National Library of Energy BETA

Sample records for toad bufo boreas

  1. Multi-level effects of low dose rate ionizing radiation on southern toad, Anaxyrus [Bufo] terrestris

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Stark, Karolina; Scott, David E.; Tsyusko, Olga; Coughlin, Daniel P.; Hinton, Thomas G.; Amendola, Roberto

    2015-04-30

    Despite their potential vulnerability to contaminants from exposure at multiple life stages, amphibians are one of the least studied groups of vertebrates in ecotoxicology, and research on radiation effects in amphibians is scarce. We used multiple endpoints to assess the radiosensitivity of the southern toad (Anaxyrus [Bufo] terrestris) during its pre-terrestrial stages of development –embryonic, larval, and metamorphic. Toads were exposed, from several hours after oviposition through metamorphosis (up to 77 days later), to four low dose rates of ¹³⁷Cs at 0.13, 2.4, 21, and 222 mGy d⁻¹, resulting in total doses up to 15.8 Gy. Radiation treatments did notmore » affect hatching success of embryos, larval survival, or the length of the larval period. The individual family variation in hatching success of embryos was larger than the radiation response. In contrast, newly metamorphosed individuals from the higher dose-rate treatments had higher mass and mass/length body indices, a measure which may relate to higher post-metamorphic survival. The increased mass and index at higher dose rates may indicate that the chronic, low dose rate radiation exposures triggered secondary responses. Additionally, the increases in growth were linked to a decrease in DNA damage (as measured by the Comet Assay) in red blood cells at a dose rate of 21mGy d⁻¹ and a total dose of 1.1 Gy. In conclusion, the complex effects of low dose rates of ionizing radiation may trigger growth and cellular repair mechanisms in amphibian larvae.« less

  2. Interactive effects of maternal and environmental exposure to coal combustion wastes decrease survival of larval southern toads (Bufo terrestris)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Interactive effects of maternal and environmental exposure to coal combustion wastes decrease survival of larval southern toads (Bufo terrestris) Brian S. Metts a, * , Kurt A. Buhlmann a , David E. Scott a , Tracey D. Tuberville a , William A. Hopkins b a Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802, USA b Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA 24061, USA a r t i c l e i n f o Article history: Received 16 August 2011 Received in revised form

  3. Multi-level effects of low dose rate ionizing radiation on southern toad, Anaxyrus [Bufo] terrestris

    SciTech Connect (OSTI)

    Stark, Karolina; Scott, David E.; Tsyusko, Olga; Coughlin, Daniel P.; Hinton, Thomas G.; Amendola, Roberto

    2015-04-30

    Despite their potential vulnerability to contaminants from exposure at multiple life stages, amphibians are one of the least studied groups of vertebrates in ecotoxicology, and research on radiation effects in amphibians is scarce. We used multiple endpoints to assess the radiosensitivity of the southern toad (Anaxyrus [Bufo] terrestris) during its pre-terrestrial stages of development –embryonic, larval, and metamorphic. Toads were exposed, from several hours after oviposition through metamorphosis (up to 77 days later), to four low dose rates of ¹³⁷Cs at 0.13, 2.4, 21, and 222 mGy d⁻¹, resulting in total doses up to 15.8 Gy. Radiation treatments did not affect hatching success of embryos, larval survival, or the length of the larval period. The individual family variation in hatching success of embryos was larger than the radiation response. In contrast, newly metamorphosed individuals from the higher dose-rate treatments had higher mass and mass/length body indices, a measure which may relate to higher post-metamorphic survival. The increased mass and index at higher dose rates may indicate that the chronic, low dose rate radiation exposures triggered secondary responses. Additionally, the increases in growth were linked to a decrease in DNA damage (as measured by the Comet Assay) in red blood cells at a dose rate of 21mGy d⁻¹ and a total dose of 1.1 Gy. In conclusion, the complex effects of low dose rates of ionizing radiation may trigger growth and cellular repair mechanisms in amphibian larvae.

  4. Boreas E licas | Open Energy Information

    Open Energy Info (EERE)

    Boreas E licas Jump to: navigation, search Name: Boreas Elicas Place: Spain Sector: Wind energy Product: Wind project developer References: Boreas Elicas1 This article is...

