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2009-11-15
In the Swedish repository concept for nuclear waste (KBS-3 concept), the spent nuclear fuel will be stored in copper canisters surrounded by compacted bentonite. The decaying power of the fuel will increase the temperature in the repository which, in combination with the uptake of ground-water, are expected to result in minor mineralogical changes in the bentonite. The ongoing LOT test series at the Aespoe Hard Rock Laboratory (HRL) are focused on identifying and quantifying such mineralogical alterations in the bentonite exposed to typical repository-like conditions. Further, buffer-related processes concerning copper corrosion, cation transport, and bacterial survival/activity are studied. In total, the LOT project includes seven test parcels, which contain a central Cu-tube surrounded by cylindrical bentonite blocks with a diameter of 30 cm, and gauges for temperature, total pressure, water pressure and humidity. Electrical heaters placed inside the copper tube are used to simulate the power from the decaying spent fuel. Three parcels are exposed to standard KBS-3 conditions (maximum temperature below 100 deg C) and four parcels to adverse conditions (maximum temperature below approx140 deg C). Both the standard and the adverse test series include short term tests (1 to 2 years), medium term tests (>5 years) and long term tests (>10 years). The present report concerns the A2 test parcel, which was a medium term test exposed to adverse conditions. Cu-coupons, 60Co tracers, bacteria and specific chemical substances were placed in the bentonite at defined positions. After field exposure, the entire test parcel was released from the rock by overlapping percussion drilling and wire sawing. The parcel was lifted and divided at test site and the bentonite material was sampled for specified analyses performed by nine different laboratories in five countries. The main aspects of the various tests and analyses may be summarized in the following items: - physical properties (water content, density, swelling pressure, hydraulic conductivity, and rheology), - mineralogical alteration of the bentonite, - distribution of added substances (e.g. diffusional transport of 60Co), - copper corrosion, - bacterial survival/activity. The main focus was on bentonite mineralogy, which, was studied by Andra, BGR, Nagra, and Posiva in addition to SKB. The results of the former studies are reported in separate appendices. Reference and exposed bentonite material were analyzed by the various groups for a number of parameters by use of an array of techniques such as mineralogy by X-ray diffraction, exchange of cations, element distribution and electron microscopy. Some specific results of interest may be summarized by the following items: - reorganization of easily dissolved accessory minerals in the bentonite, in particular CaSO{sub 4}, - increase in cation exchange capacity of the bentonite in parts exposed to high temperature, - no formation of illite or other typical montmorillonite alteration minerals, - decrease in strain at failure of bentonite exposed to high temperature, - diffusive transport of trace elements in accordance with previous studies, - corrosion rate of metallic copper in agreement with model predictions and previous tests, - a minor survival of bacteria. An overarching conclusion is that the observed mineralogical alterations, as a consequence of the water saturation process and the exposure to high temperature, are relatively small and that these alterations did not change the physical properties to such an extent that the buffer function is jeopardized
2009-01-01
In the Swedish repository concept for nuclear waste (KBS-3 concept), the spent nuclear fuel will be stored in copper canisters surrounded by compacted bentonite. The decaying power of the fuel will increase the temperature in the repository which, in combination with the uptake of ground-water, are expected to result in minor mineralogical changes in the bentonite. The ongoing LOT test series at the Aespoe Hard Rock Laboratory (HRL) are focused on identifying and quantifying such mineralogical alterations in the bentonite exposed to typical repository-like conditions. Further, buffer-related processes concerning copper corrosion, cation transport, and bacterial survival/activity are studied. In total, the LOT project includes seven test parcels, which contain a central Cu-tube surrounded by cylindrical bentonite blocks with a diameter of 30 cm, and gauges for ... >>
Chemical conditions in the A2 parcel of the long-term test of buffer material in Aespoe (LOT)
2006-10-15
The Long-Term Test of Buffer Material (LOT) is underway in the Aespoe Hard Rock Laboratory in Sweden to test the buffer material for nuclear waste disposal. The test parcels contain prefabricated bentonite blocks placed around a copper tube. A heater is placed in the lower part of the copper tube in order to simulate the heating effect of the spent fuel. The parcels are 300 mm in a diameter and placed in 4 m-long vertical boreholes in granitic rock at a depth of 450 m. This report concerns the chemical studies performed on the parcel A2, which was excavated after about five years of experiment period. Two sample blocks were taken from the hot part of the parcel for studies. One of them was without additives while in the other one, cement plugs had been placed. In the block without additives the water content, which was close to the heater 28 - 30 wt% of the dry bentonite, increased to 32 - 33 wt% close to the rock. The total concentrations of dissolving chloride and sulphate in bentonite were determined by dispersing bentonite samples in deionized water. It was obvious that sulphate had redistributed and precipitated close to the heater during the experiment. The initial chloride concentration of bentonite had increased during the experiment approximately by a factor of ten. The increase in the chloride concentration was caused by chloride in the saturating groundwater. Porewaters were squeezed out from the bentonite samples and their Na{sup +}, K{sup +}, Ca{sup 2+}, Mg{sup 2+}, Cl{sup -}, SO{sub 4}{sup 2-} and HCO{sub 3}{sup -} concentrations determined. The chloride, sodium and potassium concentrations were rather independent of the distance from the heater. The calcium, magnesium and sulphate concentrations increased and bicarbonate concentrations decreased proceeding from the outer surface towards close to the heater. The chloride concentration in the squeezed porewater was slightly higher than that determined by the dispersion method, but about half of the concentration in the Aespoe groundwater. The Eh and pH were measured directly in bentonite samples. Close to the outer surface, the pH in the bentonite was 7.2 and increased to 8.3 close to the heater. The Eh measurements suggest that the conditions in the bentonite were reducing. With the gold electrode, the Eh varied from -183 to -228 mV and with the Pt electrode from -287 to -366 mV, where the more negative values represent the conditions close to the heater. In the block with the cement plugs the water content was somewhat higher than in the block without cement, which may be caused by the effect of the lower temperature in the block with cement. The concentrations of Na{sup +}, K{sup +}, Ca{sup 2+}, Mg{sup 2+}, Cl{sup -}, SO{sub 4}{sup 2-} and HCO{sub 3}{sup -} in the squeezed porewaters were practically independent of the distance from the cement but clearly higher than in the block without cement. The pH values were generally somewhat higher than in the block without cement, (orig.)
