Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

2011

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 13351 - 13380 of 20348

Full-Text Articles in Entire DC Network

Effect Of Grain Size On Uranium(Vi) Surface Complexation Kinetics And Adsorption Additivity, Jianying Shang, Chongxuan Liu, Zheming Wang, John M. Zachara Jan 2011

Effect Of Grain Size On Uranium(Vi) Surface Complexation Kinetics And Adsorption Additivity, Jianying Shang, Chongxuan Liu, Zheming Wang, John M. Zachara

United States Department of Energy: Publications

The contribution of variable grain sizes to uranium adsorption/ desorption was studied using a sediment from the US DOE Hanford site. The sediment was wet sieved into four size fractions: coarse sand (1−2 mm), medium sand (0.2−1 mm), fine sand (0.053−0.2 mm), and clay/silt fraction (<0.053 mm). For each size fraction and their composite (sediment), batch and flow-cell experiments were performed to determine uranium adsorption isotherms and kinetic uranium adsorption and subsequent desorption. The results showed that uranium adsorption isotherms and adsorption/desorption kinetics were size specific, reflecting the effects of size-specific adsorption site concentration and kinetic rate constants. The larger-size fraction had a larger mass percentage in the sediment but with a smaller adsorption site concentration and generally a slower uranium adsorption/desorption rate. The same equilibrium surface complexation reaction and reaction constant could describe uranium adsorption isotherms for all size fractions and the composite after accounting for the effect of adsorption site concentration. Mass-weighted, linear additivity was observed for both uranium adsorption isotherms and adsorption/desorption kinetics in the composite. One important implication of this study is that grain-size distribution may be used to estimate uranium adsorption site and adsorption/desorption kinetic rates in heterogeneous sediments from a common location.

Go to article

Determining Individual Mineral Contributions To U(Vi) Adsorption In A Contaminated Aquifer Sediment: A Fluorescence Spectroscopy Study, Zheming Wang, John M. Zachara, Jean-Francois Boily, Yuanxian Xia, Tom C. Resch, Dean A. Moore, Chongxuan Liu Jan 2011

Determining Individual Mineral Contributions To U(Vi) Adsorption In A Contaminated Aquifer Sediment: A Fluorescence Spectroscopy Study, Zheming Wang, John M. Zachara, Jean-Francois Boily, Yuanxian Xia, Tom C. Resch, Dean A. Moore, Chongxuan Liu

United States Department of Energy: Publications

The adsorption and speciation of U(VI) was investigated on contaminated, fine grained sediment materials from the Hanford 300 area (SPP1 GWF) in simulated groundwater using cryogenic laser-induced U(VI) fluorescence spectroscopy combined with chemometric analysis. A series of reference minerals (montmorillonite, illite, Michigan chlorite, North Carolina chlorite, California clinochlore, quartz and synthetic 6-line ferrihydrite) was used for comparison that represents the mineralogical constituents of SPP1 GWF. Surface area-normalized Kd values were measured at U(VI) concentrations of 5 X 10−7 and 5 X 10−6 mol L−1 that displayed the following affinity series: 6-line-ferrihydrite > North Carolina chlorite ≈ California clinochlore …

Go to article

Interfacial Reactivity Of Radionuclides: Emerging Paradigms From Molecular-Level Observations, A.R. Felmy, E.S. Ilton, K.M. Rosso, John M. Zachara Jan 2011

Interfacial Reactivity Of Radionuclides: Emerging Paradigms From Molecular-Level Observations, A.R. Felmy, E.S. Ilton, K.M. Rosso, John M. Zachara

United States Department of Energy: Publications

Over the past few decades an increasing array of molecular-level analytical probes has provided new detailed insight into mineral and radionuclide interfacial reactivity in subsurface environments. This capability has not only helped change the way mineral surface reactivity is studied but also how field scale contaminant migration problems are addressed and ultimately resolved. Here we review relatively new interfacial reactivity paradigms and assess their implications for future research directions. Specific examples include understanding the following: the role of site-to-site electron conduction at mineral surfaces and through bulk mineral phases and the effects of local chemical environment on the stability of …

Go to article

Structure Of A Bacterial Cell Surface Decaheme Electron Conduit, Thomas A. Clarke, Marcus Edwards, Andrew J. Gates, Andrea Hall, Gaye F. White, Justin Bradley, Catherine L. Reardon, Liang Shi, Alexander Beliaev, Matthew Marshall, Zheming Wang, Nicholas Watmough, James K. Fredrickson, John M. Zachara, Julea Butt, David J. Richardson Jan 2011