  5. Within- and among-population level differences in response to chronic copper exposure in southern toads, Anaxyrus terrestris

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Within- and among-population level differences in response to chronic copper exposure in southern toads, Anaxyrus terrestris Stacey L. Lance * , R. Wesley Flynn, Matthew R. Erickson 1 , David E. Scott Savannah River Ecology Laboratory, University of Georgia, P.O. Drawer E, Aiken, SC 29802, USA a r t i c l e i n f o Article history: Received 5 September 2012 Received in revised form 29 January 2013 Accepted 5 February 2013 Keywords: Anaxyrus (Bufo) terrestris Amphibian Copper Ecotoxicology Metal

  6. AmeriFlux CA-Man Manitoba - Northern Old Black Spruce (former BOREAS Northern Study Area)

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Amiro, Brian [University of Manitoba

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site CA-Man Manitoba - Northern Old Black Spruce (former BOREAS Northern Study Area). Site Description - 55.880° N, 98.481° W, elevation of 259 m, Boreal coniferous: Black spruce; occasional larch present in poorly-drained areas. Groundcover is moss (feathermosses and Sphagnum), Labrador Tea, Vaccinium, and willows are a main component of the understory. It was established in 1993 as a BOREAS site.

  7. Effect of parathyroid hormone on transport by toad and turtle bladder

    SciTech Connect (OSTI)

    Sabatini, S.; Kurtzman, N.A.

    1987-01-01

    The authors recently demonstrated that parathyroid hormone (PTH) inhibited both vasopressin- and cyclic AMP-stimulated water transport in the toad bladder. This was associated with an increase in calcium uptake by isolated epithelial cells. They postulated that PTH exerts its action on H/sub 2/O transport by directly stimulating calcium uptake. The current study was designed to compare the effects of PTH and the calcium ionophore, A23187, on H/sub 2/O and Na transport and H..mu.. secretion in toad and turtle bladders. In toad bladder, PTH and A23187 decreased arginine vasopressin (AVP)-stimulated H/sub 2/O flow and short-circuit current (SCC) after 60 min serosal incubation. In turtle bladder A23187 decreased SCC to 79.3 +/- 3.6% of base line (P < 0.05), and significantly decreased RSCC as well. PTH had no effect on SCC or H/sup +/ secretion in turtle bladders. Both PTH and A23187 increased /sup 45/Ca uptake in toad bladder epithelial cells; only A23187 increased /sup 45/Ca uptake in the turtle bladder. The different action of PTH in these two membranes, compared with that of the calcium ionophore, illustrates the selectivity of PTH on membrane transport. PTH increases calcium uptake and decreases transport only in a hormone-sensitive epithelium, whereas the ionophore works in virtually all living membranes. The mode of action of these two agents to increase calcium uptake is, therefore likely different.

  8. Effects of copper exposure on hatching success and early larval...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Rand GM. 2009. Effects of copper in flooded Florida agricultural soils on Hyalella azteca. ... to coal combustion wastes decrease survival of larval southern toads (Bufo terrestris). ...

  9. Microsoft Word - Scott-CV2013Sept.docx

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... TD, Scott DE, and Hopkins WA. Maternal transfer of contaminants and reduced reproductive success of southern toads (Bufo Anaxyrus terrestris) exposed to coal combustion waste. ...

  10. SREL Reprint #3245

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Maternal transfer of contaminants and reduced reproductive success of southern toads (Bufo Anaxyrus terrestris) exposed to coal combustion waste Brian S. Metts1, Kurt A. ...

  11. Lethal and sublethal measures of chronic copper toxicity in the eastern narrowmouth toad, Gastrophryne carolinensis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    LETHAL AND SUBLETHAL MEASURES OF CHRONIC COPPER TOXICITY IN THE EASTERN NARROWMOUTH TOAD, GASTROPHRYNE CAROLINENSIS R. WESLEY FLYNN,*y DAVID E. SCOTT,y WENDY KUHNE,zx DIANA SOTEROPOULOS,y and STACEY L. LANCEx ySavannah River Ecology Laboratory, University of Georgia, Aiken, South Carolina, USA zSavannah River National Laboratory, Department of Energy, University of Georgia,, Aiken, South Carolina, USA xDepartment of Biology, University of South Carolina-Aiken, Aiken, South Carolina, USA

  12. Ba2+-inhibitable /sup 86/Rb+ fluxes across membranes of vesicles from toad urinary bladder

    SciTech Connect (OSTI)

    Garty, H.; Civan, M.M.