Chemical conditions in the A2 parcel of the long-term test of buffer material in Aespoe (LOT)
2006-01-01
The Long-Term Test of Buffer Material (LOT) is underway in the Aespoe Hard Rock Laboratory in Sweden to test the buffer material for nuclear waste disposal. The test parcels contain prefabricated bentonite blocks placed around a copper tube. A heater is placed in the lower part of the copper tube in order to simulate the heating effect of the spent fuel. The parcels are 300 mm in a diameter and placed in 4 m-long vertical boreholes in granitic rock at a depth of 450 m. This report concerns the chemical studies performed on the parcel A2, which was excavated after about five years of experiment period. Two sample blocks were taken from the hot part of the parcel for studies. One of them was without additives while in the other one, cement plugs had been placed. In the block without additives the water content, which was close to the heater 28 - 30 wt% of the dry bentonite, increased to 32 - 33 wt% ... >>
2008-10-29
In standard experimental environments, a constant proportion of CA1 principal cells are place cells, each with a spatial receptive field called a place field. Although the properties of place...Full Text Available
2008-10-29
Full Text Available.In standard experimental environments, a constant proportion of CA1 principal cells are place cells, each with a spatial receptive field called a place field. Although the properties of place cells are a basis for understanding the mammalian representation of spatial knowledge, there is no consensus on which of the two fundamental neural-coding hypotheses correctly accounts for how place cells encode spatial information. Within the dedicated-coding hypothesis, each cell’s current activity is an independent estimate of the location with respect to its place field. The average of the location estimates from many cells represents current location, so a dedicated place code would degrade if single cells had multiple place fields. Within the alternative, ensemble-coding hypothesis, the concurrent discharge of many place cells is a vector that represents current location. An ensemble place code is not degraded if single cells have multiple place fields as long as the discharge vector at each location is unique. Place cells with multiple place fields might be required to represent the substantially larger space in more natural environments. To distinguish between the dedicated-coding and ensemble-coding hypotheses, we compared the characteristics of CA1 place fields in a standard cylinder and a ~6-times larger chamber. Compared to the cylinder, in the chamber, more CA1 neurons were place cells, each with multiple, irregularly-arranged, and enlarged place fields. The results indicate that multiple place fields is a fundamental feature of CA1 place cell activity and that, consequently, an ensemble place code is required for CA1 discharge to accurately signal location.
Twelve-Month Evaluation of UPS Diesel Hybrid Electric Delivery Vans
2009-12-01
Results of an NREL study of a parallel hybrid electric-diesel propulsion system in United Parcel Service-operated delivery vans show that the hybrids had higher fuel economy than standard diesel vans.
Tiger Team Assessment, Energy Technology Engineering Center
1991-04-01
The Office Special Projects within the Office of Environment, Safety, and Health (EH) has the responsibility to conduct Tiger Team Assessments for the Secretary of Energy. This report presents the assessment of the buildings, facilities, and activities under the DOE/Rockwell Contract No. DE-AM03-76SF00700 for the Energy Technology Engineering Center (ETEC) and of other DOE-owned buildings and facilities at the Santa Susana Field Laboratory (SSFL) site in southeastern Ventura County, California, not covered under Contract No. DE-AM03-76SF00700, but constructed over the years under various other contracts between DOE and Rockwell International. ETEC is an engineering development complex operated for DOE by the Rocketdyne Division of Rockwell International Corporation. ETEC is located within SSFL on land owned by Rockwell. The balance of the SSFL complex is owned and operated by Rocketdyne, with the exception of a 42-acre parcel owned by the National Aeronautics and Space Administration (NASA). The primary mission of ETEC is to provide engineering, testing, and development of components related to liquid metals technology and to conduct applied engineering development of emerging energy technologies.
