fjord system began in 2008 and has continued to date. We found that warm, Atlantic Water flows into the fjord, drives melting of the glacier, and is regularly replenished through shelf-forced and glacier-driven circulations. In summer, the release of surface melt at the base of the glacier has a pronounced impact on local ocean circulation, the properties of the glacier, and its melt rate. Measurements taken in the fjord indicate that it is virtually impossible to derive submarine melt rates from hydrographic (including moored) data due to the fjord’s pronounced water mass variability and uncertain contribution from iceberg melt. Efforts to correlate glacier behavior with ocean forcing on seasonal and interannual time scales yield no straightforward connections, likely because of a dependence on a wider range of parameters, including subglacial discharge and bedrock geometry. This project emphasizes the need for sustained long-term measurements of multiple glacier/ocean/atmosphere systems to understand the different dynamics that control their evolution.This work has been supported directly or indirectly by the National Science Foundation; NASA; the Woods Hole Oceanographic Institution; the universities of Kansas, Maine, and Oregon; the Kerr, Clark, and Haas Foundations; and Greenpeace

A Post-Fire Index For Describing Mixed Severity Outcomes After Wildfire

Kimmins (1997) argues that “words” and their correct usage are important and that the “careless use of language often causes confusion and misunderstanding and is a factor in many conflicts.” The public often lacks the technical knowledge to understand and interpret the use of inconsistent terminology and each discipline within resource science and management has developed their own definitions and application of specific terms. The fire community is no different. The only consistent component in the fire literature is the interchangeable use of the terms fire intensity, fire severity, and burn severity. Moreover, within each of these definitions, the terms low, moderate, and high severity and/or intensity and associated definitions are also inconsistent. Although some recognize the inconsistent use in terminology to describe different aspects of fire behavior and effects, discussions tend to favor the continuation of the incompatible use of terms. Furthermore, some suggest that a severity description should be specific to a particular interest, leaving it up to the reader to decipher the meaning of the terms. The objective of this oral presentation is to present a post-fire index (PFI) for temperate forests designed to diminish the inconsistent application of severity. We developed this index by synthesizing current severity literature and its potential relation to chemical, physical, and biological responses. We then validated the index using actual data collected post-fire from landscapes that contain mixed-severity fire regimes within the cold, moist, and dry forests within the Rocky Mountains of the United States

Predictors of Burden in Carers of Patients with Impulse Control Behaviors in Parkinson's Disease

Background: Impulse control behaviors (ICBs) are problematic, reward-based behaviors, affecting 15% to 35% of patients with Parkinson's disease. Evidence exists of increased carer burden as a result of these behaviors; however, little is known about the variables mediating this effect and their management. Objective: To identify factors predictive of carer burden in a cohort of patients with Parkinson's disease with ICBs to enable the development of targeted therapeutic interventions for carers. Methods: Data were collected from 45 patients with clinically significant ICBs and their carers, including levodopa equivalent daily dosage, motor and neuropsychiatric symptoms, cognitive function, and ICB severity. Carer burden was quantified by Zarit Burden Interview (ZBI). Univariate analyses were performed using the Spearman rank correlation. Linear regression was used to create a multivariate model for predicting ZBI. Results: Univariate analysis identified significant correlations between ZBI and patient total Neuropsychiatric Inventory (NPI) (rs = 0.50), 4 NPI subscores (agitation/aggression, rs = 0.41; depression/dysphoria, rs = 0.47; apathy/indifference, rs = 0.49; and irritability/lability, rs = 0.38; all P < 0.02), and the carer 28-item General Health Questionnaire (GHQ-28) (rs = 0.52, P < 0.0005). Multivariate linear regression retained total NPI and GHQ-28 scores and were collectively predictive of 36.6% of the variance in the ZBI. Conclusions: Our study suggests that depressive symptoms and aspects of executive dysfunction (apathy and disinhibition) in the patient are potential drivers of carer burden in patients with ICBs. Such findings suggest the presence of executive difficulties and/or mood disturbance should point the clinician to inquire about burden in the caring role and encourage the carer to seek help for any of their own general health problems, which may compound carer burden

Gender and Species Use in Amazonian Home Gardens: the Social and Economic Context of Biodiversity Conservation