    1987-01-01

    /sup 86/Rb+ fluxes have been measured in suspensions of vesicles prepared from the epithelium of toad urinary bladder. A readily measurable barium-sensitive, ouabain-insensitive component has been identified; the concentration of external Ba2+ required for half-maximal inhibition was 0.6 mM. The effects of externally added cations on /sup 86/Rb+ influx and efflux have established that this pathway is conductive, with a selectivity for K+, Rb+ and Cs+ over Na+ and Li+. The Rb+ uptake is inversely dependent on external pH, but not significantly affected by internal Ca2+ or external amiloride, quinine, quinidine or lidocaine. It is likely, albeit not yet certain, that the conductive Rb+ pathway is incorporated in basolateral vesicles oriented right-side-out. It is also not yet clear whether this pathway comprises the principle basolateral K+ channel in vivo, and that its properties have been unchanged during the preparative procedures. Subject to these caveats, the data suggest that the inhibition by quinidine of Na+ transport across toad bladder does not arise primarily from membrane depolarization produced by a direct blockage of the basolateral channels. It now seems more likely that the quinidine-induced elevation of intracellular Ca2+ activity directly blocks apical Na+ entry.

  13. Breeding pond selection and movement patterns by eastern spadefoot toads (Scaphiopus holbrookii) in relation to weather and edaphic conditions.

    SciTech Connect (OSTI)

    Greenberg, Cathyrn, H.; Tanner, George, W.

    2004-08-31

    Cathryn H. Greenberg and George W. Tanner. 2004. Breeding pond selection and movement patterns by eastern spadefoot toads (Scaphiopus holbrookii) in relation to weather and edaphic conditions. J. Herp. 38(4):569-577. Abstract: Eastern Spadefoot Toads (Scaphiopus holbrookii) require fish-free, isolated, ephemeral ponds for breeding but otherwise inhabit the surrounding uplands, commonly xeric longleaf pine (Pinus palustris) ?wiregrass (Aristida beyrichiana). Hence both pond and upland conditions can potentially affect their breeding biology, and population persistence. Hardwood invasion due to fire suppression in sandhills could alter upland and pond suitability by higher hardwood density and increased transpiration. In this paper we explore breeding and neonatal emigration movements in relation to weather, hydrological conditions of ponds, and surrounding upland matrices. We use 9 years of data from continuous monitoring with drift fences and pitfall traps at 8 ephemeral ponds in 2 upland matrices: regularly-burned, savanna-like sandhills (n = 4), and hardwood-invaded sandhills (n = 4). Neither adult nor neonate captures differed between ponds within the 2 upland matrices, suggesting that they are tolerant of upland heterogeneity created by fire frequency. Explosive breeding occurred during 9 periods and in all seasons; adults were captured rarely otherwise. At a landscape-level rainfall, maximum change in barometric pressure, and an interaction between those 2 variables were significant predictors of explosive breeding. At a pond-level, rainfall, change in pond depth during the month prior to breeding, and days since a pond was last dry were significant predictors of adult captures. Transformation date, rather than weather, was associated with neonatal emigrations, which usually were complete within a week. Movement by first-captured adults and neonates was directional, but adult emigrations were apparently not always toward their origin. Our results suggest that

  14. Studies of Annual and Seasonal Variations in Four Species of Reptiles and Amphibians at Los Alamos National Laboratory

    SciTech Connect (OSTI)

    Keller, D.C.; Nelson, E.I.; Mullen, M.A.; Foxx, T.S.; Haarmann, T.K.

    1998-07-01

    Baseline studies of reptiles and amphibians of the Pajarito wetlands at Los Alamos National Laboratory have been conducted by the Ecology group since 1990. With the data gathered from 1990-1997 (excluding 1992), we examined the annual and seasonal population changes of four species of reptiles and amphibians over the past seven years. The four species studied are the Woodhouse toad (Bufo woodhousii), the western chorus frog (Pseudacris triseriata), the many-lined skink (Eunzeces nudtivirgatus), and the plateau striped whiptail lizard (Cnemidophorus velox). Statistical analyses indicate a significant change on a seasonal basis for the western chorus frog and the many-lined skink. Results indicate a significant difference in the annual population of the Woodhouse toad.