Thermal diffusion factors for binary gas systems at low pressures. Estimation from theory. Part 1
1994-12-31
A procedure is presented for an easy-to-program procedure for estimating thermal diffusion factors for mixtures of nonpolar gases as a function of both temperature and composition. According to kinetic theory of multicomponent gaseous mixtures, there is coupling between concentration and temperature gradients such that each contributes to both the mass and energy fluxes. These additional effects, a transport of mass due to a temperature gradient (thermal diffusion or Soret effect) and a transport of energy due to concentration gradient (diffusion-thermo effect or Dufour effect) are in many cases small and therefore usually neglected. Nevertheless, there are applications where thermodiffusional effects are desirable or their contribution needs to be considered. Some examples are: the separation of isotopes, chemical depositions of metallic coatings from vapor phase compounds (CVD), transpiration cooling, and deposition of salts on gas turbine blades. The Onsager reciprocal relations show that only one additional transport property - the thermal diffusion factor of {alpha} - is necessary to describe both thermodiffusional phenomena
TWRS privatization phase I site development engineering study
1996-09-30
The DOE-RL is pursuing a new business strategy of hiring private contractors for treatment of Hanford Site tank wastes. This strategy is called `privatization` and includes design, permitting, construction, operation and deactivation of facilities for tank waste treatment. The TWRS Privatization Infrastructure Project consists of several sub-projects which will provide key services needed to support the privatization mission. One sub-project is to develop the selected site for the privatization facilities. This study addresses the pertinent issues related to the development of the site and specific parcels to be assigned to each of two private contractors. It also summarizes other studies that address provisions for utilities and other site services.
Studies of buffers behaviour in KBS-3H concept. Work during 2002-2004
2005-08-01
In the KBS-3H concept, the deposition tunnels are replace by horizontal 300-m long circular deposition drifts which are excavated from a niche in the transport tunnel. About 40 disposal containers will be deposited in each drift. In order to make the deposition process easier the buffer material and one copper canister are assembled in a steel disposal container, which then is pushed into the deposition drift. The disposal container consists of a perforated steel cylinder in which the buffer material and one copper canister are assembled. Distance blocks of bentonite are placed between each disposal container. The purpose of the distance blocks is to seal off each canister position from the other and to prevent transport of water and bentonite along the drift. The distance blocks also separate one canister from the other in order to get the right temperature of the canister. The total thickness of the distance blocks between the disposal containers is mainly determined by the thermal conductivity of the rock and is expected to be in the range of 3-6 m. The main objective for the KBS-3H concept is that the method provides a more efficient way of depositing the canisters in the rock. The reason is that the deposition tunnels of the KBS-3V concept are not needed and the reduction of rock excavation is therefore about 50 percent. This leads to a lower environmental impact during the construction of the repository but also to a reduced disturbance on the hydro-geological situation in the rock mass. Furthermore, the reduction in rock excavation leads to a significant cost saving for the excavation phase and backfilling of the repository. KBS-3H and KBS-3V are very similar with respect to the behaviour of the bentonite buffer. However, there are some differences that require special attention. An early survey of the differences yielded that there are a number of processes and functions that needed to be investigated for evaluating the feasibility of the concept: 1. The function of the distance block. Scenario analyses of different concepts for design and installation of the distance blocks for finding critical issues. 2. Sealing ability of the distance plugs during water inflow. 3. Influence of rapid increase of water pressure inside the distance blocks. 4. Piping and erosion phenomena of the swelling bentonite during the installation phase and during the water saturation phase. 5. Mechanical interaction between the container and the buffer during the homogenisation of the bentonite and breakage of the container. 6. Near field thermal and hydraulic evolution. These processes have been studied by Clay Technology in a number of tests and analyses during 2002 to 2004. The studies can be structured in the following way: 1. Test scaled 1:10 of a simulated part of a deposition tunnel with two canisters. 2. Design and planning of a large-scale test of the interaction between the bentonite and the perforated deposition container and manufacturing of components (Big Bertha). 3. Investigation of sealing/piping/erosion phenomena during wetting of the buffer material. a) Basic laboratory tests. b) Study of processes and scenarios in the scale 1:10. c) Study of processes and scenarios in full scale. 4. Investigation of the effect of rapid water pressure increase inside the distance blocks by model tests in the scale 1:10 and in full scale. 4. Modelling a) Modelling of the interaction between the bentonite and the perforated deposition container. b) Modelling of temperature conditions for design and safety analysis purpose. c) Modelling of the water saturation phase and the influence of the hydraulic properties of the rock. d) Modelling of the wetting of the test scaled 1:10. e) Scenario analyses and conceptual modelling of the function of different distance block concepts. These studies and the results and conclusions reached will be presented in this report. The report should be considered a state of the art report at the end of 2004. The studies are planned to continue during the coming years.
1996-11-01
This report documents a research project undertaken to assess the feasibility of using scrap reground expanded polystyrene (EPS) in the manufacture of structural insulated panels (SIPs) in order to save material costs and reduce the amount of EPS waste products to be disposed. The project team, managed by Steven Winter Associates, Inc., a Norwalk, Connecticut-based building systems research and consulting firm included: Thermal Foams, Inc., a Buffalo-based manufacturer of EPS products; BASF Corp., the world`s largest producer of EPS beads; Oak Ridge National Laboratory, which performed thermal tests (ASTM C-518); RADCO, Inc. which performed material properties tests: density (ASTM C-303), flexural strength (ASTM C-203), tensile strength (ASTM D-1623), and transverse load test of SIPs panels (ASTM E-72). The report documents the manufacturing and testing process and concludes that there was relatively little difference in the thermal and structural characteristics under normal loading conditions of the panels tested with varying amount of regrind (from 10% - 25%) and those made with 100% virgin beads. The report recommends that additional tests be undertaken, but suggests that, based on the test results, reground EPS can be successfully used in the cores of SIPs in amounts up to 25%.
Size distributions of boundary-layer clouds
1996-04-01
Scattered fair-weather clouds are triggered by thermals rising from the surface layer. Not all surface layer air is buoyant enough to rise. Also, each thermal has different humidities and temperatures, resulting in interthermal variability of their lifting condensation levels (LCL). For each air parcel in the surface layer, it`s virtual potential temperature and it`s LCL height can be computed.
