Science.gov

Sample records for dominant precipitation processes

  1. Assessing Precipitation Isotope Variations during Atmospheric River Events to Reveal Dominant Atmospheric/Hydrologic Processes

    NASA Astrophysics Data System (ADS)

    McCabe-Glynn, S. E.; Johnson, K. R.; Yoshimura, K.; Buenning, N. H.; Welker, J. M.

    2015-12-01

    Extreme precipitation events across the Western US commonly associated with atmospheric rivers (ARs), whereby extensive fluxes of moisture are transported from the subtropics, can result in major damage and are projected by most climate models to increase in frequency and severity. However, they are difficult to project beyond ~ten days and the location of landfall and topographically induced precipitation is even more uncertain. Water isotopes, often used to reconstruct past rainfall variability, are useful natural tracers of atmospheric hydrologic processes. Because of the typical tropical and sub-tropical origins, ARs can carry unique water isotope (δ18O and δ2H, d-excess) signatures that can be utilized to provide source and process information that can lead to improving AR predictions. Recent analysis of the top 10 weekly precipitation total samples from Sequoia National Park, CA, of which 9 contained AR events, shows a high variability in the isotopic values. NOAA Hysplit back trajectory analyses reveals a variety of trajectories and varying latitudinal source regions contributed to moisture delivered to this site, which may explain part of the high variability (δ2H = -150.03 to -49.52 ‰, δ18O = -19.27 to -7.20 ‰, d-excess = 4.1 to 25.8). Here we examine the top precipitation totals occurring during AR events and the associated isotopic composition of precipitation samples from several sites across the Western US. We utilize IsoGSM, an isotope-enabled atmospheric general circulation model, to characterize the hydrologic processes and physical dynamics contributing to the observed isotopic variations. We investigate isotopic influences from moisture source location, AR speed, condensation height, and associated temperature. We explore the dominant controls on spatial and temporal variations of the isotopic composition of AR precipitation which highlights different physical processes for different AR events.

  2. Genetic Dominance & Cellular Processes

    ERIC Educational Resources Information Center

    Seager, Robert D.

    2014-01-01

    In learning genetics, many students misunderstand and misinterpret what "dominance" means. Understanding is easier if students realize that dominance is not a mechanism, but rather a consequence of underlying cellular processes. For example, metabolic pathways are often little affected by changes in enzyme concentration. This means that…

  3. URANIUM PRECIPITATION PROCESS

    DOEpatents

    Thunaes, A.; Brown, E.A.; Smith, H.W.; Simard, R.

    1957-12-01

    A method for the recovery of uranium from sulfuric acid solutions is described. In the present process, sulfuric acid is added to the uranium bearing solution to bring the pH to between 1 and 1.8, preferably to about 1.4, and aluminum metal is then used as a reducing agent to convert hexavalent uranium to the tetravalent state. As the reaction proceeds, the pH rises amd a selective precipitation of uranium occurs resulting in a high grade precipitate. This process is an improvement over the process using metallic iron, in that metallic aluminum reacts less readily than metallic iron with sulfuric acid, thus avoiding consumption of the reducing agent and a raising of the pH without accomplishing the desired reduction of the hexavalent uranium in the solution. Another disadvantage to the use of iron is that positive ferric ions will precipitate with negative phosphate and arsenate ions at the pH range employed.

  4. Precipitation Process and Apparatus Therefor

    DOEpatents

    Stang, Jr, L C

    1950-12-05

    This invention concerns an apparatus for remotely-controlled precipitation and filtration operations. Liquid within a precipitation chamber is maintained above a porous member by introducing air beneath the member; pressure beneath the porous member is reduced to suck the liquid through the member and effect filtration.

  5. Identifying Anomality in Precipitation Processes

    NASA Astrophysics Data System (ADS)

    Jiang, P.; Zhang, Y.

    2014-12-01

    Safety, risk and economic analyses of engineering constructions such as storm sewer, street and urban drainage, and channel design are sensitive to precipitation storm properties. Whether the precipitation storm properties exhibit normal or anomalous characteristics remains obscure. In this study, we will decompose a precipitation time series as sequences of average storm intensity, storm duration and interstorm period to examine whether these sequences could be treated as a realization of a continuous time random walk with both "waiting times" (interstorm period) and "jump sizes" (average storm intensity and storm duration). Starting from this viewpoint, we will analyze the statistics of storm duration, interstorm period, and average storm intensity in four regions in southwestern United States. We will examine whether the probability distribution is temporal and spatial dependent. Finally, we will use fractional engine to capture the randomness in precipitation storms.

  6. Do oxygen stable isotopes track precipitation moisture source in vascular plant dominated peatlands?

    NASA Astrophysics Data System (ADS)

    Charman, D.; Amesbury, M. J.; Newnham, R.; Loader, N.; Goodrich, J. P.; Gallego-Sala, A. V.; Royles, J.; Keller, E. D.; Baisden, W. T.

    2014-12-01

    Variations in the isotopic composition of precipitation are determined by fractionation processes which occur during temperature and humidity dependent phase changes associated with evaporation and condensation. Oxygen stable isotope ratios have therefore been frequently used as a source of palaeoclimate data from a variety of proxy archives. Exploitation of this record from ombrotrophic peatlands, where the source water used in cellulose synthesis is derived solely from precipitation, has been mostly limited to Northern Hemisphere Sphagnum-dominated bogs, with limited application in the Southern Hemisphere (SH) or in peatlands dominated by vascular plants. Throughout New Zealand (NZ), the preserved root matrix of the restionaceous wire rush (Empodisma spp.) forms deep peat deposits. NZ provides an ideal location to undertake empirical research into oxygen isotope fractionation in vascular peatlands because sites are ideally suited to single taxon analysis, preserve potentially high resolution full Holocene palaeoclimate records and are situated in the climatically sensitive SH mid-latitudes. Crucially, large gradients exist in the mean isotopic composition of precipitation across NZ, caused primarily by the relative influence of different climate modes. We test the capacity for δ18O analysis of Empodisma alpha cellulose from ombrotrophic restiad peatlands in NZ to provide a methodology for developing palaeoclimate records. We took surface plant, water and precipitation samples over spatial (six sites spanning >10° latitude) and temporal (monthly measurements over one year) gradients. We found a strong link between the isotopic compositions of surface root water, the most likely source water for plant growth, and precipitation in both datasets. Back-trajectory modelling of precipitation moisture source for rain days prior to sampling showed clear seasonality in the temporal data that was reflected in surface root water. The link between source water and plant

  7. IMPROVED PROCESS OF PLUTONIUM CARRIER PRECIPITATION

    DOEpatents

    Faris, B.F.

    1959-06-30

    This patent relates to an improvement in the bismuth phosphate process for separating and recovering plutonium from neutron irradiated uranium, resulting in improved decontamination even without the use of scavenging precipitates in the by-product precipitation step and subsequently more complete recovery of the plutonium in the product precipitation step. This improvement is achieved by addition of fluomolybdic acid, or a water soluble fluomolybdate, such as the ammonium, sodium, or potassium salt thereof, to the aqueous nitric acid solution containing tetravalent plutonium ions and contaminating fission products, so as to establish a fluomolybdate ion concentration of about 0.05 M. The solution is then treated to form the bismuth phosphate plutonium carrying precipitate.

  8. Calcite precipitation dominates the electrical signatures of zero valent iron columns under simulated field conditions

    SciTech Connect

    Wu, Yuxin; Versteeg, R.; Slater, L.; LaBrecque, D.

    2009-06-01

    Calcium carbonate is a secondary mineral precipitate influencing zero valent iron (ZVI) barrier reactivity and hydraulic performance. We conducted column experiments to investigate electrical signatures resulting from concurrent CaCO{sub 3} and iron oxides precipitation under simulated field geochemical conditions. We identified CaCO{sub 3} as a major mineral phase throughout the columns, with magnetite present primarily close to the influent based on XRD analysis. Electrical measurements revealed decreases in conductivity and polarization of both columns, suggesting that electrically insulating CaCO{sub 3} dominates the electrical response despite the presence of electrically conductive iron oxides. SEM/EDX imaging suggests that the electrical signal reflects the geometrical arrangement of the mineral phases. CaCO{sub 3} forms insulating films on ZVI/magnetite surfaces, restricting charge transfer between the pore electrolyte and ZVI particles, as well as across interconnected ZVI particles. As surface reactivity also depends on the ability of the surface to engage in redox reactions via charge transfer, electrical measurements may provide a minimally invasive technology for monitoring reactivity loss due to CaCO{sub 3} precipitation. Comparison between laboratory and field data shows consistent changes in electrical signatures due to iron corrosion and secondary mineral precipitation.

  9. Scattering by chorus waves as the dominant cause of diffuse auroral precipitation.

    PubMed

    Thorne, Richard M; Ni, Binbin; Tao, Xin; Horne, Richard B; Meredith, Nigel P

    2010-10-21

    Earth's diffuse aurora occurs over a broad latitude range and is primarily caused by the precipitation of low-energy (0.1-30-keV) electrons originating in the central plasma sheet, which is the source region for hot electrons in the nightside outer magnetosphere. Although generally not visible, the diffuse auroral precipitation provides the main source of energy for the high-latitude nightside upper atmosphere, leading to enhanced ionization and chemical changes. Previous theoretical studies have indicated that two distinct classes of magnetospheric plasma wave, electrostatic electron cyclotron harmonic waves and whistler-mode chorus waves, could be responsible for the electron scattering that leads to diffuse auroral precipitation, but it has hitherto not been possible to determine which is the more important. Here we report an analysis of satellite wave data and Fokker-Planck diffusion calculations which reveals that scattering by chorus is the dominant cause of the most intense diffuse auroral precipitation. This resolves a long-standing controversy. Furthermore, scattering by chorus can remove most electrons as they drift around Earth's magnetosphere, leading to the development of observed pancake distributions, and can account for the global morphology of the diffuse aurora. PMID:20962841

  10. The Dominant Synoptic-Scale Modes of North American Monsoon Precipitation

    NASA Astrophysics Data System (ADS)

    Serra, Y. L.; Seastrand, S.; Castro, C. L.; Ritchie, E.

    2014-12-01

    In this study we explore the mechanisms of synoptic rainfall variability using observations from the Tropical Rainfall Measuring Mission satellite. While previously shown to have an important impact on North American monsoon rainfall, tropical cyclones are excluded from this analysis, in order to focus on more frequent synoptic disturbances within the region. A rotated empirical orthogonal function analysis of North American monsoon rainfall for June through September 2002-2009 suggests low-level tropical disturbances contribute to the leading two modes of precipitation variability within this region. The low-level disturbances result in gulf surges, or low-level surges of moisture up the Gulf of California, and provide a key low-level moisture source to facilitate development of organized convection. In the first mode the low-level trough brings precipitation to lower elevations along the western slopes of the Sierra Madre Occidental south of Hermosillo, Mexico and over the southern Baja Peninsula. In the second mode the low-level trough interacts with an upper-level inverted trough enhancing precipitation into the southwestern United States and northwest Mexico. In particular, the upper-level trough contributes to the easterly-northeasterly shear across the region, favoring mesoscale convective organization and enhanced deep convection over the Sierra Madre Occidental and higher elevations in southeast Arizona. The EOF methodology offers an objective approach for determining the dominant modes of precipitation for the monsoon region useful for identifying past and monitoring future low-frequency impacts on these modes.

  11. Modeling precipitate-dominant clogging for landfill leachate with NICA-Donnan theory.

    PubMed

    Li, Zhenze

    2014-06-15

    Bioclogging of leachate drains is ubiquitous in landfills for municipal solid wastes. Formation of calcium precipitates and biofilms in pore space is the principal reason for clogging. But the calcium speciation in leachte rich in dissolved organic matters (DOM) remains to be uncovered. In spite of its complexity, NICA-Donnan model has been used to compute the speciation of metals and the binding capacities of humic substances. This study applies NICA-Donnan theory into the simulation of calcium speciation during the formation of precipitate-dominant clogging in leachate drainage aggregates for the first time. The consideration of DOC-Ca complexation gives reasonable explanation to the speciation of calcium, which is viewed as oversaturated, in leachate with concentrated DOM. The modeling results for calcium speciation are in good agreement with a large collection of experimental observations, suggesting that NICA-Donnan theory could be used in the modelings of reactive transport and clogging of landfill leachate collection systems. PMID:24806870

  12. Skill and predictability in multimodel ensemble forecasts for Northern Hemisphere regions with dominant winter precipitation

    NASA Astrophysics Data System (ADS)

    Ehsan, Muhammad Azhar; Tippett, Michael K.; Almazroui, Mansour; Ismail, Muhammad; Yousef, Ahmed; Kucharski, Fred; Omar, Mohamed; Hussein, Mahmoud; Alkhalaf, Abdulrahman A.

    2016-07-01

    Northern Hemisphere winter precipitation reforecasts from the European Centre for Medium Range Weather Forecast System-4 and six of the models in the North American Multi-Model Ensemble are evaluated, focusing on two regions (Region-A: 20°N-45°N, 10°E-65°E and Region-B: 20°N-55°N, 205°E-255°E) where winter precipitation is a dominant fraction of the annual total and where precipitation from mid-latitude storms is important. Predictability and skill (deterministic and probabilistic) are assessed for 1983-2013 by the multimodel composite (MME) of seven prediction models. The MME climatological mean and variability over the two regions is comparable to observation with some regional differences. The statistically significant decreasing trend observed in Region-B precipitation is captured well by the MME and most of the individual models. El Niño Southern Oscillation is a source of forecast skill, and the correlation coefficient between the Niño3.4 index and precipitation over region A and B is 0.46 and 0.35, statistically significant at the 95 % level. The MME reforecasts weakly reproduce the observed teleconnection. Signal, noise and signal to noise ratio analysis show that the signal variance over two regions is very small as compared to noise variance which tends to reduce the prediction skill. The MME ranked probability skill score is higher than that of individual models, showing the advantage of a multimodel ensemble. Observed Region-A rainfall anomalies are strongly associated with the North Atlantic Oscillation, but none of the models reproduce this relation, which may explain the low skill over Region-A. The superior quality of multimodel ensemble compared with individual models is mainly due to larger ensemble size.

  13. Can oxygen stable isotopes be used to track precipitation moisture source in vascular plant-dominated peatlands?

    NASA Astrophysics Data System (ADS)

    Amesbury, Matthew J.; Charman, Dan J.; Newnham, Rewi M.; Loader, Neil J.; Goodrich, Jordan; Royles, Jessica; Campbell, David I.; Keller, Elizabeth D.; Baisden, W. Troy; Roland, Thomas P.; Gallego-Sala, Angela V.

    2015-11-01

    Variations in the isotopic composition of precipitation are determined by fractionation processes which occur during temperature- and humidity-dependent phase changes associated with evaporation and condensation. Oxygen stable isotope ratios have therefore been frequently used as a source of palaeoclimate data from a variety of proxy archives, which integrate this signal over time. Applications from ombrotrophic peatlands, where the source water used in cellulose synthesis is derived solely from precipitation, have been mostly limited to Northern Hemisphere Sphagnum-dominated bogs, with few in the Southern Hemisphere or in peatlands dominated by vascular plants. New Zealand (NZ) provides an ideal location to undertake empirical research into oxygen isotope fractionation in vascular peatlands because single taxon analysis can be easily carried out, in particular using the preserved root matrix of the restionaceous wire rush (Empodisma spp.) that forms deep Holocene peat deposits throughout the country. Furthermore, large gradients are observed in the mean isotopic composition of precipitation across NZ, caused primarily by the relative influence of different climate modes. Here, we test whether δ18O of Empodisma α-cellulose from ombrotrophic restiad peatlands in NZ can provide a methodology for developing palaeoclimate records of past precipitation δ18O. Surface plant, water and precipitation samples were taken over spatial (six sites spanning >10° latitude) and temporal (monthly measurements over one year) gradients. A link between the isotopic composition of root-associated water, the most likely source water for plant growth, and precipitation in both datasets was found. Back-trajectory modelling of precipitation moisture source for rain days prior to sampling showed clear seasonality in the temporal data that was reflected in root-associated water. The link between source water and plant cellulose was less clear, although mechanistic modelling predicted mean

  14. Calcite precipitation dominates the electrical signatures of zero valent iron columns under simulated field conditions

    SciTech Connect

    Yuxin Wu; Roelof Versteeg; Lee Slater; Doug Labrecque

    2009-05-01

    Calcium carbonate is a major secondary mineral precipitate that influences PRB reactivity and hydraulic performance. In this study, we conducted column experiments to investigate electrical signatures resulting from concurrent CaCO3 and iron oxides precipitation in two simulated PRB media. Solid phase analysis identified CaCO3 (calcite and aragonite) as a major mineral phase throughout the columns, with magnetite being another major phase present close to the influent. Electrical measurements revealed a consistent decrease in conductivity and polarization magnitude of both columns, suggesting that the electrically insulating CaCO3 dominates the electrical response despite the presence of both electrically conductive iron oxides and CaCO3 precipitates. SEM/EDX imaging suggests that the electrical properties result from the geometrical arrangement of the mineral phases. The CaCO3 forms an insulating film on ZVI/magnetite surfaces, which we assume restricts redox-driven transfer of electric charge between the pore electrolyte and ZVI particles, as well as across interconnected ZVI particles. As surface reactivity also depends on the ability of the surface to engage in redox reactions, electrical measurements may provide a minimally invasive technology for monitoring reactivity loss.

  15. Response of two dominant boreal freshwater wetland plants to manipulated warming and altered precipitation.

    PubMed

    Zou, Yuanchun; Wang, Guoping; Grace, Michael; Lou, Xiaonan; Yu, Xiaofei; Lu, Xianguo

    2014-01-01

    This study characterized the morphological and photosynthetic responses of two wetland plant species when they were subject to 2-6 °C fluctuations in growth temperature and ± 50% of precipitation, in order to predict the evolution of natural wetlands in Sanjiang Plain of North-eastern China. We investigated the morphological and photosynthetic responses of two dominant and competitive boreal freshwater wetland plants in Northeastern China to manipulation of warming (ambient, +2.0 °C, +4.0 °C, +6.0 °C) and altered precipitation (-50%, ambient, +50%) simultaneously by incubating the plants from seedling to senescence within climate-controlled environmental chambers. Post-harvest, secondary growth of C. angustifolia was observed to explore intergenerational effects. The results indicated that C. angustifolia demonstrated a greater acclimated capacity than G. spiculosa to respond to climate change due to higher resistance to temperature and precipitation manipulations. The accumulated effect on aboveground biomass of post-harvest secondary growth of C. angustifolia was significant. These results explain the expansion of C. angustifolia during last 40 years and indicate the further expansion in natural boreal wetlands under a warmer and wetter future. Stability of the natural surface water table is critical for the conservation and restoration of G. spiculosa populations reacting to encroachment stress from C. angustifolia expansion. PMID:25105764

  16. Dominant plant taxa predict plant productivity responses to CO2 enrichment across precipitation and soil gradients.

    PubMed

    Fay, Philip A; Newingham, Beth A; Polley, H Wayne; Morgan, Jack A; LeCain, Daniel R; Nowak, Robert S; Smith, Stanley D

    2015-01-01

    The Earth's atmosphere will continue to be enriched with carbon dioxide (CO2) over the coming century. Carbon dioxide enrichment often reduces leaf transpiration, which in water-limited ecosystems may increase soil water content, change species abundances and increase the productivity of plant communities. The effect of increased soil water on community productivity and community change may be greater in ecosystems with lower precipitation, or on coarser-textured soils, but responses are likely absent in deserts. We tested correlations among yearly increases in soil water content, community change and community plant productivity responses to CO2 enrichment in experiments in a mesic grassland with fine- to coarse-textured soils, a semi-arid grassland and a xeric shrubland. We found no correlation between CO2-caused changes in soil water content and changes in biomass of dominant plant taxa or total community aboveground biomass in either grassland type or on any soil in the mesic grassland (P > 0.60). Instead, increases in dominant taxa biomass explained up to 85 % of the increases in total community biomass under CO2 enrichment. The effect of community change on community productivity was stronger in the semi-arid grassland than in the mesic grassland, where community biomass change on one soil was not correlated with the change in either the soil water content or the dominant taxa. No sustained increases in soil water content or community productivity and no change in dominant plant taxa occurred in the xeric shrubland. Thus, community change was a crucial driver of community productivity responses to CO2 enrichment in the grasslands, but effects of soil water change on productivity were not evident in yearly responses to CO2 enrichment. Future research is necessary to isolate and clarify the mechanisms controlling the temporal and spatial variations in the linkages among soil water, community change and plant productivity responses to CO2 enrichment. PMID

  17. Indian summer monsoon precipitating clouds: role of microphysical process rates

    NASA Astrophysics Data System (ADS)

    Hazra, Anupam; Chaudhari, Hemantkumar S.; Pokhrel, Samir; Saha, Subodh K.

    2016-04-01

    The budget analysis of microphysical process rates based on Modern Era Retrospective-analysis for Research and Applications (MERRA) products are presented in the study. The relative importance of different microphysical process rates, which is crucial for GCMs, is investigated. The autoconversion and accretion processes are found to be vital for Indian Summer Monsoon (ISM). The map-to-map correlations are examined between observed precipitation and MERRA reanalysis. The pattern correlations connote the fidelity of the MERRA datasets used here. Results of other microphysical parameters (e.g. ice water content from CloudSat, high cloud fraction from CALIPSO and MODIS, latent heating from TRMM, cloud ice mixing ratio from MERRA) are presented in this study. The tropospheric temperature from reanalysis product of MERRA and NCEP are also analyzed. Furthermore, the linkages between cloud microphysics production rates and dynamics, which are important for North-South tropospheric temperature gradient for maintaining the ISM circulation, are also discussed. The study demonstrates the microphysical process rates, which are actually responsible for the cloud hydrometeors and precipitation formation on the monsoon intraseasonal oscillations timescale. Cloud to rain water auto-conversion and snow accretion rates are the dominant processes followed by the rain accretion. All these tendency terms replicates the similar spatial patterns as that of precipitation. The quantification of microphysical process rates and precipitation over different regions are shown here. The freezing rate is also imperative for the formation of cloud ice as revealed by the observation. Freezing rates at upper level and snow accretion at middle level may have effect on latent heating release. Further it can modulate the north-south temperature gradient which can influence the large-scale monsoon dynamics. The rain water evaporation is also considered as a key aspect for controlling the low level

  18. Processing NPP Bottoms by Ferrocyanide Precipitation

    SciTech Connect

    Savkin, A. E.; Slastennikov Y. T.; Sinyakin O. G.

    2002-02-25

    The purpose of work is a laboratory test of a technological scheme for cleaning bottoms from radionuclides by use of ozonization, ferrocyanide precipitation, filtration and selective sorption. At carrying out the ferrocyanide precipitation after ozonization, the specific activity of bottoms by Cs{sup 137} is reduced in 100-500 times. It has been demonstrated that the efficiency of ferrocyanide precipitation depends on the quality of consequent filtration. Pore sizes of a filter has been determined to be less than 0.2 {micro}m for complete separation of ferrocyanide residue. The comparison of two technological schemes for cleaning bottoms from radionuclides, characterized by presence of the ferrocyanide precipitation stage has been performed. Application of the proposed schemes allows reducing volumes of radioactive waste in many times.

  19. Modeling greenup date of dominant grass species in the Inner Mongolian Grassland using air temperature and precipitation data

    NASA Astrophysics Data System (ADS)

    Chen, Xiaoqiu; Li, Jing; Xu, Lin; Liu, Li; Ding, Deng

    2014-05-01

    This work was undertaken to examine the combined effect of air temperature and precipitation during late winter and early spring on modeling greenup date of grass species in the Inner Mongolian Grassland. We used the traditional thermal time model and developed two revised thermal time models coupling air temperature and precipitation to simulate greenup date of three dominant grass species at six stations from 1983 to 2009. Results show that climatic controls on greenup date of grass species were location-specific. The revised thermal time models coupling air temperature and precipitation show higher simulation parsimony and efficiency than the traditional thermal time model for five of 11 data sets at Bayartuhushuo, Xilinhot and Xianghuangqi, whereas the traditional thermal time model indicates higher simulation parsimony and efficiency than the revised thermal time models coupling air temperature and precipitation for the other six data sets at E'ergunayouqi, Ewenkeqi and Chaharyouyihouqi. The mean root mean square error of the 11 models is 4.9 days. Moreover, the influence of late winter and early spring precipitation on greenup date seems to be stronger at stations with scarce precipitation than at stations with relatively abundant precipitation. From the mechanism perspectives, accumulated late winter and early spring precipitation may play a more important role as the precondition of forcing temperature than as the supplementary condition of forcing temperature in triggering greenup. Our findings suggest that predicting responses of grass phenology to global climate change should consider both thermal and moisture scenarios in some semiarid and arid areas.

  20. Local biomass burning is a dominant cause of the observed precipitation reduction in southern Africa

    PubMed Central

    Hodnebrog, Øivind; Myhre, Gunnar; Forster, Piers M.; Sillmann, Jana; Samset, Bjørn H.

    2016-01-01

    Observations indicate a precipitation decline over large parts of southern Africa since the 1950s. Concurrently, atmospheric concentrations of greenhouse gases and aerosols have increased due to anthropogenic activities. Here we show that local black carbon and organic carbon aerosol emissions from biomass burning activities are a main cause of the observed decline in southern African dry season precipitation over the last century. Near the main biomass burning regions, global and regional modelling indicates precipitation decreases of 20–30%, with large spatial variability. Increasing global CO2 concentrations further contribute to precipitation reductions, somewhat less in magnitude but covering a larger area. Whereas precipitation changes from increased CO2 are driven by large-scale circulation changes, the increase in biomass burning aerosols causes local drying of the atmosphere. This study illustrates that reducing local biomass burning aerosol emissions may be a useful way to mitigate reduced rainfall in the region. PMID:27068129

  1. Local biomass burning is a dominant cause of the observed precipitation reduction in southern Africa.

    PubMed

    Hodnebrog, Øivind; Myhre, Gunnar; Forster, Piers M; Sillmann, Jana; Samset, Bjørn H

    2016-01-01

    Observations indicate a precipitation decline over large parts of southern Africa since the 1950s. Concurrently, atmospheric concentrations of greenhouse gases and aerosols have increased due to anthropogenic activities. Here we show that local black carbon and organic carbon aerosol emissions from biomass burning activities are a main cause of the observed decline in southern African dry season precipitation over the last century. Near the main biomass burning regions, global and regional modelling indicates precipitation decreases of 20-30%, with large spatial variability. Increasing global CO2 concentrations further contribute to precipitation reductions, somewhat less in magnitude but covering a larger area. Whereas precipitation changes from increased CO2 are driven by large-scale circulation changes, the increase in biomass burning aerosols causes local drying of the atmosphere. This study illustrates that reducing local biomass burning aerosol emissions may be a useful way to mitigate reduced rainfall in the region. PMID:27068129

  2. Local biomass burning is a dominant cause of the observed precipitation reduction in southern Africa

    NASA Astrophysics Data System (ADS)

    Hodnebrog, Øivind; Myhre, Gunnar; Forster, Piers M.; Sillmann, Jana; Samset, Bjørn H.

    2016-04-01

    Observations indicate a precipitation decline over large parts of southern Africa since the 1950s. Concurrently, atmospheric concentrations of greenhouse gases and aerosols have increased due to anthropogenic activities. Here we show that local black carbon and organic carbon aerosol emissions from biomass burning activities are a main cause of the observed decline in southern African dry season precipitation over the last century. Near the main biomass burning regions, global and regional modelling indicates precipitation decreases of 20-30%, with large spatial variability. Increasing global CO2 concentrations further contribute to precipitation reductions, somewhat less in magnitude but covering a larger area. Whereas precipitation changes from increased CO2 are driven by large-scale circulation changes, the increase in biomass burning aerosols causes local drying of the atmosphere. This study illustrates that reducing local biomass burning aerosol emissions may be a useful way to mitigate reduced rainfall in the region.

  3. Modeling greenup date of dominant grass species in the Inner Mongolian Grassland using air temperature and precipitation data.

    PubMed

    Chen, Xiaoqiu; Li, Jing; Xu, Lin; Liu, Li; Ding, Deng

    2014-05-01

    This work was undertaken to examine the combined effect of air temperature and precipitation during late winter and early spring on modeling greenup date of grass species in the Inner Mongolian Grassland. We used the traditional thermal time model and developed two revised thermal time models coupling air temperature and precipitation to simulate greenup date of three dominant grass species at six stations from 1983 to 2009. Results show that climatic controls on greenup date of grass species were location-specific. The revised thermal time models coupling air temperature and precipitation show higher simulation parsimony and efficiency than the traditional thermal time model for five of 11 data sets at Bayartuhushuo, Xilinhot and Xianghuangqi, whereas the traditional thermal time model indicates higher simulation parsimony and efficiency than the revised thermal time models coupling air temperature and precipitation for the other six data sets at E'ergunayouqi, Ewenkeqi and Chaharyouyihouqi. The mean root mean square error of the 11 models is 4.9 days. Moreover, the influence of late winter and early spring precipitation on greenup date seems to be stronger at stations with scarce precipitation than at stations with relatively abundant precipitation. From the mechanism perspectives, accumulated late winter and early spring precipitation may play a more important role as the precondition of forcing temperature than as the supplementary condition of forcing temperature in triggering greenup. Our findings suggest that predicting responses of grass phenology to global climate change should consider both thermal and moisture scenarios in some semiarid and arid areas. PMID:24065573

  4. Right Hemispheric Dominance in Processing of Unconscious Negative Emotion

    ERIC Educational Resources Information Center

    Sato, Wataru; Aoki, Satoshi

    2006-01-01

    Right hemispheric dominance in unconscious emotional processing has been suggested, but remains controversial. This issue was investigated using the subliminal affective priming paradigm combined with unilateral visual presentation in 40 normal subjects. In either left or right visual fields, angry facial expressions, happy facial expressions, or…

  5. Sediment chronologies of atmospheric deposition in a precipitation-dominated seepage lake.

    SciTech Connect

    Doskey, P. V.; Talbot, R. W.; Environmental Research; Univ. of New Hampshire

    2000-01-01

    Chronologies of Pb, polycyclic aromatic hydrocarbons (PAHs), Al, carbon, and n-alkanes in pelagic sediments of Crystal Lake, a precipitation-dominated seepage lake in north-central Wisconsin, were determined to investigate the geochemistry of sediments derived from atmospheric deposition and to evaluate the impact of environmental changes in the region on the geochemistry of this oligotrophic lake. Concentrations of Pb and combustion-derived PAHs in Crystal Lake sediments have increased by factors of 8 and 3, respectively, over the past 150 years. In contrast, levels of perylene increased with depth in the sediment, indicating that postdepositional formation of this PAH might be occurring. Atmospheric fluxes of anthropogenic Pb and combustion-derived PAHs were estimated to be 10,000 {mu}g m{sup -2} a{sup -1} and 34 {mu}g m{sup 02} a{sup -1}, respectively. The settling sediment fluxes of planktonic n-alkanes ({Sigma} C{sub 15}, C{sub 17}, C{sub 19}) and terrestrial n-alkanes ({Sigma} C{sub 25}, C{sub 27}, C{sub 29}, C{sub 31}) in Crystal Lake were 4,400 {mu}g m{sup -2} a{sup -1} and 10,500 {mu}g m{sup 2} a{sup 1}, respectively, whereas their accumulation rates in pelagic sediments were 270 {mu}g m{sup -2} a{sup -1} and 7,100 {mu}g m 2 a{sup 1}, respectively. The large difference between the settling sediment flux and the accumulation rate of the planktonic n-alkanes in the sediments is ascribed to microbial degradation during or soon after deposition. In contrast, the terrestrial n-alkanes are incorporated in a wax matrix and are protected from degradation. The contribution of terrestrial n-alkanes to the organic carbon of the sediments has remained relatively constant over the past 150 years. About 20% of the organic carbon that is incorporated in the present-day sediments of Crystal Lake can be attributed to the deposition of pine pollen in the lake. Deforestation of the region in the late 1800s apparently caused terrigenous inputs and primary productivity of

  6. Ecophysiological responses of two dominant grasses to altered temperature and precipitation regimes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ecosystem responses to climate change will largely be driven by responses of the dominant species. However, if co-dominant species have traits that lead them to differential responses, then predicting how ecosystem structure and function will be altered is more challenging. We assessed differences i...

  7. Interactive effects of elevated CO2 and precipitation change on leaf nitrogen of dominant Stipa L. species

    PubMed Central

    Shi, Yaohui; Zhou, Guangsheng; Jiang, Yanling; Wang, Hui; Xu, Zhenzhu; Song, Jian

    2015-01-01

    Nitrogen (N) serves as an important mineral element affecting plant productivity and nutritional quality. However, few studies have addressed the interactive effects of elevated CO2 and precipitation change on leaf N of dominant grassland genera such as Stipa L. This has restricted our understanding of the responses of grassland to climate change. We simulated the interactive effects of elevated CO2 concentration and varied precipitation on leaf N concentration (Nmass) of four Stipa species (Stipa baicalensis, Stipa bungeana, Stipa grandis, and Stipa breviflora; the most dominant species in arid and semiarid grassland) using open-top chambers (OTCs). The relationship between the Nmass of these four Stipa species and precipitation well fits a logarithmic function. The sensitivity of these four species to precipitation change was ranked as follows: S. bungeana > S. breviflora > S. baicalensis > S. grandis. The Nmass of S. bungeana was the most sensitive to precipitation change, while S. grandis was the least sensitive among these Stipa species. Elevated CO2 exacerbated the effect of precipitation on Nmass. Nmass decreased under elevated CO2 due to growth dilution and a direct negative effect on N assimilation. Elevated CO2 reduced Nmass only in a certain precipitation range for S. baicalensis (163–343 mm), S. bungeana (164–355 mm), S. grandis (148–286 mm), and S. breviflora (130–316 mm); severe drought or excessive rainfall would be expected to result in a reduced impact of elevated CO2. Elevated CO2 affected the Nmass of S. grandis only in a narrow precipitation range. The effect of elevated CO2 reached a maximum when the amount of precipitation was 253, 260, 217, and 222 mm for S. baicalensis, S. bungeana, S. grandis, and S. breviflora, respectively. The Nmass of S. grandis was the least sensitive to elevated CO2. The Nmass of S. breviflora was more sensitive to elevated CO2 under a drought condition compared with the other Stipa

  8. Interactive effects of elevated CO2 and precipitation change on leaf nitrogen of dominant Stipa L. species.

    PubMed

    Shi, Yaohui; Zhou, Guangsheng; Jiang, Yanling; Wang, Hui; Xu, Zhenzhu; Song, Jian

    2015-07-01

    Nitrogen (N) serves as an important mineral element affecting plant productivity and nutritional quality. However, few studies have addressed the interactive effects of elevated CO2 and precipitation change on leaf N of dominant grassland genera such as Stipa L. This has restricted our understanding of the responses of grassland to climate change. We simulated the interactive effects of elevated CO2 concentration and varied precipitation on leaf N concentration (Nmass) of four Stipa species (Stipa baicalensis, Stipa bungeana, Stipa grandis, and Stipa breviflora; the most dominant species in arid and semiarid grassland) using open-top chambers (OTCs). The relationship between the Nmass of these four Stipa species and precipitation well fits a logarithmic function. The sensitivity of these four species to precipitation change was ranked as follows: S. bungeana > S. breviflora > S. baicalensis > S. grandis. The Nmass of S. bungeana was the most sensitive to precipitation change, while S. grandis was the least sensitive among these Stipa species. Elevated CO2 exacerbated the effect of precipitation on Nmass. Nmass decreased under elevated CO2 due to growth dilution and a direct negative effect on N assimilation. Elevated CO2 reduced Nmass only in a certain precipitation range for S. baicalensis (163-343 mm), S. bungeana (164-355 mm), S. grandis (148-286 mm), and S. breviflora (130-316 mm); severe drought or excessive rainfall would be expected to result in a reduced impact of elevated CO2. Elevated CO2 affected the Nmass of S. grandis only in a narrow precipitation range. The effect of elevated CO2 reached a maximum when the amount of precipitation was 253, 260, 217, and 222 mm for S. baicalensis, S. bungeana, S. grandis, and S. breviflora, respectively. The Nmass of S. grandis was the least sensitive to elevated CO2. The Nmass of S. breviflora was more sensitive to elevated CO2 under a drought condition compared with the other Stipa species

  9. Daily spatiotemporal precipitation simulation using latent and transformed Gaussian processes

    NASA Astrophysics Data System (ADS)

    Kleiber, William; Katz, Richard W.; Rajagopalan, Balaji

    2012-01-01

    A daily stochastic spatiotemporal precipitation generator that yields spatially consistent gridded quantitative precipitation realizations is described. The methodology relies on a latent Gaussian process to drive precipitation occurrence and a probability integral transformed Gaussian process for intensity. At individual locations, the model reduces to a Markov chain for precipitation occurrence and a gamma distribution for precipitation intensity, allowing statistical parameters to be included in a generalized linear model framework. Statistical parameters are modeled as spatial Gaussian processes, which allows for interpolation to locations where there are no direct observations via kriging. One advantage of such a model for the statistical parameters is that stochastic generator parameters are immediately available at any location, with the ability to adapt to spatially varying precipitation characteristics. A second advantage is that parameter uncertainty, generally unavailable with deterministic interpolators, can be immediately quantified at all locations. The methodology is illustrated on two data sets, the first in Iowa and the second over the Pampas region of Argentina. In both examples, the method is able to capture the local and domain aggregated precipitation behavior fairly well at a wide range of time scales, including daily, monthly, and annually.