  15. SREL Reprint #3002

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Habitat Selection by Recently Metamorphosed Bufo terrestris and Scaphiopus holbrookii Brooke Baughman and Brian D. Todd University of Georgia, Savannah River Ecology Laboratory,...

  16. SREL Reprint #3060

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Habitat selection by southern toads did not vary according to body size, sex, or the environmental cues we measured. However, marbled salamanders were more likely to enter ...

  17. SREL Reprint #3311

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Lethal and sublethal measures of chronic copper toxicity in the eastern narrowmouth toad, ... and for some metals, such as copper (Cu), even low-level chronic ...

  18. SREL Reprint #3158

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of a species facing continued destruction of its breeding habitat (small isolated wetlands) as well as fragmentation of upland life zones. Keywords: Scaphiopus, Spadefoot toad,...

  19. SREL Reprint #3361

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    1 Effects of metal and predator stressors in larval southern toads (Anaxyrus terrestris) Caitlin T. Rumrill, David E. Scott, and Stacey L. Lance Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802, USA Abstract: Natural and anthropogenic stressors typically do not occur in isolation; therefore, understanding ecological risk of contaminant exposure should account for potential interactions of multiple stressors. Realistically, common contaminants can also occur chronically

  20. AmeriFlux CA-NS4 UCI-1964 burn site wet

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Goulden, Mike [University of California - Irvine

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site CA-NS4 UCI-1964 burn site wet. Site Description - The UCI-1964 wet site is located in a continental boreal forest, dominated by black spruce trees, within the BOREAS northern study area in central Manitoba, Canada. The site is a member of a chronological series of sites that are representative secondary succession growth stages after large stand replacement fires. Black spruce trees undergo a slow growth process enabling the accurate determination of the chronosequence of stand age disturbance. Additionally, boreal forests make up approximately 25% of forest ecosystems on earth. With both of these in mind, the UCI sites provide an excellent location to study the CO2 exchange between the atmosphere and boreal forest ecosystems as a function of sequential wildfires.

  1. AmeriFlux CA-NS3 UCI-1964 burn site

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Goulden, Mike [University of California - Irvine

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site CA-NS3 UCI-1964 burn site. Site Description - The UCI-1964 site is located in a continental boreal forest, dominated by black spruce trees, within the BOREAS northern study area in central Manitoba, Canada. The site is a member of a chronological series of sites that are representative secondary succession growth stages after large stand replacement fires. Black spruce trees undergo a slow growth process enabling the accurate determination of the chronosequence of stand age disturbance. Additionally, boreal forests make up approximately 25% of forest ecosystems on earth. With both of these in mind, the UCI sites provide an excellent location to study the CO2 exchange between the atmosphere and boreal forest ecosystems as a function of sequential wildfires.

  2. AmeriFlux CA-NS7 UCI-1998 burn site

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Goulden, Mike [University of California - Irvine

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site CA-NS7 UCI-1998 burn site. Site Description - The UCI-1998 site is located in a continental boreal forest, dominated by black spruce trees, within the BOREAS northern study area in central Manitoba, Canada. The site is a member of a chronological series of sites that are representative secondary succession growth stages after large stand replacement fires. Black spruce trees undergo a slow growth process enabling the accurate determination of the chronosequence of stand age disturbance. Additionally, boreal forests make up approximately 25% of forest ecosystems on earth. With both of these in mind, the UCI sites provide an excellent location to study the CO2 exchange between the atmosphere and boreal forest ecosystems as a function of sequential wildfires.

  3. AmeriFlux CA-NS8 UCI-2003 burn site

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Goulden, Mike [University of California - Irvine

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site CA-NS8 UCI-2003 burn site. Site Description - The UCI-2003 site is located in a continental boreal forest, dominated by black spruce trees, within the BOREAS northern study area in central Manitoba, Canada. The site is a member of a chronological series of sites that are representative secondary succession growth stages after large stand replacement fires. Black spruce trees undergo a slow growth process enabling the accurate determination of the chronosequence of stand age disturbance. Additionally, boreal forests make up approximately 25% of forest ecosystems on earth. With both of these in mind, the UCI sites provide an excellent location to study the CO2 exchange between the atmosphere and boreal forest ecosystems as a function of sequential wildfires.