Structure Of A Bacterial Cell Surface Decaheme Electron Conduit, Thomas A. Clarke, Marcus Edwards, Andrew J. Gates, Andrea Hall, Gaye F. White, Justin Bradley, Catherine L. Reardon, Liang Shi, Alexander Beliaev, Matthew Marshall, Zheming Wang, Nicholas Watmough, James K. Fredrickson, John M. Zachara, Julea Butt, David J. Richardson

United States Department of Energy: Publications

Some bacterial species are able to utilize extracellular mineral forms of iron and manganese as respiratory electron acceptors. In Shewanella oneidensis this involves decaheme cytochromes that are located on the bacterial cell surface at the termini of transouter- membrane electron transfer conduits. The cell surface cytochromes can potentially play multiple roles in mediating electron transfer directly to insoluble electron sinks, catalyzing electron exchange with flavin electron shuttles or participating in extracellular intercytochrome electron exchange along “nanowire” appendages. We present a 3.2-Å crystal structure of one of these decaheme cytochromes, MtrF, that allows the spatial organization of the 10 hemes to …

Go to article

Sop For Pathway Inference In Integrated Microbial Genomes (Img), Iain Anderson, Amy Chen, Victor Markowitz, Nikos Kyrpides, Natalia Ivanova Jan 2011

Sop For Pathway Inference In Integrated Microbial Genomes (Img), Iain Anderson, Amy Chen, Victor Markowitz, Nikos Kyrpides, Natalia Ivanova

United States Department of Energy: Publications

One of the most important aspects of genomic analysis is the prediction of which pathways, both metabolic and non-metabolic, are present in an organism. In IMG, this is carried out by the assignment of IMG terms, which are organized into IMG pathways. Based on manual and automatic assignment of IMG terms, the presence or absence of IMG pathways is automatically inferred. The three categories of pathway assertion are asserted (likely present), not asserted (likely absent), and unknown. In the unknown category, at least one term necessary for the pathway is missing, but an ortholog in another organism has the corresponding …

Go to article

Complete Genome Sequence Of The Cellulolytic Thermophile Clostridium Thermocellum Dsm1313, Lawrence Feinberg, Justine Foden, Trisha Barrett, Karen Walston Davenport, David Bruce, Chris Detter, Roxanne Tapia, Cliff Han, Alla Lapidus, Susan Lucas, Jan-Fang Cheng, Samuel Pitluck, Tanja Woyke, Natalia Ivanova, Natalia Mikhailova, Miriam Land, Loren Hauser, D. Aaron Argyros, Lynne Goodwin, David Hogsett, Nicky Caiazza Jan 2011

Complete Genome Sequence Of The Cellulolytic Thermophile Clostridium Thermocellum Dsm1313, Lawrence Feinberg, Justine Foden, Trisha Barrett, Karen Walston Davenport, David Bruce, Chris Detter, Roxanne Tapia, Cliff Han, Alla Lapidus, Susan Lucas, Jan-Fang Cheng, Samuel Pitluck, Tanja Woyke, Natalia Ivanova, Natalia Mikhailova, Miriam Land, Loren Hauser, D. Aaron Argyros, Lynne Goodwin, David Hogsett, Nicky Caiazza

United States Department of Energy: Publications

Clostridium thermocellum DSM1313 is a thermophilic, anaerobic bacterium with some of the highest rates of cellulose hydrolysis reported. The complete genome sequence reveals a suite of carbohydrate-active enzymes and demonstrates a level of diversity at the species level distinguishing it from the type strain ATCC 27405.