Seasonal Variability and Transport of Suspended Microfungi in a Southeastern Salt Marsh †
1982-02-01
Tidally induced fluctuations and transports of microfungi were investigated. Samples were collected at three depths from three stations positioned at a transect in a large salt marsh creek. Samples...Full Text Available
Seasonal Variability and Transport of Suspended Microfungi in a Southeastern Salt Marsh †
1982-02-01
Full Text Available.Tidally induced fluctuations and transports of microfungi were investigated. Samples were collected at three depths from three stations positioned at a transect in a large salt marsh creek. Samples were taken every 1.5 h for 50 consecutive h during neap tides and 50 consecutive h during the corresponding spring tides. In each season, microfungi concentrations fluctuated out of phase with the tides during both neap and spring tides. Mean concentrations of suspended microfungi did not vary appreciably throughout the year. Fungi were exported from the marsh during the majority of the tidal cycles studied. The results suggest that microfungi may serve as indicators of water mass movements.
2009-01-01
Full Text Available.An international External Quality Assurance System (EQAS) for antimicrobial susceptibility testing of Salmonella was initiated in 2000 by the World Health Organization (WHO) Global Salm-Surv in order to enhance the capacities of national reference laboratories to obtain reliable data for surveillance purposes worldwide. Seven EQAS iterations have been conducted from 2000 to 2007. In each iteration, participating laboratories submitted susceptibility results from 10 to 15 antimicrobial agents for eight Salmonella isolates and an Escherichia coli reference strain (ATCC 25922). A total of 287 laboratories in 102 countries participated in at least one EQAS iteration. A large number of laboratories reported results for the E. coli ATCC 25922 reference strain which were outside the quality control ranges. Critical deviations for susceptibility testing of the Salmonella isolates varied from 4% in 2000 to 3% in 2007. Consistent difficulties were observed in susceptibility testing of amoxicillin-clavulanic acid, cefotaxime, ceftazidime, streptomycin, sulfonamides, and tetracycline. Regional variations in performance were observed, with laboratories in central Asia, Africa, and the Middle East not performing as well as those in other regions. Results from the WHO Global Salm-Surv EQAS show that most laboratories worldwide are capable of correctly performing antimicrobial susceptibility testing of Salmonella isolates, but they also indicate that further improvement for some laboratories is needed. In particular, further training and dissemination of information on quality control, appropriate interpretive criteria (breakpoints), and harmonization of the methodology worldwide through WHO Global Salm-Surv and other programs will contribute to the generation of comparable and reliable antimicrobial susceptibility data (D. M. A. Lo Fo Wong, R. S. Hendriksen, D. J. Mevius, K. T. Veldman, and F. M. Aarestrup, Vet. Microbiol. 115:128-139, 2006).
2009-01-01
An international External Quality Assurance System (EQAS) for antimicrobial susceptibility testing of Salmonella was initiated in 2000 by the World Health Organization (WHO) Global...Full Text Available
1989-05-01
Pressure versus distance relations have been obtained for solid (gel) and neat (liquid-crystalline) phase uncharged lipid bilayers by the use of x-ray diffraction analysis of osmotically stressed monoglyceride...Full Text Available
1989-05-01
Full Text Available.Pressure versus distance relations have been obtained for solid (gel) and neat (liquid-crystalline) phase uncharged lipid bilayers by the use of x-ray diffraction analysis of osmotically stressed monoglyceride aqueous dispersions and multilayers. For solid phase monoelaidin bilayers, the interbilayer repulsive pressure decays exponentially from a bilayer separation of approximately 7 A at an applied pressure of 3 x 10(7) dyn/cm2 to a separation of approximately 11 A at zero applied pressure, where an excess water phase forms. The decay length is approximately 1.3 A, which is similar to the value previously measured for gel phase phosphatidylcholine bilayers. This implies that the decay length of the hydration pressure does not depend critically on the presence of zwitterionic head groups in the bilayer surface. For liquid-crystalline monocaprylin, the repulsive pressure versus distance curve has two distinct regions. In the first region, for bilayer separations of approximately 3-8 A and applied pressures of 3 x 10(8) to 4 x 10(6) dyn/cm2, the pressure decays exponentially with a decay length of approximately 1.3 A. In the second region, for bilayer separations of approximately 8-22 A and applied pressures of 4 x 10(6) to 1 x 10(5) dyn/cm2, the pressure decays much more gradually and is inversely proportional to the cube of the distance between bilayers. These data imply that two repulsive pressures operate between liquid-crystalline monocaprylin bilayers, the hydration pressure, which dominates at small (3-8 A) bilayer separations, and the fluctuation pressure, which dominates at larger bilayer separations (greater than 8 A) and strongly influences the hydration properties of the liquid-crystalline bilayers. Thus, due primarily to thermally induced fluctuations, monocaprylin bilayers imbibe considerably more water than do monoelaidin bilayers. For both monoelaidin andmonocaprylin, the measured magnitude of the hydration pressure is found to be proportional to the square of the dipole potential.
