1,225 research outputs found
Recommended from our members
INEEL Subregional Conceptual Model Report; Volume 1 - Summary of Existing Knowledge of Natural and Anthropogenic Influences Governing Subsurface Contaminant Transport in the INEEL Subregion of the Eastern Snake River Plain
The National Research Council has defined a conceptual model as ''an evolving hypothesis identifying the important features, processes, and events controlling fluid flow and contaminant transport of consequence at a specific field site in the context of a recognized problem''. Presently, several subregional conceptual models are under development at the Idaho National Engineering and Environmental Laboratory (INEEL). Additionally, facility-specific conceptual models have been described as part of INEEL environmental restoration activities. Compilation of these models is required to develop a comprehensive conceptual model that can be used to strategically plan for future groundwater research activities at the INEEL. Conceptual models of groundwater flow and contaminant transport at the INEEL include the description of the geologic framework, matrix hydraulic properties, and inflows and outflows. They also include definitions of the contaminant source term and contaminant transport mechanisms. The geologic framework of the INEEL subregion is described by the geometry of the system, stratigraphic units within the system, and structural features that affect groundwater flow and contaminant transport. These elements define geohydrologic units that make up the Snake River Plain Aquifer (SRPA). The United States Geological Survey (USGS) conceptual model encompasses approximately 1,920 mi2 of the eastern Snake River Plain. The Waste Area Group (WAG)-10 model includes the USGS area and additional areas to the northeast and southeast. Both conceptual models are bounded to the northwest by the Pioneer Mountains, Lost River Range, and Lemhi Mountains. They are bounded to the southeast by groundwater flow paths determined from aquifer water-level contours. The upgradient extent of the USGS model is a water-level contour that includes the northeastern boundary of the INEEL. The WAG-10 model includes more of the Mud Lake area to utilize previous estimates of underflow into the subregion. Both conceptual models extend approximately 25 miles to the southwest of the INEEL, a distance sufficient to include known concentrations of contaminant tracers. Several hypotheses have been developed concerning the effective thickness of the SRPA at the INEEL. The USGS model has defined the effective thickness from electrical resistivity and borehole data to be as much as 2,500 ft in the eastern part of the subregion and as much as 4,000 ft in the southwestern part. The WAG-10 model has developed two alternatives using aquifer-temperature and electrical resistivity data. The ''thick'' aquifer interpretation utilizes colder temperature data and includes a northtrending zone in which the thickness exceeds 1,300 ft and with a maximum thickness of 1,700 ft. The ''thin'' aquifer interpretation minimizes aquifer thickness, with thickness ranging from 328 to 1,300 ft. Facility-specific models generally have focused efforts on the upper 250 ft of saturation. Conceptual models have utilized a stratigraphic data set to define geohydrologic units within the INEEL subregion. This data set, compiled from geophysical logs and cores from boreholes, correlates the thick, complex stack of basalt flows across the subregion. Conceptual models generally concur that the upper geohydrologic unit consists of a section of highly fractured, multiple, thin basalt flows and sedimentary interbeds. Beneath this unit is an areally extensive, thick, unfractured basalt flow that rises above the water table southwest of the INEEL. The bottom unit consists of a thick section of slightly- to moderately-altered basalt. A key objective of the DOE water-integration project at the INEEL is to coordinate development of a subregional conceptual model of groundwater flow and contaminant transport that is based on the best available understanding of geologic and hydrologic features. The first step in this process is to compile and summarize the current conceptual models of groundwater flow and contaminant transport at the INEEL that have been developed from extensive geohydrologic studies conducted during the last 50 years
Hybridization and rapid differentiation after secondary contact between the native green anole (\u3cem\u3eAnolis carolinensis\u3c/em\u3e) and the introduced green anole (\u3cem\u3eAnolis porcatus\u3c/em\u3e)
In allopatric species, reproductive isolation evolves through the accumulation of genetic incompatibilities. The degree of divergence required for complete reproductive isolation is highly variable across taxa, which makes the outcome of secondary contact between allopatric species unpredictable. Since before the Pliocene, two species of Anolis lizards, Anolis carolinensis and Anolis porcatus, have been allopatric, yet this period of independent evolution has not led to substantial speciesâspecific morphological differentiation, and therefore, they might not be reproductively isolated. In this study, we determined the genetic consequences of localized, secondary contact between the native green anole, A. carolinensis, and the introduced Cuban green anole, A. porcatus, in South Miami. Using 18 microsatellite markers, we found that the South Miami population formed a genetic cluster distinct from both parental species. Mitochondrial DNA revealed maternal