Go to article

Img/M: The Integrated Metagenome Data Management And Comparative Analysis System, Victor M. Markowitz, I-Min A. Chen, Ken Chu, Ernest Szeto, Krishna Palaniappan, Yuri Grechkin, Anna Ratner, Biju Jacob, Amrita Pati, Marcel Huntemann, Konstantinos Liolios, Ioanna Pagani, Iain Anderson, Konstantinos Mavromatis, Natalia N. Ivanova, Nikos C. Kyrpides Jan 2011

Img/M: The Integrated Metagenome Data Management And Comparative Analysis System, Victor M. Markowitz, I-Min A. Chen, Ken Chu, Ernest Szeto, Krishna Palaniappan, Yuri Grechkin, Anna Ratner, Biju Jacob, Amrita Pati, Marcel Huntemann, Konstantinos Liolios, Ioanna Pagani, Iain Anderson, Konstantinos Mavromatis, Natalia N. Ivanova, Nikos C. Kyrpides

United States Department of Energy: Publications

The integrated microbial genomes and metagenomes (IMG/M) system provides support for comparative analysis of microbial community aggregate genomes (metagenomes) in a comprehensive integrated context. IMG/M integrates metagenome data sets with isolate microbial genomes from the IMG system. IMG/M’s data content and analytical capabilities have been extended through regular updates since its first release in 2007. IMG/M is available at http://img.jgi.doe.gov/m. A companion IMG/M systems provide support for annotation and expert review of unpublished metagenomic data sets (IMG/M ER: http://img.jgi.doe.gov/mer).

Go to article

Vista Region Viewer (Rviewer)—A Computational System For Prioritizing Genomic Intervals For Biomedical Studies, Igor Lukashin, Pavel Novichkov, Dario Boffelli, Alex R. Paciorkowski, Simon Minovitsky, Song Yang, Inna Dubchak Jan 2011

Vista Region Viewer (Rviewer)—A Computational System For Prioritizing Genomic Intervals For Biomedical Studies, Igor Lukashin, Pavel Novichkov, Dario Boffelli, Alex R. Paciorkowski, Simon Minovitsky, Song Yang, Inna Dubchak

United States Department of Energy: Publications

Summary:
Current genome browsers are designed for linear browsing of individual genomic regions, but the high-throughput nature of experiments aiming to elucidate the genetic component of human disease makes it very important to develop user-friendly tools for comparing several genomic regions in parallel and prioritizing them based on their functional content. We introduce VISTA Region Viewer (RViewer), an interactive online tool that allows for efficient screening and prioritization of regions of the human genome for follow-up studies. The tool takes as input genetic variation data from different biomedical studies, determines a number of various functional parameters for both coding …

Go to article

Complete Genome Sequence Of The Plant Growth-Promoting Endophyte Burkholderia Phytofirmans Strain Psjn, Alexandra Weilharter, Birgit Mitter, Maria V. Shin, Patrick S. G. Chain, Jerzy Nowak, Angela Sessitsch Jan 2011

Complete Genome Sequence Of The Plant Growth-Promoting Endophyte Burkholderia Phytofirmans Strain Psjn, Alexandra Weilharter, Birgit Mitter, Maria V. Shin, Patrick S. G. Chain, Jerzy Nowak, Angela Sessitsch

United States Department of Energy: Publications

Burkholderia phytofirmans PsJNT is able to efficiently colonize the rhizosphere, root, and above-ground plant tissues of a wide variety of genetically unrelated plants, such as potatoes, canola, maize, and grapevines. Strain PsJN shows strong plant growth-promoting effects and was reported to enhance plant vigor and resistance to biotic and abiotic stresses. Here, we report the genome sequence of this strain, which indicates the presence of multiple traits relevant for endophytic colonization and plant growth promotion.

Go to article

Transient Groundwater Chemistry Near A River: Effects On U(Vi) Transport In Laboratory Column Experiments, Jun Yin, Roy Haggerty, Deborah L. Stoliker, Douglas B. Kent, Jonathan D. Istok, Janek Greskowiak, John M. Zachara Jan 2011

Transient Groundwater Chemistry Near A River: Effects On U(Vi) Transport In Laboratory Column Experiments, Jun Yin, Roy Haggerty, Deborah L. Stoliker, Douglas B. Kent, Jonathan D. Istok, Janek Greskowiak, John M. Zachara

United States Department of Energy: Publications

In the 300 Area of a U(VI)-contaminated aquifer at Hanford, Washington, USA, inorganic carbon and major cations, which have large impacts on U(VI) transport, change on an hourly and seasonal basis near the Columbia River. Batch and column experiments were conducted to investigate the factors controlling U(VI) adsorption/desorption by changing chemical conditions over time. Low alkalinity and low Ca concentrations (Columbia River water) enhanced adsorption and reduced aqueous concentrations. Conversely, high alkalinity and high Ca concentrations (Hanford groundwater) reduced adsorption and increased aqueous concentrations of U(VI). An equilibrium surface complexation model calibrated using laboratory batch experiments accounted for the decrease …