Real-time monitoring of copper corrosion at the Aespoe HRL
2004-07-01
In Sweden the principal strategy for high-level radioactive waste disposal is to enclose the spent nuclear fuel in tightly sealed copper canisters that are embedded in bentonite clay about 500 m down in the Swedish bed-rock. Initially, a limited amount of air will be left in a repository after emplacement. The entrapped oxygen will be consumed through reactions with minerals in the rock and the bentonite and also through microbial activity. After the oxygen has been consumed in the repository, after a few hundred years at the very most, corrosion will be controlled completely by the supply of dissolved sulphide to the canister. The present work concerns the oxic period after emplacement. The main hypothesis is that the average corrosion rate of the canister under oxic conditions will be less than 7 {mu}m/year, and that pitting will only be possible under these conditions. The Aespoe Hard Rock Laboratory offers a realistic environment for different experiments and tests under the conditions that will prevail in a deep repository. Real-time monitoring of copper corrosion is presently performed with polarization resistance, harmonic distortion analysis and electrochemical noise techniques. The first two techniques are used to derive information regarding the general corrosion rate and the third to derive information regarding localized corrosion. In order to support these measurements at Aespoe, laboratory work is also performed at the Royal Institute of Technology in Stockholm using the very same corrosion monitoring equipment and also other equipment and techniques. Copper coupons are also exposed at Aespoe. Results from the work at Aespoe and in Stockholm are presented with an emphasis on the gained information concerning localized corrosion. The recorded corrosion rates at Aespoe are well below the value given above, and the recorded localization factors are interpreted as indicating only a slight tendency to local attack. (authors)
On the modeling of fuel sprays
1997-12-01
This report concerns on the modelling of fuel sprays in a non-combustible case using an own developed fuel spray code module. The spray code is made as an independent module to simplify the use of different gas flow solvers together with the spray module. This enables the possibility to use different turbulence models. In the report two turbulence models has been used, the standard k-{epsilon} and the LES (Large Eddy Simulation) model. The report presents results obtained from a sensitivity study of both numerical and physical parameters on an evaporating spray under diesel like conditions (light duty diesel engine) with the spray code module attached to a cylindrical gas phase flow solver. The results from the sensitivity analysis showed that these effects were not so pronounced as has been reported. It was suggested that this was due to the `easy` nature of the investigated case, where the flow field could be sufficiently resolved without violating the droplet void fraction criteria and break-up, collision and combustion that may increase the grid spacing sensitivity were not modelled. An investigation was performed to valuate the feasibility of using LES as turbulence model. Calculations of the initial phase of a developing jet were made and it was found that in the initial phase of the spray and the flow structure were similar to that of a spatially developing jet flow, which is in agreement with experimental observations. Results from LES calculations on a developing spray jet was also compared with k-{epsilon} based ones. This result showed that the spray-LES approach captured the transition from a laminar to a turbulent flow field with an increase in turbulent kinetic energy k along the injection direction 45 refs, 37 figs, 2 tabs
2008-01-01
The purpose of this study was to evaluate whether children with a history of disorganized attachment in infancy were more likely than children without a history of disorganized attachment to...Full Text Available
2008-01-01
Full Text Available.The purpose of this study was to evaluate whether children with a history of disorganized attachment in infancy were more likely than children without a history of disorganized attachment to exhibit symptoms of posttraumatic stress disorder (PTSD) at school age following trauma exposure. The sample consisted of 78 8.5-year-old children from a larger, ongoing prospective study evaluating the effects of intrauterine cocaine exposure (IUCE) on children's growth and development from birth to adolescence. At the 12-month visit, children's attachment status was scored from videotapes of infant–caregiver dyads in Ainsworth's strange situation. At the 8.5-year visit, children were administered the Violence Exposure Scale—Revised, a child-report trauma exposure inventory, and the Diagnostic Interview for Children and Adolescents by an experienced clinical psychologist masked to children's attachment status and IUCE status. Sixteen of the 78 children (21%) were classified as insecure–disorganized/insecure–other at 12 months. Poisson regressions covarying IUCE, gender, and continuity of maternal care indicated that disorganized attachment status at 12 months, compared with nondisorganized attachment status, significantly predicted both higher avoidance cluster PTSD symptoms and higher reexperiencing cluster PTSD symptoms. These findings suggest that the quality of early dyadic relationships may be linked to differences in children's later development of posttraumatic stress symptoms following a traumatic event.
Landscape as a Model: The Importance of Geometry
2007-10-01
In all models, but especially in those used to predict uncertain processes (e.g., climate change and nonnative species establishment), it is important to identify and remove any sources of bias that...Full Text Available
Landscape as a Model: The Importance of Geometry
2007-10-01
Full Text Available.In all models, but especially in those used to predict uncertain processes (e.g., climate change and nonnative species establishment), it is important to identify and remove any sources of bias that may confound results. This is critical in models designed to help support decisionmaking. The geometry used to represent virtual landscapes in spatially explicit models is a potential source of bias. The majority of spatial models use regular square geometry, although regular hexagonal landscapes have also been used. However, there are other ways in which space can be represented in spatially explicit models. For the first time, we explicitly compare the range of alternative geometries available to the modeller, and present a mechanism by which uncertainty in the representation of landscapes can be incorporated. We test how geometry can affect cell-to-cell movement across homogeneous virtual landscapes and compare regular geometries with a suite of irregular mosaics. We show that regular geometries have the potential to systematically bias the direction and distance of movement, whereas even individual instances of landscapes with irregular geometry do not. We also examine how geometry can affect the gross representation of real-world landscapes, and again show that individual instances of regular geometries will always create qualitative and quantitative errors. These can be reduced by the use of multiple randomized instances, though this still creates scale-dependent biases. In contrast, virtual landscapes formed using irregular geometries can represent complex real-world landscapes without error. We found that the potential for bias caused by regular geometries can be effectively eliminated by subdividing virtual landscapes using irregular geometry. The use of irregular geometry appears to offer spatial modellers other potential advantages, which are as yet underdeveloped. We recommend their use in all spatially explicit models, but especially for predictive models that are used in decisionmaking.