  10. Global Precipitation Measurement (GPM) Mission: Precipitation Processing System (PPS) GPM Mission Gridded Text Products Provide Surface Precipitation Retrievals

    NASA Technical Reports Server (NTRS)

    Stocker, Erich Franz; Kelley, O.; Kummerow, C.; Huffman, G.; Olson, W.; Kwiatkowski, J.

    2015-01-01

    In February 2015, the Global Precipitation Measurement (GPM) mission core satellite will complete its first year in space. The core satellite carries a conically scanning microwave imager called the GPM Microwave Imager (GMI), which also has 166 GHz and 183 GHz frequency channels. The GPM core satellite also carries a dual frequency radar (DPR) which operates at Ku frequency, similar to the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar, and a new Ka frequency. The precipitation processing system (PPS) is producing swath-based instantaneous precipitation retrievals from GMI, both radars including a dual-frequency product, and a combined GMIDPR precipitation retrieval. These level 2 products are written in the HDF5 format and have many additional parameters beyond surface precipitation that are organized into appropriate groups. While these retrieval algorithms were developed prior to launch and are not optimal, these algorithms are producing very creditable retrievals. It is appropriate for a wide group of users to have access to the GPM retrievals. However, for researchers requiring only surface precipitation, these L2 swath products can appear to be very intimidating and they certainly do contain many more variables than the average researcher needs. Some researchers desire only surface retrievals stored in a simple easily accessible format. In response, PPS has begun to produce gridded text based products that contain just the most widely used variables for each instrument (surface rainfall rate, fraction liquid, fraction convective) in a single line for each grid box that contains one or more observations.This paper will describe the gridded data products that are being produced and provide an overview of their content. Currently two types of gridded products are being produced: (1) surface precipitation retrievals from the core satellite instruments GMI, DPR, and combined GMIDPR (2) surface precipitation retrievals for the partner constellation

  11. Principal uncertainty patterns in precipitation among CMIP5 models: Dominant modes of intermodel disagreement in precipitation climatologies and projected change patterns

    NASA Astrophysics Data System (ADS)

    Langenbrunner, B.; Neelin, J.; Anderson, B. T.

    2013-12-01

    Projections of modeled precipitation change in global warming scenarios demonstrate marked intermodel disagreement, especially at regional scales. While these differences are often considered within a geographically local domain, they are in part caused by intermodel uncertainty inherited from the large scale. It is therefore important to identify the major aspects of model disagreement at larger scales in order to better understand differences at the regional level. One way to do this is to pinpoint the major modes of intermodel disagreement through objective analysis of modeled precipitation change patterns, as well as the disagreement in precipitation climatologies in historical and radiative forcing scenarios. For brevity, these modes are labeled Principal Uncertainty Patterns (PUPs). For the Coupled Model Intercomparison Project phase 5 (CMIP5) models, a PUP analysis is applied to projected changes in precipitation, upper-level wind, and temperature fields, for both coupled model runs (36 models) and atmosphere-only simulations (30 models). This analysis is also applied to the simulated historical and future climatologies for the same ensembles. We take a global approach first, and then focus on specific regions: Africa, the tropical and subtropical Americas, and the mid-latitude Pacific storm tracks. For Africa, the leading June-July-August (JJA) PUP is associated with disagreement in the amplitude of positive end-of-century precipitation changes in the monsoon region. For the tropical Americas, intermodel uncertainty in the amount of end-of-century drying is the dominant PUP for JJA. The two leading December-January-February (DJF) PUPs in the storm tracks region appear to represent (1) an amplitude mode that shows the eastward extension of mid-latitude Pacific storm tracks trailing into the North American coast, and (2) a gradient mode associated with the meridional shift of these storm tracks. Relationships of precipitation uncertainties to model

  12. Impact of Urban Surfaces on Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Shepherd, J. M.

    2004-01-01

    The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by two United Nations organizations, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to assess the "risk of human-induced climate change". Such reports are used by decision-makers around the world to assess how our climate is changing. Its reports are widely respected and cited and have been highly influential in forming national and international responses to climate change. The Fourth Assessment report includes a section on the effects of surface processes on climate. This sub-chapter provides an overview of recent developments related to the impact of cities on rainfall. It highlights the possible mechanisms that buildings, urban heat islands, urban aerosols or pollution, and other human factors in cities that can affect rainfall.

  13. The Role of Aerosols on Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Li, X.; Khain, A.; Simpson, S.

    2006-01-01

    Cloud physics is inevitably affected by the smoke particle (CCN, cloud condensation nuclei) size distribution below the clouds. Therefore, the size distributions parameterized as spectral bin microphysics are needed to explicitly study the effects of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates for convective clouds. Recently, a detailed spectral--bin microphysical scheme was implemented into the Goddard Cumulus Ensemble (GCE) model. The formulation for the explicit spectral-bin microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e., pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), graupel and frozen drops/hail]. Each type is described by a special size distribution function containing many categories (i.e., 33 bins). Atmospheric aerosols are also described using number density size-distribution functions.

  14. Is the interannual variability of summer rainfall in China dominated by precipitation frequency or intensity? An analysis of relative importance

    NASA Astrophysics Data System (ADS)

    Lu, Er; Ding, Ying; Zhou, Bing; Zou, Xukai; Chen, Xianyan; Cai, Wenyue; Zhang, Qiang; Chen, Haishan

    2016-07-01

    The summer rainfall in China has a large interannual variability, which results from the concurrent variations of precipitation frequency and intensity. Using the observed daily precipitation in the 194 stations during recent 62 years, we examine the relative importance of the frequency and intensity in the variability of the rainfall. A simple method, based on linear regression, is used to estimate the relative importance. The products of the change rates of rainfall with respect to frequency and intensity, determined from the regression, and the corresponding standard deviations of the two variables, which reflect their variation scales, are defined to measure the importance of frequency and intensity. To determine the frequency, rainfall amount, and intensity from daily precipitation, we need a threshold to define the "rainy day". In this study, we use a series of thresholds, ranging from 1 to 30 mm/day. So, while presenting the result of relative importance for each threshold, we also examine how the relative importance varies with the threshold. Results show that for the threshold of 1 mm/day, with which the rainfall may include even the light rains, the variabilities of summer rainfall in most stations are dominated by intensity. With the increase in threshold, the importance of frequency increases, while the importance of intensity decreases. When the threshold reaches 30 mm/day, with which the rainfall includes only moderate-to-heavy rains, the variabilities of the rainfall in all stations are dominated by frequency. Analysis suggests that such a change, in the dominance with the threshold, is reasonable. This reasonability, in turn, supports the reliability and robustness of the method.

  15. Modeling Cloud and Precipitation Processes - Considerations for Future Satellite Missions

    NASA Astrophysics Data System (ADS)

    van den Heever, S. C.; Tao, W. K.; Saleeby, S. M.; Wu, D.

    2014-12-01

    Rapid developments in computing resources have allowed for cloud resolving model (CRM) simulations to be conducted over larger domains at higher spatial and temporal resolutions. Indeed, global CRMs are now a reality. Within such modeling frameworks, microphysical processes cannot be isolated from the vertical velocity that drives them, from the impact of energy exchanges due to phase changes, nor from the precipitation they produce, as has historically been the case with more highly parameterized frameworks. The increasing utilization of such high resolution, large-domain CRMs therefore introduces a new set of observational challenges. Instead of only taking into account global distributions of clouds and precipitation, observational strategies now need to be adapted to focus on the actual microphysical processes and feedbacks that are responsible for such cloud and precipitation distributions. Incorrectly representing such processes and feedbacks has significant implications for precipitation rates, efficiency and partitioning; the horizontal and vertical distribution of clouds; anvil ice properties; the partitioning between the liquid water and ice phase; and the location and amount of latent energy release associated with phase changes, all of which have subsequent implications for the global energy and water budget. Numerous microphysical and dynamical processes, and the feedbacks between them, are not well represented in CRMs. However, correctly simulating the magnitude of vertical velocity, as well as various ice processes appear to be particularly challenging. This talk will focus on the range of precipitation and cloud responses obtained within CRM simulations due to changes in the manner various ice processes are represented including melting, riming and shedding. Those parameters causing the greatest simulated cloud and precipitation responses will be identified. Factors impacting the representation of vertical velocity will also be addressed. Finally

  16. Stoichiometric hydroxyapatite obtained by precipitation and sol gel processes

    NASA Astrophysics Data System (ADS)

    Vazquez, C. G.; Barba, C. P.; Munguia, N.

    2005-06-01

    Three methods for obtaining hydroxiapatite (HA) are described. HA is a very interesting ceramic because of its many medical applications. The first two precipitation methods start from calcium and phosphorous compounds, whereas the third method is a sol-gel process that uses alcoxides. The products were characterized and compared. The observed differences are important for practical applications.

  17. Process of precipitating zirconium or hafnium from spent pickling solutions

    SciTech Connect

    Aguilar, C.L.; Walker, R.G.

    1991-12-31

    This patent describes a process for regenerating a spent, fluoride-containing pickle solution used in the pickling of zirconium or hafnium metal or their alloys. It comprises adding to the spent pickle solution a sufficient amount of sodium sulfate to precipitate sodium zirconium or hafnium fluoride.

  18. Same catchment, different models, same dominant processes? - How temporal patterns of dominant parameters vary between two hydrological models

    NASA Astrophysics Data System (ADS)

    Guse, Björn; Pechlivanidis, Ilias; Pfannerstill, Matthias; Donnelly, Chantal; Arheimer, Berit; Fohrer, Nicola

    2016-04-01

    Dominant hydrological processes change during the year. The variations in the dominance of modelled processes also lead to changes in the sensitivity of model parameters over time. An analysis of the temporal dynamics in parameter sensitivity (TEDPAS) provides daily sensitivity values for each model parameter. Thus, TEDPAS shows seasonal patterns of model parameter sensitivities and the seasonality of the corresponding processes. Each hydrological model consists of model-specific structures and parameters. Depending on differences in the model concepts, the parameters are partly similar or can be partly difficult to compare. Thus, the application of TEDPAS to different models is expected to lead to different seasonal patterns of dominant model parameters. However, in a world of perfect models, seasonal patterns of the corresponding dominant processes of the same catchment should be identical in different models. To investigate this, TEDPAS is applied on the hydrological models SWAT (Soil and Water Assessment Tool) and HYPE (Hydrological Predictions for the Environment) for the Treene catchment in Northern Germany. By comparing daily sensitivities of parameters between both models, similarities and differences in the seasonal patterns of parameter dominance are detected. These results are analyzed and explained in relation to differences in the model structure of SWAT and HYPE. The comparison of SWAT and HYPE shows differences in the seasonal variations in dominant parameters and corresponding processes. Similar patterns of dominant processes in both models provide more confidence on the model structures. In contrast, differences in these patterns give insights which model components need to be reconsidered for an appropriate use in the study catchment. Based on the TEDPAS analysis it could be clearly derived which process needs to be investigated more detailed. This study contributes thus to improved hydrological consistency during model construction and a better

  19. Gene expression patterns of two dominant tallgrass prairie species differ in response to warming and altered precipitation

    DOE PAGESBeta

    Smith, Melinda D.; Hoffman, Ava M.; Avolio, Meghan L.

    2016-05-13

    To better understand the mechanisms underlying plant species responses to climate change, we compared transcriptional profiles of the co-dominant C4 grasses, Andropogon gerardii Vitman and Sorghastrum nutans (L.) Nash, in response to increased temperatures and more variable precipitation regimes in a long-term field experiment in native tallgrass prairie. We used microarray probing of a closely related model species (Zea mays) to assess correlations in leaf temperature (Tleaf) and leaf water potential (LWP) and abundance changes of ~10,000 transcripts in leaf tissue collected from individuals of both species. A greater number of transcripts were found to significantly change in abundance levelsmore » with Tleaf and LWP in S. nutans than in A. gerardii. S. nutans also was more responsive to short-term drought recovery than A. gerardii. Water flow regulating transcripts associated with stress avoidance (e.g., aquaporins), as well as those involved in the prevention and repair of damage (e.g., antioxidant enzymes, HSPs), were uniquely more abundant in response to increasing Tleaf in S. nutans. Furthermore, the differential transcriptomic responses of the co-dominant C4 grasses suggest that these species may cope with and respond to temperature and water stress at the molecular level in distinct ways, with implications for tallgrass prairie ecosystem function.« less

  20. Gene expression patterns of two dominant tallgrass prairie species differ in response to warming and altered precipitation

    PubMed Central

    Smith, Melinda D.; Hoffman, Ava M.; Avolio, Meghan L.

    2016-01-01

    To better understand the mechanisms underlying plant species responses to climate change, we compared transcriptional profiles of the co-dominant C4 grasses, Andropogon gerardii Vitman and Sorghastrum nutans (L.) Nash, in response to increased temperatures and more variable precipitation regimes in a long-term field experiment in native tallgrass prairie. We used microarray probing of a closely related model species (Zea mays) to assess correlations in leaf temperature (Tleaf) and leaf water potential (LWP) and abundance changes of ~10,000 transcripts in leaf tissue collected from individuals of both species. A greater number of transcripts were found to significantly change in abundance levels with Tleaf and LWP in S. nutans than in A. gerardii. S. nutans also was more responsive to short-term drought recovery than A. gerardii. Water flow regulating transcripts associated with stress avoidance (e.g., aquaporins), as well as those involved in the prevention and repair of damage (e.g., antioxidant enzymes, HSPs), were uniquely more abundant in response to increasing Tleaf in S. nutans. The differential transcriptomic responses of the co-dominant C4 grasses suggest that these species may cope with and respond to temperature and water stress at the molecular level in distinct ways, with implications for tallgrass prairie ecosystem function. PMID:27174156

  1. Gene expression patterns of two dominant tallgrass prairie species differ in response to warming and altered precipitation.

    PubMed

    Smith, Melinda D; Hoffman, Ava M; Avolio, Meghan L

    2016-01-01

    To better understand the mechanisms underlying plant species responses to climate change, we compared transcriptional profiles of the co-dominant C4 grasses, Andropogon gerardii Vitman and Sorghastrum nutans (L.) Nash, in response to increased temperatures and more variable precipitation regimes in a long-term field experiment in native tallgrass prairie. We used microarray probing of a closely related model species (Zea mays) to assess correlations in leaf temperature (Tleaf) and leaf water potential (LWP) and abundance changes of ~10,000 transcripts in leaf tissue collected from individuals of both species. A greater number of transcripts were found to significantly change in abundance levels with Tleaf and LWP in S. nutans than in A. gerardii. S. nutans also was more responsive to short-term drought recovery than A. gerardii. Water flow regulating transcripts associated with stress avoidance (e.g., aquaporins), as well as those involved in the prevention and repair of damage (e.g., antioxidant enzymes, HSPs), were uniquely more abundant in response to increasing Tleaf in S. nutans. The differential transcriptomic responses of the co-dominant C4 grasses suggest that these species may cope with and respond to temperature and water stress at the molecular level in distinct ways, with implications for tallgrass prairie ecosystem function. PMID:27174156

  2. Process Control for Precipitation Prevention in Space Water Recovery Systems

    NASA Technical Reports Server (NTRS)

    Sargusingh, Miriam; Callahan, Michael R.; Muirhead, Dean

    2015-01-01

    The ability to recover and purify water through physiochemical processes is crucial for realizing long-term human space missions, including both planetary habitation and space travel. Because of their robust nature, rotary distillation systems have been actively pursued by NASA as one of the technologies for water recovery from wastewater primarily comprised of human urine. A specific area of interest is the prevention of the formation of solids that could clog fluid lines and damage rotating equipment. To mitigate the formation of solids, operational constraints are in place that limits such that the concentration of key precipitating ions in the wastewater brine are below the theoretical threshold. This control in effected by limiting the amount of water recovered such that the risk of reaching the precipitation threshold is within acceptable limits. The water recovery limit is based on an empirically derived worst case wastewater composition. During the batch process, water recovery is estimated by monitoring the throughput of the system. NASA Johnson Space Center is working on means of enhancing the process controls to increase water recovery. Options include more precise prediction of the precipitation threshold. To this end, JSC is developing a means of more accurately measuring the constituent of the brine and/or wastewater. Another means would be to more accurately monitor the throughput of the system. In spring of 2015, testing will be performed to test strategies for optimizing water recovery without increasing the risk of solids formation in the brine.

  3. Precipitation softening: a pretreatment process for seawater desalination.

    PubMed

    Ayoub, George M; Zayyat, Ramez M; Al-Hindi, Mahmoud

    2014-02-01

    Reduction of membrane fouling in reverse osmosis systems and elimination of scaling of heat transfer surfaces in thermal plants are a major challenge in the desalination of seawater. Precipitation softening has the potential of eliminating the major fouling and scaling species in seawater desalination plants, thus allowing thermal plants to operate at higher top brine temperatures and membrane plants to operate at a reduced risk of fouling, leading to lower desalinated water costs. This work evaluated the use of precipitation softening as a pretreatment step for seawater desalination. The effectiveness of the process in removing several scale-inducing materials such as calcium, magnesium, silica, and boron was investigated under variable conditions of temperature and pH. The treatment process was also applied to seawater spiked with other known fouling species such as iron and bacteria to determine the efficiency of removal. The results of this work show that precipitation softening at a pH of 11 leads to complete elimination of calcium, silica, and bacteria; to very high removal efficiencies of magnesium and iron (99.6 and 99.2 %, respectively); and to a reasonably good removal efficiency of boron (61 %). PMID:24151028

  4. Precipitation processes as deduced by combining Doppler radar and disdrometer

    NASA Astrophysics Data System (ADS)

    Thomson, Alan Douglas

    Precipitation processes are investigated in stratiform and convective weather systems by combining Doppler radar and disdrometer measurements. Vertical scans are designed to measure the standard radar data fields and the power spectrum of the vertical Doppler velocities with high spatial and temporal resolution. A new method, based on iterative application of a disdrometer-determined Z-R relation, is developed to estimate vertical winds from the vertical scan data. Using this method, radar-based raindrop size spectra calculated near the surface in light stratiform rain compare well with simultaneous measurements from a collocated disdrometer. A full raindrop size spectrum profile is deduced for a specific steady state case. It is found that the spectrum does not vary with height, suggesting that the spectral shape is mainly controlled by the ice particles occurring above the 0oC level. Vertical scan data are also combined with volume scan data obtained by the Atmospheric Environment Service King City radar to examine the precipitation structure of a hail producing region within a severe squall line. The vertical scan shows a large variation in precipitation structure and also reveals important storm features which, in this case, are not detected by the conventional volume scans, such as a weak echo vault, a downdraught outflow, and streaks of very high downward velocity corresponding to separate hail trajectories. The power spectra were used to identify and locate hailstones, to deduce the growth of descending hailstones, and to qualitatively examine properties of raindrop size spectra. A conceptual model of hail formation is proposed by comparing the deduced storm structure and precipitation processes with the analyses of two somewhat similar storms documented in the literature.

  5. Upscaling Empirically Based Conceptualisations to Model Tropical Dominant Hydrological Processes for Historical Land Use Change

    NASA Astrophysics Data System (ADS)

    Toohey, R.; Boll, J.; Brooks, E.; Jones, J.

    2009-12-01

    Surface runoff and percolation to ground water are two hydrological processes of concern to the Atlantic slope of Costa Rica because of their impacts on flooding and drinking water contamination. As per legislation, the Costa Rican Government funds land use management from the farm to the regional scale to improve or conserve hydrological ecosystem services. In this study, we examined how land use (e.g., forest, coffee, sugar cane, and pasture) affects hydrological response at the point, plot (1 m2), and the field scale (1-6ha) to empirically conceptualize the dominant hydrological processes in each land use. Using our field data, we upscaled these conceptual processes into a physically-based distributed hydrological model at the field, watershed (130 km2), and regional (1500 km2) scales. At the point and plot scales, the presence of macropores and large roots promoted greater vertical percolation and subsurface connectivity in the forest and coffee field sites. The lack of macropores and large roots, plus the addition of management artifacts (e.g., surface compaction and a plough layer), altered the dominant hydrological processes by increasing lateral flow and surface runoff in the pasture and sugar cane field sites. Macropores and topography were major influences on runoff generation at the field scale. Also at the field scale, antecedent moisture conditions suggest a threshold behavior as a temporal control on surface runoff generation. However, in this tropical climate with very intense rainstorms, annual surface runoff was less than 10% of annual precipitation at the field scale. Significant differences in soil and hydrological characteristics observed at the point and plot scales appear to have less significance when upscaled to the field scale. At the point and plot scales, percolation acted as the dominant hydrological process in this tropical environment. However, at the field scale for sugar cane and pasture sites, saturation-excess runoff increased as

  6. Right Hemisphere Dominance for Emotion Processing in Baboons

    ERIC Educational Resources Information Center

    Wallez, Catherine; Vauclair, Jacques

    2011-01-01

    Asymmetries of emotional facial expressions in humans offer reliable indexes to infer brain lateralization and mostly revealed right hemisphere dominance. Studies concerned with oro-facial asymmetries in nonhuman primates largely showed a left-sided asymmetry in chimpanzees, marmosets and macaques. The presence of asymmetrical oro-facial…

  7. Monaural Congenital Deafness Affects Aural Dominance and Degrades Binaural Processing

    PubMed Central

    Tillein, Jochen; Hubka, Peter; Kral, Andrej

    2016-01-01

    Cortical development extensively depends on sensory experience. Effects of congenital monaural and binaural deafness on cortical aural dominance and representation of binaural cues were investigated in the present study. We used an animal model that precisely mimics the clinical scenario of unilateral cochlear implantation in an individual with single-sided congenital deafness. Multiunit responses in cortical field A1 to cochlear implant stimulation were studied in normal-hearing cats, bilaterally congenitally deaf cats (CDCs), and unilaterally deaf cats (uCDCs). Binaural deafness reduced cortical responsiveness and decreased response thresholds and dynamic range. In contrast to CDCs, in uCDCs, cortical responsiveness was not reduced, but hemispheric-specific reorganization of aural dominance and binaural interactions were observed. Deafness led to a substantial drop in binaural facilitation in CDCs and uCDCs, demonstrating the inevitable role of experience for a binaural benefit. Sensitivity to interaural time differences was more reduced in uCDCs than in CDCs, particularly at the hemisphere ipsilateral to the hearing ear. Compared with binaural deafness, unilateral hearing prevented nonspecific reduction in cortical responsiveness, but extensively reorganized aural dominance and binaural responses. The deaf ear remained coupled with the cortex in uCDCs, demonstrating a significant difference to deprivation amblyopia in the visual system. PMID:26803166

  8. Monaural Congenital Deafness Affects Aural Dominance and Degrades Binaural Processing.

    PubMed

    Tillein, Jochen; Hubka, Peter; Kral, Andrej

    2016-04-01

    Cortical development extensively depends on sensory experience. Effects of congenital monaural and binaural deafness on cortical aural dominance and representation of binaural cues were investigated in the present study. We used an animal model that precisely mimics the clinical scenario of unilateral cochlear implantation in an individual with single-sided congenital deafness. Multiunit responses in cortical field A1 to cochlear implant stimulation were studied in normal-hearing cats, bilaterally congenitally deaf cats (CDCs), and unilaterally deaf cats (uCDCs). Binaural deafness reduced cortical responsiveness and decreased response thresholds and dynamic range. In contrast to CDCs, in uCDCs, cortical responsiveness was not reduced, but hemispheric-specific reorganization of aural dominance and binaural interactions were observed. Deafness led to a substantial drop in binaural facilitation in CDCs and uCDCs, demonstrating the inevitable role of experience for a binaural benefit. Sensitivity to interaural time differences was more reduced in uCDCs than in CDCs, particularly at the hemisphere ipsilateral to the hearing ear. Compared with binaural deafness, unilateral hearing prevented nonspecific reduction in cortical responsiveness, but extensively reorganized aural dominance and binaural responses. The deaf ear remained coupled with the cortex in uCDCs, demonstrating a significant difference to deprivation amblyopia in the visual system. PMID:26803166

  9. Dominant hydrological processes at three contrasting small permafrost watersheds in changing climate

    NASA Astrophysics Data System (ADS)

    Lebedeva, Liudmila; Semenova, Olga

    2016-04-01

    The most pronounced climatic changes are observed and projected in the Arctic. Large part of the Arctic is influenced by permanently or seasonally frozen ground that controls river runoff generation. The research aims at assessment of observed and projected changes of hydrological regime and identification of dominant hydrological processes at three small watersheds in different landscape and permafrost conditions of Siberia for the last sixty years by data analysis and process-based modelling. Three studied watersheds are located within the Yenisei, Lena and Kolyma river basins. The Graviyka river basin (323 km2) is situated in discontinuous permafrost in transition zone between tundra and taiga ecotones in the lower Yenisei region. Mean annual precipitation is 510 mm/year and air temperature is -8°C (1936-2014). Both air temperature and precipitation have shown significant increase for the last forty years. The Shestakovka river basin (170 km2), a tributary of the Lena river near Yakutsk, is characterized by extremely dry (240 mm/year) and cold (-9.5°C) climate of Central Yakutiya. Larch and pine forests grow on sandy deposits covered by continuous permafrost. Air temperature and river flow have increased for the last thirty years but precipitation have shown no significant changes. The Kontaktovy creek watershed (22 km2) is located in mountains of upper Kolyma river basin. The permafrost is continuous. Main land cover types are bare rocks, mountain tundra and sparse larch forest. Only insignificant changes of air temperature, precipitation and river flow were detected for the last decades. To assess dominant hydrological processes and to project their future changes in each studied watershed the process-based Hydrograph model was applied to historical and future time periods using temperate and extreme climate scenarios. The Hydrograph model does not rely on calibration and the parameters were estimated using all available a-priori information - thematic maps

  10. Stochastic investigation of precipitation process for climatic variability identification

    NASA Astrophysics Data System (ADS)

    Sotiriadou, Alexia; Petsiou, Amalia; Feloni, Elisavet; Kastis, Paris; Iliopoulou, Theano; Markonis, Yannis; Tyralis, Hristos; Dimitriadis, Panayiotis; Koutsoyiannis, Demetris

    2016-04-01

    The precipitation process is important not only to hydrometeorology but also to renewable energy resources management. We use a dataset consisting of daily and hourly records around the globe to identify statistical variability with emphasis on the last period. Specifically, we investigate the occurrence of mean, maximum and minimum values and we estimate statistical properties such as marginal probability distribution function and the type of decay of the climacogram (i.e., mean process variance vs. scale). Acknowledgement: This research is conducted within the frame of the undergraduate course "Stochastic Methods in Water Resources" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided moral support for the participation of the students in the Assembly.

  11. Experimental investigation of Mars meandering rivers: Chemical precipitation process

    NASA Astrophysics Data System (ADS)

    Kim, W.; Lim, Y.; Cleveland, J.; Reid, E.; Jew, C.

    2014-12-01

    On Earth, meandering streams occur where the banks are resistant to erosion, which enhances narrow and deep channels. Often this is because the stream banks are held firm by vegetation. The ancient, highly sinuous channels with cutoffs found on Mars are enigmatic because vegetation played no role in providing bank cohesion and enhancing fine sediment deposition. Possible causes of the meandering therefore include ice under permafrost conditions and chemical processes. We conducted carbonate flume experiments to investigate possible mechanisms creating meandering channels other than vegetation. The experiment includes a tank that dissolves limestone by adding CO2 gas and produces artificial spring water, peristaltic pumps to drive water through the system, a heater to control the temperature of the spring water, and a flume where carbonate sediment deposits. Spring water containing dissolved calcium and carbonate ions moves through a heater to increase temperature, and then into the flume. The flume surface is open to the air to allow CO2 degassing, decrease temperature, and increase pH, which promotes carbonate precipitation. A preliminary experiment was done and successfully created a meander pattern that evolved over a 3-day experiment. The experiment showed lateral migration of the bend and avulsion of the stream, similar to a natural meander. The lateral variation in flow speed increased the local residence time of water, thus increasing the degassing of CO2 on the two sides of the flow and promoting more precipitation. This enhanced precipitation on the sides provided a mechanism to build levees along the channel and created a stream confined in a narrow path. This mechanism also potentially applies to Earthly single thread and/or meandering rivers developed and recorded before vegetation appeared on Earth's surface.

  12. Technical bases for precipitate hydrolysis process operating parameters

    SciTech Connect

    Bannochie, C.J.

    1992-10-05

    This report provides the experimental data and rationale in support of the operating parameters for precipitate hydrolysis specified in WSRC-RP-92737. The report is divided into two sections, the first dealing with lab-scale precipitate hydrolysis experimentation while the second part addresses large-scale runs conducted to demonstrate the revised operating parameters in the Precipitate Hydrolysis Experimental Facility (PHEF).

  13. Evaluating process origins of sand-dominated fluvial stratigraphy

    NASA Astrophysics Data System (ADS)

    Chamberlin, E.; Hajek, E. A.

    2015-12-01

    Sand-dominated fluvial stratigraphy is often interpreted as indicating times of relatively slow subsidence because of the assumption that fine sediment (silt and clay) is reworked or bypassed during periods of low accommodation. However, sand-dominated successions may instead represent proximal, coarse-grained reaches of paleo-river basins and/or fluvial systems with a sandy sediment supply. Differentiating between these cases is critical for accurately interpreting mass-extraction profiles, basin-subsidence rates, and paleo-river avulsion and migration behavior from ancient fluvial deposits. We explore the degree to which sand-rich accumulations reflect supply-driven progradation or accommodation-limited reworking, by re-evaluating the Castlegate Sandstone (Utah, USA) and the upper Williams Fork Formation (Colorado, USA) - two Upper Cretaceous sandy fluvial deposits previously interpreted as having formed during periods of relatively low accommodation. Both units comprise amalgamated channel and bar deposits with minor intra-channel and overbank mudstones. To constrain relative reworking, we quantify the preservation of bar deposits in each unit using detailed facies and channel-deposit mapping, and compare bar-deposit preservation to expected preservation statistics generated with object-based models spanning a range of boundary conditions. To estimate the grain-size distribution of paleo-sediment input, we leverage results of experimental work that shows both bed-material deposits and accumulations on the downstream side of bars ("interbar fines") sample suspended and wash loads of active flows. We measure grain-size distributions of bar deposits and interbar fines to reconstruct the relative sandiness of paleo-sediment supplies for both systems. By using these novel approaches to test whether sand-rich fluvial deposits reflect river systems with accommodation-limited reworking and/or particularly sand-rich sediment loads, we can gain insight into large

  14. Oxygen isotope values of precipitation and surface waters in northern Central America (Belize and Guatemala) are dominated by temperature and amount effects

    NASA Astrophysics Data System (ADS)

    Lachniet, Matthew S.; Patterson, William P.

    2009-07-01

    An understanding of the climatic controls on precipitation δ18O is required to interpret isotopic records of paleoclimate and paleoaltimetry. However, variations in precipitation δ18O in time and space are only poorly known in northern Central America. To test the hypothesis that precipitation and surface water δ18O values are dominated by temporal and spatial amount effects, we analyzed δ18O in surface waters collected from Guatemala and Belize, and in precipitation from the Global Network for Isotopes in Precipitation database for Veracruz, Mexico, and San Salvador, El Salvador. Herein we show that the dominant controls on δ18O values of precipitation and surface waters are fairly simple. Temporally, the dominant control on precipitation δ18O values is the amount effect, whereby there is an inverse correlation between rainfall amount and δ18O. Precipitation δ18O values decrease by 1.24‰ per 100 mm increase of monthly rainfall. Spatially, only two variables - distance from the coast and mean catchment altitude - explain 84% of the surface water δ18O variability. Surface water δ18O values show an altitude effect of - 1.9 to - 2.4‰ km - 1 and a continental effect of 0.69‰ per 100 km once corrected for altitude effects. A decrease in surface water δ18O by 3 to 4‰ from the Caribbean Sea to the Pacific Ocean is evident as an isotopic rain shadow on the Pacific slope. Our data also show that river waters in this humid tropical environment are good proxies for δ18O values of precipitation in northern Central America. The Guatemala/Belize surface water line is defined as δD = 8.0 × δ18O + 8.7, which is similar to the meteoric water line at San Salvador of δD = 8.1 × δ18O + 10.9. Spatial variability in δ18O values is interpreted to reflect 1) progressive rainout of Caribbean-sourced air masses upon traverse of Central America, and 2) the temperature-dependent equilibrium fractionation between vapor and condensate related to the altitude effect

  15. Responses of Precipitation and Hydrologic Processes to Tropical SST

    NASA Technical Reports Server (NTRS)

    Sui, C.-H.; Lau, K.-M.; Li, X.

    2001-01-01

    The goal of the research is to identify the mechanisms in the response of tropical precipitation and atmospheric hydrologic cycle to sea surface temperature (SST) variability at seasonal-to-interannual time scales, and to utilize the knowledge for better understanding of climate feedback processes relevant to global change. As a first step to achieve the goal, we characterize the inter-relationship among convective/stratiform rain, ice/water clouds water vapor, and SST using TRMM satellite data and a cloud-resolving model. We examined the daily hydrologic variables [column water vapor (PW), cloud liquid water (CW), rainfall rates (RR)] as a function of SST using high-resolution data (0.25 x 0.25, daily) derived from TRMM satellite measurements. Comparing the winter of 97/98 (El Nino condition) against the winter of 99/00 (La Nina condition), area-mean values of all four hydrologic variables in cloudy areas within the tropical Pacific are higher in the El Nino winter than in the La Nina winter. This is consistent with previous observational analyses and SST warming experiments (idealized or ENSO-like) that showed the interaction between hydrologic cyclic and radiation at the seasonal to interannual time scales leads to intensified tropical circulation and hydrologic cycle. However, there is evidence that the enhanced hydrologic cycle over the warm pool is accompanied by an expansion of radiatively -driven subsidence in response to a stronger SST gradient between warm pool and surrounding cold pool. The expanding subsidence effectively reduces cloud amounts over the warm pool. Our analysis of daily variability further indicates a more vigorous water cycle characterized by higher PW, CW, and RR in response to overall warming. This is expected from the Clausius Clapeyron relation as a thermodynamic response to warming. However cloudy areas decrease in response to overall warming. This may be due to factors that are fundamentally different. One possibility is that in a

  16. Technical bases for precipitate hydrolysis process operating parameters

    SciTech Connect

    Bannochie, C.J.; Lambert, D.P.

    1992-11-09

    This report provides the experimental data and rationale in support of the operating parameters for tetraphenylborate precipitate hydrolysis specified in WSRC-RP-92-737. The report is divided into two sections, the first dealing with lab-scale precipitate hydrolysis experimentation while the second part addresses large-scale runs conducted to demonstrate the revised operating parameters in the Precipitate Hydrolysis Experimental Facility (PHEF). The program was in conjunction with reducing the nitrite ion level in DWPF feed.

  17. Technical bases for precipitate hydrolysis process operating parameters. Revision 1

    SciTech Connect

    Bannochie, C.J.; Lambert, D.P.

    1992-11-09

    This report provides the experimental data and rationale in support of the operating parameters for tetraphenylborate precipitate hydrolysis specified in WSRC-RP-92-737. The report is divided into two sections, the first dealing with lab-scale precipitate hydrolysis experimentation while the second part addresses large-scale runs conducted to demonstrate the revised operating parameters in the Precipitate Hydrolysis Experimental Facility (PHEF). The program was in conjunction with reducing the nitrite ion level in DWPF feed.