Go to article

Simulating Adsorption Of U(Vi) Under Transient Groundwater Flow And Hydrochemistry: Physical Versus Chemical Nonequilibrium Model, Janek Greskowiak, Michael Hay, Henning Prommer, Chongxuan Liu, Vincent Post, Rui Ma, James Davis, Chunmiao Zheng, John M. Zachara Jan 2011

Simulating Adsorption Of U(Vi) Under Transient Groundwater Flow And Hydrochemistry: Physical Versus Chemical Nonequilibrium Model, Janek Greskowiak, Michael Hay, Henning Prommer, Chongxuan Liu, Vincent Post, Rui Ma, James Davis, Chunmiao Zheng, John M. Zachara

United States Department of Energy: Publications

Coupled intragrain diffusional mass transfer and nonlinear surface complexation processes play an important role in the transport behavior of U(VI) in contaminated aquifers. Two alternative model approaches for simulating these coupled processes were analyzed and compared: (1) the physical nonequilibrium approach that explicitly accounts for aqueous speciation and instantaneous surface complexation reactions in the intragrain regions and approximates the diffusive mass exchange between the immobile intragrain pore water and the advective pore water as multirate first-order mass transfer and (2) the chemical nonequilibrium approach that approximates the diffusion-limited intragrain surface complexation reactions by a set of multiple first-order surface complexation …

Go to article

Transition Of Cellulose Crystalline Structure And Surface Morphology Of Biomass As A Function Of Ionic Liquid Pretreatment And Its Relation To Enzymatic Hydrolysis, Gang Cheng, Patanjali Varanasi, Chenlin Li, Hanbin Liu, Yuri B. Melnichenko, Blake A. Simmons, Michael S. Kent, Seema Singh Jan 2011

Transition Of Cellulose Crystalline Structure And Surface Morphology Of Biomass As A Function Of Ionic Liquid Pretreatment And Its Relation To Enzymatic Hydrolysis, Gang Cheng, Patanjali Varanasi, Chenlin Li, Hanbin Liu, Yuri B. Melnichenko, Blake A. Simmons, Michael S. Kent, Seema Singh

United States Department of Energy: Publications

Cellulose is inherently resistant to breakdown, and the native crystalline structure (cellulose I) of cellulose is considered to be one of themajor factors limiting its potential in terms of cost-competitive lignocellulosic biofuel production. Here we report the impact of ionic liquid pretreatment on the cellulose crystalline structure in different feedstocks, including microcrystalline cellulose (Avicel), switchgrass (Panicum virgatum), pine (Pinus radiata), and eucalyptus (Eucalyptus globulus), and its influence on cellulose hydrolysis kinetics of the resultant biomass. These feedstocks were pretreated using 1-ethyl-3-methyl imidazolium acetate ([C2mim][OAc]) at 120 and 160°C for 1, 3, 6, and 12 …

Go to article

Modification Of Native Grasses For Biofuel Production May Increase Virus Susceptibility, Abbie C. Schrotenboer, Michael S. Allen, Carolyn M. Malmstrom Jan 2011

Modification Of Native Grasses For Biofuel Production May Increase Virus Susceptibility, Abbie C. Schrotenboer, Michael S. Allen, Carolyn M. Malmstrom

United States Department of Energy: Publications

Bioenergy production is driving modifications to native plant species for use as novel biofuel crops. Key aims are to increase crop growth rates and to enhance conversion efficiency by reducing biomass recalcitrance to digestion. However, selection for these biofuel-valuable traits has potential to compromise plant defenses and alter interactions with pests and pathogens. Insect-vectored plant viruses are of particular concern because perennial crops have potential to serve as virus reservoirs that influence regional disease dynamics. In this study, we examined relationships between growth rates and biomass recalcitrance in five switchgrass (Panicum virgatum) populations, ranging from near wild type …

Go to article

Time To Evolve? Potential Evolutionary Responses Of Fraser River Sockeye Salmon To Climate Change And Effects On Persistence, Thomas E. Reed, Daniel E. Schindler, Merran J. Hague, David A. Patterson, Eli Meir, Robin Waples, Scott G. Hinch Jan 2011

Time To Evolve? Potential Evolutionary Responses Of Fraser River Sockeye Salmon To Climate Change And Effects On Persistence, Thomas E. Reed, Daniel E. Schindler, Merran J. Hague, David A. Patterson, Eli Meir, Robin Waples, Scott G. Hinch