1996-10-27
For the development of a unified performance test method for solar DHW (domestic hot water) systems, the Japan Quality Assurance Organization test was applied to three types. In an individual test, each specimen is exposed to irradiation from a solar simulator for 8 hours in a specified pattern. Upon completion of the 8-hour irradiation, hot water is taken from the specimen, the amount being 1.1 times as large as the heat accumulation tank capacity, for the measurement of the collected heat. The control of the heat medium circulation pump, flow rate, and density, all supposed to affect the heat collecting performance, are examined. Stable data, not subject to meteorological factors and high in reproducibility, is obtained, allowing a single test to represent the heat collecting performance. A system test continues for 24 hours, from 8 o`clock on this morning through 8 o`clock on the following morning, with water collected in a specified pattern. This test is suitable for examining the in-service performance of a solar hot water system including the auxiliary heat source. If temperature is not set properly in the auxiliary heat source before testing, the system performance coefficient and sun-dependency coefficient will not be expressed in a uniform manner. For a correct evaluation, measurements should be made only after a several days` uninterrupted operation for the removal of the adverse effect of the heat residual in the heat accumulation tank. 4 refs., 5 figs., 9 tabs.
1983-01-01
The growing use of coal for heating and electric power generation and diesel engines in light duty motor vehicles will increase not only the existing atmospheric concentrations of criteria pollutants...Full Text Available
1983-01-01
Full Text Available.The growing use of coal for heating and electric power generation and diesel engines in light duty motor vehicles will increase not only the existing atmospheric concentrations of criteria pollutants such as NO2, SO2, O3 and fine particulates, but also the concentrations of a number of highly reactive gaseous copollutants such as HONO, HONO2, PAN and the nitrate radical, NO3. These gaseous noncriteria pollutants are of interest not only because of their roles in the chemistry of the "clean" and polluted troposphere, including "acid rain," but also because they may pose health risks disproportionate to their relatively low ambient concentrations, and through complex heterogeneous reactions, they may serve as precursors or catalysts in the formation of "nonclassical" particulate mutagens and carcinogens such as certain nitroarenes associated with combustion generated particulate polycyclic organic matter (POM). Results of research efforts to establish current ambient levels of these noncriteria pollutants and to develop an understanding of their sources, formation and sinks are reported here. First, long pathlength (greater than or equal to 1 km) infrared and UV-visible spectroscopic studies of ambient levels of gaseous HONO, NO3, HONO2, PAN, HCHO and HCOOH in southern California atmospheres are described, and data given on their ambient concentrations. Second, an integrated chemical/microbiological investigation is described. It is directed toward identifying the nature of direct-acting mutagens found in extracts of diesel and ambient POM, as well as those formed upon exposure of environmentally relevant PAH to simulated natural and polluted atmospheres. The identification of certain of these mutagens, including a newly identified class of mutagenic PAH-lactones is discussed, along with the mechanisms of their formation and fate in the natural and polluted troposphere.
Finnish Association for Aerosol Research. Report Series in Aerosol Science. No. 25 (1994)
1994-12-31
This report series discusses aerosol science conducted by the Aerosol Technology Group at the Finnish Association for Aerosol Research. Topics discussed include: thermal diffusion factors for binary gas systems and air parcel models with multicomponent condensation which can be used as a tool for the study of cloud microphysics. This is the lead abstract. Individual papers have been indexed separately for the databases.
1979-08-01
The City of El Centro is proposing the development of a geothermal energy utility core field experiment to demonstrate the engineering and economic feasibility of utilizing moderate temperature geothermal heat, on a pilot scale, for space cooling, space heating, and domestic hot water. The proposed facility is located on part of a 2.48 acre (1 hectare) parcel owned in fee by the City in the southeastern sector of El Centro in Imperial County, California. Geothermal fluid at an anticipated temperature of about 250/sup 0/F (121/sup 0/C) will heat a secondary fluid (water) which will be utilized directly or processed through an absorption chiller, to provide space conditioning and water heating for the El Centro Community Center, a public recreational facility located approximately one-half mile north of the proposed well site. The geothermal production well will be drilled to 8500 feet (2590m) and an injection well to 4000 feet (1220m) at the industrially designated City property. Once all relevant permits are obtained it is estimated that site preparation, facility construction, the completion and testing of both wells would be finished in approximately 26 weeks. The environmental impacts are described.
Device Assembly Facility (DAF) Glovebox Radioactive Waste Characterization
2001-12-18
The Device Assembly Facility (DAF) at the Nevada Test Site (NTS) provides programmatic support to the Joint Actinide Shock Physics Experimental Research (JASPER) Facility in the form of target assembly. The target assembly activities are performed in a glovebox at DAF and include Special Nuclear Material (SNM). Currently, only activities with transuranic SNM are anticipated. Preliminary discussions with facility personnel indicate that primarily two distributions of SNM will be used: Weapons Grade Plutonium (WG-Pu), and Pu-238 enhanced WG-Pu. Nominal radionuclide distributions for the two material types are included in attachment 1. Wastes generated inside glove boxes is expected to be Transuranic (TRU) Waste which will eventually be disposed of at the Waste Isolation Pilot Plant (WIPP). Wastes generated in the Radioactive Material Area (RMA), outside of the glove box is presumed to be low level waste (LLW) which is destined for disposal at the NTS. The process knowledge quantification methods identified herein may be applied to waste generated anywhere within or around the DAF and possibly JASPER as long as the fundamental waste stream boundaries are adhered to as outlined below. The method is suitable for quantification of waste which can be directly surveyed with the Blue Alpha meter or swiped. An additional quantification methodology which requires the use of a high resolution gamma spectroscopy unit is also included and relies on the predetermined radionuclide distribution and utilizes scaling to measured nuclides for quantification.