  18. Hand Dominance Influences the Processing of Observed Bodies

    ERIC Educational Resources Information Center

    Gardner, Mark R.; Potts, Rosalind

    2010-01-01

    In motor tasks, subgroups of lefthanders have been shown to differ in the distribution of attention about their own bodies. The present experiment examined whether similar attentional biases also apply when processing observed bodies. Sixteen right handers (RHs), 22 consistent left handers (CLHs) and 11 relatively ambidextrous inconsistent left…

  19. Effect of grassland vegetation type on the responses of hydrological processes to seasonal precipitation patterns

    NASA Astrophysics Data System (ADS)

    Salve, Rohit; Sudderth, Erika A.; St. Clair, Samuel B.; Torn, Margaret S.

    2011-11-01

    SummaryUnder future climate scenarios, rainfall patterns and species composition in California grasslands are predicted to change, potentially impacting soil-moisture dynamics and ecosystem function. The primary objective of this study was to assess the impact of altered rainfall on soil-moisture dynamics in three annual grassland vegetation types. We monitored seasonal changes in soil moisture under three different rainfall regimes in mesocosms planted with: (1) a mixed forb-grass community, (2) an Avena barbata monoculture, and (3) an Erodium botrys monoculture. We applied watering treatments in pulses, followed by dry periods that are representative of natural rainfall patterns in California annual grasslands. While rainfall was the dominant treatment, its impact on hydrological processes varied over the growing season. Surprisingly, there were only small differences in the hydrologic response among the three vegetation types. We found significant temporal variability in evapotranspiration, seepage, and soil-moisture content. Both Water Use Efficiency (WUE) and Rain Use Efficiency (RUE) decreased as annual precipitation totals increased. Results from this investigation suggest that both precipitation and vegetation have a significant interactive effect on soil-moisture dynamics. When combined, seasonal precipitation and grassland vegetation influence near-surface hydrology in ways that cannot be predicted from manipulation of a single variable.

  20. Determination of dominant biogeochemical processes in a contaminated aquifer-wetland system using multivariate statistical analysis

    USGS Publications Warehouse

    Baez-Cazull, S. E.; McGuire, J.T.; Cozzarelli, I.M.; Voytek, M.A.

    2008-01-01

    Determining the processes governing aqueous biogeochemistry in a wetland hydrologically linked to an underlying contaminated aquifer is challenging due to the complex exchange between the systems and their distinct responses to changes in precipitation, recharge, and biological activities. To evaluate temporal and spatial processes in the wetland-aquifer system, water samples were collected using cm-scale multichambered passive diffusion samplers (peepers) to span the wetland-aquifer interface over a period of 3 yr. Samples were analyzed for major cations and anions, methane, and a suite of organic acids resulting in a large dataset of over 8000 points, which was evaluated using multivariate statistics. Principal component analysis (PCA) was chosen with the purpose of exploring the sources of variation in the dataset to expose related variables and provide insight into the biogeochemical processes that control the water chemistry of the system. Factor scores computed from PCA were mapped by date and depth. Patterns observed suggest that (i) fermentation is the process controlling the greatest variability in the dataset and it peaks in May; (ii) iron and sulfate reduction were the dominant terminal electron-accepting processes in the system and were associated with fermentation but had more complex seasonal variability than fermentation; (iii) methanogenesis was also important and associated with bacterial utilization of minerals as a source of electron acceptors (e.g., barite BaSO4); and (iv) seasonal hydrological patterns (wet and dry periods) control the availability of electron acceptors through the reoxidation of reduced iron-sulfur species enhancing iron and sulfate reduction. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  1. Processing energetic materials with supercritical fluid precipitation techniques

    NASA Astrophysics Data System (ADS)

    Essel, Jonathan

    Research has shown that nano-sized particles of explosives have a reduced sensitivity to impact and shock. Nano-sized energetic particles have also shown promise in improving the performance of propellants and explosives. Therefore, a method to produce nano-sized explosive particles could be ideal for sensitivity and performance reasons. Supercritical fluid precipitation has been shown to produce nano-sized explosive particles effectively. This research explores the feasibility of processing energetic materials using three different supercritical fluid precipitation techniques. The first technique is called the Rapid Expansion of a Supercritical Solution (RESS). The RESS process dissolves a solute in a supercritical fluid and then rapidly expands the resulting solution through a nozzle to produce small (nano-sized) and uniform particles from a high degree of supersaturation. The second technique is the Rapid Expansion of a Supercritical Solution into a Liquid Solvent (RESOLV) Process. This process is similar to the RESS process except the supercritical solution is expanded into a liquid and dispersant solution to reduce particle agglomeration and to reduce the size of the particles further. The final technique investigated is the Rapid Expansion of a Supercritical Solution with a Nonsolute (RESS-N) process in which the precipitating solute is used to encapsulate or coat a nonsoluble substance by heterogeneous nucleation. This works takes both a theoretical an empirical approach. On the theoretical side, a numerical code that accounts for nucleation and condensation in the RESS process was written in FORTRAN to predict how altering pre-expansion pressures and pre-expansion temperatures in the RESS process could affect the final particle size of the produced RDX. It was determined that pre-expansion temperature had a marginal impact on final particle size but higher pre-expansion pressures were beneficial in forming smaller particles. Also, a software program called

  2. Significant differences in biogeochemical processes between a glaciated and a permafrost dominated catchment

    NASA Astrophysics Data System (ADS)

    Hindshaw, Ruth; Heaton, Tim; Boyd, Eric; Lang, Susan; Tipper, Ed

    2014-05-01

    It is increasingly recognised that microbially mediated processes have a significant impact on chemical fluxes from glaciated catchments. One important reaction is the oxidation of pyrite since the production of sulphuric acid facilitates the dissolution of minerals without the need for acidity generated by dissolved atmospheric CO2. Thus weathering processes can still continue even when isolated from the atmosphere, as is thought to occur under large ice masses. However, as a glacier melts, it is expected that the microbial community will change with knock-on effects on the stream water chemistry. Understanding the difference in solute generation processes between glaciated and un-glaciated terrain is key to understanding how glacial-interglacial cycles affect atmospheric CO2 consumption by chemical weathering. In order to investigate whether biogeochemical processes differ between glaciated and un-glaciated terrain we collected stream water samples from two small catchments (each approximately 3 km2) in Svalbard. One catchment is glaciated and the other catchment is un-glaciated but is affected by permafrost and a seasonal snow-pack. The two catchments are situated next to each other with identical bedrock (shale with minor siltstone and sandstone). The proximity of the catchments to each other ensures that meteorological variables such as temperature and precipitation are very similar. Sampling was conducted early in the melt-season when there was still significant snow-cover and in mid-summer when most of the seasonal snow-pack had melted. The water samples were analysed for δ34S-SO4, δ18O-SO4, δ18O-H2O, δ13C-DIC and δ13C-DOC, together with major anions and cations. Despite the nominally identical lithology, there were significant differences in the stream water chemistry between the two catchments. For example, sulphate was the dominant anion in the un-glaciated catchment whereas bicarbonate was the dominant anion in the glaciated catchment. Pyrite

  3. Investigating dominant processes in ZVI permeable reactive barriers using reactive transport modeling.

    PubMed

    Weber, Anne; Ruhl, Aki S; Amos, Richard T

    2013-08-01

    The reactive and hydraulic efficacy of zero valent iron permeable reactive barriers (ZVI PRBs) is strongly affected by geochemical composition of the groundwater treated. An enhanced version of the geochemical simulation code MIN3P was applied to simulate dominating processes in chlorinated hydrocarbons (CHCs) treating ZVI PRBs including geochemical dependency of ZVI reactivity, gas phase formation and a basic formulation of degassing. Results of target oriented column experiments with distinct chemical conditions (carbonate, calcium, sulfate, CHCs) were simulated to parameterize the model. The simulations demonstrate the initial enhancement of anaerobic iron corrosion due to carbonate and long term inhibition by precipitates (chukanovite, siderite, iron sulfide). Calcium was shown to enhance long term corrosion due to competition for carbonate between siderite, chukanovite, and aragonite, with less inhibition of iron corrosion by the needle like aragonite crystals. Application of the parameterized model to a field site (Bernau, Germany) demonstrated that temporarily enhanced groundwater carbonate concentrations caused an increase in gas phase formation due to the acceleration of anaerobic iron corrosion. PMID:23743511

  4. Meaning Dominance and Semantic Context in the Processing of Lexical Ambiguity.

    ERIC Educational Resources Information Center

    Simpson, Greg B.

    1981-01-01

    Describes two experiments on the processing of ambiguous words: one involving lexical decisions for words related to dominant or subordinate meanings of homograph primes, the other involving ambiguous words ending sentences that bias the homographs at varying degrees. Concludes that dominance and context contribute independently to processing of…

  5. Warming and increased precipitation frequency on the Colorado Plateau: implications for biological soil crusts and soil processes

    SciTech Connect

    Zelikova, Tamara J.; Housman, David C.; Grote, Ed E.; Neher, Deborah A.; Belnap, Jayne

    2012-01-20

    Changes in temperature and precipitation are expected to influence ecosystem processes worldwide. Despite their globally large extent, few studies to date have examined the effects of climate change in desert ecosystems, where biological soil crusts are key nutrient cycling components. The goal of this work was to assess how increased temperature and frequency of summertime precipitation affect the contributions of crust organisms to soil processes. With a combination of experimental 2°C warming and altered summer precipitation frequency applied over 2 years, we measured soil nutrient cycling and the structure and function of crust communities. We saw no change in crust cover, composition, or other measures of crust function in response to 2°C warming and no effects on any measure of soil chemistry. In contrast, crust cover and function responded to increased frequency of summer precipitation, shifting from moss to cyanobacteria-dominated crusts; however, in the short timeframe we measured, there was no accompanying change in soil chemistry. Total bacterial and fungal biomass was also reduced in watered plots, while the activity of two enzymes increased, indicating a functional change in the microbial community. Taken together, our results highlight the limited effects of warming alone on biological soil crust communities and soil chemistry, but demonstrate the substantially larger effects of altered summertime precipitation.

  6. Modeling the neutralizing processes of acid precipitation in soils and glacial sediments of northern Ohio

    NASA Astrophysics Data System (ADS)

    Eckstein, Yoram; Hau, Joseph A.

    1992-02-01

    Most studies of the acidic deposition phenomena have been focused on processes occurring in the northeastern USA and Scandinavia. In these regions the soil cover is thin, the bedrock is acidic, and the terrain has very poor acid buffering capacity. Most of the US Midwest, including northern Ohio, has been ignored because the terrain is covered by glacial sediments with an abundance of carbonate minerals. Yet, for the last three decades the area has been experiencing acidic precipitation with a pH range of 3.5-4.5. the lowest in the USA. Samples of precipitation, soil water, and shallow ground water from Leroy Township in Lake County, Ohio, and from Wooster Township in Wayne County, Ohio, were analyzed and processed using WATEQ3 and PHREEQE computer models to quantify the effects of the acidic deposition. The two regions are characterized by very similar topographic, geological and hydrogeological conditions. Although the cation content of the precipitation in both regions is similar, the anion concentrations are much higher (sulfate by 70%, nitrate by 14% and chloride by 167%) in Leroy, located 50 km east-northeast and downwind of the Cleveland-Akron industrial complex, than in Wooster, located 80 km south-southwest and off-wind from the industrial complex. Computer modeling results indicate that buffering of acidic deposition in the surficial sediments and glacial tills of the two regions is dominated apparently by calcite dissolution, and dissolution and exchange of hydrogen for magnesium ions are the dominant neutralizing processes. However, reaction simulations also suggest that the buffering capacity of the Leroy soils and tills has been depleted to a much greater degree than in Wooster Township. In Leroy more acidic input is reacting with less buffering material to produce lower soil and groundwater pH. The depletion of carbonate and alumino-silicate minerals in the soils of Leroy Township is occurring at a rate that is 3-5 times faster than in the same type

  7. Genomic and Resistance Gene Homolog Diversity of the Dominant Tallgrass Prairie Species across the U.S. Great Plains Precipitation Gradient

    PubMed Central

    Rouse, Matthew N.; Saleh, Amgad A.; Seck, Amadou; Keeler, Kathleen H.; Travers, Steven E.; Hulbert, Scot H.; Garrett, Karen A.

    2011-01-01

    Background Environmental variables such as moisture availability are often important in determining species prevalence and intraspecific diversity. The population genetic structure of dominant plant species in response to a cline of these variables has rarely been addressed. We evaluated the spatial genetic structure and diversity of Andropogon gerardii populations across the U.S. Great Plains precipitation gradient, ranging from approximately 48 cm/year to 105 cm/year. Methodology/Principal Findings Genomic diversity was evaluated with AFLP markers and diversity of a disease resistance gene homolog was evaluated by PCR-amplification and digestion with restriction enzymes. We determined the degree of spatial genetic structure using Mantel tests. Genomic and resistance gene homolog diversity were evaluated across prairies using Shannon's index and by averaging haplotype dissimilarity. Trends in diversity across prairies were determined using linear regression of diversity on average precipitation for each prairie. We identified significant spatial genetic structure, with genomic similarity decreasing as a function of distance between samples. However, our data indicated that genome-wide diversity did not vary consistently across the precipitation gradient. In contrast, we found that disease resistance gene homolog diversity was positively correlated with precipitation. Significance Prairie remnants differ in the genetic resources they maintain. Selection and evolution in this disease resistance homolog is environmentally dependent. Overall, we found that, though this environmental gradient may not predict genomic diversity, individual traits such as disease resistance genes may vary significantly. PMID:21532756

  8. Estimating the effects of potential climate and land use changes on hydrologic processes of a large agriculture dominated watershed

    NASA Astrophysics Data System (ADS)

    Neupane, Ram P.; Kumar, Sandeep

    2015-10-01

    Land use and climate are two major components that directly influence catchment hydrologic processes, and therefore better understanding of their effects is crucial for future land use planning and water resources management. We applied Soil and Water Assessment Tool (SWAT) to assess the effects of potential land use change and climate variability on hydrologic processes of large agriculture dominated Big Sioux River (BSR) watershed located in North Central region of USA. Future climate change scenarios were simulated using average output of temperature and precipitation data derived from Special Report on Emission Scenarios (SRES) (B1, A1B, and A2) for end-21st century. Land use change was modeled spatially based on historic long-term pattern of agricultural transformation in the basin, and included the expansion of corn (Zea mays L.) cultivation by 2, 5, and 10%. We estimated higher surface runoff in all land use scenarios with maximum increase of 4% while expanding 10% corn cultivation in the basin. Annual stream discharge was estimated higher with maximum increase of 72% in SRES-B1 attributed from higher groundwater contribution of 152% in the same scenario. We assessed increased precipitation during spring season but the summer precipitation decreased substantially in all climate change scenarios. Similar to decreased summer precipitation, discharge of the BSR also decreased potentially affecting agricultural production due to reduced future water availability during crop growing season in the basin. However, combined effects of potential land use change with climate variability enhanced for higher annual discharge of the BSR. Therefore, these estimations can be crucial for implications of future land use planning and water resources management of the basin.

  9. Microstructure and Crystallographic Texture Evolution During the Friction-Stir Processing of a Precipitation-Hardenable Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Nadammal, Naresh; Kailas, Satish V.; Szpunar, Jerzy; Suwas, Satyam

    2015-05-01

    Friction-stir processing (FSP) has been proven as a successful method for the grain refinement of high-strength aluminum alloys. The most important attributes of this process are the fine-grain microstructure and characteristic texture, which impart suitable properties in the as-processed material. In the current work, FSP of the precipitation-hardenable aluminum alloy 2219 has been carried out and the consequent evolution of microstructure and texture has been studied. The as-processed materials were characterized using electron back-scattered diffraction, x-ray diffraction, and electron probe microanalysis. Onion-ring formation was observed in the nugget zone, which has been found to be related to the precipitation response and crystallographic texture of the alloy. Texture development in the alloy has been attributed to the combined effect of shear deformation and dynamic recrystallization. The texture was found heterogeneous even within the nugget zone. A microtexture analysis revealed the dominance of shear texture components, with C component at the top of nugget zone and the B and A2* components in the middle and bottom. The bulk texture measurement in the nugget zone revealed a dominant C component. The development of a weaker texture along with the presence of some large particles in the nugget zone indicates particle-stimulated nucleation as the dominant nucleation mechanism during FSP. Grain growth follows the Burke and Turnbull mechanism and geometrical coalescence.

  10. Application of a Process Based Hydrologic Model in a Snow Dominant WaterShed: Upper Feather River Basin in California

    NASA Astrophysics Data System (ADS)

    Chung, F. I.; Kadir, T.; Galef, J.

    2008-12-01

    Milly et al. in a recent article (Science, Vol319, 1February, 2008, pp573-574) declared that "stationarity is dead." They went on stating, "Finding a suitable successor is crucial for human adaptation to changing climate." California's Department of Water Resources' (DWR's) search for a suitable successor led to the conclusion that a "temperature based approach" might be a good candidate to replace or supplement the traditional "precipitation based" hydrology. In this paper application of a physically based model that begins with ambient air temperature is presented. The projections of precipitation by various GCM's are wide spread and uncertainties on the wetness (or dryness) are abound whereas the future temperature projections, through also wide spread, are unanimous in directional sense-going up or getting warmer over time. Noting this robust nature of the future temperature projections and also noting that the cause of the future precipitation changes is due to the rising temperature, the authors take an approach that the temperature, rather than the precipitation, should be the commencing point in the development of the changing future hydrology. We claim that the main cause of the "death" of the stationarity in a snow dominant high elevation watershed is the warming temperature. Therefore, by commencing with the temperature in the hydrologic process, either the form of precipitation or the melting of the accumulated snow can be captured and the non-stationary future hydrology can be generated for water resources planning and management. The USGS under a contract to DWR completed development of the Precipitation-Runoff Modeling System (PRMS) application for simulating daily streamflow for the Upper Feather River Basin. PRMS simulates all the major snowmelt/precipitation related physical processes including snowpack accumulation/melting, sublimation, evapotranspiration, surface runoff, subsurface flow, and ground water flow. The model was calibrated for Water

  11. Advanced process for precipitation of lignin from ethanol organosolv spent liquors.

    PubMed

    Schulze, Peter; Seidel-Morgenstern, Andreas; Lorenz, Heike; Leschinsky, Moritz; Unkelbach, Gerd

    2016-01-01

    An advanced process for lignin precipitation from organosolv spent liquors based on ethanol evaporation was developed. The process avoids lignin incrustations in the reactor, enhances filterability of the precipitated lignin particles and significantly reduces the liquor mass in downstream processes. Initially, lignin solubility and softening properties were understood, quantified and exploited to design an improved precipitation process. Lignin incrustations were avoided by targeted precipitation of solid lignin at specific conditions (e.g. 100 mbar evaporation pressure, 43°C and 10%wt. of ethanol in lignin dispersion) in fed-batch operation at lab and pilot scale. As result of evaporation the mass of spent liquor was reduced by about 50%wt., thus avoiding large process streams. By controlled droplet coalescence the mean lignin particle size increased from below 10 μm to sizes larger than 10 μm improving the significantly filterability. PMID:26459197

  12. The Dominant Snow-forming Process in Warm and Cold Mixed-phase Orographic Clouds: Effects of Cloud Condensation Nuclei and Ice Nuclei

    NASA Astrophysics Data System (ADS)

    Fan, J.; Rosenfeld, D.; Leung, L. R.; DeMott, P. J.

    2014-12-01

    Mineral dust aerosols often observed over California in winter and spring from long-range transport can be efficient ice nuclei (IN) and enhance snow precipitation in mixed-phase orographic clouds. On the other hand, local pollution particles can serve as good CCN and suppress warm rain, but their impacts on cold rain processes are uncertain. The main snow-forming mechanism in warm and cold mixed-phase orographic clouds (refer to as WMOC and CMOC, respectively) could be very different, leading to different precipitation response to CCN and IN. We have conducted 1-km resolution model simulations using the Weather Research and Forecasting (WRF) model coupled with a spectral-bin cloud microphysical model for WMOC and CMOC cases from CalWater2011. We investigated the response of cloud microphysical processes and precipitation to CCN and IN with extremely low to extremely high concentrations using ice nucleation parameterizations that connect with dust and implemented based on observational evidences. We find that riming is the dominant process for producing snow in WMOC while deposition plays a more important role than riming in CMOC. Increasing IN leads to much more snow precipitation mainly due to an increase of deposition in CMOC and increased rimming in WMOC. Increasing CCN decreases precipitation in WMOC by efficiently suppressing warm rain, although snow is increased. In CMOC where cold rain dominates, increasing CCN significantly increases snow, leading to a net increase in precipitation. The sensitivity of supercooled liquid to CCN and IN has also been analyzed. The mechanism for the increased snow by CCN and caveats due to uncertainties in ice nucleation parameterizations will be discussed.

  13. Dominant modes of blocking variability in the North Atlantic region and their relationship with extreme temperature and precipitation events over Europe

    NASA Astrophysics Data System (ADS)

    Rimbu, Norel; Lohmann, Gerrit; Ionita, Monica

    2013-04-01

    precipitation are higher than the corresponding 90th percentile. The frequency of extreme low temperature events is defined as the number of days in a winter when minimum daily temperature is lower than the corresponding 10th percentile. A correlation analysis reveals that the dominant blocking variability patterns are related with large-scale anomalies in the frequency of temperature and precipitation extreme events. The first blocking pattern is associated with a north-south dipole in the frequency of temperature and precipitation extreme events. The second blocking pattern is responsible for interannual to decadal variations in extreme events mainly over western Europe while the third controls mainly the extreme temperature and precipitation variability over the southeastern Europe. We argue that a large part of the interannual to multidecadal variability of the extreme temperature and precipitation events over Europe are induced by the dominant climate modes, i.e. the NAO and AMO, through modulation of blocking activity in the Atlantic-European region.

  14. Firmicutes dominate the bacterial taxa within sugar-cane processing plants.

    PubMed

    Sharmin, Farhana; Wakelin, Steve; Huygens, Flavia; Hargreaves, Megan

    2013-01-01

    Sugar cane processing sites are characterised by high sugar/hemicellulose levels, available moisture and warm conditions, and are relatively unexplored unique microbial environments. The PhyloChip microarray was used to investigate bacterial diversity and community composition in three Australian sugar cane processing plants. These ecosystems were highly complex and dominated by four main Phyla, Firmicutes (the most dominant), followed by Proteobacteria, Bacteroidetes, and Chloroflexi. Significant variation (p < 0.05) in community structure occurred between samples collected from 'floor dump sediment', 'cooling tower water', and 'bagasse leachate'. Many bacterial Classes contributed to these differences, however most were of low numerical abundance. Separation in community composition was also linked to Classes of Firmicutes, particularly Bacillales, Lactobacillales and Clostridiales, whose dominance is likely to be linked to their physiology as 'lactic acid bacteria', capable of fermenting the sugars present. This process may help displace other bacterial taxa, providing a competitive advantage for Firmicutes bacteria. PMID:24177592

  15. Left hemispheric dominance of vestibular processing indicates lateralization of cortical functions in rats.

    PubMed

    Best, Christoph; Lange, Elena; Buchholz, Hans-Georg; Schreckenberger, Mathias; Reuss, Stefan; Dieterich, Marianne

    2014-11-01

    Lateralization of cortical functions such as speech dominance, handedness and processing of vestibular information are present not only in humans but also in ontogenetic older species, e.g. rats. In human functional imaging studies, the processing of vestibular information was found to be correlated with the hemispherical dominance as determined by the handedness. It is located mainly within the right hemisphere in right handers and within the left hemisphere in left handers. Since dominance of vestibular processing is unknown in animals, our aim was to study the lateralization of cortical processing in a functional imaging study applying small-animal positron emission tomography (microPET) and galvanic vestibular stimulation in an in vivo rat model. The cortical and subcortical network processing vestibular information could be demonstrated and correlated with data from other animal studies. By calculating a lateralization index as well as flipped region of interest analyses, we found that the vestibular processing in rats follows a strong left hemispheric dominance independent from the "handedness" of the animals. These findings support the idea of an early hemispheric specialization of vestibular cortical functions in ontogenetic older species. PMID:23979449

  16. PROCESS OF TREATING OR FORMING AN INSOLUBLE PLUTONIUM PRECIPITATE IN THE PRESENCE OF AN ORGANIC ACTIVE AGENT

    DOEpatents

    Balthis, J.H.

    1961-07-18

    Carrier precipitation processes for the separation of plutonium from fission products are described. In a process in which an insoluble precipitate is formed in a solution containing plutonium and fission products under conditions whereby plutonium is carried by the precipitate, and the precipitate is then separated from the remaining solution, an organic surface active agent is added to the mixture of precipitate and solution prior to separation of the precipitate from the supernatant solution, thereby improving the degree of separation of the precipitate from the solution.

  17. Drought and Snow: Analysis of Drivers, Processes and Impacts of Streamflow Droughts in Snow-Dominated Regions

    NASA Astrophysics Data System (ADS)

    Van Loon, Anne; Laaha, Gregor; Van Lanen, Henny; Parajka, Juraj; Fleig, Anne; Ploum, Stefan

    2016-04-01

    Around the world, drought events with severe socio-economic impacts seem to have a link with winter snowpack. That is the case for the current California drought, but analysing historical archives and drought impact databases for the US and Europe we found many impacts that can be attributed to snowpack anomalies. Agriculture and electricity production (hydropower) were found to be the sectors that are most affected by drought related to snow. In this study, we investigated the processes underlying hydrological drought in snow-dominated regions. We found that drought drivers are different in different regions. In Norway, more than 90% of spring streamflow droughts were preceded by below-average winter precipitation, while both winter air temperature and spring weather were indifferent. In Austria, however, spring streamflow droughts could only be explained by a combination of factors. For most events, winter and spring air temperatures were above average (70% and 65% of events, respectively), and winter and spring precipitation was below average (75% and 80%). Because snow storage results from complex interactions between precipitation and temperature and these variables vary strongly with altitude, snow-related drought drivers have a large spatial variability. The weather input is subsequently modified by land properties. Multiple linear regression between drought severity variables and a large number of catchment characteristics for 44 catchments in Austria showed that storage influences both drought duration and deficit volume. The seasonal storage of water in snow and glaciers was found to be a statistically important variable explaining streamflow drought deficit. Our drought impact analysis in Europe also showed that 40% of the selected drought impacts was caused by a combination of snow-related and other drought types. For example, the combination of a winter drought with a preceding or subsequent summer drought was reported to have a large effect on

  18. Drought and Snow: Analysis of Drivers, Processes and Impacts of Streamflow Droughts in Snow-Dominated Regions

    NASA Astrophysics Data System (ADS)

    Van Loon, A.; Laaha, G.; Van Lanen, H.; Parajka, J.; Fleig, A. K.; Ploum, S.

    2015-12-01

    Around the world, drought events with severe socio-economic impacts seem to have a link with winter snowpack. That is the case for the current California drought, but analysing historical archives and drought impact databases for the US and Europe we found many impacts that can be attributed to snowpack anomalies. Agriculture and electricity production (hydropower) were found to be the sectors that are most affected by drought related to snow. In this study, we investigated the processes underlying hydrological drought in snow-dominated regions. We found that drought drivers are different in different regions. In Norway, more than 90% of spring streamflow droughts were preceded by below-average winter precipitation, while both winter air temperature and spring weather were indifferent. In Austria, however, spring streamflow droughts could only be explained by a combination of factors. For most events, winter and spring air temperatures were above average (70% and 65% of events, respectively), and winter and spring precipitation was below average (75% and 80%). Because snow storage results from complex interactions between precipitation and temperature and these variables vary strongly with altitude, snow-related drought drivers have a large spatial variability. The weather input is subsequently modified by land properties. Multiple linear regression between drought severity variables and a large number of catchment characteristics for 44 catchments in Austria showed that storage influences both drought duration and deficit volume. The seasonal storage of water in snow and glaciers was found to be a statistically important variable explaining streamflow drought deficit. Our drought impact analysis in Europe also showed that 40% of the selected drought impacts was caused by a combination of snow-related and other drought types. For example, the combination of a winter drought with a preceding or subsequent summer drought was reported to have a large effect on

  19. Responses of plant biomass, photosynthesis and lipid peroxidation to warming and precipitation change in two dominant species (Stipa grandis and Leymus chinensis) from North China Grasslands.

    PubMed

    Song, Xiliang; Wang, Yuhui; Lv, Xiaomin

    2016-03-01

    Influential factors of global change affect plant carbon uptake and biomass simultaneously. Although the effects from warming and precipitation change have been extensive studied separately, the responses of plant biomass, photosynthesis, and lipid peroxidation to the interaction of these factors are still not fully understood. In this study, we examined the physiological responses of two dominant plant species from grasslands of northern China with different functional traits to combinations of five simulated warming patterns and five simulated precipitation patterns in environment-controlled chambers. Our results showed that the biomass, net CO 2 assimilation rate (P n), maximal efficiency of photosystem II photochemistry (F v/F m), and chlorophyll content (Chl) of Stipa grandis and Leymus chinensis were enhanced by moderate warming and plus precipitation, but they declined drastically with high temperature and drought. High temperature and drought also led to significant malondialdehyde (MDA) accumulation, which had a negative correlation with leaf biomass. The lower level of lipid peroxidation in leaves of S. grandis suggests that this species is better protected from oxidative damage under heat stress, drought stress and their interactive conditions than L. chinensis. Using the subordinate function values method, we found S. grandis to be more sensitive to climate change than L. chinensis and the gross biomass and root biomass of S. grandis and the leaf biomass of L. chinensis were most sensitive to climate change. Furthermore, the P n of both S. grandis and L. chinensis had a significant linear relationship with F v/F m and Chl, indicating that carbon assimilation may be caused by nonstomatal limitations. PMID:26933491

  20. The Effects of Gender and Dominant Mental Processes on Hypermedia Learning

    ERIC Educational Resources Information Center

    Ellis, Holly; Howard, W. Gary; Donofrio, Heather H.

    2012-01-01

    The effects of gender and dominant mental process on learning is an area of increased interest among educators. This study was designed to explore those effects on hypermedia learning. The hypermedia module was created using a modified hierarchical structure, and a pre-test/post-test was conducted. The Myers-Briggs Type Indicator (MBTI) was…

  1. Removal of an anionic dye by adsorption/precipitation processes using alkaline white mud.

    PubMed

    Zhu, Mao-Xu; Lee, Li; Wang, Hai-Hua; Wang, Zheng

    2007-11-19

    Alkaline white mud (AWM) has been investigated as a low-cost material for removal of an anionic dye, acid blue 80. The effects of contact time, initial pH of dye solution, AWM dosage, and the presence of inorganic anion sulphate or phosphate ion on removal of the dye were evaluated. The results show that AWM could be used as an effective material for removal of acid blue 80 in a pre or main process, particularly at high dye concentration (>300 mgL(-1)), reaching maximum removal efficiency of 95%. At low dye concentration, surface adsorption is mainly responsible for the dye removal, while chemical precipitation of the dye anions with soluble Ca(2+) and Mg(2+) may play a dominant role for the dye removal at high concentration, producing much less sludge than conventional adsorption method. Solution pH has only a limited effect on the dye removal due to high alkalinity and large pH buffer capacity of AWM suspension and thereby pH is not a limiting factor in pursuing high dye removal. The presence of SO(4)(2-) could reduce the dye removal by AWM only when SO(4)(2-) concentration is beyond 0.7 mmolL(-1). The dye removal may be significantly suppressed by the presence of phosphate with increasing concentration, and the reduction in the dye removal is much larger at high dye concentrations than at low ones. PMID:17532132

  2. Direct solid-state precipitation-processed A15 /Nb3Al/ superconducting material

    NASA Astrophysics Data System (ADS)

    Hong, M.; Morris, J. W., Jr.

    1980-12-01

    A 'solid-state precipitation' process was used to prepare superconducting tapes containing Nb3Al in a niobium matrix. Small ingots of Nb-(17-19 at. %)Al were prepared by arc melting, homogenizing, quenching, warm rolling into tape, and aging at 750-900 C to precipitate the A15 phase. Transmission electron microscopy studies revealed Nb3Al precipitation in fine particles which formed a semicontinuous network over subgrain boundaries formed by the recovery of deformation-induced dislocations. Promising high-field critical currents were obtained (current density approximately 10 thousand A/sq cm in a field of 14 T at 4.2 K).

  3. Detection of dominant modelled nitrate processes with a high temporally resolved parameter sensitivity analysis

    NASA Astrophysics Data System (ADS)

    Haas, Marcelo; Guse, Björn; Pfannerstill, Matthias; Fohrer, Nicola

    2015-04-01

    The river systems in the catchment are impacted by nutrient inputs from different sources of the landscape. The input of nitrate from agricultural areas into the river systems is related to numerous processes which occur simultaneously and influence each other permanently. These complex nitrate processes are represented in eco-hydrological models. To obtain reliable future predictions of nitrate concentrations in rivers, the nitrogen cycle needs to be reproduced accurately in these models. For complex research questions dealing with nitrate impacts, it is thus essential to better understand the nitrate process dynamics in models and to reduce the uncertainties in water quality predictions. This study aims to improve the understanding of nitrate process dynamics by using a temporal parameter sensitivity analysis, which is applied on an eco-hydrological model. With this method, the dominant model parameters are detected for each day. Thus, by deriving temporal variations in dominant model parameters, the nitrate process dynamic is investigated for phases with different conditions for nitrate transport and transformations. The results show that the sensitivity of different nitrate parameters varies temporally. These temporal dynamics in dominant parameters are explained by temporal variations in nitrate transport and plant uptake processes. An extended view on the dynamics of the temporal parameter sensitivity is obtained by analysing different modelled runoff components and nitrate pathways. Thereby, the interpretation of seasonal variations in dominant nitrate pathways is assisted and a better understanding of the role of nitrate in the environment is achieved. We conclude that this method improves the reliability of modelled nitrate processes. In this way, a better basis for recent and future scenarios of nitrate loads management is provided.

  4. Use of surfactants in alumina precipitation in the bayer process

    SciTech Connect

    Owen, D.O.; Davis, D.C.

    1988-04-12

    In the method for producing alumina trihydrate crystals by crystallization of alumina trihydrate from a hot, caustic pregnant Bayer process liquor, to obtain a reduced percent of small size crystals -325 mesh fraction thereby to increase the yield of crystals coarser than -325 mesh subsequently to be processed to yield aluminum, the improvement is described comprising the addition to the pregnant liquor, after red mud separation and immediately prior to crystallization of alumina trihydrate, of two mutually soluble components (A) and (B) in an amount effective to increase the yield of the coarser crystals, component (A) being a surfactant which will disperse component (B) in the pregnant liquor and component (B) being an oil in which the surfactant is dissolved and having a boiling point above the temperature prevailing alumina hydrate crystallization.

  5. Flotation process for removal of precipitates from electrochemical chromate reduction unit

    DOEpatents

    DeMonbrun, James R.; Schmitt, Charles R.; Williams, Everett H.

    1976-01-01

    This invention is an improved form of a conventional electrochemical process for removing hexavalent chromium or other metal-ion contaminants from cooling-tower blowdown water. In the conventional process, the contaminant is reduced and precipitated at an iron anode, thus forming a mixed precipitate of iron and chromium hydroxides, while hydrogen being evolved copiously at a cathode is vented from the electrochemical cell. In the conventional process, subsequent separation of the fine precipitate has proved to be difficult and inefficient. In accordance with this invention, the electrochemical operation is conducted in a novel manner permitting a much more efficient and less expensive precipitate-recovery operation. That is, the electrochemical operation is conducted under an evolved-hydrogen partial pressure exceeding atmospheric pressure. As a result, most of the evolved hydrogen is entrained as bubbles in the blowdown in the cell. The resulting hydrogen-rich blowdown is introduced to a vented chamber, where the entrained hydrogen combines with the precipitate to form a froth which can be separated by conventional techniques. In addition to the hydrogen, two materials present in most blowdown act as flotation promoters for the precipitate. These are (1) air, with which the blowdown water becomes saturated in the course of normal cooling-tower operation, and (2) surfactants which commonly are added to cooling-tower recirculating-water systems to inhibit the growth of certain organisms or prevent the deposition of insoluble particulates.

  6. Tributylphosphate in the In-Tank Precipitation Process Facilities

    SciTech Connect

    Barnes, M.J.; Hobbs, D.T.; Swingle, R.F.

