Peer-Reviewed Journal Articles

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Browsing Peer-Reviewed Journal Articles by Author "Butler, J. Russell"

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    Assessing the Spatial Pattern of Iron in Well Water from a Small Central Florida Community
    (Journal of water and health, 2018-02) Hudgins, Jason; Lambert, Nicholas; Duranceau, Steven; Butler, J. Russell
    Iron is one of the most common elements in the Earth's crust, which corresponds to it being a common constituent in drinking water supplies. Residents of Bithlo, an unincorporated community in east-central Florida, have observed that their drinking water tastes like metal and stains clothing and teeth. An evaluation of water samples collected from over 200 private drinking water wells revealed iron concentrations that exceeded the US Environmental Protection Agency's (EPA's) secondary standard of 0.3 mg/L. Households with and without point-of-entry treatment were found to have over three times (0.92 mg/L) and ten times (3.86 mg/L) more iron than the EPA's secondary standard, respectively. The human health-based threshold of 4.2 mg/L established by the Centers for Disease Control and Prevention was exceeded in 38.6% of untreated residences. Community-wide statistical and spatial water-quality trends were developed by combining the collected well water quality data with historically available water quality reports. Spatial analyses revealed that greater than 99% of the Bithlo community's private household supplies would exceed the EPA's drinking water secondary standard.
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    A Computational Tool Integrating Host Immunity with Antibiotic Dynamics to Study Tuberculosis Treatment
    (Journal of Theoretical Biology, 2015) Pienaar, Elsje; Clifone, Nicholas A.; Lin, Philana Ling; Dartois, Veronique; Mattila, Joshua; Butler, J. Russell; Flynn, JoAnne L.; Kirschner, Denise E.; Linderman, Jennifer J.
    While active tuberculosis (TB) is a treatable disease, many complex factors prevent its global elimination. Part of the difficulty in developing optimal therapies is the large design space of antibiotic doses, regimens and combinations. Computational models that capture the spatial and temporal dynamics of antibiotics at the site of infection can aid in reducing the design space of costly and time-consuming animal pre-clinical and human clinical trials. The site of infection in TB is the granuloma, a collection of immune cells and bacteria that form in the lung, and new data suggest that penetration of drugs throughout granulomas is problematic. Here we integrate our computational model of granuloma formation and function with models for plasma pharmacokinetics, lung tissue pharmacokinetics and pharmacodynamics for two first line anti-TB antibiotics. The integrated model is calibrated to animal data. We make four predictions. First, antibiotics are frequently below effective concentrations inside granulomas, leading to bacterial growth between doses and contributing to the long treatment periods required for TB. Second, antibiotic concentration gradients form within granulomas, with lower concentrations toward their centers. Third, during antibiotic treatment, bacterial subpopulations are similar for INH and RIF treatment: mostly intracellular with extracellular bacteria located in areas non-permissive for replication (hypoxic areas), presenting a slowly increasing target population over time. Finally, we find that on an individual granuloma basis, pre-treatment infection severity (including bacterial burden, host cell activation and host cell death) is predictive of treatment outcome.
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    Multi-Scale Breeding Bird and Land-cover Associations
    (Journal of the Tennessee Academy of Science, 2001) Butler, J. Russell
    The association patterns between breeding bird diversity and amount of different land cover types at five spatial scales were analyzed. Breeding bird surveys were conducted at 2,021 randomly selected roadside locations in a 500,000 ha area of north-central Tennessee. The land cover of the area was classified from satellite imagery. Both bird and land cover data were separated into relevant groups: birds into migration guilds, and land cover into natural and artificial types. The study area was subdivided into geographic blocks ranging from 36 to 62,000 ha. Study-area richness-distribution maps for each migration guild were created. The multiscale association patterns between bird species richness and proportion of land cover types were statistically analyzed using canonical and bivariate procedures. Residents displayed relatively even distributions. However, Neotropical migrant species displayed a large distribution gap in the southeast corner of the study area. Furthermore, residents did not display land cover associations, but Neotropical and short-distance migrants were significantly correlated with amount of land cover type over the breadth of the study scales. These findings suggest that migrants may be more sensitive to habitat changes than resident bird species. In addition, the multiscale results indicate the contextual and interrelated characteristics of the small- and large-scale patterns and processes. This suggests that local as well as regional scale areas need to be assessed in order to more effectively design management and conservation strategies.
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    The Spatial Impact of an Urban Area on Breeding Birds
    (Journal of the Tennessee Academy of Science, 2003) Butler, J. Russell
    Urbanization alters the landscape profoundly affecting plant and animal distributions and abundances. Urbanized areas negatively affect bird communities by favoring resident generalist or invasive species, in turn, reducing diversity and promoting local extinction. Even though urbanization affects biodiversity in many systems, the spatial extent to which a metropolitan area impacts biodiversity is not well characterized. The goal of the present study was to elucidate the areal extent to which an urban/suburban landscape affects avian diversity. I conducted a breeding-bird distribution study containing over 2,000 roadside survey locations in a 500,000 ha study area in north-central Tennessee, that contained areas of natural and urban (mainly the city of Nashville) land cover. Breeding bird species were divided into three guilds: those that breed and winter in the same area—residents; those that breed and winter in different but relatively close areas—short-distance migrants; and those that breed in North America and winter in Central and South America—Neotropical migrants. These data were spatially analyzed through spatial interpolation surface models: Kriging and linear surface models. Neotropical migrant richness exhibited stronger negative associations with urban land cover than either residents or short-distance migrants. The surface model for urban land cover formed urban density zones. Neotropical migrant total richness spatial patterns significantly corresponded to the urban spatial patterns. Neotropical migrant breeding bird richness was significantly less over a 150,000 ha area of urban/suburban-developed landscape, or an area 50 times larger than Nashville's downtown district. Assessment of the overall metropolitan spatial effect to diversity will provide a benchmark for areal urban/suburban impacts that can assist conservation and management strategies directed towards controlling environmental impacts of urban sprawl.
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    Temperature-associated Dynamics of Songbird Winter Distribution and Abundances
    (2007) Butler, J. Russell; MacMynowski, Dena P.; Laurent, Chad; Root, Terry L.
    Using Christmas Bird Count data, we analyze the annual spatio-temporal abundances of six passerine species in the upper Great Plains, US (1960-1990). This study provides new insight into how global warming could cause separation of species within present-day communities. We find that winter relative abundances of similarly-sized songbirds are differentially affected by ambient winter temperature. As such, average annual winter temperature fluctuations (i.e., severity of winter) are significantly (P < 0.05) correlated with the relative abundances of three species while the other three are not. Our conditional probability-of-occurrence analysis indicates that the abundances of the three temperature-associated species declined markedly below -4°C while the abundances of the other three species fluctuated little from 8°C to -16°C. We conclude that even in colder climates i) the winter distributions of some, but not all, songbirds are directly or indirectly limited by temperature; and ii) these birds have dynamic abundances that can quickly respond to temperature changes.