2003-02-26
This Corrective Action Investigation Plan contains the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office's approach to collect the data necessary to evaluate corrective action alternatives appropriate for the closure of Corrective Action Unit (CAU) 529, Area 25 Contaminated Materials, Nevada Test Site (NTS), Nevada, under the Federal Facility Agreement and Consent Order. CAU 529 consists of one Corrective Action Site (25-23-17). For the purpose of this investigation, the Corrective Action Site has been divided into nine parcels based on the separate and distinct releases. A conceptual site model was developed for each parcel to address the translocation of contaminants from each release. The results of this investigation will be used to support a defensible evaluation of corrective action alternatives in the corrective action decision document.
Comparative studies on Salmonella-isolation in eight European laboratories.
1968-01-01
Full Text Available.
1994-12-31
A one-dimensional parcel model describing the formation of a convective cloud was constructed. Simultaneous condensation of two species is allowed for. The inclusion of explicit dependence of the time derivative of number concentration on the air density was found to decrease the liquid water content. Numerical simulations suggest that the inclusion of small nucleation mode particles in the distribution of pre-existing particles enhances the activation in the upper portion of the cloud broadening the cloud droplet distribution. The presence of condensable nitric acid vapour enhances the activation especially in the lower portion of the cloud
Aespoe Hard Rock Laboratory. Annual report 1997
1998-05-01
The Aespoe Hard Rock Laboratory has been constructed as part of the preparations for the deep geological repository for spent nuclear fuel in Sweden. The surface and borehole investigations and the research work performed in parallel with construction have provided a thorough test of methods for investigation and evaluation of bedrock conditions for construction of a deep repository. The Tracer Retention Understanding Experiments are made to gain a better understanding of radionuclide retention in the rock and create confidence in the radionuclide transport models that are intended to be used in the licensing of a deep repository for spent fuel. The experimental results of the first tracer test with sorbing radioactive tracers have been obtained. These tests have been subject to blind predictions by the Aespoe Task Force on groundwater flow and transports of solutes. The manufacturing of the CHEMLAB probe was completed during 1996, and the first experiments were started early in 1997. During 1997 three experiments on diffusion in bentonite using {sup 57}Co, {sup 114}Cs,{sup 85}Sr, {sup 99}Tc, and {sup 131}I were conducted. The Prototype Repository Test is focused on testing and demonstrating repository system function. A full scale prototype including six deposition holes with canisters with electric heaters surrounded by highly compacted bentonite will be built and instrumented. The characterization of the rock mass in the area of the prototype repository is in progress. The objectives of the Demonstration of Repository Technology are to develop, test, and demonstrate methodology and equipment for encapsulation and deposition of spent nuclear fuel. The demonstration of handling and deposition will be made in a new drift. The Backfill and Plug Test includes tests of backfill materials and emplacement methods and a test of a full scale plug. The backfill and rock will be instrumented with about 230 transducers for measuring the thermo-hydro-mechanical processes. The Retrieval Test is aiming at demonstrating the readiness for recovering of emplaced canisters also after the time when the bentonite has swollen. Planning and preparations for these experiments has continued during 1997. The Long Term Tests of Buffer Material aim to validate models of buffer performance at standard KBS-3 repository conditions, and at quantifying clay buffer alteration processes at adverse conditions. Two test holes were instrumented late 1996 and the temperature has been raised to 90 and 130 deg C, respectively. Nine organisations from eight countries are currently participating in the Aespoe Hard Rock Laboratory in addition to SKB 43 refs, 66 figs, 7 tabs
Aespoe Hard Rock Laboratory. Annual Report 2008
2009-07-15
The Aespoe Hard Rock Laboratory (HRL) is an important part of SKB's work with the design and construction of a deep geological repository for the final disposal of spent nuclear fuel. The main activities in the geoscientific fields have been: (1) Geology - completion of the feasibility study concerning geological mapping techniques and mapping of rock surfaces in the new tunnel, (2) Hydrogeology - monitoring and storage of data in the computerised Hydro Monitoring System, (3) Geochemistry - sampling of groundwater in the yearly campaign and for specific experiments and (4) Rock Mechanics - field tests to evaluate the counterforce needed to prevent thermally-induced spalling in deposition holes. At Aespoe HRL, experiments are performed under the conditions that are expected to prevail at repository depth. The aim is to provide information about the long-term function of natural and repository barriers. Experiments are performed to develop and test methods and models for the description of groundwater flow, radionuclide migration, and chemical conditions at repository depth. The programme includes projects which aim to determine parameter values that are required as input to the conceptual and numerical models. A number of large-scale field experiments and supporting activities concerning Engineered barriers are carried out at Aespoe HRL. The experiments focus on different aspects of engineering technology and performance testing: The Prototype Repository is a demonstration of the integrated function of the repository and provides a full-scale reference for tests of predictive models concerning individual components as well as the complete repository system; The Long Term Test of Buffer Material (Lot-experiment) aims at validating models and hypotheses concerning physical properties in a bentonite buffer material and of related processes regarding microbiology, radionuclide