    1993-11-23

    A material balance investigation and evaluation of n- tributylphosphate (TBP) recycle throughout ITP and its carryover to Defense Waste Processing Facility (DWPF) was performed. Criticality and DWPF-related issues were determined to pose no adverse consequences due to TBP addition. Effects of decomposition products were also considered. Flammability of 1-butanol, a TBP decomposition product, in Tank 22 was investigated. Calculations show that Tank 22 would be ventilated with air at a rate sufficient to maintain a 1-butanol concentration (volume percent) well below 25 percent of the lower flammability limit (LFL) for 1-butanol.

  7. A Preliminary Analysis of Precipitation Properties and Processes during NASA GPM IFloodS

    NASA Technical Reports Server (NTRS)

    Carey, Lawrence; Gatlin, Patrick; Petersen, Walt; Wingo, Matt; Lang, Timothy; Wolff, Dave

    2014-01-01

    The Iowa Flood Studies (IFloodS) is a NASA Global Precipitation Measurement (GPM) ground measurement campaign, which took place in eastern Iowa from May 1 to June 15, 2013. The goals of the field campaign were to collect detailed measurements of surface precipitation using ground instruments and advanced weather radars while simultaneously collecting data from satellites passing overhead. Data collected by the radars and other ground instruments, such as disdrometers and rain gauges, will be used to characterize precipitation properties throughout the vertical column, including the precipitation type (e.g., rain, graupel, hail, aggregates, ice crystals), precipitation amounts (e.g., rain rate), and the size and shape of raindrops. The impact of physical processes, such as aggregation, melting, breakup and coalescence on the measured liquid and ice precipitation properties will be investigated. These ground observations will ultimately be used to improve rainfall estimates from satellites and in particular the algorithms that interpret raw data for the upcoming GPM mission's Core Observatory satellite, which launches in 2014. The various precipitation data collected will eventually be used as input to flood forecasting models in an effort to improve capabilities and test the utility and limitations of satellite precipitation data for flood forecasting. In this preliminary study, the focus will be on analysis of NASA NPOL (S-band, polarimetric) radar (e.g., radar reflectivity, differential reflectivity, differential phase, correlation coefficient) and NASA 2D Video Disdrometers (2DVDs) measurements. Quality control and processing of the radar and disdrometer data sets will be outlined. In analyzing preliminary cases, particular emphasis will be placed on 1) documenting the evolution of the rain drop size distribution (DSD) as a function of column melting processes and 2) assessing the impact of range on ground-based polarimetric radar estimates of DSD properties.

  8. PROCESS USING BISMUTH PHOSPHATE AS A CARRIER PRECIPITATE FOR FISSION PRODUCTS AND PLUTONIUM VALUES

    DOEpatents

    Finzel, T.G.

    1959-03-10

    A process is described for separating plutonium from fission products carried therewith when plutonium in the reduced oxidation state is removed from a nitric acid solution of irradiated uranium by means of bismuth phosphate as a carrier precipitate. The bismuth phosphate carrier precipitate is dissolved by treatment with nitric acid and the plutonium therein is oxidized to the hexavalent oxidation state by means of potassium dichromate. Separation of the plutonium from the fission products is accomplished by again precipitating bismuth phosphate and removing the precipitate which now carries the fission products and a small percentage of the plutonium present. The amount of plutonium carried in this last step may be minimized by addition of sodium fluoride, so as to make the solution 0.03N in NaF, prior to the oxidation and prccipitation step.

  9. An Improved Process for Precipitating Cyanide Ions from the Barren Solution at Different pHs

    NASA Astrophysics Data System (ADS)

    Figueroa, Gabriela V.; Parga, José R.; Valenzuela, Jesus L.; Vázquez, Victor; Valenzuela, Alejandro; Rodriguez, Mario

    2016-02-01

    In recent decades, the use of metal sulfides instead of hydroxide precipitation in hydrometallurgical processes has gained prominence. Some arguments for its preferential use are as follows: a high degree of metal removal at relatively low pH values, the sparingly soluble nature of sulfide precipitates, favorable dewatering characteristics, and the stability of the formed metal sulfides. The Merrill-Crowe zinc-precipitation process has been applied worldwide in a large number of operations for the recovery of gold and silver from cyanide solutions. However, in some larger plants, the quality of this precious precipitate is low because copper, zinc and especially lead are precipitated along with gold and silver. This results in higher consumption of zinc dust and flux during the smelting of the precipitate, the formation of the matte, and a shorter crucible life. The results show that pH has a significant effect on the removal efficiency of zinc and copper cyanide ions. The optimal pH range was determined to be 3-4, and the removal efficiency of zinc and copper cyanide ions was up to 99%.

  10. Contributions of TRMM to Our Understanding of Precipitation Processes and Climate Variability

    NASA Technical Reports Server (NTRS)

    Adler, Robert F.

    2005-01-01

    The Tropical Rainfall Measuring Mission (TRMM), a joint U.S./Japan effort, has completed seven and a half years in orbit. This successful research mission studying precipitation processes and climatology has also become a key element in the routine monitoring of global precipitation. The package of rain measuring instrumentation, including the first rain radar and microwave radiometer combination in space, continues to function perfectly, and the satellite has the capability to operate for a number of additional years, providing a unique, long-term record of global tropical precipitation characteristics. A summary of research highlights will be presented covering topics ranging over climate analysis, improving forecasts, and storm and precipitation processes. A focus of the talk will be the important role of TRMM data in multi-satellite precipitation analyses at fine time scales and in improving our understanding of the validity of climate-scale variations through comparison with, and eventual improvement of, the GEWEX Global Precipitation Climatology Project (GPCP) 25-year data set.

  11. Ultra-processed products are becoming dominant in the global food system.

    PubMed

    Monteiro, C A; Moubarac, J-C; Cannon, G; Ng, S W; Popkin, B

    2013-11-01

    The relationship between the global food system and the worldwide rapid increase of obesity and related diseases is not yet well understood. A reason is that the full impact of industrialized food processing on dietary patterns, including the environments of eating and drinking, remains overlooked and underestimated. Many forms of food processing are beneficial. But what is identified and defined here as ultra-processing, a type of process that has become increasingly dominant, at first in high-income countries, and now in middle-income countries, creates attractive, hyper-palatable, cheap, ready-to-consume food products that are characteristically energy-dense, fatty, sugary or salty and generally obesogenic. In this study, the scale of change in purchase and sales of ultra-processed products is examined and the context and implications are discussed. Data come from 79 high- and middle-income countries, with special attention to Canada and Brazil. Results show that ultra-processed products dominate the food supplies of high-income countries, and that their consumption is now rapidly increasing in middle-income countries. It is proposed here that the main driving force now shaping the global food system is transnational food manufacturing, retailing and fast food service corporations whose businesses are based on very profitable, heavily promoted ultra-processed products, many in snack form. PMID:24102801

  12. PROCESS USING POTASSIUM LANTHANUM SULFATE FOR FORMING A CARRIER PRECIPITATE FOR PLUTONIUM VALUES

    DOEpatents

    Angerman, A.A.

    1958-10-21

    A process is presented for recovering plutonium values in an oxidation state not greater than +4 from fluoride-soluble fission products. The process consists of adding to an aqueous acidic solution of such plutonium values a crystalline potassium lanthanum sulfate precipitate which carries the plutonium values from the solution.

  13. EVALUATION OF THE E-SOX PROCESS ON THE EPA PILOT ELECTROSTATIC PRECIPITATOR

    EPA Science Inventory

    The report gives results of a small pilot-scale evaluation of the E-SOx process, undertaken to obtain information needed to conduct a planned 5 MWe field pilot demonstration. he process uses an electrostatic precipitator (ESP) for combined sulfur dioxide (SO2) removal and particu...

  14. Identifying Hydrologic Processes in Agricultural Watersheds Using Precipitation-Runoff Models

    USGS Publications Warehouse

    Linard, Joshua I.; Wolock, David M.; Webb, Richard M.T.; Wieczorek, Michael E.

    2009-01-01

    Understanding the fate and transport of agricultural chemicals applied to agricultural fields will assist in designing the most effective strategies to prevent water-quality impairments. At a watershed scale, the processes controlling the fate and transport of agricultural chemicals are generally understood only conceptually. To examine the applicability of conceptual models to the processes actually occurring, two precipitation-runoff models - the Soil and Water Assessment Tool (SWAT) and the Water, Energy, and Biogeochemical Model (WEBMOD) - were applied in different agricultural settings of the contiguous United States. Each model, through different physical processes, simulated the transport of water to a stream from the surface, the unsaturated zone, and the saturated zone. Models were calibrated for watersheds in Maryland, Indiana, and Nebraska. The calibrated sets of input parameters for each model at each watershed are discussed, and the criteria used to validate the models are explained. The SWAT and WEBMOD model results at each watershed conformed to each other and to the processes identified in each watershed's conceptual hydrology. In Maryland the conceptual understanding of the hydrology indicated groundwater flow was the largest annual source of streamflow; the simulation results for the validation period confirm this. The dominant source of water to the Indiana watershed was thought to be tile drains. Although tile drains were not explicitly simulated in the SWAT model, a large component of streamflow was received from lateral flow, which could be attributed to tile drains. Being able to explicitly account for tile drains, WEBMOD indicated water from tile drains constituted most of the annual streamflow in the Indiana watershed. The Nebraska models indicated annual streamflow was composed primarily of perennial groundwater flow and infiltration-excess runoff, which conformed to the conceptual hydrology developed for that watershed. The hydrologic

  15. Firmicutes dominate the bacterial taxa within sugar-cane processing plants

    PubMed Central

    Sharmin, Farhana; Wakelin, Steve; Huygens, Flavia; Hargreaves, Megan

    2013-01-01

    Sugar cane processing sites are characterised by high sugar/hemicellulose levels, available moisture and warm conditions, and are relatively unexplored unique microbial environments. The PhyloChip microarray was used to investigate bacterial diversity and community composition in three Australian sugar cane processing plants. These ecosystems were highly complex and dominated by four main Phyla, Firmicutes (the most dominant), followed by Proteobacteria, Bacteroidetes, and Chloroflexi. Significant variation (p < 0.05) in community structure occurred between samples collected from ‘floor dump sediment’, ‘cooling tower water’, and ‘bagasse leachate’. Many bacterial Classes contributed to these differences, however most were of low numerical abundance. Separation in community composition was also linked to Classes of Firmicutes, particularly Bacillales, Lactobacillales and Clostridiales, whose dominance is likely to be linked to their physiology as ‘lactic acid bacteria’, capable of fermenting the sugars present. This process may help displace other bacterial taxa, providing a competitive advantage for Firmicutes bacteria. PMID:24177592

  16. DECONTAMINATION OF PLUTONIUM FOR FLUORIDE AND CHLORIDE DURING OXALATE PRECIPITATION, FILTRATION AND CALCINATION PROCESSES

    SciTech Connect

    Kyser, E.

    2012-07-25

    Due to analytical limitations for the determination of fluoride (F) and chloride (Cl) in a previous anion exchange study, an additional study of the decontamination of Pu from F and Cl by oxalate precipitation, filtration and calcination was performed. Anion product solution from the previous impurity study was precipitated as an oxalate, filtered, and calcined to produce an oxide for analysis by pyrohydrolysis for total Cl and F. Analysis of samples from this experiment achieved the purity specification for Cl and F for the proposed AFS-2 process. Decontamination factors (DF's) for the overall process (including anion exchange) achieved a DF of {approx}5000 for F and a DF of {approx}100 for Cl. Similar experiments where both HF and HCl were spiked into the anion product solution to a {approx}5000 {micro}g /g Pu concentration showed a DF of 5 for F and a DF of 35 for Cl across the combined precipitation-filtration-calcination process steps.

  17. CSER 00-003 Criticality Safety Evaluation report for PFP Magnesium Hydroxide Precipitation Process for Plutonium Stabilization Glovebox 3

    SciTech Connect

    LAN, J.S.

    2000-07-13

    This Criticality Safety Evaluation Report analyzes the stabilization of plutonium/uranium solutions in Glovebox 3 using the magnesium hydroxide precipitation process at PFP. The process covered are the receipt of diluted plutonium solutions into three precipitation tanks, the precipitation of plutonium from the solution, the filtering of the plutonium precipitate from the solution, the scraping of the precipitate from the filter into boats, and the initial drying of the precipitated slurry on a hot plate. A batch (up to 2.5 kg) is brought into the glovebox as plutonium nitrate, processed, and is then removed in boats for further processing. This CSER establishes limits for the magnesium hydroxide precipitation process in Glovebox 3 to maintain criticality safety while handling fissionable material.

  18. Differences in somatosensory processing due to dominant hemispheric motor impairment in cerebral palsy

    PubMed Central

    2014-01-01

    Background Although cerebral palsy (CP) is usually defined as a group of permanent motor disorders due to non-progressive disturbances in the developing fetal or infant brain, recent research has shown that CP individuals are also characterized by altered somatosensory perception, increased pain and abnormal activation of cortical somatosensory areas. The present study was aimed to examine hemispheric differences on somatosensory brain processing in individuals with bilateral CP and lateralized motor impairments compared with healthy controls. Nine CP individuals with left-dominant motor impairments (LMI) (age range 5–28 yrs), nine CP individuals with right-dominant motor impairments (RMI) (age range 7–29 yrs), and 12 healthy controls (age range 5–30 yrs) participated in the study. Proprioception, touch and pain thresholds, as well as somatosensory evoked potentials (SEP) elicited by tactile stimulation of right and left lips and thumbs were compared. Results Pain sensitivity was higher, and lip stimulation elicited greater beta power and more symmetrical SEP amplitudes in individuals with CP than in healthy controls. In addition, although there was no significant differences between individuals with RMI and LMI on pain or touch sensitivity, lip and thumb stimulation elicited smaller beta power and more symmetrical SEP amplitudes in individuals with LMI than with RMI. Conclusions Our data revealed that brain processing of somatosensory stimulation was abnormal in CP individuals. Moreover, this processing was different depending if they presented right- or left-dominant motor impairments, suggesting that different mechanisms of sensorimotor reorganization should be involved in CP depending on dominant side of motor impairment. PMID:24410983

  19. Polarization fluctuation dominated electrical transport processes of polymer-based ferroelectric field effect transistors

    NASA Astrophysics Data System (ADS)

    Senanayak, Satyaprasad P.; Guha, S.; Narayan, K. S.

    2012-03-01

    Ferroelectric field effect transistors (FE-FETs) consisting of tunable dielectric layers are utilized to investigate interfacial transport processes. Large changes in the dielectric constant as a function of temperature are observed in FE-FETs in conjunction with the ferroelectric to paraelectric transition. The devices offer a test bed to evaluate specific effects of polarization on the electrical processes. FE-FETs have dominant contributions from polarization fluctuation rather than static dipolar disorder prevalent in high k paraelectric dielectric-based FETs. Additionally, photo-excitation measurements in the depletion mode reveal clear features in the FET response at different temperatures, indicative of different transport regimes.

  20. Precipitate hydrolysis process for the removal of organic compounds from nuclear waste slurries

    DOEpatents

    Doherty, Joseph P.; Marek, James C.

    1989-01-01

    A process for removing organic compounds from a nuclear waste slurry comprising reacting a mixture of radioactive waste precipitate slurry and an acid in the presence of a catalytically effective amount of a copper (II) catalyst whereby the organic compounds in the precipitate slurry are hydrolyzed to form volatile organic compounds which are separated from the reacting mixture. The resulting waste slurry, containing less than 10 percent of the orginal organic compounds, is subsequently blended with high level radioactive sludge and transferred to a virtrification facility for processing into borosilicate glass for long-term storage.

  1. Precipitate hydrolysis process for the removal of organic compounds from nuclear waste slurries

    DOEpatents

    Doherty, J.P.; Marek, J.C.

    1987-02-25

    A process for removing organic compounds from a nuclear waste slurry comprising reacting a mixture of radioactive waste precipitate slurry and an acid in the presence of a catalytically effective amount of a copper(II) catalyst whereby the organic compounds in the precipitate slurry are hydrolyzed to form volatile organic compounds which are separated from the reacting mixture. The resulting waste slurry, containing less than 10 percent of the original organic compounds, is subsequently blended with high level radioactive sludge land transferred to a vitrification facility for processing into borosilicate glass for long-term storage. 2 figs., 3 tabs.

  2. Precipitation process in a Mg–Gd–Y alloy grain-refined by Al addition

    SciTech Connect

    Dai, Jichun; Zhu, Suming; Easton, Mark A.; Xu, Wenfan; Wu, Guohua; Ding, Wenjiang

    2014-02-15

    The precipitation process in Mg–10Gd–3Y (wt.%) alloy grain-refined by 0.8 wt.% Al addition has been investigated by transmission electron microscopy. The alloy was given a solution treatment at 520 °C for 6 h plus 550 °C for 7 h before ageing at 250 °C. Plate-shaped intermetallic particles with the 18R-type long-period stacking ordered structure were observed in the solution-treated state. Upon isothermal ageing at 250 °C, the following precipitation sequence was identified for the α-Mg supersaturated solution: β″ (D0{sub 19}) → β′ (bco) → β{sub 1} (fcc) → β (fcc). The observed precipitation process and age hardening response in the Al grain-refined Mg–10Gd–3Y alloy are compared with those reported in the Zr grain-refined counterpart. - Highlights: • The precipitation process in Mg–10Gd–3Y–0.8Al (wt.%) alloy has been investigated. • Particles with the 18R-type LPSO structure were observed in the solution state. • Upon ageing at 250 °C, the precipitation sequence is: β″ → β′ → β1 (fcc) → β. • The Al grain-refined alloy has a lower hardness than the Zr refined counterpart.

  3. Forecasting and nowcasting process: A case study analysis of severe precipitation event in Athens, Greece

    NASA Astrophysics Data System (ADS)

    Matsangouras, Ioannis; Nastos, Panagiotis; Avgoustoglou, Euripides; Gofa, Flora; Pytharoulis, Ioannis; Kamberakis, Nikolaos

    2016-04-01

    An early warning process is the result of interplay between the forecasting and nowcasting interactions. Therefore, (1) an accurate measurement and prediction of the spatial and temporal distribution of rainfall over an area and (2) the efficient and appropriate description of the catchment properties are important issues in atmospheric hazards (severe precipitation, flood, flash flood, etc.). In this paper, a forecasting and nowcasting analysis is presented, regarding a severe precipitation event that took place on September 21, 2015 in Athens, Greece. The severe precipitation caused a flash flood event at the suburbs of Athens, with significant impacts to the local society. Quantitative precipitation forecasts from European Centre for Medium-Range Weather Forecasts and from the COSMO.GR atmospheric model, including ensemble forecast of precipitation and probabilistic approaches are analyzed as tools in forecasting process. Satellite remote sensing data close and six hours prior to flash flood are presented, accompanied with radar products from Hellenic National Meteorological Service, illustrating the ability to depict the convection process.

  4. Mapping and modelling spatial patterns of dominant processes in a karstic catchment

    NASA Astrophysics Data System (ADS)

    Reszler, Christian; Stadler, Hermann; Komma, Jürgen; Blöschl, Günter

    2014-05-01

    This paper presents a framework of combining hydrogeological mapping and hydrological modelling for dominant processes identification in karstic catchments. The aim is to identify areas with a potential of surface erosion and solute input into a karst system. Hydrogeological mapping is based on a mapping catalogue, where the items can be transferred directly to model structure and parameters. The items contain mappable properties such as geological units, overlaying loose material/debris and soils. The synthesis of these properties leads to identification of dominant hydrological mechanisms, particularly the interplay between direct infiltration and surface runoff. Model structure and a priori model parameters can be set and modified based on hydrogeological expert evaluation. This enhances the calibration and validation procedure and includes the formulation of a conceptual karst drainage module. Besides discharge data of springs water quality data (e.g. SAC 254) are used to obtain a better understanding of the karst system and its drainage characteristics and to estimate particle travel time.

  5. Odourant dominance in olfactory mixture processing: what makes a strong odourant?

    PubMed Central

    Schubert, Marco; Sandoz, Jean-Christophe; Galizia, Giovanni; Giurfa, Martin

    2015-01-01

    The question of how animals process stimulus mixtures remains controversial as opposing views propose that mixtures are processed analytically, as the sum of their elements, or holistically, as unique entities different from their elements. Overshadowing is a widespread phenomenon that can help decide between these alternatives. In overshadowing, an individual trained with a binary mixture learns one element better at the expense of the other. Although element salience (learning success) has been suggested as a main explanation for overshadowing, the mechanisms underlying this phenomenon remain unclear. We studied olfactory overshadowing in honeybees to uncover the mechanisms underlying olfactory-mixture processing. We provide, to our knowledge, the most comprehensive dataset on overshadowing to date based on 90 experimental groups involving more than 2700 bees trained either with six odourants or with their resulting 15 binary mixtures. We found that bees process olfactory mixtures analytically and that salience alone cannot predict overshadowing. After normalizing learning success, we found that an unexpected feature, the generalization profile of an odourant, was determinant for overshadowing. Odourants that induced less generalization enhanced their distinctiveness and became dominant in the mixture. Our study thus uncovers features that determine odourant dominance within olfactory mixtures and allows the referring of this phenomenon to differences in neural activity both at the receptor and the central level in the insect nervous system. PMID:25652840

  6. Vanadium recovery from oil fly ash by leaching, precipitation and solvent extraction processes.

    PubMed

    Navarro, R; Guzman, J; Saucedo, I; Revilla, J; Guibal, E

    2007-01-01

    In order to reduce the environmental impact due to land disposal of oil fly ash from power plants and to valorize this waste material, the removal of vanadium was investigated using leaching processes (acidic and alkaline treatments), followed by a second step of metal recovery from leachates involving either solvent extraction or selective precipitation. Despite a lower leaching efficiency (compared to sulfuric acid), sodium hydroxide was selected for vanadium leaching since it is more selective for vanadium (versus other transition metals). Precipitation was preferred to solvent extraction for the second step in the treatment since: (a) it is more selective; enabling complete recovery of vanadate from the leachate in the form of pure ammonium vanadate; and (b) stripping of the loaded organic phase (in the solvent extraction process) was not efficient. Precipitation was performed in a two-step procedure: (a) aluminum was first precipitated at pH 8; (b) then ammonium chloride was added at pH 5 to bring about vanadium precipitation. PMID:16563726

  7. Extreme Daily Precipitation in North American Climate Simulations: Scales and Processes

    NASA Astrophysics Data System (ADS)

    Gutowski, W. J., Jr.; Glisan, J. M.; Kawazoe, S.; Smalley, K. M.

    2014-12-01

    We analyze the ability of global and regional climate models to simulate extreme daily precipitation and supporting processes for midlatitude and Arctic regions of North America. Regional model output comes from the NARCCAP archive and simulations by an Arctic version of WRF; global model output comes from the CMIP5 archive. The NARCCAP results also include output from a time-slice, high-resolution global simulation. All regional model output is at half degree resolution, whereas the CMIP5 resolutions vary but are coarser than the regional model resolutions. The combined analysis allows us to assess added value of finer resolution in simulating extreme precipitation. Analysis focuses on selected regions of North America for winter (DJF) and summer (JJA), building on several previous analyses focused on this region. In addition to comparing results from the different models, we also compare simulated precipitation and supporting processes with those obtained from observed precipitation and reanalysis atmospheric states. In the central U.S., the models generally reproduce well the precipitation-vs.-intensity spectrum seen in observations, with a tendency for coarse-resolution global models to produce somewhat less intense precipitation. In contrast, all models are deficient in high intensity precipitation in Alaska. Further analysis focuses on precipitation events exceeding the 99.5 percentile that occur simultaneously at several points in the region, yielding so-called "widespread events". Analysis of 500 hPa heights, near-surface circulation and fields such as temperature and humidity reveal the processes leading to extreme events in the models and observations. The finer resolution models generally reproduce the physical behavior of these extreme events, with the coarser models showing a smoother rendition. In the central U.S., for winter, these events are produced by slowly moving low-pressure systems that all models simulate fairly well. In Alaska, these events

  8. Evaluation of Co-precipitation Processes for the Synthesis of Mixed-Oxide Fuel Feedstock Materials

    SciTech Connect

    Collins, Emory D; Voit, Stewart L; Vedder, Raymond James

    2011-06-01

    The focus of this report is the evaluation of various co-precipitation processes for use in the synthesis of mixed oxide feedstock powders for the Ceramic Fuels Technology Area within the Fuels Cycle R&D (FCR&D) Program's Advanced Fuels Campaign. The evaluation will include a comparison with standard mechanical mixing of dry powders and as well as other co-conversion methods. The end result will be the down selection of a preferred sequence of co-precipitation process for the preparation of nuclear fuel feedstock materials to be used for comparison with other feedstock preparation methods. A review of the literature was done to identify potential nitrate-to-oxide co-conversion processes which have been applied to mixtures of uranium and plutonium to achieve recycle fuel homogeneity. Recent studies have begun to study the options for co-converting all of the plutonium and neptunium recovered from used nuclear fuels, together with appropriate portions of recovered uranium to produce the desired mixed oxide recycle fuel. The addition of recycled uranium will help reduce the safeguard attractiveness level and improve proliferation resistance of the recycled fuel. The inclusion of neptunium is primarily driven by its chemical similarity to plutonium, thus enabling a simple quick path to recycle. For recycle fuel to thermal-spectrum light water reactors (LWRs), the uranium concentration can be {approx}90% (wt.), and for fast spectrum reactors, the uranium concentration can typically exceed 70% (wt.). However, some of the co-conversion/recycle fuel fabrication processes being developed utilize a two-step process to reach the desired uranium concentration. In these processes, a 50-50 'master-mix' MOX powder is produced by the co-conversion process, and the uranium concentration is adjusted to the desired level for MOX fuel recycle by powder blending (milling) the 'master-mix' with depleted uranium oxide. In general, parameters that must be controlled for co-precipitation

  9. FORMATION PROCESSES AND CONSEQUENCES OF REACTIVE AND NON-REACTIVE MINERAL PRECIPITATES IN PERMEABLE REACTIVE BARRIERS

    EPA Science Inventory

    Mineral precipitates in zero-valent iron PRBs can be classified by formation processes into three groups: 1) those that result from changes in chemical conditions (i.e., change in pH, e.g., calcite); 2) those that are a consequence of microbial activity (i.e., sulfate reduction, ...

  10. Effects of Outer Plasmasphere Processes on Atmospheric Precipitation: A Multipoint Observational Study

    NASA Astrophysics Data System (ADS)

    Erickson, P. J.; Foster, J. C.; Coster, A. J.; Halford, A.; Millan, R. M.; Wygant, J. R.

    2014-12-01

    Earth's inner and outer radiation belts are surrounded by a natural high intensity radiation environment, composed of high energy and relativistic particles. The dynamic outer plasmasphere overlaps the outer radiation belt beyond L=2.5 and can play a key role in modulating the outer radiation belt. In particular, ambient cold plasma density associated with plasmaspheric structure and density gradients in the plasmasphere boundary layer (PBL) can regulate the occurrence and characteristics of wave-particle interactions (WPI) leading to large changes in precipitation/loss efficiency. These interactions are efficient at scattering high energy particles into the atmospheric loss cone, resulting in spatially localized enhancements in outer radiation belt acceleration and precipitation. We discuss a multi-point observational case study of the relationship of dayside radiation belt precipitation temporal and spatial dynamics to outer plasmasphere processes during a coronal mass ejection driven shock injection and plasmasphere reconfiguration event on 2014-01-09. We combine in-situ magnetosphere diagnostics from the Van Allen Probes A and B spacecraft with in-situ data from multiple BARREL balloons measuring atmospheric precipitation in the afternoon MLT sector, near the Van Allen Probes magnetic footprints. Van Allen Probes and THEMIS E data from their respective EFW instruments determines electric field structure and thermal electron density configurations to L~7. Finally, we place the in-situ diagnostics in a larger context using GPS ground based total electron content observations of L <= 4 wide field plasmaspheric structure and PBL dynamics. We present analysis explaining the observed atmospheric precipitation, and demonstrating the significance of the outer plasmasphere boundary location in processes leading to energetic electron precipitation. Such multi-instrument analysis demonstrates that consideration of interconnected system-level processes leads to a clearer

  11. Dominant processes controlling water chemistry of the Pecos River in American southwest

    NASA Astrophysics Data System (ADS)

    Yuan, Fasong; Miyamoto, Seiichi

    2005-09-01

    Here we show an analysis of river flow and water chemistry data from eleven gauging stations along the Pecos River in eastern New Mexico and western Texas, with time spanning 1959-2002. Analysis of spatial relationship between the long-term average flow and total dissolved solids (TDS) concentration allows us to illuminate four major processes controlling river chemistry, namely saline water addition, evaporative concentration with salt gain or loss, dilution with salt gain or loss, and salt storage. Of the 10 river reaches studied, six reaches exhibit the process dominated by evaporative concentration or freshwater dilution with little change in salt load. Four reaches show considerable salt gains or losses that are induced by surface-ground water interactions. This analysis suggests that the evaporative concentration and freshwater dilution are the prevailing mechanisms, but local processes (e.g., variations in hydrologic flowpath and lithologic formation) also play an important role in regulating the hydrochemistry of the Pecos River.

  12. Interacting Physical and Biological Processes Affecting Nutrient Transport Through Human Dominated Landscapes

    NASA Astrophysics Data System (ADS)

    Finlay, J. C.

    2015-12-01

    Human activities increasingly dominate biogeochemical cycles of limiting nutrients on Earth. Urban and agricultural landscapes represent the largest sources of excess nutrients that drive water quality degradation. The physical structure of both urban and agricultural watersheds has been extensively modified, and these changes have large impacts on water and nutrient transport. Despite strong physical controls over nutrient transport in human dominated landscapes, biological processes play important roles in determining the fates of both nitrogen and phosphorus. This talk uses examples from research in urban and agricultural watersheds in the Midwestern USA to illustrate interactions of physical and biological controls over nutrient cycles that have shifted nitrogen (N) and phosphorus (P) sources and cycling in unexpected ways in response to management changes. In urban watersheds, efforts to improve water quality have been hindered by legacy sources of phosphorus added to storm water through transport to drainage systems by vegetation. Similarly, reductions in field erosion in agricultural watersheds have not led to major reductions in phosphorus transport, because of continued release of biological sources of P. Where management of phosphorus has been most effective in reducing eutrophication of lakes, decreases in N removal processes have led to long term increases in N concentration and transport. Together, these examples show important roles for biological processes affecting nutrient movement in highly modified landscapes. Consideration of the downstream physical and biological responses of management changes are thus critical toward identification of actions that will most effectively reduce excess nutrients watersheds and coastal zones.

  13. Extraction of rare earth elements from hydrate-phosphate precipitates of apatite processing

    NASA Astrophysics Data System (ADS)

    Andropov, M. O.; Anufrieva, A. V.; Buynovskiy, A. S.; Makaseev, Y. N.; Mazov, I. N.; Nefedov, R. A.; Sachkov, V. I.; Stepanova, O. B.; Valkov, AV

    2016-01-01

    The features of extraction of rare earth elements (REE) were considered from hydrate-phosphate precipitates of REE of apatite processing by nitric acid technology. The preliminary purification of nitrate solution of REE from impurities of titanium, aluminum, iron, uranium and thorium was suggested to obtain stable solutions not forming precipitates. Washing the extract was recommended with the evaporated reextract that allows to obtain directly on the cascade of REE extraction the concentrated solutions suitable for the separation into groups by the extraction method. Technical decisions were suggested for the separation of REE in groups without the use of salting-out agent.

  14. Effect of some organic solvent-water mixtures composition on precipitated calcium carbonate in carbonation process

    NASA Astrophysics Data System (ADS)

    Konopacka-Łyskawa, Donata; Kościelska, Barbara; Karczewski, Jakub

    2015-05-01

    Precipitated calcium carbonate particles were obtained during carbonation of calcium hydroxide slurry with carbon dioxide. Aqueous solutions of isopropyl alcohol, n-butanol and glycerol were used as solvents. Concentration of organic additives in the reactive mixture was from 0% to 20% (vol). Precipitation process were performed in a stirred tank reactor equipped with gas distributor. Multimodal courses of particles size distribution were determined for produced CaCO3 particles. Calcium carbonate as calcite was precipitated in all experiments. The mean Sauter diameter of CaCO3 particles decreased when the concentration of all used organic additives increased. The amount of small particle fraction in the product increased with the increasing concentration of organic solvents. Similar physical properties of used liquid phase resulted in the similar characteristics of obtained particles.

  15. A Data System Architecture for Measurement Based Systems: Precipitation Processing System

    NASA Technical Reports Server (NTRS)

    Stocker, Erich Franz

    2003-01-01

    NASA s Earth Science Enterprise (ESE) is changing focus from single satellite missions to measurement oriented programs. An example of this paradigm shift is the Global Precipitation Measurement (GPM) project. GPM is conceptualized as a rolling-wave of measurement possibilities all focused on the key precipitation parameter. In response to this shift to measurement programs and also integral to the ESE s new strategy for processing and management its data, a measurement based approach is also critical for data processing system that support measurement programs like GPM. This paper provides an overview of the paradigm shift from mission to measurement. It also presents a summary of the ESE s new strategy for its data systems. Building on this background the paper details the architectural, design and implementation aspects of the Precipitation Processing System (PPS). The PPS is an evolution of a single point system developed for the Tropical Rainfall Measurement Mission to a generic precipitation data system. The paper provides the context within which PPS will support the GPM program.

  16. The air-water exchange of C{sub 15}-C{sub 31} n-alkanes in a precipitation-dominated seepage lake.

    SciTech Connect

    Doskey, P. V.; Environmental Research

    2000-01-01

    The air-water exchange of semivolatile n-alkanes in Crystal Lake, a small precipitation-dominated seepage lake in northern Wisconsin, was investigated with modeling and mass balance approaches. The results suggest that atmospheric deposition contributes approximately 80% of the allochthonous input of n-alkanes to Crystal Lake. Atmospheric deposition accounts for about 50% of the total annual input of n-alkanes to Crystal Lake, and an additional 30% is contributed by in situ production of planktonic n-alkanes ({Sigma}C{sub 15}, C{sub 17}, C{sub 19}). Contributions to the particle dry flux of terrestrial n-alkanes ({Sigma}C{sub 25}, C{sub 27}, C{sub 29}, C{sub 31}) by pine pollen dispersal and by dry deposition of particles containing leaf waxes are similar in magnitude and constitute about 60% of the atmospheric input, with particle wet deposition being responsible for the remainder. Approximately 30% of the atmospheric input of the n-alkanes occurs during a two-week episode of pine pollen dispersal in spring. Concentration gradients between gaseous n-alkanes in the atmosphere and dissolved n-alkanes in the water column of Crystal Lake favor volatilization of n-alkanes from the lake surface; however, distributions of dissolved n-alkanes are characteristic of bacteria, and therefore are contained in organic matter and not available for air-water exchange. The estimated net atmospheric input of terrestrial n-alkanes is about 20% less than the settling sediment flux. Additional allochthonous sources of the terrestrial n-alkanes might include diffuse surface runoff or episodes of coarse-particle deposition. The discrepancies in the results from the modeling and mass balance approaches indicate that direct measurements of air-water exchange rates and measurements of the seasonal variations of particle size distributions in air and rain would greatly improve our ability to quantify air-water exchange rates of n-alkanes.

  17. Processes and mechanisms of persistent extreme precipitation events in East China

    NASA Astrophysics Data System (ADS)

    Zhai, Panmao; Chen, Yang

    2014-11-01

    This study mainly presents recent progresses on persistent extreme precipitation events (PEPEs) in East China. A definition focusing both persistence and extremity of daily precipitation is firstly proposed. An identification method for quasi-stationary regional PEPEs is then designed. By utilizing the identified PEPEs in East China, typical circulation configurations from the lower to the upper troposphere are confirmed, followed by investigations of synoptic precursors for key components with lead time of 1-2 weeks. Two characteristic circulation patterns responsible for PEPEs in East China are identified: a double blocking high type and a single blocking high type. They may account for occurrence of nearly 80% PEPEs during last 60 years. For double blocking high type, about two weeks prior to PEPEs, two blockings developed and progressed towards the Ural Mountains and the Sea of Okhotsk, respectively. A northwestward progressive anomalous anticyclone conveying abundant moisture and eastward-extended South Asia High favoring divergence can be detected about one week in advance. A dominant summertime teleconnection over East Asia, East Asia/ Pacific (EAP) pattern, is deemed as another typical regime inducing PEPEs in the East China. Key elements of the EAP pattern initiated westward movement since one week prior to PEPEs. Eastward energy dispersion and poleward energy dispersion contributed to early development and subsequent maintenance of this teleconnection pattern, respectively. These typical circulation patterns and significant precursors may offer local forecasters some useful clues in identifying and predicting such high-impact precipitation events about 1-2 weeks in advance.