United States Department of Commerce: Staff Publications

Evolutionary adaptation affects demographic resilience to climate change but few studies have attempted to project changes in selective pressures or quantify impacts of trait responses on population dynamics and extinction risk. We used a novel individual-based model to explore potential evolutionary changes in migration timing and the consequences for population persistence in sockeye salmon Oncorhynchus nerka in the Fraser River, Canada, under scenarios of future climate warming. Adult sockeye salmon are highly sensitive to increases in water temperature during their arduous upriver migration, raising concerns about the fate of these ecologically, culturally, and commercially important fish in a warmer future. …

Go to article

State Of The Climate In 2010, Jessica Blunden, Derek S. Arndt, Molly O. Baringer Jan 2011

State Of The Climate In 2010, Jessica Blunden, Derek S. Arndt, Molly O. Baringer

United States Department of Commerce: Staff Publications

Several large-scale climate patterns influenced climate conditions and weather patterns across the globe during 2010. The transition from a warm El Niño phase at the beginning of the year to a cool La Niña phase by July contributed to many notable events, ranging from record wetness across much of Australia to historically low Eastern Pacific basin and near-record high North Atlantic basin hurricane activity. The remaining five main hurricane basins experienced below- to well-below-normal tropical cyclone activity. The negative phase of the Arctic Oscillation was a major driver of Northern Hemisphere temperature patterns during 2009/10 winter and again in late …

Go to article

Enso And Nao Impacts On Plains Winter Seasons In Modern And Historical Periods, Barbara E. Mayes Jan 2011

Enso And Nao Impacts On Plains Winter Seasons In Modern And Historical Periods, Barbara E. Mayes

United States Department of Commerce: Staff Publications

Climatological teleconnection patterns, including the phase of the El Niño-Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO), are known predictors for variables such as seasonal temperature and precipitation and tropical cyclone activity. ENSO is known to affect synoptic patterns across the continental United States, particularly by its impact on the upper tropospheric jet stream position. Likewise, NAO is associated with changes in sea level pressure and upper-level jet strengths over the Atlantic Ocean, with upstream impacts affecting North American temperatures and precipitation distribution. While ENSO and NAO are two of many factors that influence global circulations, and by distillation …

Go to article

Ecosystem Services Altered By Human Changes In The Nitrogen Cycle: A New Perspective For Us Decision Making, Jana E. Compton, John A. Harrison, Robin L. Dennis, Tara L. Greaver, Brian H. Hill, Stephen J. Jordan, Henry Walker, Holly V. Campbell Jan 2011

Ecosystem Services Altered By Human Changes In The Nitrogen Cycle: A New Perspective For Us Decision Making, Jana E. Compton, John A. Harrison, Robin L. Dennis, Tara L. Greaver, Brian H. Hill, Stephen J. Jordan, Henry Walker, Holly V. Campbell

United States Environmental Protection Agency: Publications

Human alteration of the nitrogen (N) cycle has produced benefits for health and well-being, but excess N has altered many ecosystems and degraded air and water quality. US regulations mandate protection of the environment in terms that directly connect to ecosystem services. Here, we review the science quantifying effects of N on key ecosystem services, and compare the costs of N-related impacts or mitigation using the metric of cost per unit of N. Damage costs to the provision of clean air, reflected by impaired human respiratory health, are well characterized and fairly high (e.g. costs of ozone and particulate damages …

Go to article

Toxicity And Recovery In The Pregnant Mouse After Gestational Exposure To The Cyanobacterial Toxin, Cylindrospermopsin, N. Chernoff, E. H. Rogers, R. D. Zehr, M. I. Gage, D. E. Malarkey, C. A. Bradfield, Y. Liu, J. E. Schmid, R. H. Jaskot, J. H. Richards, C. R. Wood, M. B. Rosen Jan 2011

Toxicity And Recovery In The Pregnant Mouse After Gestational Exposure To The Cyanobacterial Toxin, Cylindrospermopsin, N. Chernoff, E. H. Rogers, R. D. Zehr, M. I. Gage, D. E. Malarkey, C. A. Bradfield, Y. Liu, J. E. Schmid, R. H. Jaskot, J. H. Richards, C. R. Wood, M. B. Rosen