transport, copper corrosion and gas transport; The objective of the project Alternative Buffer Materials is to study clay materials that in laboratory tests have shown to be conceivable buffer materials. Three test parcels with different combinations of clay materials are installed in boreholes at Aespoe HRL; The Backfill and Plug Test is a test of the hydraulic and mechanical function of different backfill materials, emplacement methods and a full-scale plug; The aim of the Canister Retrieval Test was to demonstrate readiness for recovering emplaced canisters even after the time when the surrounding bentonite buffer is fully saturated; The Temperature Buffer Test aims at improving our current understanding of the thermo-hydromechanical behaviour of buffers with a temperature around and above 100 deg C during the water saturation transient. The main goal of the project Sealing of Tunnel at Great Depth is to confirm that silica sol is a useful grout at the water pressures prevailing at repository level. To achieve this, the Tass-tunnel has been constructed at the -450 m level at Aespoe HRL. The objective of the project In situ Corrosion Testing of Miniature Canisters is to obtain a better understanding of the corrosion processes inside a failed canister. In Aespoe HRL in situ experiments are performed with miniature copper canisters with cast iron inserts. The Task Force on Engineered Barrier Systems addresses, in the first phase, two tasks: (1) THM processes and (2) gas migration in buffer material. However, at the end of 2006 it was decided to start a parallel Task Force that deals with geochemical processes in engineered barriers. During 2008, two Task Force meetings have been held. In Benchmark 1 (laboratory tests) the modelling of THM processes and gas breakthrough is finalised. In Benchmark 2 (large scale field tests) the main work has been within modelling of the Canister retrieval test at Aespoe HRL and the finalising of the modelling of the URL tests. Laboratory experiments and results from the experiment Long term test of buffer materials have been used as benchmarks for the performed geochemical modelling. In addition to SKB, eight organisations from seven countries participated in the international co-operation at Aespoe HRL during 2008. Six of them: Andra, BMWi, CRIEPI, JAEA, NWMO and Posiva together with SKB form the Aespoe International Joint Committee which is responsible for the co-ordination of the experimental work arising from the international participation. The international organisations are participating in the experimental work at Aespoe HRL as well as in the two Aespoe Task Forces: (1) Task Force on Modelling of Groundwater Flow and Transport of Solutes and (2) Task Force on Engineered Barrier Systems
A shallow convection parameterization for the non-hydrostatic MM5 mesoscale model
1996-04-01
A shallow convection parameterization suitable for the Pennsylvannia State University (PSU)/National Center for Atmospheric Research nonhydrostatic mesoscale model (MM5) is being developed at PSU. The parameterization is based on parcel perturbation theory developed in conjunction with a 1-D Mellor Yamada 1.5-order planetary boundary layer scheme and the Kain-Fritsch deep convection model.
Species inventories are essential for documenting global diversity and generating necessary material for taxonomic study and conservation planning. However, for inventories to be immediately...Full Text Available
Full Text Available.Species inventories are essential for documenting global diversity and generating necessary material for taxonomic study and conservation planning. However, for inventories to be immediately relevant, the taxonomic process must reduce the time to describe and identify specimens. To address these concerns for the inventory of arthropods across the Malagasy region, we present here a collaborative approach to taxonomy where collectors, morphologists and DNA barcoders using cytochrome c oxidase 1 (CO1) participate collectively in a team-driven taxonomic process. We evaluate the role of DNA barcoding as a tool to accelerate species identification and description.This revision is primarily based on arthropod surveys throughout the Malagasy region from 1992 to 2006. The revision is based on morphological and CO1 DNA barcode analysis of 500 individuals. In the region, five species of Anochetus (A. boltoni sp. nov., A. goodmani sp. nov., A. grandidieri, and A. madagascarensis from Madagascar, and A. pattersoni sp. nov. from Seychelles) and three species of Odontomachus (O. coquereli, O. troglodytes and O. simillimus) are recognized. DNA barcoding (using cytochrome c oxidase 1 (CO1)) facilitated caste association and type designation, and highlighted population structure associated with reproductive strategy, biogeographic and evolutionary patterns for future exploration.This study provides an example of collaborative taxonomy, where morphology is combined with DNA barcoding. We demonstrate that CO1 DNA barcoding is a practical tool that allows formalized alpha-taxonomy at a speed, detail, precision, and scale unattainable by employing morphology alone.
1977-07-01
Full Text Available.A comparison of blastogenic responsiveness to antigens and mitogen by human lymphocytes was made between cells which had been processed for culture immediately following blood collection and cells obtained from blood collected 9-11 hr previously and transported via commercial airline from the patients' homes to our laboratory. There were no significant differences in the responses of transported and non-transported cells if the blood was maintained at ambient temperature during the period of shipment. Chilling the blood during transport, however, resulted both in decreased stimulation of the cells and increased 'background' activity in unstimulated cultures. These findings indicate the feasibility of carrying out both limited immunological evaluations and extended periods of follow-up for patients located at considerable distances from a research laboratory.
1977-07-01
A comparison of blastogenic responsiveness to antigens and mitogen by human lymphocytes was made between cells which had been processed for culture immediately following blood collection and cells obtained...Full Text Available
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