  18. Dominance of Saccharomyces cerevisiae in alcoholic fermentation processes: role of physiological fitness and microbial interactions.

    PubMed

    Albergaria, Helena; Arneborg, Nils

    2016-03-01

    Winemaking, brewing and baking are some of the oldest biotechnological processes. In all of them, alcoholic fermentation is the main biotransformation and Saccharomyces cerevisiae the primary microorganism. Although a wide variety of microbial species may participate in alcoholic fermentation and contribute to the sensory properties of end-products, the yeast S. cerevisiae invariably dominates the final stages of fermentation. The ability of S. cerevisiae to outcompete other microbial species during alcoholic fermentation processes, such as winemaking, has traditionally been ascribed to its high fermentative power and capacity to withstand the harsh environmental conditions, i.e. high levels of ethanol and organic acids, low pH values, scarce oxygen availability and depletion of certain nutrients. However, in recent years, several studies have raised evidence that S. cerevisiae, beyond its remarkable fitness for alcoholic fermentation, also uses defensive strategies mediated by different mechanisms, such as cell-to-cell contact and secretion of antimicrobial peptides, to combat other microorganisms. In this paper, we review the main physiological features underlying the special aptitude of S. cerevisiae for alcoholic fermentation and discuss the role of microbial interactions in its dominance during alcoholic fermentation, as well as its relevance for winemaking. PMID:26728020

  19. Quantitative analysis of precipitation over Fukushima to understand the wet deposition process in March 2011

    NASA Astrophysics Data System (ADS)

    Yatagai, A.; Onda, Y.; Watanabe, A.

    2012-04-01

    The Great East Japan Earthquake caused a severe accident at the Fukushima-Daiichi nuclear power plant (NPP), leading to the emission of large amounts of radioactive pollutants into the environment. The transport and diffusion of these radioactive pollutants in the atmosphere caused a disaster for residents in and around Fukushima. Studies have sought to understand the transport, diffusion, and deposition process, and to understand the movement of radioactive pollutants through the soil, vegetation, rivers, and groundwater. However, a detailed simulation and understanding of the distribution of radioactive compounds depend on a simulation of precipitation and on the information on the timing of the emission of these radioactive pollutants from the NPP. Past nuclear expansion studies have demonstrated the importance of wet deposition in distributing pollutants. Hence, this study examined the quantitative precipitation pattern in March 2011 using rain-gauge observations and X-band radar data from Fukushima University. We used the AMeDAS rain-gauge network data of 1) the Japan Meteorological Agency (1273 stations in Japan) and 2) the Water Information System (47 stations in Fukushima prefecture) and 3) the rain-gauge data of the Environmental Information Network of NTT Docomo (30 stations in Fukushima) to construct 0.05-degree mesh data using the same method used to create the APHRODITE daily grid precipitation data (Yatagai et al., 2009). Since some AMeDAS data for the coastal region were lost due to the earthquake, the complementary network of 2) and 3) yielded better precipitation estimates. The data clarified that snowfall was observed on the night of Mar 15 into the morning of Mar 16 throughout Fukushima prefecture. This had an important effect on the radioactive contamination pattern in Fukushima prefecture. The precipitation pattern itself does not show one-on-one correspondence with the contamination pattern. While the pollutants transported northeast of the

  20. Diffusion dominated process for the crystal growth of a binary alloy

    NASA Astrophysics Data System (ADS)

    Hu, Wen-Rui; Hirata, Akira; Nishizawa, Shin-ichi

    1996-11-01

    The pure diffusion process has been often used to study the crystal growth of a binary alloy in the microgravity environment. In the present paper, a geometric parameter, the ratio of the maximum deviation distance of curved solidification and melting interfaces from the plane to the radius of the crystal rod, was adopted as a small parameter, and the analytical solution was obtained based on the perturbation theory. The radial segregation of a diffusion dominated process was obtained for cases of arbitrary Peclet number in a region of finite extension with both a curved solidification interface and a curved melting interface. Two types of boundary conditions at the melting interface were analyzed. Some special cases such as infinite extension in the longitudinal direction and special range of Peclet number were reduced from the general solution and discussed in detail.

  1. Unmasking the effect of a precipitation pulse on the biological processes composing Net Ecosystem Carbon Exchange

    NASA Astrophysics Data System (ADS)

    Lopez-Ballesteros, Ana; Sanchez-Cañete, Enrique P.; Serrano-Ortiz, Penelope; Oyonarte, Cecilio; Kowalski, Andrew S.; Perez-Priego, Oscar; Domingo, Francisco

    2015-04-01

    Drylands occupy 47.2% of the global terrestrial area and are key ecosystems that significantly determine the inter-annual variability of the global carbon balance. However, it is still necessary to delve into the functional behavior of arid and semiarid ecosystems due to the complexity of drivers and interactions between underpinning processes (whether biological or abiotic) that modulate net ecosystem CO2 exchange (NEE). In this context, water inputs are crucial to biological organisms survival in arid ecosystems and frequently arrive via rain events that are commonly stochastic and unpredictable (i.e. precipitation pulses) and strongly control arid land ecosystem structure and function. The eddy covariance technique can be used to investigate the effect of precipitation pulses on NEE, but provide limited understanding of what exactly happens after a rain event. The chief reasons are that, firstly, we cannot measure separately autotrophic and heterotrophic components, and secondly, the partitioning techniques widely utilized to separate Gross Primary Production and Total Ecosystem Respiration, do not work properly in these water-limited ecosystems, resulting in biased estimations of plant and soil processes. Consequently, it is essential to combine eddy covariance measurements with other techniques to disentangle the different biological processes composing NEE that are activated by a precipitation pulse. Accordingly, the main objectives of this work were: (i) to quantify the contribution of precipitation pulse events to annual NEE using the eddy covariance technique in a semiarid steppe located in Almería (Spain), and (ii) to simulate a realistic precipitation pulse in order to understand its effect on the ecosystem, soil and plant CO2 exchanges by using a transitory-state closed canopy chamber, soil respiration chambers and continuous monitoring CO2 sensors inserted in the subsoil. Preliminary results showed, as expected, a delay between soil and plant

  2. X-band radar field campaign data analysis for orographic/warm-rain precipitation processes

    NASA Astrophysics Data System (ADS)

    Porcacchia, Leonardo; Kirstetter, Pierre-Emmanuel; Gourley, Jonathan J.; Anagnostou, Marios N.; Anagnostou, Emmanouil N.; Bousquet, Olivier; Cheong, Boon-Leng; Maggioni, Viviana; Hong, Yang

    2016-04-01

    Accurate quantitative precipitation estimation over mountainous basins is of great importance because of their susceptibility to hazards such as flash floods, shallow landslides, and debris flows. It is usually hard to obtain reliable weather radar information in mountainous areas, due to difficulties connected to non-meteorological scattering and the elevation of the study sites. Such regions are particularly interested by orographic/warm-rain precipitation processes, characterized by no ice phase in the cloud and prevailing concentration of small drops in the drop size distribution. Field campaigns are able to provide complete and solid datasets in mountainous regions, thanks to mobile radars and the complementary information provided by rain gauges and disdrometers. This study analyzes datasets collected during the Hymex, IPHEX, and Colorado field campaigns in mountainous areas in Italy, France, North Carolina, and Colorado. Mobile X-band radars from the NOAA National Severe Storm Laboratory and the Advanced Radar Research Center at the University of Oklahoma are utilized. The X-band dual polarimetric radar data are corrected for attenuation through the SCOP algorithm, and evaluated against disdrometer and rain-gauge data. Warm-rain events are identified by looking at the Gorgucci, Cao-Zhang, and Kumjian-Ryzhkov parameter spaces relating polarimetric radar variables to precipitation development processes in the cloud and rain size distributions. A conceptual model for the vertical profile of precipitation and microphysical structure of the cloud is also derived, to be contrasted against other typical convective and stratiform profiles.

  3. IPHEx 2014: Observations of Orographic Precipitation Processes in the Southern Appalachians

    NASA Astrophysics Data System (ADS)

    Barros, A. P.; Petersen, W. A.; Lang, T. J.; Wilson, A. M.; Duan, Y.; Nesbitt, S. W.; Cifelli, R.; Schwaller, M.; Wolff, D. B.; Miller, D. K.; Gourley, J. J.; Petters, M.

    2014-12-01

    The focus of the Integrated Precipitation and Hydrology Experiment (IPHEx) in the Southern Appalachians and including the Piedmont and Coastal Plain regions of North Carolina was to characterize warm season orographic precipitation regimes, and to investigate the relationship between precipitation regimes and hydrologic processes in regions of complex terrain. IPHEX consisted of two phases: 1) an extended observing period (EOP) from October 2013 through October 2014 including a science-grade high elevation raingauge network, in addition to the fixed regional observing system; a disdrometer network consisting of twenty separate clusters; three mobile profiling facilities including MicroRain Radars, microwave radiometers, radiosondes, and microphysics characterization instruments; and 2) an intense observing period (IOP) from May-July of 2014 post GPM launch focusing on 4D mapping of precipitation structure during which NASA's NPOL S-band scanning dual-polarization radar, the dual-frequency Ka-Ku, dual polarimetric, Doppler radar (D3R), four additional MRRs, and the NOAA NOXP radar were deployed along with the long-term fixed instrumentation. During the IOP, high altitude and "in the column" measurements were conducted using the NASA ER-2 and the UND Citation aircraft. By taking place after the launch of the GPM satellite, IPHEx provided the first opportunity for coordinated observations among all platforms. Here, we present a first synthesis of ground-based observations of precipitation processes and science findings from IPHEx, including a 4D physically-based integration of multisensor observations incorporating DPR Level 1 products in the inner mountain region that captures the complex vertical structure of microphysical processes modulated by orography, and a first interrogation of GMI and DPR Level 2 products in the IPHEX domain.

  4. Denitrification as the dominant nitrogen loss process in the Arabian Sea.

    PubMed

    Ward, B B; Devol, A H; Rich, J J; Chang, B X; Bulow, S E; Naik, Hema; Pratihary, Anil; Jayakumar, A

    2009-09-01

    Primary production in over half of the world's oceans is limited by fixed nitrogen availability. The main loss term from the fixed nitrogen inventory is the production of dinitrogen gas (N(2)) by heterotrophic denitrification or the more recently discovered autotrophic process, anaerobic ammonia oxidation (anammox). Oceanic oxygen minimum zones (OMZ) are responsible for about 35% of oceanic N(2) production and up to half of that occurs in the Arabian Sea. Although denitrification was long thought to be the only loss term, it has recently been argued that anammox alone is responsible for fixed nitrogen loss in the OMZs. Here we measure denitrification and anammox rates and quantify the abundance of denitrifying and anammox bacteria in the OMZ regions of the Eastern Tropical South Pacific and the Arabian Sea. We find that denitrification rather than anammox dominates the N(2) loss term in the Arabian Sea, the largest and most intense OMZ in the world ocean. In seven of eight experiments in the Arabian Sea denitrification is responsible for 87-99% of the total N(2) production. The dominance of denitrification is reproducible using two independent isotope incubation methods. In contrast, anammox is dominant in the Eastern Tropical South Pacific OMZ, as detected using one of the isotope incubation methods, as previously reported. The abundance of denitrifying bacteria always exceeded that of anammox bacteria by up to 7- and 19-fold in the Eastern Tropical South Pacific and Arabian Sea, respectively. Geographic and temporal variability in carbon supply may be responsible for the different contributions of denitrification and anammox in these two OMZs. The large contribution of denitrification to N(2) loss in the Arabian Sea indicates the global significance of denitrification to the oceanic nitrogen budget. PMID:19727197

  5. The Goddard Cumulus Ensemble Model (GCE): Improvements and Applications for Studying Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Lang, Stephen E.; Zeng, Xiping; Li, Xiaowen; Matsui, Toshi; Mohr, Karen; Posselt, Derek; Chern, Jiundar; Peters-Lidard, Christa; Norris, Peter M.; Kang, In-Sik; Choi, Ildae; Hou, Arthur; Lau, K.-M.; Yang, Young-Min

    2014-01-01

    Convection is the primary transport process in the Earth's atmosphere. About two-thirds of the Earth's rainfall and severe floods derive from convection. In addition, two-thirds of the global rain falls in the tropics, while the associated latent heat release accounts for three-fourths of the total heat energy for the Earth's atmosphere. Cloud-resolving models (CRMs) have been used to improve our understanding of cloud and precipitation processes and phenomena from micro-scale to cloud-scale and mesoscale as well as their interactions with radiation and surface processes. CRMs use sophisticated and realistic representations of cloud microphysical processes and can reasonably well resolve the time evolution, structure, and life cycles of clouds and cloud systems. CRMs also allow for explicit interaction between clouds, outgoing longwave (cooling) and incoming solar (heating) radiation, and ocean and land surface processes. Observations are required to initialize CRMs and to validate their results. The Goddard Cumulus Ensemble model (GCE) has been developed and improved at NASA/Goddard Space Flight Center over the past three decades. It is amulti-dimensional non-hydrostatic CRM that can simulate clouds and cloud systems in different environments. Early improvements and testing were presented in Tao and Simpson (1993) and Tao et al. (2003a). A review on the application of the GCE to the understanding of precipitation processes can be found in Simpson and Tao (1993) and Tao (2003). In this paper, recent model improvements (microphysics, radiation and land surface processes) are described along with their impact and performance on cloud and precipitation events in different geographic locations via comparisons with observations. In addition, recent advanced applications of the GCE are presented that include understanding the physical processes responsible for diurnal variation, examining the impact of aerosols (cloud condensation nuclei or CCN and ice nuclei or IN) on

  6. Numerical Simulation of Tuff Dissolution and Precipitation Experiments: Validation of Thermal-Hydrologic-Chemical (THC) Coupled-Process Modeling

    NASA Astrophysics Data System (ADS)

    Dobson, P. F.; Kneafsey, T. J.

    2001-12-01

    As part of an ongoing effort to evaluate THC effects on flow in fractured media, we performed a laboratory experiment and numerical simulations to investigate mineral dissolution and precipitation. To replicate mineral dissolution by condensate in fractured tuff, deionized water equilibrated with carbon dioxide was flowed for 1,500 hours through crushed Yucca Mountain tuff at 94° C. The reacted water was collected and sampled for major dissolved species, total alkalinity, electrical conductivity, and pH. The resulting steady-state fluid composition had a total dissolved solids content of about 140 mg/L; silica was the dominant dissolved constituent. A portion of the steady-state reacted water was flowed at 10.8 mL/hr into a 31.7-cm tall, 16.2-cm wide vertically oriented planar fracture with a hydraulic aperture of 31 microns in a block of welded Topopah Spring tuff that was maintained at 80° C at the top and 130° C at the bottom. The fracture began to seal within five days. A 1-D plug-flow model using the TOUGHREACT code developed at Berkeley Lab was used to simulate mineral dissolution, and a 2-D model was developed to simulate the flow of mineralized water through a planar fracture, where boiling conditions led to mineral precipitation. Predicted concentrations of the major dissolved constituents for the tuff dissolution were within a factor of 2 of the measured average steady-state compositions. The fracture-plugging simulations result in the precipitation of amorphous silica at the base of the boiling front, leading to a hundred-fold decrease in fracture permeability in less than 6 days, consistent with the laboratory experiment. These results help validate the use of the TOUGHREACT code for THC modeling of the Yucca Mountain system. The experiment and simulations indicate that boiling and concomitant precipitation of amorphous silica could cause significant reductions in fracture porosity and permeability on a local scale. The TOUGHREACT code will be used

  7. River flow forecasting with artificial neural networks using satellite observed precipitation pre-processed with flow length and travel time information: case study of the Ganges river basin

    NASA Astrophysics Data System (ADS)

    Akhtar, M. K.; Corzo, G. A.; van Andel, S. J.; Jonoski, A.

    2009-09-01

    This paper explores the use of flow length and travel time as a pre-processing step for incorporating spatial precipitation information into Artificial Neural Network (ANN) models used for river flow forecasting. Spatially distributed precipitation is commonly required when modelling large basins, and it is usually incorporated in distributed physically-based hydrological modelling approaches. However, these modelling approaches are recognised to be quite complex and expensive, especially due to the data collection of multiple inputs and parameters, which vary in space and time. On the other hand, ANN models for flow forecasting are frequently developed only with precipitation and discharge as inputs, usually without taking into consideration the spatial variability of precipitation. Full inclusion of spatially distributed inputs into ANN models still leads to a complex computational process that may not give acceptable results. Therefore, here we present an analysis of the flow length and travel time as a basis for pre-processing remotely sensed (satellite) rainfall data. This pre-processed rainfall is used together with local stream flow measurements of previous days as input to ANN models. The case study for this modelling approach is the Ganges river basin. A comparative analysis of multiple ANN models with different hydrological pre-processing is presented. The ANN showed its ability to forecast discharges 3-days ahead with an acceptable accuracy. Within this forecast horizon, the influence of the pre-processed rainfall is marginal, because of dominant influence of strongly auto-correlated discharge inputs. For forecast horizons of 7 to 10 days, the influence of the pre-processed rainfall is noticeable, although the overall model performance deteriorates. The incorporation of remote sensing data of spatially distributed precipitation information as pre-processing step showed to be a promising alternative for the setting-up of ANN models for river flow

  8. River flow forecasting with Artificial Neural Networks using satellite observed precipitation pre-processed with flow length and travel time information: case study of the Ganges river basin

    NASA Astrophysics Data System (ADS)

    Akhtar, M. K.; Corzo, G. A.; van Andel, S. J.; Jonoski, A.

    2009-04-01

    This paper explores the use of flow length and travel time as a pre-processing step for incorporating spatial precipitation information into Artificial Neural Network (ANN) models used for river flow forecasting. Spatially distributed precipitation is commonly required when modelling large basins, and it is usually incorporated in distributed physically-based hydrological modelling approaches. However, these modelling approaches are recognised to be quite complex and expensive, especially due to the data collection of multiple inputs and parameters, which vary in space and time. On the other hand, ANN models for flow forecasting are frequently developed only with precipitation and discharge as inputs, usually without taking into consideration the spatial variability of precipitation. Full inclusion of spatially distributed inputs into ANN models still leads to a complex computational process that may not give acceptable results. Therefore, here we present an analysis of the flow length and travel time as a basis for pre-processing remotely sensed (satellite) rainfall data. This pre-processed rainfall is used together with local stream flow measurements of previous days as input to ANN models. The case study for this modelling approach is the Ganges river basin. A comparative analysis of multiple ANN models with different hydrological pre-processing is presented. The ANN showed its ability to forecast discharges 3-days ahead with an acceptable accuracy. Within this forecast horizon, the influence of the pre-processed rainfall is marginal, because of dominant influence of strongly auto-correlated discharge inputs. For forecast horizons of 7 to 10 days, the influence of the pre-processed rainfall is noticeable, although the overall model performance deteriorates. The incorporation of remote sensing data of spatially distributed precipitation information as pre-processing step showed to be a promising alternative for the setting-up of ANN models for river flow

  9. Evaluating Cloud and Precipitation Processes in Numerical Models using Current and Potential Future Satellite Missions

    NASA Astrophysics Data System (ADS)

    van den Heever, S. C.; Tao, W. K.; Skofronick Jackson, G.; Tanelli, S.; L'Ecuyer, T. S.; Petersen, W. A.; Kummerow, C. D.

    2015-12-01

    Cloud, aerosol and precipitation processes play a fundamental role in the water and energy cycle. It is critical to accurately represent these microphysical processes in numerical models if we are to better predict cloud and precipitation properties on weather through climate timescales. Much has been learned about cloud properties and precipitation characteristics from NASA satellite missions such as TRMM, CloudSat, and more recently GPM. Furthermore, data from these missions have been successfully utilized in evaluating the microphysical schemes in cloud-resolving models (CRMs) and global models. However, there are still many uncertainties associated with these microphysics schemes. These uncertainties can be attributed, at least in part, to the fact that microphysical processes cannot be directly observed or measured, but instead have to be inferred from those cloud properties that can be measured. Evaluation of microphysical parameterizations are becoming increasingly important as enhanced computational capabilities are facilitating the use of more sophisticated schemes in CRMs, and as future global models are being run on what has traditionally been regarded as cloud-resolving scales using CRM microphysical schemes. In this talk we will demonstrate how TRMM, CloudSat and GPM data have been used to evaluate different aspects of current CRM microphysical schemes, providing examples of where these approaches have been successful. We will also highlight CRM microphysical processes that have not been well evaluated and suggest approaches for addressing such issues. Finally, we will introduce a potential NASA satellite mission, the Cloud and Precipitation Processes Mission (CAPPM), which would facilitate the development and evaluation of different microphysical-dynamical feedbacks in numerical models.

  10. Using Multi-Scale Modeling Systems to Study the Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2010-01-01

    In recent years, exponentially increasing computer power has extended Cloud Resolving Model (CRM) integrations from hours to months, the number of computational grid points from less than a thousand to close to ten million. Three-dimensional models are now more prevalent. Much attention is devoted to precipitating cloud systems where the crucial 1-km scales are resolved in horizontal domains as large as 10,000 km in two-dimensions, and 1,000 x 1,000 km2 in three-dimensions. Cloud resolving models now provide statistical information useful for developing more realistic physically based parameterizations for climate models and numerical weather prediction models. It is also expected that NWP and mesoscale model can be run in grid size similar to cloud resolving model through nesting technique. Recently, a multi-scale modeling system with unified physics was developed at NASA Goddard. It consists of (1) a cloud-resolving model (Goddard Cumulus Ensemble model, GCE model), (2) a regional scale model (a NASA unified weather research and forecast, WRF), (3) a coupled CRM and global model (Goddard Multi-scale Modeling Framework, MMF), and (4) a land modeling system. The same microphysical processes, long and short wave radiative transfer and land processes and the explicit cloud-radiation, and cloud-land surface interactive processes are applied in this multi-scale modeling system. This modeling system has been coupled with a multi-satellite simulator to use NASA high-resolution satellite data to identify the strengths and weaknesses of cloud and precipitation processes simulated by the model. In this talk, a review of developments and applications of the multi-scale modeling system will be presented. In particular, the results from using multi-scale modeling system to study the interactions between clouds, precipitation, and aerosols will be presented. Also how to use of the multi-satellite simulator to improve precipitation processes will be discussed.

  11. Using Multi-Scale Modeling Systems and Satellite Data to Study the Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, Wei--Kuo; Chern, J.; Lamg, S.; Matsui, T.; Shen, B.; Zeng, X.; Shi, R.

    2010-01-01

    In recent years, exponentially increasing computer power extended Cloud Resolving Model (CRM) integrations from hours to months, the number of computational grid points from less than a thousand to close to ten million. Three-dimensional models are now more prevalent. Much attention is devoted to precipitating cloud systems where the crucial 1-km scales are resolved in horizontal domains as large as 10,000 km in two-dimensions, and 1,000 x 1,000 sq km in three-dimensions. Cloud resolving models now provide statistical information useful for developing more realistic physically based parameterizations for climate models and numerical weather prediction models. It is also expected that NWP and mesoscale models can be run in grid size similar to cloud resolving models through nesting technique. Recently, a multi-scale modeling system with unified physics was developed at NASA Goddard. It consists of (1) a cloud-resolving model (Goddard Cumulus Ensemble model, GCE model). (2) a regional scale model (a NASA unified weather research and forecast, W8F). (3) a coupled CRM and global model (Goddard Multi-scale Modeling Framework, MMF), and (4) a land modeling system. The same microphysical processes, long and short wave radiative transfer and land processes and the explicit cloud-radiation and cloud-land surface interactive processes are applied in this multi-scale modeling system. This modeling system has been coupled with a multi-satellite simulator to use NASA high-resolution satellite data to identify the strengths and weaknesses of cloud and precipitation processes simulated by the model. In this talk, a review of developments and applications of the multi-scale modeling system will be presented. In particular, the results from using multi-scale modeling systems to study the interactions between clouds, precipitation, and aerosols will be presented. Also how to use the multi-satellite simulator to improve precipitation processes will be discussed.

  12. Atmospheric circulation processes contributing to a multidecadal variation in reconstructed and modeled Indian monsoon precipitation

    NASA Astrophysics Data System (ADS)

    Wu, Qianru; Hu, Qi

    2015-01-01

    analysis of the recently reconstructed gridded May-September total precipitation in the Indian monsoon region for the past half millennium discloses significant variations at multidecadal timescales. Meanwhile, paleo-climate modeling outputs from the National Center for Atmospheric Research Community Climate System Model 4.0 show similar multidecadal variations in the monsoon precipitation. One of those variations at the frequency of 40-50 years per cycle is examined in this study. Major results show that this variation is a product of the processes in that the meridional gradient of the atmospheric enthalpy is strengthened by radiation loss in the high-latitude and polar region. Driven by this gradient and associated baroclinicity in the atmosphere, more heat/energy is generated in the tropical and subtropical (monsoon) region and transported poleward. This transport relaxes the meridional enthalpy gradient and, subsequently, the need for heat production in the monsoon region. The multidecadal timescale of these processes results from atmospheric circulation-radiation interactions and the inefficiency in generation of kinetic energy from the potential energy in the atmosphere to drive the eddies that transport heat poleward. This inefficiency creates a time delay between the meridional gradient of the enthalpy and the poleward transport. The monsoon precipitation variation lags that in the meridional gradient of enthalpy but leads that of the poleward heat transport. This phase relationship, and underlining chasing process by the transport of heat to the need for it driven by the meridional enthalpy gradient, sustains this multidecadal variation. This mechanism suggests that atmospheric circulation processes can contribute to multidecadal timescale variations. Interactions of these processes with other forcing, such as sea surface temperature or solar irradiance anomalies, can result in resonant or suppressed variations in the Indian monsoon precipitation.

  13. Frequency of deflagration in the in-tank precipitation process tanks due to loss of nitrogen purge system. Revision 2

    SciTech Connect

    Jansen, J.M.; Mason, C.L.; Olsen, L.M.; Shapiro, B.J.; Gupta, M.K.; Britt, T.E.

    1994-01-01

    High-level liquid wastes (HLLW) from the processing of nuclear material at the Savannah River Site (SRS) are stored in large tanks in the F- and H-Area tank farms. The In-Tank Precipitation (ITP) process is one step in the processing and disposal of HLLW. The process hazards review for the ITP identified the need to implement provisions that minimize deflagration/explosion hazards associated with the process. The objective of this analysis is to determine the frequency of a deflagration in Tank 48 and/or 49 due to nitrogen purge system failures (including external events) and coincident ignition source. A fault tree of the nitrogen purge system coupled with ignition source probability is used to identify dominant system failures that contribute to the frequency of deflagration. These system failures are then used in the recovery analysis. Several human actions, recovery actions, and repair activities are identified that reduce total frequency. The actions are analyzed and quantified as part of a Human Reliability Analysis (HRA). The probabilities of failure of these actions are applied to the fault tree cutsets and the event trees.

  14. Higher-level linguistic categories dominate lower-level acoustics in lexical tone processing.

    PubMed

    Zhao, T Christina; Kuhl, Patricia K

    2015-08-01

    Native tonal-language speakers exhibit reduced sensitivity to lexical tone differences within, compared to across, categories (higher-level linguistic category influence). Yet, sensitivity is enhanced among musically trained, non-tonal-language-speaking individuals (lower-level acoustics processing influence). The current study investigated the relative contribution of higher- and lower-level influences when both are present. Seventeen Mandarin musicians completed music pitch and lexical tone discrimination tasks. Similar to English musicians [Zhao and Kuhl (2015). J. Acoust. Soc. Am. 137(3), 1452-1463], Mandarin musicians' overall sensitivity to lexical tone differences was associated with music pitch score, suggesting lower-level contributions. However, the musician's sensitivities to lexical tone pairs along a continuum were similar to Mandarin non-musicians, reflecting dominant higher-level influences. PMID:26328738

  15. Engineering evaluation of neutralization and precipitation processes applicable to sludge treatment project

    SciTech Connect

    Klem, M.J.

    1998-08-25

    Engineering evaluations have been performed to determine likely unit operations and methods required to support the removal, storage, treatment and disposal of solids/sludges present in the K Basins at the Hanford Site. This evaluation was initiated to select a neutralization process for dissolver product solution resulting from nitric acid treatment of about 50 m{sup 3} of Hanford Site K Basins sludge. Neutralization is required to meet Tank Waste Remediation Waste System acceptance criteria for storage of the waste in the double shell tanks after neutralization, the supernate and precipitate will be transferred to the high level waste storage tanks in 200E Area. Non transuranic (TRU) solids residue will be transferred to the Environmental Restoration Disposal Facility (ERDF). This report presents an overview of neutralization and precipitation methods previously used and tested. This report also recommends a neutralization process to be used as part of the K Basins Sludge Treatment Project and identifies additional operations requiring further evaluation.

  16. The Doubting Process: A Longitudinal Study of the Precipitants and Consequences of Religious Doubt

    PubMed Central

    Krause, Neal; Ellison, Christopher G.

    2010-01-01

    Religious doubt arises from a process in which there is a precipitant, the experience of doubt, a coping response, and a health-related outcome. We explore this process by assessing whether social factors precipitate doubt and the coping responses that are invoked to deal with it. Moreover, we evaluate whether these coping responses are, in turn, associated with health. The data reveal that, over time, people who encounter more negative interaction with fellow congregants have more doubts about religion, whereas more spiritual support and greater involvement in prayer groups are associated with less religious doubt. The findings further indicate that people who encounter more negative interaction are more likely to suppress religious doubts, but people who attend Bible study groups are more likely to seek spiritual growth when faced with doubt. Finally, the results suggest that suppressing religious doubt is associated with less favorable health, whereas seeking spiritual growth does not have a significant effect. PMID:20300487

  17. Influence of Surface Processes over Africa on the Atlantic Marine ITCZ and South American Precipitation.

    NASA Astrophysics Data System (ADS)

    Hagos, Samson M.; Cook, Kerry H.

    2005-12-01

    Previous studies show that the climatological precipitation over South America, particularly the Nordeste region, is influenced by the presence of the African continent. Here the influence of African topography and surface wetness on the Atlantic marine ITCZ (AMI) and South American precipitation are investigated.Cross-equatorial flow over the Atlantic Ocean introduced by north south asymmetry in surface conditions over Africa shifts the AMI in the direction of the flow. African topography, for example, introduces an anomalous high over the southern Atlantic Ocean and a low to the north. This results in a northward migration of the AMI and dry conditions over the Nordeste region.The implications of this process on variability are then studied by analyzing the response of the AMI to soil moisture anomalies over tropical Africa. Northerly flow induced by equatorially asymmetric perturbations in soil moisture over northern tropical Africa shifts the AMI southward, increasing the climatological precipitation over northeastern South America. Flow associated with an equatorially symmetric perturbation in soil moisture, however, has a very weak cross-equatorial component and very weak influence on the AMI and South American precipitation. The sensitivity of the AMI to soil moisture perturbations over certain regions of Africa can possibly improve the skill of prediction.

  18. Analyses of precipitation processes of BIS(dimethylglyoximato)Ni(II) and related complexes

    NASA Astrophysics Data System (ADS)

    Kozlovskii, M. I.; Wakita, H.; Masuda, I.

    1983-03-01

    Precipitates of Ni(dioximato) 2 complexes, where dioximato is 2,3-butanedione dioximate (dimethyglyoximate: dmgH), 2,3-pentanedione dioximate (ethylmethylglyoximate: emgH) or 1,2-cyclohexanedione dioximate (nioximate: nioxH) monoanions, were formed by a manner of direct mixing of NiCl 2 and dioxime solutions in the molar ratios: [dioxime]/[NiCl 2] is 0.57-5.0 for dmgH 2, 1.0-2.2 for emgH 2, and 0.03-0.09 for nioxH 2. The precipitation processes followed by light-scattering measurements were found to fit Avrami's equation. This fact made it possible for us to obtain the induction periods for the precipitation. The p values, the number of molecules in a "nucleus", were estimated from these induction periods and the evaluated concentrations for the supersaturated solutions of the complexes; these values were 3.58 for Ni(dmgH) 2, 2.73 for Ni(emgH) 2, and 2.81 for Ni(nioxH) 2 precipitates.

  19. Water balance and magnesium control in electrolytic zinc plants using the E.Z. selective zinc precipitation process

    NASA Astrophysics Data System (ADS)

    Matthew, I. G.; Newman, O. M. G.; Palmer, D. J.

    1980-03-01

    There is an increasing tendency for modern electrolytic zinc plants to experience water balance and magnesium control problems because of the simultaneous need to maximize zinc recovery and produce environmentally acceptable leach residues and precipitates. The Selective Zinc Precipitation process developed by the Electrolytic Zinc Company of Australasia involves the precipitation of basic zinc sulfate using limestone. Water balance and magnesium control may be achieved by either discarding the process filtrate, or by using it to wash precipitates in a closed circuit operation. The process filter cake is used as a neutralizing agent in the zinc plant. The process can be operated over a wide range of temperatures and calcined zinc concentrate may be preferred to limestone as a zinc precipitant to minimize the discard of sulfate. This paper is particularly concerned with a quantitative assessment of various modes of integrating the process into modern electrolytic zinc plants.

  20. [Using instantaneous spectra to determine dominant species in the DDT process of epoxypropane].

    PubMed

    Li, Ping; Hu, Dong; Yuan, Chang-Ying; Dai, Song-Hui; Xiao, Hai-Bo

    2006-09-01

    After solving problems of weak light detection, the calibration of the spectral sensitivity of the measuring system, and the synchronization of the measuring system, instantaneous emission spectra of epoxypropane in the process of deflagration to detonation transition (DDT) with the exposure time of 2-8 micros and the resolution of 0. 2 nm were acquired from six different side windows of an explosion shock tube. Using the corrected spectral data, curves of the optical radiant intensity of main reaction products versus the DDT distance from the ignition point were obtained. These curves provided information about the evolution of the reaction and the products during the DDT process. Results indicate that the chemical reaction rate of the gaseous fuel and the corresponding concentrations of intermediate products increased gradually at the deflagration stage, but at the moment of deflagration to detonation transition, the reaction rate increased rapidly and the concentrations! of products increased sharply. Among these main products, concentration increments of molecule CO, and radicals CHO and OH were greater than other products, which means that CO, CHO and OH are the dominant species that affect the DDT process greatly. PMID:17112018

  1. Kinetics and thermodynamics of anaerobic ammonium oxidation process using Brocadia spp. dominated mixed cultures.

    PubMed

    Puyol, D; Carvajal-Arroyo, J M; Garcia, B; Sierra-Alvarez, R; Field, J A

    2014-01-01

    Anaerobic ammonium oxidation (anammox) is a recently discovered microbial process commonly applied to treat ammonium pollution in effluents with low organic carbon content. Modeling anammox processes is important for simulating and controlling full-scale plants. In this study, the anammox process was simulated using three models, and substrate and growth parameters obtained by different research groups. Two Brocadia spp.-dominated mixed cultures, one granular and the other flocculent, were used for this purpose. A very good correlation between experimental data using both sludges and model predictions was achieved by one of the models, obtaining correlation coefficients higher than 0.997. Other models and stoichiometric equations tested were unable to predict the anammox kinetics and stoichiometry. Furthermore, the thermodynamic behavior of the two mixed cultures was compared through the determination of the energy of activation of the anammox conversion at temperatures ranging from 9 to 40 °C. Optimum temperature for anammox activity was established at 30-35 °C in both cases. The energy of activation values calculated for granular sludge and flocculent sludge were 64 and 124 kJ mol(-1), respectively. PMID:24759529

  2. Recovery of ammonia in digestates of calf manure through a struvite precipitation process using unconventional reagents.