Home gardens, “the peridomestic area belonging to the household where members plant and/or tend useful plants” (Perrault-Archambault and Coomes 2008), are found throughout the world. However, their use and importance vary from region to region. In the Peruvian Amazon, owners use home gardens for a domestic supply of foods, craft materials, medicines, condiments, and shade (Miller and Nair 2006). With this wide range in function, reflected in species content, home gardens are very biodiverse. Home garden biodiversity may be increasingly important in a rapidly changing Amazonia (Betts et al. 2008). Thus, the sociocultural and economic factors contributing to home garden diversity warrant in-depth study. Existing data posit a direct positive relationship between female garden tenders and species diversity (Perrault-Archambault and Coomes 2008) as well as report a simultaneous increase in sales of indigenous plant products and monocropping (Perreault2005). Nevertheless, limited research exists on home gardens as reservoirs for species conservation (Ban and Coomes2004b). We hypothesize both the gender of the caretaker and market integration impact levels of species richness in home gardens, with female garden managers increasing biodiversity and market integration decreasing biodiversity as caretakers favor more marketable species.https://scholarship.richmond.edu/geography-posters/1005/thumbnail.jp

Terminal Pleistocene through Holocene Evolution of Whiteoak Bottoms, a Southern Blue Ridge Mountains Peatland

Abstract Our primary objective was to develop an understanding of the geomorphic evolution of Whiteoak Bottoms (WOB), a peatland along the Nantahala River in the Southern Blue Ridge Mountains (SBRM) of western North Carolina. Radiocarbon dates directly above basal fluvial sediments returned ages of 14,000 to 15,000 cal yr BP. These ages indicate WOB is the oldest dated peatland in the SBRM and that such wetlands have persisted throughout the Holocene. Below the relatively flat surface of the wetland, paleochannels, similar to those of the modern channel, were found; suggesting a persistence of similar channel morphology since the terminal Pleistocene. The wetland&apos;s stratigraphy reveals a consistent pattern with basal fluvial cobbles being overlain by sandy channel-fill grading up into peat. Two different distinct inorganic deposits separate the lower organic deposits from the sapric peat deposits at the surface. Interestingly, we estimate more than 56% of the organic matter preserved by the wetland accumulated during the first 6,000 years of development. Overall, WOB has accumulated approximately 424 Mg/ha of carbon during the past 15,000 years. Maintenance of this wetland initially depended on the Nantahala River; however, today it is ground water and beavers that allows for the persistence of this rare landscape

Accessing Healthy Food: A sentinel mapping study of healthy food retailing in Scotland

This study on the availability of an affordable healthy food shopping basket was commissioned by the Food Standards Agency Scotland and undertaken between 2005 and 2007 by the Centre for the Study of Retailing in Scotland

Human rhinovirus infection up-regulates MMP-9 production in airway epithelial cells via NF-{kappa}B

Human rhinovirus (HRV) infections up-regulate proinflammatory mediators and growth factors that are associated with exacerbations of inflammatory airway diseases, such as asthma and chronic obstructive pulmonary disease (COPD). Matrix metalloproteinase (MMP)-9 was shown to be increased in the airways of patients with asthma and COPD. We sought to determine whether HRV infection modulated the expression of MMP-9 and its highest-affinity inhibitor, the tissue inhibitor of metalloproteinase (TIMP)-1, and we explored the mechanism by which this modulation occurs. In vitro studies, using RT-PCR, ELISA, zymography, and a fluorescent activity assay, demonstrated that MMP-9 mRNA, protein, and activity were increased upon infection with HRV, whereas TIMP-1 mRNA and protein remained unchanged. These results were verified in vivo, using nasal lavage samples obtained from subjects with confirmed rhinovirus infections. Human rhinovirus infections were shown to up-regulate NF-kappaB, and NF-kappaB has also been reported to play a role in the expression of MMP-9. We therefore investigated the role of NF-kappaB in HRV-induced MMP-9 expression. Using two inhibitors of IkappaBalpha kinase beta, we observed a concentration-dependent decrease in HRV-induced MMP-9 expression. The role of NF-kappaB in HRV-induced MMP-9 expression was further confirmed using MMP-9 promoter luciferase constructs, which demonstrated that an NF-kappaB site at -620/-607 base pairs was necessary for HRV-induced MMP-9 expression. Electrophoretic mobility shift assays and supershift assays confirmed the nuclear translocation and binding of p50/p65 NF-kappaB subunits to an MMP-9-specific NF-kappaB oligonucleotide. This increase in MMP-9 may be a mechanism by which rhinovirus infections contribute to airway inflammation and, potentially, to airway remodeling