  4. AmeriFlux CA-NS1 UCI-1850 burn site

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Goulden, Mike [University of California - Irvine

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site CA-NS1 UCI-1850 burn site. Site Description - The UCI-1850 site is located in a continental boreal forest, dominated by black spruce trees, within the BOREAS northern study area in central Manitoba, Canada. The site is a member of a chronological series of sites that are representative secondary succession growth stages after large stand replacement fires. Black spruce trees undergo a slow growth process enabling the accurate determination of the chronosequence of stand age disturbance. Additionally, boreal forests make up approximately 25% of forest ecosystems on earth. With both of these in mind, the UCI sites provide an excellent location to study the CO2 exchange between the atmosphere and boreal forest ecosystems as a function of sequential wildfires.

  5. AmeriFlux CA-NS5 UCI-1981 burn site

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Goulden, Mike [University of California - Irvine

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site CA-NS5 UCI-1981 burn site. Site Description - The UCI-1981 site is located in a continental boreal forest, dominated by black spruce trees, within the BOREAS northern study area in central Manitoba, Canada. The site is a member of a chronological series of sites that are representative secondary succession growth stages after large stand replacement fires. Black spruce trees undergo a slow growth process enabling the accurate determination of the chronosequence of stand age disturbance. Additionally, boreal forests make up approximately 25% of forest ecosystems on earth. With both of these in mind, the UCI sites provide an excellent location to study the CO2 exchange between the atmosphere and boreal forest ecosystems as a function of sequential wildfires.

  6. AmeriFlux CA-NS6 UCI-1989 burn site

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Goulden, Mike [University of California - Irvine

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site CA-NS6 UCI-1989 burn site. Site Description - The UCI-1989 site is located in a continental boreal forest, dominated by black spruce trees, within the BOREAS northern study area in central Manitoba, Canada. The site is a member of a chronological series of sites that are representative secondary succession growth stages after large stand replacement fires. Black spruce trees undergo a slow growth process enabling the accurate determination of the chronosequence of stand age disturbance. Additionally, boreal forests make up approximately 25% of forest ecosystems on earth. With both of these in mind, the UCI sites provide an excellent location to study the CO2 exchange between the atmosphere and boreal forest ecosystems as a function of sequential wildfires.

  7. AmeriFlux CA-NS2 UCI-1930 burn site

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Goulden, Mike [University of California - Irvine

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site CA-NS2 UCI-1930 burn site. Site Description - The UCI-1930 site is located in a continental boreal forest, dominated by black spruce trees, within the BOREAS northern study area in central Manitoba, Canada. The site is a member of a chronological series of sites that are representative secondary succession growth stages after large stand replacement fires. Black spruce trees undergo a slow growth process enabling the accurate determination of the chronosequence of stand age disturbance. Additionally, boreal forests make up approximately 25% of forest ecosystems on earth. With both of these in mind, the UCI sites provide an excellent location to study the CO2 exchange between the atmosphere and boreal forest ecosystems as a function of sequential wildfires.

  8. Assessment & Commitment Tracking System (ACTS)

    Energy Science and Technology Software Center (OSTI)

    2004-12-20

    The ACTS computer code provides a centralized tool for planning and scheduling assessments, tracking and managing actions associated with assessments or that result from an event or condition, and "mining" data for reporting and analyzing information for improving performance. The ACTS application is designed to work with the MS SQL database management system. All database interfaces are written in SQL. The following software is used to develop and support the ACTS application: Cold Fusion HTMLmoreJavaScript Quest TOAD Microsoft Visual Source Safe (VSS) HTML Mailer for sending email Microsoft SQL Microsoft Internet Information Serverless

  9. Tank Closure and Waste Management Environmental Impact Statement for the Hanford Site, Richland, Washington

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Chapter 5 ▪ Long-Term Environmental Consequences 5-1163 5.3.3 Ecological Risk This section presents the results of the evaluation of long-term impacts on ecological resources of releases to air and groundwater under the Waste Management alternatives. Risk indices-Hazard Quotient and Hazard Index-were calculated by comparing the predicted dose to the benchmark dose (see Appendix P). Risk indices could not be calculated for soil-dwelling invertebrates, lizards, toads, or birds exposed to organic