United States Environmental Protection Agency: Publications

Cylindrospermopsin (CYN) is a tricyclic alkaloid toxin produced by fresh water cyanobacterial species worldwide. CYN has been responsible for both livestock and human poisoning after oral exposure. This study investigated the toxicity of CYN to pregnant mice exposed during different segments of gestation. The course of recovery and individual responses to the toxin were evaluated. Adverse effects of CYN were monitored up to 7 weeks post-dosing by clinical examination, histopathology, biochemistry and gene expression. Exposure on gestational days (GD) 8–12 induced significantly more lethality than GD13–17 exposure. Periorbital, gastrointestinal and distal tail hemorrhages were seen in both groups. Serum markers …

Go to article

Maternal Influences On Epigenetic Programming Of The Developing Hypothalamic-Pituitary-Adrenal Axis, Curtis E. Grace, Sung-Je Kim, John M. Rogers Jan 2011

Maternal Influences On Epigenetic Programming Of The Developing Hypothalamic-Pituitary-Adrenal Axis, Curtis E. Grace, Sung-Je Kim, John M. Rogers

United States Environmental Protection Agency: Publications

Parental and environmental factors during the prenatal and postnatal periods permanently affect the physiology and metabolism of offspring, potentially increasing disease risk later in life. Underlying mechanisms are being elucidated, and effects on a number of organs and metabolic pathways are likely involved. In this review, we consider effects on the developing hypothalamic-pituitary-adrenal (HPA) axis, which may represent a common pathway for developmental programming. The focus is on prenatal and early postnatal development, during which the HPA axis may be programmed in a manner that affects health for a lifetime. Programming of the HPA axis involves, at least in part, …

Go to article

Current And Future Needs For Developmental Toxicity Testing, Susan L. Makris, James H. Kim, Amy Ellis, Willem Faber, Wafa Harrouk, Joseph M. Lewis, Merle G. Paule, Jennifer Seed, Melissa Tassinari, Rochelle Tyl Jan 2011

Current And Future Needs For Developmental Toxicity Testing, Susan L. Makris, James H. Kim, Amy Ellis, Willem Faber, Wafa Harrouk, Joseph M. Lewis, Merle G. Paule, Jennifer Seed, Melissa Tassinari, Rochelle Tyl

United States Environmental Protection Agency: Publications

A review is presented of the use of developmental toxicity testing in the United States and international regulatory assessment of human health risks associated with exposures to pharmaceuticals (human and veterinary), chemicals (agricultural, industrial, and environmental), food additives, cosmetics, and consumer products. Developmental toxicology data are used for prioritization and screening of pharmaceuticals and chemicals, for evaluating and labeling of pharmaceuticals, and for characterizing hazards and risk of exposures to industrial and environmental chemicals. The in vivo study designs utilized in hazard characterization and dose-response assessment for developmental outcomes have not changed substantially over the past 30 years and have …

Go to article

Aryl Hydrocarbon Receptor Activation During Pregnancy, And In Adult Nulliparous Mice, Delays The Subsequent Development Of Dmba-Induced Mammary Tumors, Tao Wang, Heather M. Gavin, Volker M. Arlt, B. Paige Lawrence, Suzanne E. Fenton, Daniel Medina, Beth A. Vorderstrasse Jan 2011

Aryl Hydrocarbon Receptor Activation During Pregnancy, And In Adult Nulliparous Mice, Delays The Subsequent Development Of Dmba-Induced Mammary Tumors, Tao Wang, Heather M. Gavin, Volker M. Arlt, B. Paige Lawrence, Suzanne E. Fenton, Daniel Medina, Beth A. Vorderstrasse

United States Environmental Protection Agency: Publications

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), the prototypic ligand for the aryl hydrocarbon receptor (AhR), promotes tumor formation in some model systems. However, with regard to breast cancer, epidemiological and animal studies are inconclusive as to whether exposure increases tumor incidence or may instead be protective. We have previously reported that mice exposed to TCDD during pregnancy have impaired differentiation of mammary tissue, including decreased branching and poor development of lobuloalveolar structures. Because normal pregnancy-induced mammary differentiation may protect against subsequent neoplastic transformation, we hypothesized that TCDD-treated mice would be more susceptible to chemical carcinogenesis after parturition. To test this, mice were …

Go to article

Evolution Of Natural History Information In The 21st Century – Developing An Integrated Framework For Biological And Geographical Data, Deborah A. Reusser, Henry Lee Ii Jan 2011