    PubMed

    Siciliano, A; De Rosa, S

    2014-01-01

    Land spreading of digestates causes the discharge of large quantities of nutrients into the environment, which contributes to eutrophication and depletion of dissolved oxygen in water bodies. For the removal of ammonia nitrogen, there is increasing interest in the chemical precipitation of struvite, which is a mineral that can be reused as a slow-release fertilizer. However, this process is an expensive treatment of digestate because large amounts of magnesium and phosphorus reagents are required. In this paper, a struvite precipitation-based process is proposed for an efficient recovery of digestate nutrients using low-cost reagents. In particular, seawater bittern, a by-product of marine salt manufacturing and bone meal, a by-product of the thermal treatment of meat waste, have been used as low-cost sources of magnesium and phosphorus, respectively. Once the operating conditions are defined, the process enables the removal of more than 90% ammonia load, the almost complete recovery of magnesium and phosphorus and the production of a potentially valuable precipitate containing struvite crystals. PMID:24645466

  3. Synthesis of nano precipitated calcium carbonate by using a carbonation process through a closed loop reactor

    NASA Astrophysics Data System (ADS)

    Thriveni, Thenepalli; Ahn, Ji Whan; Ramakrishna, Chilakala; Ahn, Young Jun; Han, Choon

    2016-01-01

    Nano calcium carbonate particles have a wide range of industrial applications due to their beneficial properties such as high porosity and high surface area to volume ratio and due to their strengthening the mechanical properties of plastics and paper. Consequently, significant research has been done to deliver a new approach for the synthesis of precipitated nano calcium carbonate by using a carbonation process through a closed loop reactor. Both the experimental and the instrumental parameters, i.e. the CO2 flow rate, the concentration of the starting materials (Ca(OH)2 and CaO), the pH, the orifice diameter, etc., were investigated. The carbonation efficiency was increased due to the diffusion process involved in the loop reactor. The particle size was affected by the CO2 flow rate, reaction time, and orifice diameter. Finally, precipitated nano calcite calcium carbonate (50 to 100 nm) was synthesized by optimizing all the experimental and the instrumental parameters. The synthesized precipitated nano calcium carbonate was characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. This study has proved that the carbonation efficiency can be enhanced for a short time by using a loop reactor and that the carbonation process was more energy efficient and cost effective than other conventional methods.

  4. Using Multi-Scale Modeling Systems and Satellite Data to Study the Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Chern, J.; Lamg, S.; Matsui, T.; Shen, B.; Zeng, X.; Shi, R.

    2011-01-01

    In recent years, exponentially increasing computer power has extended Cloud Resolving Model (CRM) integrations from hours to months, the number of computational grid points from less than a thousand to close to ten million. Three-dimensional models are now more prevalent. Much attention is devoted to precipitating cloud systems where the crucial 1-km scales are resolved in horizontal domains as large as 10,000 km in two-dimensions, and 1,000 x 1,000 km2 in three-dimensions. Cloud resolving models now provide statistical information useful for developing more realistic physically based parameterizations for climate models and numerical weather prediction models. It is also expected that NWP and mesoscale model can be run in grid size similar to cloud resolving model through nesting technique. Recently, a multi-scale modeling system with unified physics was developed at NASA Goddard. It consists of (l) a cloud-resolving model (Goddard Cumulus Ensemble model, GCE model), (2) a regional scale model (a NASA unified weather research and forecast, WRF), (3) a coupled CRM and global model (Goddard Multi-scale Modeling Framework, MMF), and (4) a land modeling system. The same microphysical processes, long and short wave radiative transfer and land processes and the explicit cloud-radiation, and cloud-land surface interactive processes are applied in this multi-scale modeling system. This modeling system has been coupled with a multi-satellite simulator to use NASA high-resolution satellite data to identify the strengths and weaknesses of cloud and precipitation processes simulated by the model. In this talk, the recent developments and applications of the multi-scale modeling system will be presented. In particular, the results from using multi-scale modeling system to study the precipitating systems and hurricanes/typhoons will be presented. The high-resolution spatial and temporal visualization will be utilized to show the evolution of precipitation processes. Also how to

  5. The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Li, Xiaowen; Khain, Alexander; Matsui, Toshihisa; Lang, Stephen; Simpson, Joanne

    2008-01-01

    Aerosols and especially their effect on clouds are one of the key components of the climate system and the hydrological cycle [Ramanathan et al., 2001]. Yet, the aerosol effect on clouds remains largely unknown and the processes involved not well understood. A recent report published by the National Academy of Science states "The greatest uncertainty about the aerosol climate forcing - indeed, the largest of all the uncertainties about global climate forcing - is probably the indirect effect of aerosols on clouds [NRC, 2001]." The aerosol effect on clouds is often categorized into the traditional "first indirect (i.e., Twomey)" effect on the cloud droplet sizes for a constant liquid water path [Twomey, 1977] and the "semi-direct" effect on cloud coverage [e.g., Ackerman et al ., 2001]." Enhanced aerosol concentrations can also suppress warm rain processes by producing a narrow droplet spectrum that inhibits collision and coalescence processes [e.g., Squires and Twomey, 1961; Warner and Twomey, 1967; Warner, 1968; Rosenfeld, 19991. The aerosol effect on precipitation processes, also known as the second type of aerosol indirect effect [Albrecht, 1989], is even more complex, especially for mixed-phase convective clouds. Table 1 summarizes the key observational studies identifying the microphysical properties, cloud characteristics, thermodynamics and dynamics associated with cloud systems from high-aerosol continental environments. For example, atmospheric aerosol concentrations can influence cloud droplet size distributions, warm-rain process, cold-rain process, cloud-top height, the depth of the mixed phase region, and occurrence of lightning. In addition, high aerosol concentrations in urban environments could affect precipitation variability by providing an enhanced source of cloud condensation nuclei (CCN). Hypotheses have been developed to explain the effect of urban regions on convection and precipitation [van den Heever and Cotton, 2007 and Shepherd, 2005

  6. Dissolution Dominating Calcification Process in Polar Pteropods Close to the Point of Aragonite Undersaturation

    PubMed Central

    Bednaršek, Nina; Tarling, Geraint A.; Bakker, Dorothee C. E.; Fielding, Sophie; Feely, Richard A.

    2014-01-01

    Thecosome pteropods are abundant upper-ocean zooplankton that build aragonite shells. Ocean acidification results in the lowering of aragonite saturation levels in the surface layers, and several incubation studies have shown that rates of calcification in these organisms decrease as a result. This study provides a weight-specific net calcification rate function for thecosome pteropods that includes both rates of dissolution and calcification over a range of plausible future aragonite saturation states (Ωar). We measured gross dissolution in the pteropod Limacina helicina antarctica in the Scotia Sea (Southern Ocean) by incubating living specimens across a range of aragonite saturation states for a maximum of 14 days. Specimens started dissolving almost immediately upon exposure to undersaturated conditions (Ωar∼0.8), losing 1.4% of shell mass per day. The observed rate of gross dissolution was different from that predicted by rate law kinetics of aragonite dissolution, in being higher at Ωar levels slightly above 1 and lower at Ωar levels of between 1 and 0.8. This indicates that shell mass is affected by even transitional levels of saturation, but there is, nevertheless, some partial means of protection for shells when in undersaturated conditions. A function for gross dissolution against Ωar derived from the present observations was compared to a function for gross calcification derived by a different study, and showed that dissolution became the dominating process even at Ωar levels close to 1, with net shell growth ceasing at an Ωar of 1.03. Gross dissolution increasingly dominated net change in shell mass as saturation levels decreased below 1. As well as influencing their viability, such dissolution of pteropod shells in the surface layers will result in slower sinking velocities and decreased carbon and carbonate fluxes to the deep ocean. PMID:25285916

  7. Synergistic Cellulose Hydrolysis Dominated by a Multi-Modular Processive Endoglucanase from Clostridium cellulosi

    PubMed Central

    Yang, Min; Zhang, Kun-Di; Zhang, Pei-Yu; Zhou, Xia; Ma, Xiao-Qing; Li, Fu-Li

    2016-01-01

    Recalcitrance of biomass feedstock remains a challenge for microbial conversion of lignocellulose into biofuel and biochemicals. Clostridium cellulosi, one thermophilic bacterial strain dominated in compost, could hydrolyze lignocellulose at elevated temperature by secreting more than 38 glycoside hydrolases belong to 15 different families. Though one multi-modular endoglucanase CcCel9A has been identified from C. cellulosi CS-4-4, mechanism of synergistic degradation of cellulose by various cellulases from strain CS-4-4 remains elusive. In this study, CcCel9A, CcCel9B, and CcCel48A were characterized as processive endoglucanase, non-processive endoglucanase, and exoglucanase, respectively. To understand how they cooperate with each other, we estimated the approximate concentration ratio on the zymogram and optimized it using purified enzymes in vitro. Synergism between individual glycoside hydrolase during cellulose hydrolysis in the mixture was observed. CcCel9A and CcCel48A could degrade cellulose chain from non-reducing ends and reducing ends, respectively, to cello-oligosaccharide. CcCel9B could cut cellulose chain randomly and cello-oligosaccharides with varied length were released. In addition, a β-glucosidase BlgA from Caldicellulosiruptor sp. F32 which could cleave cello-oligosaccharides including G2-G6 to glucose was added to the enzyme mixture to remove the product inhibition of its partners. The combination and ratios of these cellulases were optimized based on the release rate of glucose. Hydrolysis of corn stalk was conducted by a four-component cocktail (CcCel9A:CcCel9B:CcCel48A:BlgA = 25:25:10:18), and only glucose was detected as main production by using high-performance anion-exchange chromatography. Processive endoglucanase CcCel9A, dominated in secretome of C. cellulosi, showed good potential in developing cellulase cocktail due to its exquisite cooperation with various cellulases. PMID:27379062

  8. a Numerical Study of Cloud and Precipitation Processes in Mesoscale Rainbands.

    NASA Astrophysics Data System (ADS)

    Rutledge, Steven Allan

    Field studies conducted during the University of Washington's CYCLES PROJECT have investigated the dynamical and microphysical processes operating in mesoscale rainbands within extratropical cyclones. Conceptual models of the cloud and precipitation mechanisms present in the various types of rainbands have been developed. The test these conceptual models, a numerical modeling study was undertaken. The numerical simulations centered on warm-frontal rainbands, characterized by a "seeder-feeder" process, and the convective -like narrow cold-frontal rainband. The warm-frontal rainband simulations were divided into two categories based on the observed vertical motions in the feeder zone. In the first category (TYPE 1), the vertical air motions are typical of those associated with the widespread lifting in the vicinity of warm fronts ((TURN)10 cm s('-1)). In the second category (TYPE 2), the vertical motions are stronger ((TURN)70 cm s('-1)). In the TYPE 1 situation the growth of "seed" ice crystals within the feeder zone occurs through vapor deposition. In the TYPE 2 case, seed ice crystals grow by accreting cloud water. In both cases the seed ice crystals provide the necessary particles for the efficient removal of condensate in the feeder zone. The model simulations for the narrow cold-frontal rainband are also divided into two categories. In the first category (non-embedded case) the narrow cold-frontal rainband is considered to be independent of any surrounding precipitation. In the second case (considered more realistic), the narrow cold-frontal rainband is embedded within a region of stratiform precipitation. In the non-embedded case, graupel develops when frozen raindrops grow rapidly by accreting cloud water within the updraft region. In the embedded case snow particles (originating in the stratiform clouds) are swept into the updraft region and are converted rapidly to graupel through riming. The efficient removal of cloud water by snow particles entering the

  9. Decomposition and Precipitation Process During Thermo-mechanical Fatigue of Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Weidner, Anja; Kolmorgen, Roman; Kubena, Ivo; Kulawinski, Dirk; Kruml, Tomas; Biermann, Horst

    2016-05-01

    The so-called 748 K (475 °C) embrittlement is one of the main drawbacks for the application of ferritic-austenitic duplex stainless steels (DSS) at higher temperatures caused by a spinodal decomposition of the ferritic phase. Thermo-mechanical fatigue tests performed on a DSS in the temperature range between 623 K and 873 K (350 °C and 600 °C) revealed no negative influence on the fatigue lifetime. However, an intensive subgrain formation occurred in the ferritic phase, which was accompanied by formation of fine precipitates. In order to study the decomposition process of the ferritic grains due to TMF testing, detailed investigations using scanning and transmission electron microscopy are presented. The nature of the precipitates was determined as the cubic face centered G-phase, which is characterized by an enrichment of Si, Mo, and Ni. Furthermore, the formation of secondary austenite within ferritic grains was observed.

  10. Adsorption compared with sulfide precipitation as metal removal processes from acid mine drainage in a constructed wetland

    NASA Astrophysics Data System (ADS)

    Machemer, Steven D.; Wildeman, Thomas R.

    1992-01-01

    Metal removal processes from acid mine drainage were studied in an experimental constructed wetland in the Idaho Springs-Central City mining district of Colorado. The wetland was designed to passively remove heavy metals from the mine drainage flowing from the Big Five Tunnel. Concurrent studies were performed in the field on the waters flowing from the wetland and in the laboratory on the wetland substrate. Both studies suggest that there is competition for organic adsorption sites among Fe, Cu, Zn and Mn. Iron and Cu appear to be more strongly adsorbed than Zn and Mn. The adsorption of metals varies with the fluctuation of pH in the outflow water. Also indicated by field and laboratory studies is the microbial reduction of sulfate with a corresponding increase in the sulfide concentration of the water. As sulfide is generated. Cu and Zn are completely removed. The field results suggest that upon start up of a constructed wetland, the adsorption of dissolved metals onto organic sites in the substrate material will be an important process. Over time, sulfide precipitation becomes the dominant process for metal removal from acid mine drainage.

  11. The dominant patterns of the precipitation in China during the boreal winter and their relationship with 30-60-days intraseasonal oscillation

    NASA Astrophysics Data System (ADS)

    Yao, Yonghong; Wu, Qigang; Huang, Ying

    2013-04-01

    With the daily rainfall data from the National Meteorological Information Center of China and the National Centers for Environmental Prediction National Center for Atmospheric Research (NCEP-NCAR) reanalysis data, variability of the precipitation field during the boreal winter in China from 1979 to 2011 and its relationship with the 30-60-days intraseasonal oscillation activity is investigated in this study. It is shown that the distribution of the precipitation during the winter season (DJF) in China is featured by two typical patterns. The first one is characterized by the uniformly enhanced rainfall over the South China, and the second one is represented by meridionally banded dipole-like structure with the more or less precipitation changing alternatively between the Yangtze River Basin and the South China. The 30-60-day periodicity is found to contribute mostly to these two distribution patterns. The leading uniform pattern of the filtered precipitation with 30-60-day periodicity over the South China is closely related with the wavelike pattern of Pacific/North American (PNA) pattern, which is coupled with the dipole distribution pattern of the tropical convection, and with the convective center elongating from tropical Indian Ocean to Phillipine. The dipole-like pattern of the 30-60-day filtered precipitation is related to the North Pacific Oscillation (NPO) and the Pacific-Japan (PJ) teleconnection pattern, and to the tripole pattern of tropical convection centering at tropical Indian Ocean, Phillipine and tropical western North Pacific respectively. It is suggested that the enhanced precipitation over the South China or Yangtze River Basin induced by the intensified southwesterlies flow is the result of the interaction between the southward movement of the middle and high latitude 30-60-days oscillation and the northward movement of the tropical convection in these areas during the boreal winter.

  12. Excitatory interneurons dominate sensory processing in the spinal substantia gelatinosa of rat

    PubMed Central

    Santos, Sónia F A; Rebelo, Sandra; Derkach, Victor A; Safronov, Boris V

    2007-01-01

    Substantia gelatinosa (SG, lamina II) is a spinal cord region where most unmyelinated primary afferents terminate and the central nociceptive processing begins. It is formed by several distinct groups of interneurons whose functional properties and synaptic connections are poorly understood, in part, because recordings from synaptically coupled pairs of SG neurons are quite challenging due to a very low probability of finding connected cells. Here, we describe an efficient method for identifying synaptically coupled interneurons in rat spinal cord slices and characterizing their excitatory or inhibitory function. Using tight-seal whole-cell recordings and a cell-attached stimulation technique, we routinely tested about 1500 SG interneurons, classifying 102 of them as monosynaptically connected to neurons in lamina I–III. Surprisingly, the vast majority of SG interneurons (n = 87) were excitatory and glutamatergic, while only 15 neurons were inhibitory. According to their intrinsic firing properties, these 102 SG neurons were also classified as tonic (n = 49), adapting (n = 17) or delayed-firing neurons (n = 36). All but two tonic neurons and all adapting neurons were excitatory interneurons. Of 36 delayed-firing neurons, 23 were excitatory and 13 were inhibitory. We conclude that sensory integration in the intrinsic SG neuronal network is dominated by excitatory interneurons. Such organization of neuronal circuitries in the spinal SG can be important for nociceptive encoding. PMID:17331995

  13. GIS-based NEXRAD Stage III precipitation database: automated approaches for data processing and visualization

    NASA Astrophysics Data System (ADS)

    Xie, Hongjie; Zhou, Xiaobing; Vivoni, Enrique R.; Hendrickx, Jan M. H.; Small, Eric E.

    2005-02-01

    This study develops a geographical information system (GIS) approach for automated processing of the Next Generation Weather Radar (NEXRAD) Stage III precipitation data. The automated processing system, implemented by using commercial GIS and a number of Perl scripts and C/C++ programs, allows for rapid data display, requires less storage capacity, and provides the analytical and data visualization tools inherent in GIS as compared to traditional methods. In this paper, we illustrate the development of automatic techniques to preprocess raw NEXRAD Stage III data, transform the data to a GIS format, select regions of interest, and retrieve statistical rainfall analysis over user-defined spatial and temporal scales. Computational expense is reduced significantly using the GIS-based automated techniques. For example, 1-year Stage III data processing (˜9000 files) for the West Gulf River Forecast Center takes about 3 days of computation time instead of months of manual work. To illustrate the radar precipitation database and its visualization capabilities, we present three application examples: (1) GIS-based data visualization and integration, and ArcIMS-based web visualization and publication system, (2) a spatial-temporal analysis of monsoon rainfall patterns over the Rio Grande River Basin, and (3) the potential of GIS-based radar data for distributed watershed models. We conclude by discussing the potential applications of automated techniques for radar rainfall processing and its integration with GIS-based hydrologic information systems.

  14. [Dominant Thalamus and Aphasia].

    PubMed

    Nakano, Akiko; Shimomura, Tatsuo

    2015-12-01

    Many studies have shown that lesions of the dominant thalamus precipitate language disorders in a similar manner to transcortical aphasias, in a phenomenon known as "thalamic aphasia." In some cases, however, aphasia may not occur or may appear transiently following thalamic lesions. Furthermore, dominant thalamic lesions can produce changes in character, as observed in patients with amnesic disorder. Previous work has explored the utility of thalamic aphasia as a discriminative feature for classification of aphasia. Although the thalamus may be involved in the function of the brainstem reticular activating system and play a role in attentional network and in memory of Papez circuit or Yakovlev circuit, the mechanism by which thalamic lesion leads to the emergence of aphasic disorders is unclear. In this review, we we survey historical and recent literature on thalamic aphasia in an attempt to understand the neural processes affected by thalamic lesions. PMID:26618763

  15. A Coupled GCM-Cloud Resolving Modeling System to Study Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Chern, Jiundar; Atlas, Robert; Peters-Lidard, Christa; Hou, Arthur; Lin, Xin

    2006-01-01

    Recent GEWEX Cloud System Study (GCSS) model comparison projects have indicated that cloud resolving models (CRMs) agree with observations better than traditional single column models in simulating various types of clouds and cloud systems from different geographic locations. Current and future NASA satellite programs can provide cloud, precipitation, aerosol and other data at very fine spatial and temporal scales. It requires a coupled global circulation model (GCM) and cloud-scale model (termed a super-parameterization or multi-scale modeling framework, MMF) to use these satellite data to improve the understanding of the physical processes that are responsible for the variation in global and regional climate and hydrological systems. The use of a GCM will enable global coverage and the use of a CRM will allow for better and more sophisticated physical parameterization. NASA Satellite and field campaign cloud related data sets can provide initial conditions as well as validation for both the MMF and CRMs. Also we have implemented a Land Information System (LIS that includes the CLM and NOAH land surface models into the MMF. The Goddard MMF is based on the 2D Goddard Cumulus Ensemble (GCE) model and the Goddard finite volume general circulation model (fvGCM) This modeling system has been applied and tested its performance for two different climate scenarios, El Nino (1998) and La Nina (1999). The coupled new modeling system produced more realistic propagation and intensity of tropical rainfall systems and intraseasonal oscillations, and diurnal variation of precipitation that are very difficult to forecast using even the state-of-the-art GCMs. In this talk I will present: (1) a brief review on GCE model and its applications on precipitation processes (both Microphysical and land processes) and (2) The Goddard MMF and the Major difference between two existing MMFs (CSU MMF and Goddard MMF) and preliminary results (the comparison with traditional GCMs).

  16. Integrated Modeling of Aerosol, Cloud, Precipitation and Land Processes at Satellite-Resolved Scales

    NASA Technical Reports Server (NTRS)

    Peters-Lidard, Christa; Tao, Wei-Kuo; Chin, Mian; Braun, Scott; Case, Jonathan; Hou, Arthur; Kumar, Anil; Kumar, Sujay; Lau, William; Matsui, Toshihisa; Miller, Tim; Santanello, Joseph, Jr.; Shi, Jainn; Starr, David; Tao, Qian; Zaitchik, Benjamin

    2012-01-01

    In this talk, I will present recent results from a project led at NASA/GSFC, in collaboration with NASA/MSFC and JHU, focused on the development and application of an observation-driven integrated modeling system that represents aerosol, cloud, precipitation and land processes at satellite-resolved scales. The project, known as the NASA Unified WRF (NU-WRF), is funded by NASA's Modeling and Analysis Program, and leverages prior investments from the Air Force Weather Agency and NASA's Earth Science Technology Office (ESTO). We define "satellite-resolved" scales as being within a typical mesoscale atmospheric modeling grid (roughly 1-25 km), although this work is designed to bridge the continuum between local (microscale), regional (mesoscale) and global (synoptic) processes. NU-WRF is a superset of the standard NCAR Advanced Research WRF model, achieved by fully integrating the GSFC Land Information System (LIS, already coupled to WRF), the WRF/Chem enabled version of the Goddard Chemistry Aerosols Radiation Transport (GOCART) model, the Goddard Satellite Data Simulation Unit (SDSU), and boundary/initial condition preprocessors for MERRA and GEOS-5 into a single software release (with source code available by agreement with NASA/GSFC). I will show examples where the full coupling between aerosol, cloud, precipitation and land processes is critical for predicting local, regional, and global water and energy cycles, including some high-impact phenomena such as floods, hurricanes, mesoscale convective systems, droughts, and monsoons.

  17. Morphological study of cationic polymer-anionic surfactant complex precipitated in solution during the dilution process.

    PubMed

    Miyake, M; Kakizawa, Y

    2010-01-01

    We investigated the phase diagrams and the morphology of the complexes that were formed by cationic polymers, cationic cellulose (CC) and cationic dextran (CD), and by anionic surfactant-based sodium poly(oxyethylene) lauryl ether sulfate (LES). The anionic charge of the LES-based surfactants was changed by adding an amphoteric surfactant, lauryl amidopropyl betaine acetate (LPB), or a nonionic surfactant, polyoxyethylene stearyl ether (C18EO25). We discuss the relationship between the complex aggregation process and the morphology of the precipitated complexes. The morphologies of CC complex aggregates, which precipitated during the dilution process in a model shampoo solution, changed from membranous forms to mesh-like forms by decreasing the charges of both the CC and the surfactant. Their touch on hair in the rinsing process changed from sticky to smooth and velvety, corresponding to their rheological properties. In contrast, CD complex aggregates had a membranous form and a smooth touch independently of the charges on the polymer and surfactant. These results suggested that the control of the charges of both the polymer and surfactant and the choice of polymer structure are important for excellent conditioning effects upon rinsing with shampoo. PMID:20716437

  18. Simultaneous measurements of stable water isotopes in near-surface vapor and precipitation to constrain below-cloud processes

    NASA Astrophysics Data System (ADS)

    Graf, Pascal; Sodemann, Harald; Pfahl, Stephan; Schneebeli, Marc; Ventura, Jordi Figueras i.; Leuenberger, Andreas; Grazioli, Jacopo; Raupach, Tim; Berne, Alexis; Wernli, Heini

    2016-04-01

    Present-day observations of stable water isotopes (SWI) in precipitation on monthly time scales are abundant and the processes governing the variation of SWI on these time scales have been investigated by many studies. However, also on much shorter time scales of hours mesoscale meteorological processes lead to significant variations of SWIs, which are important to understand. There are only few studies investigating the variations of SWI on this short time scale, for which, e.g., frontal dynamics, convection and cloud microphysics play an essential role. In particular, the isotopic composition of both near-surface vapor and precipitation is significantly influenced by below-cloud processes that include precipitation evaporation and isotopic exchange between falling precipitation and surrounding vapor. In this study, simultaneous measurements of SWI in near-surface vapor and precipitation with high (sub-hourly) temporal resolution in combination with observational data from radars, disdrometers, radiosondes and standard meteorological instruments are used for a detailed analysis of the relative importance of below-cloud and in-cloud (i.e., precipitation formation) processes during the course of three rain events in Switzerland in spring 2014. Periods are identified when the isotopic composition of near-surface vapor and equilibrium vapor above liquid rain drops agree and when they differ due to either evaporation of precipitation or incomplete equilibration of precipitation with surrounding vapor. These findings are verified by the supporting observational data. In addition, calculations with a simple rain-shaft model fed with observational data are compared to the actual isotopic composition of precipitation. This combination of isotope measurements and model calculations allows us to test the sensitivity of the precipitation isotope signal to rain intensity, drop-size distribution and temperature and humidity profiles.

  19. Microstructure and Mechanical Behavior of 17-4 Precipitation Hardenable Steel Processed by Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Rafi, H. Khalid; Pal, Deepankar; Patil, Nachiket; Starr, Thomas L.; Stucker, Brent E.

    2014-12-01

    The mechanical behavior and the microstructural evolution of 17-4 precipitation hardenable (PH) stainless steel processed using selective laser melting have been studied. Test coupons were produced from 17-4 PH stainless steel powder in argon and nitrogen atmospheres. Characterization studies were carried out using mechanical testing, optical microscopy, scanning electron microscopy, and x-ray diffraction. The results show that post-process heat treatment is required to obtain typically desired tensile properties. Columnar grains of smaller diameters (<2 µm) emerged within the melt pool with a mixture of martensite and retained austenite phases. It was found that the phase content of the samples is greatly influenced by the powder chemistry, processing environment, and grain diameter.

  20. Microstructure and Mechanical Behavior of 17-4 Precipitation Hardenable Steel Processed by Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Rafi, H. Khalid; Pal, Deepankar; Patil, Nachiket; Starr, Thomas L.; Stucker, Brent E.

    2014-09-01

    The mechanical behavior and the microstructural evolution of 17-4 precipitation hardenable (PH) stainless steel processed using selective laser melting have been studied. Test coupons were produced from 17-4 PH stainless steel powder in argon and nitrogen atmospheres. Characterization studies were carried out using mechanical testing, optical microscopy, scanning electron microscopy, and x-ray diffraction. The results show that post-process heat treatment is required to obtain typically desired tensile properties. Columnar grains of smaller diameters (<2 µm) emerged within the melt pool with a mixture of martensite and retained austenite phases. It was found that the phase content of the samples is greatly influenced by the powder chemistry, processing environment, and grain diameter.

  1. Mapping dominant runoff processes: an evaluation of different approaches using similarity measures and synthetic runoff simulations

    NASA Astrophysics Data System (ADS)

    Antonetti, Manuel; Buss, Rahel; Scherrer, Simon; Margreth, Michael; Zappa, Massimiliano

    2016-07-01

    The identification of landscapes with similar hydrological behaviour is useful for runoff and flood predictions in small ungauged catchments. An established method for landscape classification is based on the concept of dominant runoff process (DRP). The various DRP-mapping approaches differ with respect to the time and data required for mapping. Manual approaches based on expert knowledge are reliable but time-consuming, whereas automatic GIS-based approaches are easier to implement but rely on simplifications which restrict their application range. To what extent these simplifications are applicable in other catchments is unclear. More information is also needed on how the different complexities of automatic DRP-mapping approaches affect hydrological simulations. In this paper, three automatic approaches were used to map two catchments on the Swiss Plateau. The resulting maps were compared to reference maps obtained with manual mapping. Measures of agreement and association, a class comparison, and a deviation map were derived. The automatically derived DRP maps were used in synthetic runoff simulations with an adapted version of the PREVAH hydrological model, and simulation results compared with those from simulations using the reference maps. The DRP maps derived with the automatic approach with highest complexity and data requirement were the most similar to the reference maps, while those derived with simplified approaches without original soil information differed significantly in terms of both extent and distribution of the DRPs. The runoff simulations derived from the simpler DRP maps were more uncertain due to inaccuracies in the input data and their coarse resolution, but problems were also linked with the use of topography as a proxy for the storage capacity of soils. The perception of the intensity of the DRP classes also seems to vary among the different authors, and a standardised definition of DRPs is still lacking. Furthermore, we argue not to use

  2. Fractionation and Assimilation Processes Dominate in the Generation of Silicic Magmas from Four Kermadec Arc Volcanoes

    NASA Astrophysics Data System (ADS)

    Barker, S. J.; Wilson, C. J.; Baker, J.; Wysoczanski, R. J.; Rotella, M. D.; Millet, M.; Wright, I. C.

    2010-12-01

    Recent work has shown that silicic volcanism can be abundant in intra-oceanic subduction settings, and is often associated with large explosive caldera forming eruptions. Several major petrogenic questions arise from the generation and eruption of large silicic magma bodies in such a simple subduction setting, where continental crust is absent. We have investigated the geochemistry of pyroclasts collected from four volcanoes along the Kermadec arc; a relatively young (<2 Ma) oceanic subduction zone. Raoul, Macauley and a newly discovered volcano in the northern Kermadec arc, and Healy volcano in the southern Kermadec arc have all erupted dacite-rhyolite pumice within the last 10 kyr. Examination of whole-rock, mineral and glass major and trace element chemical data shows patterns which indicate that evolved magmas are primarily generated through crystal fractionation and not by partial melting of lower crustal lithologies, particularly amphibolite. Silicic magmas and co-eruptive mafic enclaves show sub-parallel REE patterns, and crystal zonation suggests that mafic and silicic magmas are closely related, spatially and temporally. However, distinctive crystal populations in both pumice samples and plutonic xenoliths suggest that many of the crystals did not grow in the evolved magmas, but were mixed in from other sources including gabbros and tonalites. Such open system mixing is ubiquitous in magmas from the four Kermadec volcanoes. Although crystallization is the dominant process driving melt evolution in the Kermadec volcanoes, the magmatic systems are open to contributions from both newly arriving melts and previously crystallized plutonic bodies. Such contributions occur in variable proportions between magma batches, reflected by the chemical variations observed between eruption units in subaerial sequences on Raoul Island and between clustered pumice chemical compositions in dredged samples from the submarine volcanoes.

  3. Mapping dominant runoff processes: an evaluation of different approaches using similarity measures and synthetic runoff simulations

    NASA Astrophysics Data System (ADS)

    Antonetti, M.; Buss, R.; Scherrer, S.; Margreth, M.; Zappa, M.

    2015-12-01

    The identification of landscapes with similar hydrological behaviour is useful for runoff predictions in small ungauged catchments. An established method for landscape classification is based on the concept of dominant runoff process (DRP). The various DRP mapping approaches differ with respect to the time and data required for mapping. Manual approaches based on expert knowledge are reliable but time-consuming, whereas automatic GIS-based approaches are easier to implement but rely on simplifications which restrict their application range. To what extent these simplifications are applicable in other catchments is unclear. More information is also needed on how the different complexity of automatic DRP mapping approaches affects hydrological simulations. In this paper, three automatic approaches were used to map two catchments on the Swiss Plateau. The resulting maps were compared to reference maps obtained with manual mapping. Measures of agreement and association, a class comparison and a deviation map were derived. The automatically derived DRP-maps were used in synthetic runoff simulations with an adapted version of the hydrological model PREVAH, and simulation results compared with those from simulations using the reference maps. The DRP-maps derived with the automatic approach with highest complexity and data requirement were the most similar to the reference maps, while those derived with simplified approaches without original soil information differed significantly in terms of both extent and distribution of the DRPs. The runoff simulations derived from the simpler DRP-maps were more uncertain due to inaccuracies in the input data and their coarse resolution, but problems were also linked with the use of topography as a proxy for the storage capacity of soils. The perception of the intensity of the DRP classes also seems to vary among the different authors, and a standardised definition of DRPs is still lacking. We therefore recommend not only using expert

  4. Investigation of the effect of anthropogenic pollution on typhoon precipitation and microphysical processes using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Jiang, B.

    2015-12-01

    This letter presents an analysis of the influence of anthropogenic aerosols on typhoon, with Usagi as an example, using the Weather Research and Forecasting Model with Chemistry (WRF-Chem). Three simulations (CTL, CLEAN, EXTREME) were designed according to the emission intensity of anthropogenic pollution. The results showed that although anthropogenic pollution did not have a clear influence on typhoon track and strength, it clearly changed precipitation, the distribution of water hydrometeors, and microphysical processes. In the CLEAN experiment, precipitation rate declined because of cloud water collected by rain decreased. Similarly, precipitation rate decreased in the EXTREME experiment, because cloud water auto-conversion to rain water was restrained. Regarding precipitation type, stratiform precipitation rate in the CLEAN and EXTREME simulations was suppressed because the ice phase microphysical processes weakened. Compared to CTL run, stratiform precipitation rate at the periphery was reduced by about 28% in CLEAN and EXTREME simulations. Moreover, convective precipitation rate annulus 140-160km in EXTREME experiment was about 33% larger than that in CTL simulation. It was triggered new convection at the periphery in EXTREME simulation due to cloud water re-evaporation. Finally, compared to the CTL experiment, rainfall peaks of convective and mixed precipitation type in the CLEAN and EXTREME experiments shifted 10km toward the typhoon periphery.

  5. A potential DSD retrieval process for dual-frequency precipitation radar (DPR) on board GPM

    NASA Astrophysics Data System (ADS)

    Le, Minda; Chandresekar, V.

    2012-11-01

    Global Precipitation Measurement (GPM) is poised to be the next generation precipitation monitoring system from space after the Tropical rainfall measurement (TRMM) mission. The GPM mission is centered on the deployment of a core observatory satellite with an active dual-frequency radar DPR, operating at Ku- and Ka- band. Two independent observations from DPR provide the possibility to retrieve two independent parameters from gamma drop size distribution (DSD), namely median volume diameter (D0) and scaled intercept (NW), at each resolution volume. Dual-frequency method proposed for the DPR radar can be formulated in terms of integral equations and the two DSD parameters D0 and NW can be estimated at each bin based on the assumed microphysical models of hydrometeors. One known error in the dual frequency retrievals is the dual-valued problem when retrieving D0 from DFR for rain. Rose and Chandrasekar (2006)[1], remedied the bi-valued problem by assuming a linear model with height for D0 as well as NW (in log scale) in rain. The algorithm with the linear assumption was evaluated by Le et al. (2009) [2] based on the whole vertical profile including rain, melting ice, and ice region through a hybrid method. The hybrid method combines forward retrieval by Meneghini et al (1997) [3] in frozen and melting region and the linear assumption in rain region. The retrieval process uses recursive procedure to optimize DSD parameters at the bottom of rain by constructing the cost function along the vertical profile. This retrieval algorithm is applied to tropical storm Earl, a category 4 hurricane captured by APR-2 precipitation radar during the Genesis and Rapid Intensification Processes (GRIP) campaign in 2010.

  6. Extreme Precipitation along the Himalayan Slope - Main Processes and Long Term Trends

    NASA Astrophysics Data System (ADS)

    Bohlinger, P.; Sorteberg, A.

    2014-12-01

    The precipitation climatology for the Himalayan slope is heavily influenced by the main topographic features of the region. The precipitation variability is strongly connected to variability in the large scale Indian monsoon. In Nepal the average annual precipitation ranges from a few hundred to over 5000 mm and has been shown to be strongly linked to orography.Based on daily measurements of precipitation we calculate a climatology and long term trends for 270 meteorological stations. Especially, extreme precipitation is of increasing interest due to social impacts. Therefore, we further investigate extreme events for each measurement station. Since precipitation is influenced by large scale weather situations we relate the appearance of typical synoptical patterns to corresponding occurances of extreme precipitation events. In order to form groups with similar characteristics in precipitation we performe a cluster analysis on the stations and synoptical situations revealing typical weather patterns responsible for extreme precipitation events.

  7. Multiscale Precipitation Processes Over Mountain Terrain - Landform and Vegetation Controls of Microphysics and Convection in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Barros, A. P.; Wilson, A. M.; Sun, X.; Duan, Y.