  10. Assessment & Commitment Tracking System (ACTS)

    Energy Science and Technology Software Center (OSTI)

    2004-12-20

    The ACTS computer code provides a centralized tool for planning and scheduling assessments, tracking and managing actions associated with assessments or that result from an event or condition, and "mining" data for reporting and analyzing information for improving performance. The ACTS application is designed to work with the MS SQL database management system. All database interfaces are written in SQL. The following software is used to develop and support the ACTS application: Cold Fusion HTMLmore » JavaScript Quest TOAD Microsoft Visual Source Safe (VSS) HTML Mailer for sending email Microsoft SQL Microsoft Internet Information Server« less

  11. Assessment & Commitment Tracking System (ACTS)

    SciTech Connect (OSTI)

    Bryant, Robert A.; Childs, Teresa A.; Miller, Michael A.; Sellars, Kevin J.

    2004-12-20

    The ACTS computer code provides a centralized tool for planning and scheduling assessments, tracking and managing actions associated with assessments or that result from an event or condition, and "mining" data for reporting and analyzing information for improving performance. The ACTS application is designed to work with the MS SQL database management system. All database interfaces are written in SQL. The following software is used to develop and support the ACTS application: Cold Fusion HTML JavaScript Quest TOAD Microsoft Visual Source Safe (VSS) HTML Mailer for sending email Microsoft SQL Microsoft Internet Information Server

  12. Environmental Data from the ORNL Distributed Active Archive Center (DAAC) for Biogeochemical Dynamics

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    The Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC) is a NASA-sponsored source for biogeochemical and ecological data and models useful in environmental research. Data have been collected on the ground, by aircraft, by satellite, and from computer models. The extent of data and model products ranges from site specific to global, and durations range from days to years. Data products and models are free, but users must typically register. Major field campaigns with available data include: • The Boreal Ecosystem - Atmosphere Study (BOREAS) • The First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment (FIFE) Project) • The Large-Scale Biosphere - Atmosphere Experiment in Amazonia (LBA) • The North American Carbon Program (NACP) • Oregon Transect Ecosystem Research (OTTER) Project • The SAFARI 2000 (S2K) Project in Africa • Superior National Forest(SNF)Project Validation projects with available data include: • BigFoot • The Accelerated Canopy Chemistry Program (ACCP) • The EOS Land Validation Project • FLUXNET • MODIS • The Prototype Validation Exercise (PROVE) The ORNL DAAC also provides access to data for many regional and global projects and to a model archive. (Specialized Interface)(Registration Required)

  13. Improving the selection of bolted joint parameters by using results from finite-element analysis

    SciTech Connect (OSTI)

    Ziada, H.H.

    1992-10-01

    Finite-element techniques were used to determine the combination of parameters that would produce the optimum design for the bolted joint. A finite-element model was constructed from a combination of two-dimensional isoparametric axisymmetric solid elements and gap elements. The gap elements represented the physical contact between the plate and bolt head and the plate and nut. The model was used to determine the stress patterns, displacements, and contact areas (separation diameters) across the bolted joint. Computed results for the contact area showed the following: the contact area is determined by joint design, not bolt Toad magnitude; joint thickness, plate thickness ratio, and bolt-head dimensions have a pronounced effect on the contact area; and the maximum contact area occurs with plates of equal thickness. The change in separation diameters (D) can be presented in a simple straight-line expression D/d = 1 + 1.1 (L/d), where L = joint thickness and d = bolt diameter. The stress results indicated that neither load nor stress distribution under the bolt head or nut is constant or uniform. Bolt-head dimensions, joint thickness, and plate thickness ratio markedly affect the developed stresses, with the maximum stress value occurring at the bolt-plate interface. Beyond the bolt head, maximum stress develops at the interface plane of the bolted plates, with that stress decreasing as the plate thickness ratio increases reaching its lowest value at the equal-thickness ratio. These results indicate that design stiffness formulas used heretofore are not adequate. Results provided by this analysis should prove more effective in achieving optimum bolt design for bolted joints.