A. porcatus ancestry for 35% of the individuals sampled from this population, indicating a high degree of cytonuclear discordance. Thus, hybridization with A. porcatus, not just population structure within A. carolinensis, may be responsible for the genetic distinctiveness of this population. Using treeâbased maximumâlikelihood analysis, we found support for a more recent, secondary introduction of A. porcatus to Florida. Evidence that ~33% of the nuclear DNA resulted from a secondary introduction supports the hybrid origin of the green anole population in South Miami. We used multiple lines of evidence and multiple genetic markers to reconstruct otherwise cryptic patterns of species introduction and hybridization. Genetic evidence for a lack of reproductive isolation, as well as morphological similarities between the two species, supports revising the taxonomy of A. carolinensis to include A. porcatus from western Cuba. Future studies should target the current geographic extent of introgression originating from the past injection of genetic material from Cuban green anoles and determine the consequences for the evolutionary trajectory of green anole populations in southern Florida
Radar Altimetry as a Robust Tool for Monitoring the Active Lava Lake at Erebus Volcano, Antarctica
The level of lava within a volcanic conduit reflects the overpressure within a connected magma reservoir. Continuous monitoring of lava level can therefore provide critical insights into volcanic processes, and aid hazard assessment. However, accurate measurements of lava level are not easy to make, partly owing to the often dense fumes that hinder optical techniques. Here, we present the first radar instrument designed for the purpose of monitoring lava level, and report on its successful operation at Erebus volcano, Antarctica. We describe the hardware and data processing steps followed to extract a time series of lava lake level, demonstrating that we can readily resolve ~1 m cyclic variations in lake level that have previously been recognised at Erebus volcano. The performance of the radar (continuous, automated data collection in temperatures of around -30°C) indicates the suitability of this approach for sustained automated measurements at Erebus and other volcanoes with lava lakes
Intragenic ATM Methylation in Peripheral Blood DNA as a Biomarker of Breast Cancer Risk
Few studies have evaluated the association between DNA methylation in white blood cells (WBC) and the risk of breast cancer. The evaluation of WBC DNA methylation as a biomarker of cancer risk is of particular importance as peripheral blood is often available in prospective cohorts and easier to obtain than tumor or normal tissues. Here, we used prediagnostic blood samples from three studies to analyze WBC DNA methylation of two ATM intragenic loci (ATMmvp2a and ATMmvp2b) and genome-wide DNA methylation in long interspersed nuclear element-1 (LINE1) repetitive elements. Samples were from a case-control study derived from a cohort of high-risk breast cancer families (KConFab) and nested case-control studies in two prospective cohorts: Breakthrough Generations Study (BGS) and European Prospective Investigation into Cancer and Nutrition (EPIC). Bisulfite pyrosequencing was used to quantify methylation from 640 incident cases of invasive breast cancer and 741 controls. Quintile analyses for ATMmvp2a showed an increased risk of breast cancer limited to women in the highest quintile [OR, 1.89; 95% confidence interval (CI), 1.36-2.64; P = 1.64 x 10(-4)]. We found no significant differences in estimates across studies or in analyses stratified by family history or menopausal status. However, a more consistent association was observed in younger than in older women and individually significant in KConFab and BGS, but not EPIC. We observed no differences in LINE1 or ATMmvp2b methylation between cases and controls. Together, our findings indicate that WBC DNA methylation levels at ATM could be a marker of breast cancer risk and further support the pursuit of epigenome-wide association studies of peripheral blood DNA methylation. Cancer Res; 72(9); 2304-13. (C) 2012 AACR
Cytomegalovirus immunoevasin reveals the physiological role of âmissing selfâ recognition in natural killer cell dependent virus control in vivo
Natural killer cell recognition of âmissing selfâ contributes meaningfully to control of mouse cytomegalovirus infection in vivo
Control of viral infection by natural killer cell inhibitory receptors
Major histocompatibility complex class I (MHC-I)-restricted immune responses are largely attributed to cytotoxic T lymphocytes (CTLs). However, natural killer (NK) cells, as predicted by the missing-self hypothesis, have opposing requirements for MHC-I, suggesting that they may also demonstrate MHC-I-restricted effects. In mice, the Ly49 inhibitory receptors prevent NK cell killing of missing-self targets in effector responses, and they have a proposed second function in licensing or educating NK cells via self-MHC-I in vivo. Here we show MHC-I-restricted control of murine cytomegalovirus (MCMV) infection in vivo that is NK cell dependent. Using mice lacking specific Ly49 receptors, we show that control of MCMV requires inhibitory Ly49 receptors and an inhibitory signaling motif and the capacity for MCMV to downregulate MHC-I. Taken together, these data provide definitive evidence that the inhibitory receptors are required for missing-self rejection and are relevant to MHC-I-restricted NK cell control of a viral infection in vivo
- âŠ