    2015-12-01

    Recent precipitation observations in mountainous regions do not exhibit the classical orographic enhancement with elevation, especially where fog and multi-layer clouds are persistent. The role of landform in modulating moisture convergence patterns and constraining the thermodynamic environment that supports the development of complex vertical structures of clouds and precipitation is discussed first using observations and model results from the IPHEx (Integrated Precipitation and Hydrology Experiment) field campaign in the Southern Appalachian Mountains (SAM). Analysis of the complex spatial heterogeneity of precipitation microphysics in the SAM suggests that seeder-feeder interactions (SFI) among stratiform precipitation, low level clouds (LLC), and fog play a governing role on the diurnal and seasonal cycles of observed precipitation regimes. Further, in the absence of synoptic-scale forcing, results suggest that evapotranspiration makes a significant contribution to the moisture budget in the lower atmosphere, creating super-saturation conditions favorable to CCN activation, LLC formation, and light rainfall. To investigate the role of evapotranspiration on the diurnal cycle of mountain precipitation further, range-scale modeling studies were conducted in the Central Andes. Specifically, high resolution WRF simulations for realistic and quasi-idealized ET withdrawal case-studies show that evapotranspiration fluxes modulated by landform govern convective activity in the lower troposphere, including cloud formation and precipitation processes that account for daily precipitation amounts as high as 50-70% depending on synoptic conditions and season. These studies suggest multiscale vegetation controls of orographic precipitation processes via atmospheric instability on the one hand, and low level super-saturation and local microphysics on the other. A conceptual model of multiscale interactions among vegetation, landform and moist processes over complex

  8. Cloud processes of the main precipitation systems in Brazil- CHUVA Project

    NASA Astrophysics Data System (ADS)

    Angelis, C. F.; Sakuragi, J.; Vila, D. A.; Carvalho, I.; Schneebeli, M.

    2011-12-01

    The project CHUVA (Cloud processes of the main precipitation systems in Brazil: A contribution to cloud resolving modeling and to the GPM) is been carrying and its main goal is understand the physical processes involved on the precipitating systems which occur over Brazil. The project plans the setting up of a series of instruments in different parts of Brazil and so far many instruments had been deployed over the three field campaigns. Among the instruments, a dual polarization X band radar, two micro rain radars, a multi-channel ground radiometer, disdrometers, pluviometers are the more important equipments used to collect rainfall information from both: warn and cold clouds. Preliminary results show evident differences in some cloud microphysics observed in different rain events during the campaigns. Besides, rainfall maps produced by the radar data were compared to those similar maps produced by satellite. The X band radar radome, when wet, imposed some attenuation on the radar reflectivities values and an algorithm to compensate such attenuation had been developed based on data observed by disdrometers and micro rain radars. The preliminary results will be shown during the conference and it is expected that the community could discuss and evaluate them under the light of the GPM purposes.

  9. Effectiveness of coagulation and acid precipitation processes for the pre-treatment of diluted black liquor.

    PubMed

    Garg, Anurag; Mishra, I M; Chand, S

    2010-08-15

    The effectiveness of coagulation (using aluminium-based chemicals and ferrous sulfate) and acid precipitation (using H(2)SO(4)) processes for the pre-treatment of diluted black liquor obtained from a pulp and paper mill is reported. Commercial alum was found to be the most economical among all the aluminium and ferrous salts used as a coagulant. A maximum removal of chemical oxygen demand (COD) (ca. 63%) and colour reduction (ca. 90%) from the wastewater (COD = 7000 mg l(-1)) at pH 5.0 was obtained with alum. During the acid precipitation process, at pH < 5.0, significant COD reductions (up to 64%) were observed. Solid residue obtained from the alum treatment at a temperature of 95 degrees C showed much better (3 times) settling rate than that for the residue obtained after treatment with the same coagulant at a temperature of 25 degrees C. The settling curves had three parts, namely, hindered, transition and compression zones. Tory plots were used to determine the critical height of suspension-supernatant interface that is used in the design of a clarifier-thickener unit. High heating values and large biomass fraction of the solid residues can encourage the fuel users to use this waste derived sludge as a potential renewable energy source. PMID:20430523

  10. New, Improved Goddard Bulk-Microphysical Schemes for Studying Precipitation Processes in WRF

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2007-01-01

    An improved bulk microphysical parameterization is implemented into the Weather Research and Forecasting ()VRF) model. This bulk microphysical scheme has three different options, 2ICE (cloud ice & snow), 3ICE-graupel (cloud ice, snow & graupel) and 3ICE-hail (cloud ice, snow & hail). High-resolution model simulations are conducted to examine the impact of microphysical schemes on two different weather events (a midlatitude linear convective system and an Atlantic hurricane). The results suggest that microphysics has a major impact on the organization and precipitation processes associated with a summer midlatitude convective line system. The Goddard 3ICE scheme with a cloud ice-snow-hail configuration agreed better with observations in terms of rainfall intensity and a narrow convective line than did simulations with a cloud ice-snow-graupel or cloud ice-snow (i.e., 2ICE) configuration. This is because the 3ICE-hail scheme includes dense ice precipitating (hail) particle with very fast fall speed (over 10 in For an Atlantic hurricane case, the Goddard microphysical schemes had no significant impact on the track forecast but did affect the intensity slightly. The improved Goddard schemes are also compared with WRF's three other 3ICE bulk microphysical schemes: WSM6, Purdue-Lin and Thompson. For the summer midlatitude convective line system, all of the schemes resulted in simulated precipitation events that were elongated in the southwest-northeast direction in qualitative agreement with the observed feature. However, the Goddard 3ICE scheme with the hail option and the Thompson scheme agree better with observations in terms of rainfall intensity, expect that the Goddard scheme simulated more heavy rainfall (over 48 mm/h). For the Atlantic hurricane case, none of the schemes had a significant impact on the track forecast; however, the simulated intensity using the Purdue-Lin scheme was much stronger than the other schemes. The vertical distributions of model

  11. Studying Precipitation Processes in WRF with Goddard Bulk Microphysics in Comparison with Other Microphysical Schemes

    NASA Technical Reports Server (NTRS)

    Tao, W.K.; Shi, J.J.; Braun, S.; Simpson, J.; Chen, S.S.; Lang, S.; Hong, S.Y.; Thompson, G.; Peters-Lidard, C.

    2009-01-01

    A Goddard bulk microphysical parameterization is implemented into the Weather Research and Forecasting (WRF) model. This bulk microphysical scheme has three different options, 2ICE (cloud ice & snow), 3ICE-graupel (cloud ice, snow & graupel) and 3ICE-hail (cloud ice, snow & hail). High-resolution model simulations are conducted to examine the impact of microphysical schemes on different weather events: a midlatitude linear convective system and an Atlantic hurricane. The results suggest that microphysics has a major impact on the organization and precipitation processes associated with a summer midlatitude convective line system. The Goddard 3ICE scheme with the cloud ice-snow-hail configuration agreed better with observations ill of rainfall intensity and having a narrow convective line than did simulations with the cloud ice-snow-graupel and cloud ice-snow (i.e., 2ICE) configurations. This is because the Goddard 3ICE-hail configuration has denser precipitating ice particles (hail) with very fast fall speeds (over 10 m/s) For an Atlantic hurricane case, the Goddard microphysical scheme (with 3ICE-hail, 3ICE-graupel and 2ICE configurations) had no significant impact on the track forecast but did affect the intensity slightly. The Goddard scheme is also compared with WRF's three other 3ICE bulk microphysical schemes: WSM6, Purdue-Lin and Thompson. For the summer midlatitude convective line system, all of the schemes resulted in simulated precipitation events that were elongated in southwest-northeast direction in qualitative agreement with the observed feature. However, the Goddard 3ICE-hail and Thompson schemes were closest to the observed rainfall intensities although the Goddard scheme simulated more heavy rainfall (over 48 mm/h). For the Atlantic hurricane case, none of the schemes had a significant impact on the track forecast; however, the simulated intensity using the Purdue-Lin scheme was much stronger than the other schemes. The vertical distributions of

  12. The relationship between latent heating, vertical velocity, and precipitation processes: The impact of aerosols on precipitation in organized deep convective systems

    NASA Astrophysics Data System (ADS)

    Tao, Wei-Kuo; Li, Xiaowen

    2016-06-01

    A high-resolution, two-dimensional cloud-resolving model with spectral-bin microphysics is used to study the impact of aerosols on precipitation processes in both a tropical oceanic and a midlatitude continental squall line with regard to three processes: latent heating (LH), cold pool dynamics, and ice microphysics. Evaporative cooling in the lower troposphere is found to enhance rainfall in low cloud condensation nuclei (CCN) concentration scenarios in the developing stages of a midlatitude convective precipitation system. In contrast, the tropical case produced more rainfall under high CCN concentrations. Both cold pools and low-level convergence are stronger for those configurations having enhanced rainfall. Nevertheless, latent heat release is stronger (especially after initial precipitation) in the scenarios having more rainfall in both the tropical and midlatitude environment. Sensitivity tests are performed to examine the impact of ice and evaporative cooling on the relationship between aerosols, LH, and precipitation processes. The results show that evaporative cooling is important for cold pool strength and rain enhancement in both cases. However, ice microphysics play a larger role in the midlatitude case compared to the tropics. Detailed analysis of the vertical velocity-governing equation shows that temperature buoyancy can enhance updrafts/downdrafts in the middle/lower troposphere in the convective core region; however, the vertical pressure gradient force (PGF) is of the same order and acts in the opposite direction. Water loading is small but of the same order as the net PGF-temperature buoyancy forcing. The balance among these terms determines the intensity of convection.

  13. Process Optimization of Seed Precipitation Tank with Multiple Impellers Using Computational Fluid Dynamics

    NASA Astrophysics Data System (ADS)

    Zhao, Hong-Liang; Lv, Chao; Liu, Yan; Zhang, Ting-An

    2015-07-01

    The complex fluid flow in a large-scale tank stirred with multiple Ekato Intermig impellers used in the seed precipitation process was numerically analyzed by the computational fluid dynamics method. The flow field, liquid-solid mixing, and power consumption were simulated by adopting the Eulerian granular multiphase model and standard k- ɛ turbulence model. A steady multiple reference frame approach was used to represent impeller rotation. The simulated results showed that the five-stage multiple Intermig impeller coupled with sloped baffles could generate circulation loops in axial, which is good for solid uniform mixing. The fluid is overmixed under the current industrial condition. Compared with the current process conditions, a three-stage impeller with L/ D of 1.25 not only could meet the industrial requirements, but also more than 20% power could be saved. The results have important implications for reliable design and optimal performance for industry.

  14. Strong and Biostable Hyaluronic Acid-Calcium Phosphate Nanocomposite Hydrogel via in Situ Precipitation Process.

    PubMed

    Jeong, Seol-Ha; Koh, Young-Hag; Kim, Suk-Wha; Park, Ji-Ung; Kim, Hyoun-Ee; Song, Juha

    2016-03-14

    Hyaluronic acid (HAc) hydrogel exhibits excellent biocompatibility, but it has limited biomedical application due to its poor biomechanical properties as well as too-fast enzymatic degradation. In this study, we have developed an in situ precipitation process for the fabrication of a HAc-calcium phosphate nanocomposite hydrogel, after the formation of the glycidyl methacrylate-conjugated HAc (GMHA) hydrogels via photo-cross-linking, to improve the mechanical and biological properties under physiological conditions. In particular, our process facilitates the rapid incorporation of calcium phosphate (CaP) nanoparticles of uniform size and with minimal agglomeration into a polymer matrix, homogeneously. Compared with pure HAc, the nanocomposite hydrogels exhibit improved mechanical behavior. Specifically, the shear modulus is improved by a factor of 4. The biostability of the nanocomposite hydrogel was also significantly improved compared with that of pure HAc hydrogels under both in vitro and in vivo conditions. PMID:26878437

  15. Describing the catchment-averaged precipitation as a stochastic process improves parameter and input estimation

    NASA Astrophysics Data System (ADS)

    Del Giudice, Dario; Albert, Carlo; Rieckermann, Jörg; Reichert, Peter

    2016-04-01

    Rainfall input uncertainty is one of the major concerns in hydrological modeling. Unfortunately, during inference, input errors are usually neglected, which can lead to biased parameters and implausible predictions. Rainfall multipliers can reduce this problem but still fail when the observed input (precipitation) has a different temporal pattern from the true one or if the true nonzero input is not detected. In this study, we propose an improved input error model which is able to overcome these challenges and to assess and reduce input uncertainty. We formulate the average precipitation over the watershed as a stochastic input process (SIP) and, together with a model of the hydrosystem, include it in the likelihood function. During statistical inference, we use "noisy" input (rainfall) and output (runoff) data to learn about the "true" rainfall, model parameters, and runoff. We test the methodology with the rainfall-discharge dynamics of a small urban catchment. To assess its advantages, we compare SIP with simpler methods of describing uncertainty within statistical inference: (i) standard least squares (LS), (ii) bias description (BD), and (iii) rainfall multipliers (RM). We also compare two scenarios: accurate versus inaccurate forcing data. Results show that when inferring the input with SIP and using inaccurate forcing data, the whole-catchment precipitation can still be realistically estimated and thus physical parameters can be "protected" from the corrupting impact of input errors. While correcting the output rather than the input, BD inferred similarly unbiased parameters. This is not the case with LS and RM. During validation, SIP also delivers realistic uncertainty intervals for both rainfall and runoff. Thus, the technique presented is a significant step toward better quantifying input uncertainty in hydrological inference. As a next step, SIP will have to be combined with a technique addressing model structure uncertainty.

  16. Development and Demonstration of a Sulfate Precipitation Process for Hanford Waste Tank 241-AN-107

    SciTech Connect

    SK Fiskum; DE Kurath; BM Rapko

    2000-08-16

    A series of precipitation experiments were conducted on Hanford waste tank 241-AN-107 samples in an effort to remove sulfate from the matrix. Calcium nitrate was added directly to AN-107 sub-samples to yield several combinations of Ca:CO{sub 3} mole ratios spanning a range of 0:1 to 3:1 to remove carbonate as insoluble CaCO{sub 3}. Similarly barium nitrate was added directly to the AN-107 aliquots, or to the calcium pretreated AN-107 aliquots, giving of Ba:SO{sub 4} mole ratios spanning a range of 1:1 to 5:1 to precipitate sulfate as BaSO{sub 4}. Initial bulk carbonate removal was required for successful follow-on barium sulfate precipitation. A {ge} 1:1 mole ratio of Ca:CO{sub 3} was found to lower the carbonate concentration such that Ba would react preferentially with the sulfate. A follow-on 1:1 mole ratio of Ba:SO{sub 4} resulted in 70% sulfate removal. The experiment was scaled up with a 735-mL aliquot of AN-107 for more complete testing. Calcium carbonate and barium sulfate settling rates were determined and fates of selected cations, anions, and radionuclides were followed through the various process steps. Seventy percent of the sulfate was removed in the scale-up test while recovering 63% of the filtrate volume. Surprisingly, during the scale-up test a sub-sample of the CaCO{sub 3}/241-AN-107 slurry was found to lose fluidity upon standing for {le} 2 days. Metathesis with BaCO{sub 3} at ambient temperature was also evaluated using batch contacts at various BaCO{sub 3}:SO{sub 4} mole ratios with no measurable success.

  17. Aerosol-radiation-cloud and precipitation processes during dust events (Invited)

    NASA Astrophysics Data System (ADS)

    Kallos, G. B.; Solomos, S.; Kushta, J.; Mitsakou, C.; Athanasiadis, P.; Spyrou, C.; Tremback, C.

    2010-12-01

    In places like the Mediterranean region where anthropogenic aerosols coexist with desert dust the aerosol-radiation-cloud processes are rather complicated. The mixture of different age of air pollutants of anthropogenic origin with Saharan dust and sea salt may lead to the formation of other particles with different characteristics. The mixture of the aerosols and gases from anthropogenic and natural origin (desert dust and sea salt) results in the formation of new types of PM with different physico-chemical properties and especially hygroscopicity (e.g. inside clouds or within the marine boundary layer) through heterogeneous processes. The new particle formation has different characteristics and therefore they have different impacts on cloud formation and precipitation. In an attempt to better understand links and feedbacks between air pollution and climate the new Integrated Community Limited Area Modeling System - ICLAMS has been developed. ICLAMS is an enhanced version of RAMS.v6 modeling system. It includes sub-models for the dust and sea salt cycles, gas and aqueous phase chemistry, gas to particle conversion and heterogeneous chemistry processes. All these processes are directly coupled with meteorology. RAMS has an explicit cloud microphysical scheme with eight categories of hydrometeors. The cloud droplets spectrum is explicitly calculated from model meteorology and prognostic CCN and IN properties (total number concentration, size distribution properties and chemical composition). Sulphate coated dust particles are efficient CCN because of their increased hygroscopicity while uncoated dust particles are efficient IN. The photochemical processes are directly linked to the RAMS radiative transfer scheme, which in the new model is RRTM. Absorption of short wave solar radiation from airborne dust leads to heating of the dust layer which can also affect the cloud processes. Mid and low tropospheric warming by dust is one of the new features that the model can

  18. Figure-Background Perception and Cerebral Dominance: Hypothesized Integrated Process of Hemispheric Specialization.

    ERIC Educational Resources Information Center

    Ruggieri, Vezio; And Others

    1982-01-01

    The hypothesis was that the two hemispheres have different functions in normal vision, the dominant one analyzing the "figure," and the nondominant the "background." The investigation examined responses of 41 female psychology students. Results were consistent with the hypothesis. (Author/RD)

  19. Deuterium and oxygen 18 in precipitation: Isotropic model, including mixed cloud processes

    SciTech Connect

    Ciais, P.; Jouzel, J.

    1994-08-01

    Modeling the isotropic ratios of precipitation in cold regions meets the problem of `switching` from the vapor-liquid transition to the vapor-ice transition at the oneset of snow formation. The one-dimensional model (mixed cloud isotopic model (MCIM)) described in this paper focuses on the fractionation of water isotopes in mixed clouds, where both liquid droplets and ice crystals can coexist for a given range of temperatures. This feature is linked to the existence of specific saturation conditions within the cloud, allowing droplets to evaporate while the water vapor condensates onto ice crystals. The isotopic composition of the different airborne phases and the precipitation is calculated throughout the condensation history of an isolated air mass moving over the Antarctic ice sheet. The results of the MCIM are compared to surface snow data both for the isotopic ratios and the deuterium excesses. The sensitivity of the model is compared to previous one-dimensional models. Our main result is that accounting specifically for the microphysics of mixed stratiform clouds (Bergeron-Findesein process) does not invalidate the results of earlier modeling studies.

  20. An innovative antisolvent precipitation process as a promising technique to prepare ultrafine rifampicin particles

    NASA Astrophysics Data System (ADS)

    Viçosa, Alessandra; Letourneau, Jean-Jacques; Espitalier, Fabienne; Inês Ré, Maria

    2012-03-01

    Many existing and new drugs fail to be fully utilized because of their limited bioavailability due to poor solubility in aqueous media (BCS drug classes II and IV). In this work, for accelerating dissolution of this kind of poorly water-soluble drugs, an antisolvent precipitation method that does not require the use of conventional volatile organic solvents is proposed. To demonstrate this technique, ultrafine particles of rifampicin were prepared using a room temperature ionic liquid (1-ethyl 3- methyl imidazolium methyl-phosphonate) as an alternative solvent and a phosphate buffer as an antisolvent. Rifampicin solubility was measured in various solvents (1-ethyl 3-methyl imidazolium methylphosphonate, water and phosphate buffer), showing the RTIL good solvency for the model drug: rifampicin solubility was found to be higher than 90 mg/g in RTIL at 30 °C and lower than 1 mg/g in water at 25 °C. Additionally, it was demonstrated that introduction of rifampicin solution in 1-ethyl 3- methyl imidazolium methyl-phosphonate into the aqueous solution antisolvent can produce particles in the submicron range with or without hydroxypropyl methylcellulose as the stabilizer. The ultrafine particles (280-360 nm) are amorphous with enhanced solubility and faster dissolution rate. To our knowledge, this is the first published work examining the suitability of using RTILs for ultrafine drug nanoparticles preparation by an antisolvent precipitation process.

  1. Quantifying dominance of intra-storm phase of interception process by small isolated canopies

    NASA Astrophysics Data System (ADS)

    Yerk, Walter; Montalto, Franco

    2014-05-01

    Precipitation interception by vegetation canopies has long been recognized as a major component of the hydrologic cycle; however, historically most research has been dedicated to closed or sparse canopy forests. The goal of our research was to quantify rainfall partitioning by small isolated canopies in an urban setting. The field experiment involved small forms of four shrub species (Prunus laurocerasus, Cornus sericea, Itea virginica and Hydrangea quercifolia) with crown heights 40 - 80 cm and diameters 35 - 60 cm. Each plant had ten rain gauges to measure throughfall with a sampling frequency of 5 seconds. An on-site automated weather station provided meteorological data. Leaf area index (LAI) was measured by manual counting. We estimated the canopy storage capacities of all four species to be less than 0.5 mm. The obtained data showed statistically significant differences in interception properties among all four species, except between Cornus and Itea. Cumulative interception loss for the period of August-December 2013 was 10% for Cornus, 16% for Itea, 29% for Hydrangea, and 49% for Prunus. The observations revealed a weak relationship between interception abilities and LAI for all four species. Throughfall and precipitation intensities (mm/hr) expressed very strong linear relationship (adjusted coefficients of determination were from 0.80 to 0.95) for the entire range of observed rainfall intensities. For Cornus the ratio of throughfall to precipitation intensity was close to 0.93:1, for Itea it was 0.82:1. The ratios were lesser for Hydrangea (0.65:1), and especially for Prunus (0.48:1). Therefore we show that reduced by the canopy, throughfall intensity results in the bulk of precipitation depth intercepted during the rain events. In contrast, the amount of water stored on the canopy and evaporated between and after rain events contributes minimally to interception. Simulations of potential evaporation based on the Penman-Monteith method showed a large

  2. Temperature controls on sediment production in the Oregon Coast Range - abiotic frost-cracking processes vs. biotic-dominated processes over the last 40 ka

    NASA Astrophysics Data System (ADS)

    Marshall, J. A.; Roering, J. J.; Praskievicz, S. J.; Hales, T. C.; Gavin, D. G.; Bartlein, P. J.

    2012-12-01

    The Oregon Coast Range (OCR) is a mid-latitude soil-mantled landscape wherein measured uplift rates are broadly consistent with long-term measured erosion rates. The OCR was unglaciated during the last glacial period (~ 26 to 13 ka) and therefore is considered an ideal steady-state landscape to study and model geomorphic processes. However, previously published paleoclimate data inferred from a 42 ka paleolake fossil archive in the OCR Little Lake watershed (3 km2) strongly suggest that temperatures in the OCR during the last glacial were well within the frost cracking temperature window of -3 to -8 °C. Therefore, we suggest that while present-day OCR sediment production is dominated by biota, specifically trees, frost-driven abiotic processes may have played a significant role in modulating erosion rates and landscape evolution during the last glacial interval. A new sediment core from the Little Lake basin at the lake's edge, centered proximal to hillslopes, spans ~ 50 ka to 20 ka. We observe a fourfold increase in sediment accumulation rates from the non-glacial interval (~50 ka to ~ 26 ka) to the last glacial interval (~ 26 ka to ~ 20 ka), including > 12 m of sediment from the last glacial maximum, dated at 23,062 - 23,581 cal yr B.P. The decreased inferred temperatures and increased sedimentation rates suggest increased sediment production and transport via frost processes during the last glacial interval, in contrast to sediment production and erosion rates controlled by biotic processes in the non-glacial intervals. We present a climate-time series scenario of likely frost-cracking intensity across the entire Oregon Coast Range from the non-glacial interval (at least 3 °C cooler than present-day temperatures) through the glacial interval (7 to 14 °C cooler) and into the Holocene (January temperatures ~ 5 °C). We use the PRISM dataset, which consists of monthly temperature and precipitation for the contiguous United States, to calculate local monthly

  3. PROCESS FOR RECOVERY OF URANIUM AND VANADIUM FROM CARBONATE SOLUTIONS BY REDUCTION-PRECIPITATION

    DOEpatents

    Ellis, D.A.; Lindblom, R.O.

    1957-09-24

    A process employing carbonate leaching of ores and an advantageous methcd of recovering the uranium and vanadium from the leach solution is described. The uranium and vanadium can be precipitated from carbonate leach solutions by reaction with sodium amalgam leaving the leach solution in such a condition that it is economical to replenish for recycling. Such a carbonate leach solution is treated with a dilute sodium amalgam having a sodium concentration within a range of about 0.01 to 0.5% of sodium. Efficiency of the treatment is dependent on at least three additional factors, intimacy of contact of the amalgam with the leach solution, rate of addition of the amalgam and exclusion of oxygen (air).

  4. Using Multi-scale Modeling Systems to Study the Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2007-01-01

    Numerical cloud models, which are based the non-hydrostatic equations of motion, have been extensively applied to cloud-scale and mesoscale processes during the past four decades. Because cloud-scale dynamics are treated explicitly, uncertainties stemming from convection that have to be parameterized in (hydrostatic) large-scale models are obviated, or at least mitigated, in cloud models. Global models will use the non-hydrostatic framework when their horizontal resolution becomes about 10 km, the theoretical limit for the hydrostatic approximation. This juncture will be reached one to two decades from now. Recently, a multi-scale modeling system with unified physics was developed at NASA Goddard. It consists of (1) a cloud-resolving model (CRM), (2) a regional scale model, (3) a coupled CRM and global model, and (4) a land modeling system. The same microphysical processes, long and short wave radiative transfer processes and the explicit cloud-radiation, and cloudland surface interactive processes are applied in this multi-scale modeling system. In this talk, a review of developments and applications of the multi-scale modeling system will be presented. In particular, the results from using multi-scale modeling system to study the interactions between clouds, precipitation, and aerosols will be presented.

  5. Process parameters and morphology in puerarin, phospholipids and their complex microparticles generation by supercritical antisolvent precipitation.

    PubMed

    Li, Ying; Yang, Da-Jian; Chen, Shi-Lin; Chen, Si-Bao; Chan, Albert Sun-Chi

    2008-07-01

    The aim of the study was to develop and evaluate a new method for the production of puerarin phospholipids complex (PPC) microparticles. The advanced particle formation method, solution enhanced dispersion by supercritical fluids (SEDS), was used for the preparation of puerarin (Pur), phospholipids (PC) and their complex particles for the first time. Evaluation of the processing variables on PPC particle characteristics was also conducted. The processing variables included temperature, pressure, solution concentration, the flow rate of supercritical carbon dioxide (SC-CO2) and the relative flow rate of drug solution to CO2. The morphology, particle size and size distribution of the particles were determined. Meanwhile Pur and phospholipids were separately prepared by gas antisolvent precipitation (GAS) method and solid characterization of particles by the two supercritical methods was also compared. Pur formed by GAS was more orderly, purer crystal, whereas amorphous Pur particles between 0.5 and 1microm were formed by SEDS. The complex was successfully obtained by SEDS exhibiting amorphous, partially agglomerated spheres comprised of particles sized only about 1microm. SEDS method may be useful for the processing of other pharmaceutical preparations besides phospholipids complex particles. Furthermore adopting a GAS process to recrystallize pharmaceuticals will provide a highly versatile methodology to generate new polymorphs of drugs in addition to conventional techniques. PMID:18440736

  6. Barotropic processes associated with the development of the Mei-yu precipitation system

    NASA Astrophysics Data System (ADS)

    Li, Tingting; Li, Xiaofan

    2016-05-01

    The barotropic processes associated with the development of a precipitation system are investigated through analysis of cloud-resolving model simulations of Mei-yu torrential rainfall events over eastern China in mid-June 2011. During the model integration period, there were three major heavy rainfall events: 9-12, 13-16 and 16-20 June. The kinetic energy is converted from perturbation to mean circulations in the first and second period, whereas it is converted from mean to perturbation circulations in the third period. Further analysis shows that kinetic energy conversion is determined by vertical transport of zonal momentum. Thus, the prognostic equation of vertical transport of zonal momentum is derived, in which its tendency is associated with dynamic, pressure gradient and buoyancy processes. The kinetic energy conversion from perturbation to mean circulations in the first period is mainly associated with the dynamic processes. The kinetic energy conversion from mean to perturbation circulations in the third period is generally related to the pressure gradient processes.

  7. The mechanism underlying calcium phosphate precipitation on titanium via ultraviolet, visible, and near infrared laser-assisted biomimetic process

    NASA Astrophysics Data System (ADS)

    Mahanti, Moumita; Nakamura, Maki; Pyatenko, Alexander; Sakamaki, Ikuko; Koga, Kenji; Oyane, Ayako

    2016-08-01

    We recently developed a rapid single-step calcium phosphate (CaP) precipitation technique on several substrates using a laser-assisted biomimetic process (LAB process). In this process, ultraviolet (UV, λ  =  355 nm) pulsed laser irradiation has been applied to a substrate that is immersed in a supersaturated CaP solution. In the present study, the LAB process for CaP precipitation on a titanium substrate was successfully expanded to include not only UV but also visible (VIS, λ  =  532 nm) and near infrared (NIR, λ  =  1064 nm) lasers. Surface heating and plasma-mediated surface reactions (micro-deformation, oxidization, photoexcitation, and wetting) generated by UV, VIS, or NIR lasers are considered to be involved in the CaP precipitation on the titanium surface in the LAB process. The kinetics of these reactions and consequently of CaP precipitation were dependent on the laser wavelength and fluence. The higher laser fluence did not always accelerate CaP precipitation on the substrate; rather, it was found that an optimal range of fluence exists for each laser wavelength. These results suggest that for efficient CaP precipitation, a suitable laser wavelength should be selected according to the optical absorption properties of the substrate material and the laser fluence should also be adjusted to induce surface heating and plasma-mediated surface reactions that are favorable for CaP precipitation.

  8. Off-shell suppressions and two body radiative processes in a vector dominance model

    SciTech Connect

    Lahiri, A.; Bagchi, B.; Gautam, V.P.; Nandy, A.

    1980-08-01

    The radiative decays of rho,K*, omega and phi are studied in a one-parameter vector dominance model by introducing corrections for the off-shell vector meson-photon coupling constants. It is found that off-shell values rho and omega are suppressed by 1/1.5 while off-shell phi is suppressed by 1/1.9 compared with their on-shell values. In addition, we have also considered P ..-->.. ..gamma.. ..gamma.. decays and sigma/sub tot/ (VP), and found generally good agreement with the available data.

  9. Linear Friction Welding Process Model for Carpenter Custom 465 Precipitation-Hardened Martensitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Yavari, R.; Snipes, J. S.; Ramaswami, S.; Yen, C.-F.; Cheeseman, B. A.

    2014-06-01

    An Arbitrary Lagrangian-Eulerian finite-element analysis is combined with thermo-mechanical material constitutive models for Carpenter Custom 465 precipitation-hardened martensitic stainless steel to develop a linear friction welding (LFW) process model for this material. The main effort was directed toward developing reliable material constitutive models for Carpenter Custom 465 and toward improving functional relations and parameterization of the workpiece/workpiece contact-interaction models. The LFW process model is then used to predict thermo-mechanical response of Carpenter Custom 465 during LFW. Specifically, temporal evolutions and spatial distribution of temperature within, and expulsion of the workpiece material from, the weld region are examined as a function of the basic LFW process parameters, i.e., (a) contact-pressure history, (b) reciprocation frequency, and (c) reciprocation amplitude. Examination of the results obtained clearly revealed the presence of three zones within the weld, i.e., (a) Contact-interface region, (b) Thermo-mechanically affected zone, and (c) heat-affected zone. While there are no publicly available reports related to Carpenter Custom 465 LFW behavior, to allow an experiment/computation comparison, these findings are consistent with the results of our ongoing companion experimental investigation.

  10. Design of a continuous process setup for precipitated calcium carbonate production from steel converter slag.

    PubMed

    Mattila, Hannu-Petteri; Zevenhoven, Ron

    2014-03-01

    A mineral carbonation process "slag2PCC" for carbon capture, utilization, and storage is discussed. Ca is extracted from steel slag by an ammonium salt solvent and carbonated with gaseous CO2 after the separation of the residual slag. The solvent is reused after regeneration. The effects of slag properties such as the content of free lime, fractions of Ca, Si, Fe, and V, particle size, and slag storage on the Ca extraction efficiency are studied. Small particles with a high free-lime content and minor fractions of Si and V are the most suitable. To limit the amount of impurities in the process, the slag-to-liquid ratio should remain below a certain value, which depends on the slag composition. Also, the design of a continuous test setup (total volume ∼75 L) is described, which enables quick process variations needed to adapt the system to the varying slag quality. Different precipitated calcium carbonate crystals (calcite and vaterite) are generated in different parts of the setup. PMID:24578147

  11. Measurements of temporal and spatial sequences of events in periodic precipitation processes

    NASA Astrophysics Data System (ADS)

    Kai, Shoichi; Müller, Stefan C.; Ross, John

    1982-02-01

    A series of new experiments on Liesegang ring (or band) formation is presented which is concerned with the temporal and spatial evolution of the process of structure formation. We have chosen NH4OH and MgSO4 to form rings of Mg(OH)2 precipitate in a gelatin gel, as well as KI and Pb(NO3)2 for periodic precipitation of PbI2 in an agar gel. A temporal sequence of events during the entire period from the start of a Liesegang experiment in a test tube to the completion of the final ring pattern has been determined at many locations in the tube by visual observations and by measurements of transmitted light, of scattered light, of deflection of the transmitted light beam, and of gravity effects. After diffusion of one electrolyte into the gel medium containing the second electrolyte results in an ion product larger than three times the solubility product, at any and all points in space, we observe the onset of homogeneous nucleation of colloidal particles by a steplike increase of the index of refraction. The colloid concentration and the particle number density at the nucleation site are estimated to be 10-2 mol/l and 1015 to 1016 cm-3, respectively. Nucleation is followed by the growth of colloidal particles which gives rise to distinct light scattering (turbidity). Both nucleation and colloid formation take place in space continuously; the fronts of these phenomena move through the system and obey a simple diffusion law. A substantial time interval after their passage, there arises a localized gradient of the index of refraction at the prospective ring positions which indicates onset of structure formation by means of a focusing mechanism. While the localized gradient becomes more pronounced and narrower in space, the turbidity in the regions on either side of the ring location decreases, which indicates a depletion in colloidal material in the neighboring zones. Eventually, a sharp band of visible precipitate appears, which is clearly separated from the preceding

  12. NEXRAD quantitative precipitation estimates, data acquisition, and processing for the DuPage County, Illinois, streamflow-simulation modeling system

    USGS Publications Warehouse

    Ortel, Terry W.; Spies, Ryan R.

    2015-01-01

    Next-Generation Radar (NEXRAD) has become an integral component in the estimation of precipitation (Kitzmiller and others, 2013). The high spatial and temporal resolution of NEXRAD has revolutionized the ability to estimate precipitation across vast regions, which is especially beneficial in areas without a dense rain-gage network. With the improved precipitation estimates, hydrologic models can produce reliable streamflow forecasts for areas across the United States. NEXRAD data from the National Weather Service (NWS) has been an invaluable tool used by the U.S. Geological Survey (USGS) for numerous projects and studies; NEXRAD data processing techniques similar to those discussed in this Fact Sheet have been developed within the USGS, including the NWS Quantitative Precipitation Estimates archive developed by Blodgett (2013).

  13. A continuous and highly effective static mixing process for antisolvent precipitation of nanoparticles of poorly water-soluble drugs.

    PubMed

    Dong, Yuancai; Ng, Wai Kiong; Hu, Jun; Shen, Shoucang; Tan, Reginald B H

    2010-02-15

    Rapid and homogeneous mixing of the solvent and antisolvent is critical to achieve submicron drug particles by antisolvent precipitation technique. This work aims to develop a continuous and highly effective static mixing process for antisolvent precipitation of nanoparticles of poorly water-soluble drugs with spironolactone as a model drug. Continuous antisolvent production of drug nanoparticles was carried out with a SMV DN25 static mixer comprising 6-18 mixing elements. The total flow rate ranged from 1.0 to 3.0 L/min while the flow rate ratio of solvent to antisolvent was maintained at 1:9. It is found that only 6 mixing elements were sufficient to precipitate the particles in the submicron range. Increasing the number of elements would further reduce the precipitated particle size. Increasing flow rate from 1.0 to 3.0 L/min did not further reduce the particle size, while higher drug concentrations led to particle size increase. XRD and SEM results demonstrated that the freshly precipitated drug nanoparticles are in the amorphous state, which would, in presence of the mixture of solvent and antisolvent, change to crystalline form in short time. The lyophilized spironolactone nanoparticles with lactose as lyoprotectant possessed good redispersibility and showed 6.6 and 3.3 times faster dissolution rate than that of lyophilized raw drug formulation in 5 and 10 min, respectively. The developed static mixing process exhibits high potential for continuous and large-scale antisolvent precipitation of submicron drug particles. PMID:19922777

  14. Visualization of GPM Standard Products at the Precipitation Processing System (PPS)

    NASA Astrophysics Data System (ADS)

    Kelley, O.