Evolution Of Natural History Information In The 21st Century – Developing An Integrated Framework For Biological And Geographical Data, Deborah A. Reusser, Henry Lee Ii

United States Environmental Protection Agency: Publications

Threats to marine and estuarine species operate over many spatial scales, from nutrient enrichment at the watershed/estuarine scale to invasive species and climate change at regional and global scales. To help address research questions across these scales, we provide here a standardized framework for a biogeographical information system containing queriable biological data that allows extraction of information on multiple species, across a variety of spatial scales based on species distributions, natural history attributes and habitat requirements. As scientists shift from research on localized impacts on individual species to regional and global scale threats, macroecological approaches of studying multiple species over …

Go to article

Effects Of Biologically-Active Chemical Mixtures On Fish In A Wastewater-Impacted Urban Stream, Larry B. Barber, Gregory K. Brown, Todd G. Nettesheim, Elizabeth W. Murphy, Stephen E. Bartell, Heiko L. Schoenfuss Jan 2011

Effects Of Biologically-Active Chemical Mixtures On Fish In A Wastewater-Impacted Urban Stream, Larry B. Barber, Gregory K. Brown, Todd G. Nettesheim, Elizabeth W. Murphy, Stephen E. Bartell, Heiko L. Schoenfuss

United States Environmental Protection Agency: Publications

Stream flow in urban aquatic ecosystems often is maintained by water-reclamation plant (WRP) effluents that contain mixtures of natural and anthropogenic chemicals that persist through the treatment processes. In effluent-impacted streams, aquatic organisms such as fish are continuously exposed to biologically-active chemicals throughout their life cycles. The North Shore Channel of the Chicago River (Chicago, Illinois) is part of an urban ecosystem in which >80% of the annual flow consists of effluent from the North Side WRP. In this study, multiple samplings of the effluent and stream water were conducted and fish (largemouth bass and carp) were collected on 2 …

Go to article

Partially Acetylated Sugarcane Bagasse For Wicking Oil From Contaminated Wetlands, Seungoon Chung, Makram T. Suidan, Albert D. Venosa Jan 2011

Partially Acetylated Sugarcane Bagasse For Wicking Oil From Contaminated Wetlands, Seungoon Chung, Makram T. Suidan, Albert D. Venosa

United States Environmental Protection Agency: Publications

Sugarcane bagasse was partially acetylated to enhance its oil-wicking ability in saturated environments while holding moisture for hydrocarbon biodegradation. The water sorption capacity of raw bagasse was reduced fourfold after treatment, which indicated considerably increased hydrophobicity but not a limited capability to hold moisture for hydrocarbon biodegradation. Characterization results by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and surface area analyzer suggested that treated bagasse exhibited enhanced hydrophobicity and surface area. Oil wicking test results indicate that treated bagasse is more effective in wicking oil from highly saturated environments than raw bagasse and suggest that application …

Go to article

Time-Lapse Three-Dimensional Inversion Of Complex Conductivity Data Using An Active Time Constrained (Atc) Approach, M. Karaoulis, A. Revil, D. D. Werkema, B. J. Minsley, W. F. Woodruff, A. Kemna Jan 2011

Time-Lapse Three-Dimensional Inversion Of Complex Conductivity Data Using An Active Time Constrained (Atc) Approach, M. Karaoulis, A. Revil, D. D. Werkema, B. J. Minsley, W. F. Woodruff, A. Kemna

United States Environmental Protection Agency: Publications

Induced polarization (more precisely the magnitude and phase of impedance of the subsurface) is measured using a network of electrodes located at the ground surface or in boreholes. This method yields important information related to the distribution of permeability and contaminants in the shallow subsurface. We propose a new time-lapse 3-D modelling and inversion algorithm to image the evolution of complex conductivity over time.We discretize the subsurface using hexahedron cells. Each cell is assigned a complex resistivity or conductivity value. Using the finite-element approach, we model the in-phase and out-of-phase (quadrature) electrical potentials on the 3-D grid, which are then …

Go to article

Use Of Comparative Genomics Approaches To Characterize Interspecies Differences In Response To Environmental Chemicals: Challenges, Opportunities, And Research Needs, Sarah L. Burgess-Herbert, Susan Y. Euling Jan 2011

Use Of Comparative Genomics Approaches To Characterize Interspecies Differences In Response To Environmental Chemicals: Challenges, Opportunities, And Research Needs, Sarah L. Burgess-Herbert, Susan Y. Euling

United States Environmental Protection Agency: Publications

A critical challenge for environmental chemical risk assessment is the characterization and reduction of uncertainties introduced when extrapolating inferences from one species to another. The purpose of this article is to explore the challenges, opportunities, and research needs surrounding the issue of how genomics data and computational and systems level approaches can be applied to inform differences in response to environmental chemical exposure across species. We propose that the data, tools, and evolutionary framework of comparative genomics be adapted to inform interspecies differences in chemical mechanisms of action. We compare and contrast existing approaches, from disciplines as varied as evolutionary …

Go to article

Integrating Mechanistic And Polymorphism Data To Characterize Human Genetic Susceptibility For Environmental Chemical Risk Assessment In The 21st Century, Holly M. Mortensen, Susan Y. Euling Jan 2011

Integrating Mechanistic And Polymorphism Data To Characterize Human Genetic Susceptibility For Environmental Chemical Risk Assessment In The 21st Century, Holly M. Mortensen, Susan Y. Euling

United States Environmental Protection Agency: Publications

Response to environmental chemicals can vary widely among individuals and between population groups. In human health risk assessment, data on susceptibility can be utilized by deriving risk levels based on a study of a susceptible population and/or an uncertainty factor may be applied to account for the lack of information about susceptibility. Defining genetic susceptibility in response to environmental chemicals across human populations is an area of interest in the NAS' new paradigm of toxicity pathway-based risk assessment. Data from highthroughput/ high content (HT/HC), including -omics (e.g., genomics, transcriptomics, proteomics, metabolomics) technologies, have been integral to the identification and characterization …

Go to article

The Characterization Of Socio-Political Instability, Development And Sustainability With Fisher Information, Arunprakash T. Karunanithi, Ahjond S. Garmestani, Tarsha Eason, Heriberto Cabezas Jan 2011

The Characterization Of Socio-Political Instability, Development And Sustainability With Fisher Information, Arunprakash T. Karunanithi, Ahjond S. Garmestani, Tarsha Eason, Heriberto Cabezas

United States Environmental Protection Agency: Publications

In an effort to evaluate socio-political instability, we studied the relationship between dynamic order, socio-political upheavals and sustainability in nation states. Estimating the degree of dynamic order inherent in the socio-political regime of various countries throughout the world involved applying Fisher information theory to data from the Political Instability Task Force database. Fisher information is a key method in information theory and affords the ability to characterize the structure and dynamics of complex systems. The results of this work demonstrate that nation states bifurcate into two distinct regimes, which exhibit a negative correlation between dynamic order, as determined by Fisher …

Go to article

Threshold Transitions In A Regional Urban System, Jorge H. García, Ahjond S. Garmestani, Arunprakash T. Karunanithi Jan 2011

Threshold Transitions In A Regional Urban System, Jorge H. García, Ahjond S. Garmestani, Arunprakash T. Karunanithi

United States Environmental Protection Agency: Publications

In this paper we analyze the evolution of city size distributions over time in a regional urban system. This urban complex system is in constant flux with changing groups and city migration across existing and newly created groups. Using group formation as an emergent property, transition probabilities across the different groups were calculated. While short-term transition appears chaotic in the intermediate and lower rank groups, long-term transition across all rank groups reveals striking system structure overtime.

Go to article

Embracing Panarchy, Building Resilience And Integrating Adaptive Management Through A Rebirth Of The National Environmental Policy Act, Melinda Harm Benson, Ahjond S. Garmestani Jan 2011

Embracing Panarchy, Building Resilience And Integrating Adaptive Management Through A Rebirth Of The National Environmental Policy Act, Melinda Harm Benson, Ahjond S. Garmestani

United States Environmental Protection Agency: Publications

Environmental law plays a key role in shaping policy for sustainability of socialeecological systems. In particular, the types of legal instruments, institutions, and the response of law to the inherent variability in socialeecological systems are critical. Sustainability likely must occur via the institutions we have in place, combined with alterations in policy and regulation within the context of these institutions. This ecosystem management arrangement can be characterized as a panarchy, with research on sustainability specific to the scale of interest. In this manuscript we examine an opportunity for integrating these concepts through a regulatory rebirth of the National Environmental Policy …

Go to article

First Prev Next Last