    2010-12-01

    Many of the standard data products for the Global Precipitation Measurement (GPM) constellation of satellites will be generated at and distributed by the Precipitation Processing System (PPS) at NASA Goddard. PPS will provide several means to visualize these data products. These visualization tools will be used internally by PPS analysts to investigate potential anomalies in the data files, and these tools will also be made available to researchers. Currently, a free data viewer called THOR, the Tool for High-resolution Observation Review, can be downloaded and installed on Linux, Windows, and Mac OS X systems. THOR can display swath and grid products, and to a limited degree, the low-level data packets that the satellite itself transmits to the ground system. Observations collected since the 1997 launch of the Tropical Rainfall Measuring Mission (TRMM) satellite can be downloaded from the PPS FTP archive, and in the future, many of the GPM standard products will also be available from this FTP site. To provide easy access to this 80 terabyte and growing archive, PPS currently operates an on-line ordering tool called STORM that provides geographic and time searches, browse-image display, and the ability to order user-specified subsets of standard data files. Prior to the anticipated 2013 launch of the GPM core satellite, PPS will expand its visualization tools by integrating an on-line version of THOR within STORM to provide on-the-fly image creation of any portion of an archived data file at a user-specified degree of magnification. PPS will also provide OpenDAP access to the data archive and OGC WMS image creation of both swath and gridded data products. During the GPM era, PPS will continue to provide realtime globally-gridded 3-hour rainfall estimates to the public in a compact binary format (3B42RT) and in a GIS format (2-byte TIFF images + ESRI WorldFiles).

  15. Effects of acid precipitation and natural processes on cation leaching from four diverse forest ecosystems

    SciTech Connect

    Johnson, D.W.; Van Miegroet, H.; Cole, D.W.; Richter, D.D.

    1983-01-01

    Four forest ecosystems (two in eastern Tennessee and two in western Washington) with a history of intensive nutrient cycling research were selected for studies on the effects of acid precipitation and natural acid production processes on cation leaching rates. At the Tennessee sites, atmospheric acid input in bulk precipitation equaled or exceeded natural leaching by carbonic acid. At the less polluted Washington sites, natural leaching by carbonic acid was slightly larger than atmospheric acid input in the Douglas-fir soil. In the red alder soil, natural nitric acid formation far exceeded atmospheric acid inputs and appeared to have caused significant acidification of both soil and soil solution. The mobility of SO/sub 4//sup 2 -/ and NO/sub 3//sup -/ in these four soils was a major factor in their relative susceptibilities to leaching by H/sub 2/SO/sub 4/ and HNO/sub 3/ entering from the atmosphere. In two of the sites (chestnut oak in Tennessee and red alder in Washington), SO/sub 4//sup 2 -/ adsorption reduced the potential for sulfate-mediated leaching by H/sub 2/SO/sub 4/ by as much as one-half. Biological immobilization of NO/sub 3//sup -/ prevented leaching in all but the N-fixing red alder site. Both field and laboratory soil column studies involving artificial additions of SO/sub 4//sup 2 -/ and NO/sub 3//sup -/ verified the concept that cation leaching is controlled by the mobility of the associated anion.

  16. Mission Operations Center (MOC) - Precipitation Processing System (PPS) Interface Software System (MPISS)

    NASA Technical Reports Server (NTRS)

    Ferrara, Jeffrey; Calk, William; Atwell, William; Tsui, Tina

    2013-01-01

    MPISS is an automatic file transfer system that implements a combination of standard and mission-unique transfer protocols required by the Global Precipitation Measurement Mission (GPM) Precipitation Processing System (PPS) to control the flow of data between the MOC and the PPS. The primary features of MPISS are file transfers (both with and without PPS specific protocols), logging of file transfer and system events to local files and a standard messaging bus, short term storage of data files to facilitate retransmissions, and generation of file transfer accounting reports. The system includes a graphical user interface (GUI) to control the system, allow manual operations, and to display events in real time. The PPS specific protocols are an enhanced version of those that were developed for the Tropical Rainfall Measuring Mission (TRMM). All file transfers between the MOC and the PPS use the SSH File Transfer Protocol (SFTP). For reports and data files generated within the MOC, no additional protocols are used when transferring files to the PPS. For observatory data files, an additional handshaking protocol of data notices and data receipts is used. MPISS generates and sends to the PPS data notices containing data start and stop times along with a checksum for the file for each observatory data file transmitted. MPISS retrieves the PPS generated data receipts that indicate the success or failure of the PPS to ingest the data file and/or notice. MPISS retransmits the appropriate files as indicated in the receipt when required. MPISS also automatically retrieves files from the PPS. The unique feature of this software is the use of both standard and PPS specific protocols in parallel. The advantage of this capability is that it supports users that require the PPS protocol as well as those that do not require it. The system is highly configurable to accommodate the needs of future users.

  17. PROCESS FOR SEPARATING PLUTONIUM BY REPEATED PRECIPITATION WITH AMPHOTERIC HYDROXIDE CARRIERS

    DOEpatents

    Faris, B.F.

    1960-04-01

    A multiple carrier precipitation method is described for separating and recovering plutonium from an aqueous solution. The hydroxide of an amphoteric metal is precipitated in an aqueous plutonium-containing solution. This precipitate, which carries plutonium, is then separated from the supernatant liquid and dissolved in an aqueous hydroxide solution, forming a second plutonium- containing solution. lons of an amphoteric metal which forms an insoluble hydroxide under the conditions existing in this second solution are added to the second solution. The precipitate which forms and which carries plutonium is separated from the supernatant liquid. Amphoteric metals which may be employed are aluminum, bibmuth, copper, cobalt, iron, lanthanum, nickel, and zirconium.

  18. Modeling wildfire impact on hydrologic processes using the Precipitation Runoff Modeling System

    NASA Astrophysics Data System (ADS)

    Logan, R. J.; Hogue, T. S.; Hay, L.

    2015-12-01

    As large magnitude wildfires persist across the western United States, understanding their impact on hydrologic behavior and predicting regional streamflow response is increasingly important. Sediment and debris flows, as well as elevated flood levels in burned watersheds are often addressed, but wildfires also alter the timing and overall volume of both short and long-term runoff, making the prediction of post-fire streamflow critical for water resources management. Watershed models are a powerful tool for both representing wildfire runoff response and discerning the processes that induce that response. In the current study, selected wildfire-impacted basins across the western United States are modeled using the Precipitation Runoff Modeling System (PRMS) in order to develop a generalized approach. This distributed-parameter, physical process based watershed model allows us to target specific processes, while still having the flexibility to account for uncertainty and complex physical interactions that are not explicitly represented in model parameterization. Two change detection modeling approaches are considered. First, models calibrated using pre-fire data are applied to the post-fire period and residuals between simulated and observed flow are examined to quantify the response in each specific watershed. Here an analysis of the model's ability to detect long-term response is also presented. Second, the post-fire conditions are modeled by adjusting appropriate parameters, and the parameter differences are used to guide process learning. In this latter method, parameters are specifically tailored to represent processes affected by wildfire, and scenarios with different parameter interactions are statistically compared. The results of these analyses are synthesized to provide a framework for predicting wildfire runoff response using PRMS, which will ultimately empower water resource decisions.

  19. A novel electrochemical process for the recovery and recycling of ferric chloride from precipitation sludge.

    PubMed

    Mejia Likosova, E; Keller, J; Poussade, Y; Freguia, S

    2014-03-15

    During wastewater treatment and drinking water production, significant amounts of ferric sludge (comprising ferric oxy-hydroxides and FePO4) are generated that require disposal. This practice has a major impact on the overall treatment cost as a result of both chemical addition and the disposal of the generated chemical sludge. Iron sulfide (FeS) precipitation via sulfide addition to ferric phosphate (FePO4) sludge has been proven as an effective process for phosphate recovery. In turn, iron and sulfide could potentially be recovered from the FeS sludge, and recycled back to the process. In this work, a novel process was investigated at lab scale for the recovery of soluble iron and sulfide from FeS sludge. Soluble iron is regenerated electrochemically at a graphite anode, while sulfide is recovered at the cathode of the same electrochemical cell. Up to 60 ± 18% soluble Fe and 46 ± 11% sulfide were recovered on graphite granules for up-stream reuse. Peak current densities of 9.5 ± 4.2 A m(-2) and minimum power requirements of 2.4 ± 0.5 kWh kg Fe(-1) were reached with real full strength FeS suspensions. Multiple consecutive runs of the electrochemical process were performed, leading to the successful demonstration of an integrated process, comprising FeS formation/separation and ferric/sulfide electrochemical regeneration. PMID:24397913

  20. Intraspecific variation of a dominant grass and local adaptation in reciprocal garden communities along a US Great Plains' precipitation gradient: implications for grassland restoration with climate change.

    PubMed

    Johnson, Loretta C; Olsen, Jacob T; Tetreault, Hannah; DeLaCruz, Angel; Bryant, Johnny; Morgan, Theodore J; Knapp, Mary; Bello, Nora M; Baer, Sara G; Maricle, Brian R

    2015-08-01

    Identifying suitable genetic stock for restoration often employs a 'best guess' approach. Without adaptive variation studies, restoration may be misguided. We test the extent to which climate in central US grasslands exerts selection pressure on a foundation grass big bluestem (Andropogon gerardii), widely used in restorations, and resulting in local adaptation. We seeded three regional ecotypes of A. gerardii in reciprocal transplant garden communities across 1150 km precipitation gradient. We measured ecological responses over several timescales (instantaneous gas exchange, medium-term chlorophyll absorbance, and long-term responses of establishment and cover) in response to climate and biotic factors and tested if ecotypes could expand range. The ecotype from the driest region exhibited greatest cover under low rainfall, suggesting local adaptation under abiotic stress. Unexpectedly, no evidence for cover differences between ecotypes exists at mesic sites where establishment and cover of all ecotypes were low, perhaps due to strong biotic pressures. Expression of adaptive differences is strongly environment specific. Given observed adaptive variation, the most conservative restoration strategy would be to plant the local ecotype, especially in drier locations. With superior performance of the most xeric ecotype under dry conditions and predicted drought, this ecotype may migrate eastward, naturally or with assistance in restorations. PMID:26240607

  1. Intraspecific variation of a dominant grass and local adaptation in reciprocal garden communities along a US Great Plains’ precipitation gradient: implications for grassland restoration with climate change

    PubMed Central

    Johnson, Loretta C; Olsen, Jacob T; Tetreault, Hannah; DeLaCruz, Angel; Bryant, Johnny; Morgan, Theodore J; Knapp, Mary; Bello, Nora M; Baer, Sara G; Maricle, Brian R

    2015-01-01

    Identifying suitable genetic stock for restoration often employs a ‘best guess’ approach. Without adaptive variation studies, restoration may be misguided. We test the extent to which climate in central US grasslands exerts selection pressure on a foundation grass big bluestem (Andropogon gerardii), widely used in restorations, and resulting in local adaptation. We seeded three regional ecotypes of A. gerardii in reciprocal transplant garden communities across 1150 km precipitation gradient. We measured ecological responses over several timescales (instantaneous gas exchange, medium-term chlorophyll absorbance, and long-term responses of establishment and cover) in response to climate and biotic factors and tested if ecotypes could expand range. The ecotype from the driest region exhibited greatest cover under low rainfall, suggesting local adaptation under abiotic stress. Unexpectedly, no evidence for cover differences between ecotypes exists at mesic sites where establishment and cover of all ecotypes were low, perhaps due to strong biotic pressures. Expression of adaptive differences is strongly environment specific. Given observed adaptive variation, the most conservative restoration strategy would be to plant the local ecotype, especially in drier locations. With superior performance of the most xeric ecotype under dry conditions and predicted drought, this ecotype may migrate eastward, naturally or with assistance in restorations. PMID:26240607

  2. Gravity-flow processes and deposits in a tidally dominated coastal environment

    NASA Astrophysics Data System (ADS)

    Eidam, E.; Ogston, A. S.; Nittrouer, C. A.

    2014-12-01

    Small mountainous rivers (SMRs) are characterized by episodic sediment delivery to marine environments, and have been recognized as a source of sediment gravity flows along storm-dominated coasts. These important modes of cross-shelf sediment transport are largely dependent on suspended-sediment concentration (SSC), bottom slope, and energy supplied by waves and currents. The mechanics and deposits of gravity flows are relatively unstudied on tidally dominated coasts receiving episodic SMR sediment discharge. Data collected during and after a March 2014 sediment delivery event from the small mountainous Elwha River (WA, USA) demonstrates the challenges of forming and preserving gravity-flow deposits in a persistently energetic tidal system. The river discharges to a narrow strait; near the river mouth, maximum boundary-layer tidal currents (50 cm above bed) reach 80-100 cm/s during spring tides and 30-60 cm/s during neap tides. Since 2011, the deconstruction of two dams has generated fluvial SSCs from 3 g/L to >9 g/L (max. monitoring value) during rainstorms and freshets. Instruments stationed near the river mouth since 2011 have shown that tidal currents advect this fine-grained sediment for days to weeks after delivery, and ultimately disperse it away from the river mouth. In March 2014, fluvial SSC reached ≥9 g/L during the largest river discharge since dam removal began. One day later, boundary-layer SSCs reached 2 g/L and 1 g/L at 23 and 102 cmab, respectively, and 5-8 days later, the bed under the instrument system aggraded by ~30 cm. Currents subsequently eroded the deposit, and within 3 weeks the bed elevation returned to its pre-event level. This is consistent with evidence of little to no grain-size change of the sand/gravel seabed in 10-60 m water depth up to 5 km from the river mouth since the dam removal began. To date, the only measurable accumulation of new sediment is in an embayment adjacent to the river mouth where currents weaken. These

  3. Development of observed precipitation and meteorological database to understand the wet deposition and dispersion processes in March 2011

    NASA Astrophysics Data System (ADS)

    Yatagai, Akiyo; Watanabe, Akira; Ishihara, Masahito; Ishihara, Hirohiko; Takara, Kaoru

    2014-05-01

    The transport and diffusion of the radioactive pollutants from the Fukushima-Daiichi NPP inthe atmosphere caused a disaster for residents in and around Fukushima. Studies have sought to understand the transport, diffusion, and deposition process, and to understand the movement of radioactive pollutants through the soil, vegetation, rivers, and groundwater. However, a detailed simulation and understanding of the distribution of radioactive compounds depend on a simulation of precipitation and on the information on the timing of the emission of these radioactive pollutants from the NPP. Further, precipitation type and its amount affect the various transport process of the radioactive nuclides. Hence, this study first examine the qualitative precipitation pattern and timing in March 2011 using X-band radar data from Fukushima University and three dimensional C-band radar data network of Japan Meteorological Agency. Second, by collecting rain-gauge network and other surface meteorological data, we estimate quantitative precipitation and its type (rain/snow) according to the same method used to create APHRODITE daily grid precipitation (Yatagai et al., 2012) and judge of rain/snow (Yasutomi et al., 2011). For example, the data clarified that snowfall was observed on the night of Mar 15 into the morning of Mar 16 throughout Fukushima prefecture. This had an important effect on the radioactive contamination pattern in Fukushima prefecture. The precipitation pattern itself does not show one-on-one correspondence with the contamination pattern. While the pollutants transported northeast of the NPP and through north Kanto (about 200 km southwest of Fukushima and, 100 km north of Tokyo) went to the northeast, the timing of the precipitation causing the fallout, i.e., wet-deposition, is important. Although the hourly Radar-AMeDAS 1-km-mesh precipitation data of JMA are available publically, it does not represent the precipitation pattern in Nakadori, in central Fukushima

  4. Weathering processes and pickeringite formation in a sulfidic schist: a consideration in acid precipitation neutralization studies

    SciTech Connect

    Parnell, R.A. Jr.

    1983-01-01

    Extremely low abrasion pH values (2.8-3.3) characterize the weathering products of the Partridge Formation, a Middle-Ordovician metamorphosed, black, sulfidic shale. The local occurrence is observed of two sulfates that are rare in the Northeast: pickeringite and jarosite. X-ray diffraction studies of the weathering residues and the sulfate efflorescences have also identified dioctahedral and trioctahedral illite, kaolinite, vermiculite, and an 11-12 Angstrom phase, thought to be a type of randomly-interstratified biotite-vermiculite. From the mineralogical studies, qualitative weathering processes for the schist are formulated. A probable mechanism for the intense chemical weathering of the schist appears to be oxidation of iron sulfides to form iron oxide-hydroxides, sulfates, and sulfuric acid. This natural weathering process is proposed as an analog to anthropogenic low pH rock weathering resulting from acid precipitation. In the Northeast, natural weathering rates, may, in places, significantly affect the water chemistry and mineralogy used to quantify total (natural plus anthropogenic) weathering and leaching rates. 27 references, 4 figures.

  5. Precipitation process for the removal of technetium values from nuclear waste solutions

    DOEpatents

    Walker, D.D.; Ebra, M.A.

    1985-11-21

    High efficiency removal of techetium values from a nuclear waste stream is achieved by addition to the waste stream of a precipitant contributing tetraphenylphosphonium cation, such that a substantial portion of the technetium values are precipitated as an insoluble pertechnetate salt.

  6. Processing, Microstructures and Properties of a Dual Phase Precipitation-Hardening PM Stainless Steel

    NASA Astrophysics Data System (ADS)

    Schade, Christopher

    To improve the mechanical properties of PM stainless steels in comparison with their wrought counterparts, a PM stainless steel alloy was developed which combines a dual-phase microstructure with precipitation-hardening. The use of a mixed microstructure of martensite and ferrite results in an alloy with a combination of the optimum properties of each phase, namely strength and ductility. The use of precipitation hardening via the addition of copper results in additional strength and hardness. A range of compositions was studied in combination with various sintering conditions to determine the optimal thermal processing to achieve the desired microstructure. The microstructure could be varied from predominately ferrite to one containing a high percentage of martensite by additions of copper and a variation of the sintering temperature before rapid cooling. Mechanical properties (transverse rupture strength (TRS), yield strength, tensile strength, ductility and impact toughness) were measured as a function of the v/o ferrite in the microstructure. A dual phase alloy with the optimal combination of properties served as the base for introducing precipitation hardening. Copper was added to the base alloy at various levels and its effect on the microstructure and mechanical properties was quantified. Processing at various sintering temperatures led to a range of microstructures; dilatometry was used utilized to monitor and understand the transformations and the formation of the two phases. The aging process was studied as a function of temperature and time by measuring TRS, yield strength, tensile strength, ductility, impact toughness and apparent hardness. It was determined that optimum aging was achieved at 538°C for 1h. Aging at slightly lower temperatures led to the formation of carbides, which contributed to reduced hardness and tensile strength. As expected, at the peak aging temperature, an increase in yield strength and ultimate tensile strength as well as

  7. STRONTIUM PRECIPITATION

    DOEpatents

    McKenzie, T.R.

    1960-09-13

    A process is given for improving the precipitation of strontium from an aqueous phosphoric-acid-containing solution with nickel or cobalt ferrocyanide by simultaneously precipitating strontium or calcium phosphate. This is accomplished by adding to the ferrocyanide-containing solution calcium or strontium nitrate in a quantity to yield a concentration of from 0.004 to 0.03 and adjusting the pH of the solution to a value of above 8.

  8. Tensions and Burdens in Employment Interviewing Processes: Perspectives of Non-Dominant Group Applicants.

    ERIC Educational Resources Information Center

    Buzzanell, Patrice M.

    1999-01-01

    Contributes to scholarship on communicative processes in employment interviewing and on cultural diversity. Discusses communication processes aligned with nondominant group membership. Presents a picture of the performance burdens that members of traditionally underrepresented groups may experience when attempting to meet traditional expectations…

  9. PRECIPITATION OF PLUTONOUS PEROXIDE

    DOEpatents

    Barrick, J.G.; Manion, J.P.

    1961-08-15

    A precipitation process for recovering plutonium values contained in an aqueous solution is described. In the process for precipitating plutonium as plutonous peroxide, hydroxylamine or hydrazine is added to the plutoniumcontaining solution prior to the addition of peroxide to precipitate plutonium. The addition of hydroxylamine or hydrazine increases the amount of plutonium precipitated as plutonous peroxide. (AEC)

  10. Remote Sensing of Precipitation Using Multiparameter Radar: Statistics, Processing Algorithms and Analysis Techniques.

    NASA Astrophysics Data System (ADS)

    Liu, Li.

    With the advent of the multiparameter weather radar, i.e., dual-polarization, dual-frequency, Doppler radar, radar meteorologists have been able to study physical processes in precipitation in more detail, and the quantitative measurement of rainfall as well as the identification of different types of hydrometeors have become possible. However, the effects of propagation through the rain medium must be carefully considered whenever dual-polarization techniques are considered. The correction of propagation effects such as attenuation, differential attenuation and differential propagation phase in precipitation are very important for quantitative interpretation of echo powers at high frequencies. In this dissertation, a simplified scattering matrix with propagation effects is described. A number of parameters are derived based on the covariance matrix of the scattering element array. The processing techniques for estimating some specific parameters, such as K_{dp }, A_{x} and intrinsic LDR using the CSU-CHILL and CP-2 radar measurements, are discussed. Recent research has suggested that the copolar correlation coefficient termed rho_ {hv}(0) can be used to identify large hail and improve polarization estimates of rainfall. The typical measured values of rho_{hv }(0) at S-band vary between 0.8-1.0. For applications to hail identification the required accuracy should be within +/-0.01 while for rainfall improvement a higher accuracy is necessary, e.g., within +/-0.001. We discuss the statistics of several estimators of rho_{hv }(0) using the Gaussian spectrum approximation from both an analytical approach and via simulations. The standard deviation and bias in rho _{hv}(0) are computed as a function of number of samples, Doppler spectral width and mean rho_{hv}(0). The effect of finite signal-to-noise ratio (SNR) and phase noise are also studied via simulations. Time series data collected with the CSU-CHILL radar are analyzed and compared with the simulations. Antenna

  11. Controlled versus Automatic Processes: Which Is Dominant to Safety? The Moderating Effect of Inhibitory Control

    PubMed Central

    Xu, Yaoshan; Li, Yongjuan; Ding, Weidong; Lu, Fan

    2014-01-01

    This study explores the precursors of employees' safety behaviors based on a dual-process model, which suggests that human behaviors are determined by both controlled and automatic cognitive processes. Employees' responses to a self-reported survey on safety attitudes capture their controlled cognitive process, while the automatic association concerning safety measured by an Implicit Association Test (IAT) reflects employees' automatic cognitive processes about safety. In addition, this study investigates the moderating effects of inhibition on the relationship between self-reported safety attitude and safety behavior, and that between automatic associations towards safety and safety behavior. The results suggest significant main effects of self-reported safety attitude and automatic association on safety behaviors. Further, the interaction between self-reported safety attitude and inhibition and that between automatic association and inhibition each predict unique variances in safety behavior. Specifically, the safety behaviors of employees with lower level of inhibitory control are influenced more by automatic association, whereas those of employees with higher level of inhibitory control are guided more by self-reported safety attitudes. These results suggest that safety behavior is the joint outcome of both controlled and automatic cognitive processes, and the relative importance of these cognitive processes depends on employees' individual differences in inhibitory control. The implications of these findings for theoretical and practical issues are discussed at the end. PMID:24520338

  12. North American monsoon precipitation and its precursors: Processes at the seasonal and diurnal scale

    NASA Astrophysics Data System (ADS)

    Gaynor, Nicole June Schiffer

    The Weather Research and Forecasting (WRF) model was run at 100 km, 25 km, and 10 km resolution for the 2000 and 2004 monsoon seasons (July-September), a dry year and a wet year. These years were chosen to represent contrasting precipitation outcomes to assure that results were robust across different monsoon conditions. Model precipitation was compared to precipitation from the Modern-Era Retrospective Reanalysis (MERRA), the North American Regional Reanalysis (NARR), and Tropical Rainfall Measuring Mission (TRMM). Then WRF, MERRA, and NARR were used to investigate the relationships between precipitation and the other moisture budget variables, the large-scale flow, and atmospheric stability on the seasonal and diurnal scales. On both the seasonal and diurnal scale, flow was key to the location and intensity of precipitation. In 2004, the subtropical high over the south-central United States was about 300 km west of its location in 2000 at 700 hPa. The shift was also evident in vertically-integrated moisture flux, which then changed the pattern and intensity of moisture flux convergence (MFC), convective available potential energy (CAPE) and convective inhibition (CIN), and precipitation over Mexico and the Gulf of California. Over Arizona and New Mexico, transient disturbances, like tropical waves, were more important than the diurnal cycle to precipitation. Despite similar spatial distributions of precipitation, WRF, NARR, MERRA, and TRMM showed very different frequencies of light and heavy rain. Such uncertainty in the character of rainfall can impact a variety of stakeholders and decision makers across the NAM region. The WRF model tended to produce heavier precipitation across the NAM region compared to MERRA, NARR, and TRMM as a result of stronger MFC and higher CAPE, especially over the Gulf of California. Beyond the resolution needed to adequately reproduce the Baja California and Gulf of California, higher model resolution tended to increase and localize

  13. Classical nucleation theory for solute precipitation amended with diffusion and reaction processes near the interface

    NASA Astrophysics Data System (ADS)

    Borisenko, Alexander

    2016-05-01

    During the processes of nucleation and growth of a precipitate cluster from a supersaturated solution, the diffusion flux between the cluster and the solution changes the solute concentration near the cluster-solution interface from its average bulk value. This feature affects the rates of attachment and detachment of solute atoms at the interface, and, therefore, the entire nucleation-growth kinetics is altered. Unless quite obvious, this effect has been ignored in classical nucleation theory. To illustrate the results of this approach, for the case of homogeneous nucleation, we calculate the total solubility and the nucleation rate as functions of two parameters of the model (the reduced interface energy and the inverse second Damköhler number), and we compare these results to the classical ones. One can conclude that discrepancies with classical nucleation theory are great in the diffusion-limited regime, when the rate of bulk diffusion is small compared to the rate of interface reactions, while in the opposite interface-limited case they vanish.

  14. Synthesis and photocatalytic performances of BiVO 4 by ammonia co-precipitation process

    NASA Astrophysics Data System (ADS)

    Yu, Jianqiang; Zhang, Yan; Kudo, Akihiko

    2009-02-01

    This paper reports the preparation and photocatalytic performance of Bismuth vanadate (BiVO 4) by a facile and inexpensive approach. An amorphous BiVO 4 was first prepared by a co-precipitation process from aqueous solutions of Bi(NO 3) 3 and NH 4VO 3 using ammonia. Followed by heating treatment at various temperatures, the amorphous phase converted to crystalline BiVO 4 with a structure between monoclinic and tetragonal scheelite. The crystallization of BiVO 4 occurred at about 523 K, while the nanocrystalline BiVO 4 were formed with a heat-treatment of lower than 673 K. However, when the heat-treatment was carried out at 773 K, the accumulation of nanocrystals to bulk particles was observed. The photocatalytic performances of the materials were investigated by O 2 evolution under visible-light, and MB decomposition under solar simulator. The results demonstrated that the crystalline structure is still the vital factor for the activities of both reactions. However, the crystallinity of BiVO 4 gives a major influence on the activity of O 2 evolution, whereas the surface area, plays an important role for photocatalytic MB decomposition.

  15. A novel chemical oxo-precipitation (COP) process for efficient remediation of boron wastewater at room temperature.

    PubMed

    Shih, Yu-Jen; Liu, Chia-Hsun; Lan, Wei-Cheng; Huang, Yao-Hui

    2014-09-01

    Chemical oxo-precipitation (COP), which combines treatment with an oxidant and precipitation using metal salts, was developed for treating boron-containing water under milder conditions (room temperature, pH 10) than those of conventional coagulation processes. The concentration of boron compounds was 1000mg-BL(-1). They included boric acid (H3BO3) and perborate (NaBO3). Precipitation using calcium chloride eliminated 80% of the boron from the perborate solution, but was unable to treat boric acid. COP uses hydrogen peroxide (H2O2) to pretreat boric acid, substantially increasing the removal of boron from boric acid solution by chemical precipitation from less than 5% to 80%. Furthermore, of alkaline earth metals, barium ions are the most efficient precipitant, and can increase the 80% boron removal to 98.5% at [H2O2]/[B] and [Ba]/[B] molar ratios of 2 and 1, respectively. The residual boron in the end water of COP contained 15ppm-B: this value cannot be achieved using conventional coagulation processes. PMID:24997923

  16. Destructive processing by asparagine endopeptidase limits presentation of a dominant T cell epitope in MBP.

    PubMed

    Manoury, Bénédicte; Mazzeo, Daniela; Fugger, Lars; Viner, Nick; Ponsford, Mary; Streeter, Heather; Mazza, Graziella; Wraith, David C; Watts, Colin

    2002-02-01

    Little is known about the processing of putative human autoantigens and why tolerance is established to some T cell epitopes but not others. Here we show that a principal human HLA-DR2-restricted epitope--amino acids 85-99 of myelin basic protein, MBP(85-99)--contains a processing site for the cysteine protease asparagine endopeptidase (AEP). Presentation of this epitope by human antigen-presenting cells is inversely proportional to the amount of cellular AEP activity: inhibition of AEP in living cells greatly enhances presentation of the MBP(85-99) epitope, whereas overexpression of AEP diminishes presentation. These results indicate that central tolerance to this encephalitogenic MBP epitope may not be established because destructive processing limits its display in the thymus. Consistent with this hypothesis, AEP is expressed abundantly in thymic antigen-presenting cells. PMID:11812994

  17. Cloud Modeling Using Field Project Data for the Study of Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Shie, C.-H.; Lang, S.; Simpson, J.

    2003-01-01

    The use of cloud-resolving models (CRMs) in the study of precipitation process and their relation to the large-scale environment can be generally categorized into two approaches. The first approach is so called "cloud ensemble modeling". In this approach, many clouds of different size in various stages of their lifecycles can be present at any model simulation time. Large-scale effects are derived from observations and imposed into the model as the main forcing. The advantage of this approach is that the modeled convection will be forced to have the same intensity, thermodynamic budget and organization as the obserations.This approach will also allow CRMs to perform multi-day or multi-week time integrations. The second approach usually requires initial temperature and water vapor profiles that have a medium to large CAPE, and open lateral boundary conditions are used. The modeled clouds could be termed "self-forced convection". Model improvements, such as in the microphysics, are achieved using the second approach. In cloud ensemble modeling, accurate large-scale advective tendencies for temperature and water vapor are the main forcing for the CRMs. We found that the large-scale advective terms for temperature and water vapor are not always consistent, For example, large-scale forcing could indicate strong drying which would produce cooling in the model through evaporation but not contain large-scale advective heating to compensate. This discrepancy in forcing would cause differences between the observed and modeled latent heating profiles. Good measurements of other quantities (i.e., surface fluxes and radiation) are also required to perform variational objective analysis that computes and minimizes a "cost function" that constrains the difference between the large-scale advective forcing in temperature and water vapor. With self-forced convection, accurate vertical distributions of temperature, moisture (water vapor), and horizontal winds are required. The timing

  18. Precipitation Recycling

    NASA Technical Reports Server (NTRS)

    Eltahir, Elfatih A. B.; Bras, Rafael L.

    1996-01-01

    The water cycle regulates and reflects natural variability in climate at the regional and global scales. Large-scale human activities that involve changes in land cover, such as tropical deforestation, are likely to modify climate through changes in the water cycle. In order to understand, and hopefully be able to predict, the extent of these potential global and regional changes, we need first to understand how the water cycle works. In the past, most of the research in hydrology focused on the land branch of the water cycle, with little attention given to the atmospheric branch. The study of precipitation recycling which is defined as the contribution of local evaporation to local precipitation, aims at understanding hydrologic processes in the atmospheric branch of the water cycle. Simply stated, any study on precipitation recycling is about how the atmospheric branch of the water cycle works, namely, what happens to water vapor molecules after they evaporate from the surface, and where will they precipitate?

  19. Process-based management approaches for salt desert shrublands dominated by downy brome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Downy brome grass (Bromus tectorum L.) invasion has severely altered key ecological processes such as disturbance regimes, soil nutrient cycling, community assembly, and successional pathways in semi-arid Great Basin salt desert shrublands. Restoring the structure and function of these severly alte...

  20. Diurnal variation of dominant nitrate retention processes in an agricultural headwater stream

    NASA Astrophysics Data System (ADS)

    Schuetz, Tobias; Ryabenko, Evgenia; Stumpp, Christine

    2015-04-01

    Nitrate and ammonium are introduced by agricultural practice into the environment and are transformed and retained on their pathway through aquatic environments. In particular, biological transformation processes (i.e. microbial denitrification or ammonium oxidation and assimilation) are responsible for the largest part of nitrate removal, which are also crucial processes in headwater streams. It is well known, that most of the biological processes are influenced by available (solar) energy fluxes, temperatures and dissolved oxygen concentrations, which vary with time and space. However, looking at biogeochemical hot spots in the landscapes` hydrological interface, the stream and river network (e.g. stream sections with a high biological activity), the temporal variability of biological processes can be an important control on total nitrate export. In this study, we therefore identified most important diurnal time periods for nitrate retention in a 75 m impervious section of an agricultural headwater stream using oxygen saturation dynamics and nitrate isotopes. We regularly measured discharge, hydro-geochemical and climate parameters, as well as nitrate and water isotopes in grab samples at three locations along the reach. On average, we observed a decrease of 10% in nitrate concentration from up- to downstream, which was only caused by biological processes and not by dilution. Nitrate isotope analysis indicated distinct trends along the reach and with time of the day. Both nitrate assimilation and nitrification caused significant changes in nitrate isotope distribution in the early day. To explain the distinct observed process dynamics from the morning to the afternoon, we simulated net primary production (NEP) and respiration using the river metabolism model RIVERMETC with observed oxygen concentrations and water temperatures. Comparing the results with the observed nitrate dynamics, the short time period when NEP occurs (~10:30 -12:30) seems to be crucial for

  1. The Role of Aerosols on Precipitation Processes: Cloud Resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Li, X.; Matsui, T.

    2012-01-01

    identify the impact of ice processes, radiation and large-scale influence on cloud-aerosol interactive processes, especially regarding surface rainfall amounts and characteristics (i.e., heavy or convective versus light or stratiform types). In addition, an inert tracer was included to follow the vertical redistribution of aerosols by cloud processes. We will also give a brief review from observational evidence on the role of aerosol on precipitation processes.

  2. Interface-coupled dissolution-precipitation processes during acidic weathering of multicomponent minerals

    NASA Astrophysics Data System (ADS)

    Ruiz-Agudo, Encarnacion; King, Helen E.; Patiño-López, Luis D.; Putnis, Christine V.; Geisler, Thorsten; Rodriguez-Navarro, Carlos M.; Putnis, Andrew

    2015-04-01

    The chemical weathering of carbonate and silicate minerals on the Earth's surface controls important geochemical processes such as erosion rates and soil formation, ore genesis or climate evolution. The dissolution of most of these minerals is typically incongruent, and results in the formation of surface coatings (altered layers, also known as leached layers). These coatings may significantly affect mineral dissolution rates over geological timescales, and therefore a great deal of research has been conducted on them. However, the mechanism of leached layer formation is a matter of vigorous debate. Here we report on an in situ atomic force microscopy (AFM) and real-time Mach-Zehnder phase-shift interferometry (PSI) study of the dissolution of wollastonite, CaSiO3, and dolomite, CaMg(CO3)2, as an example of surface coating formation during acidic weathering of multicomponent minerals. Our in situ results provide clear direct experimental evidence that leached layers are formed in a tight interface-coupled two-step process: stoichiometric dissolution of the pristine mineral surfaces and subsequent precipitation of a secondary phase (silica in the case of wollastonite, or hydrated magnesium carbonate in the case of dolomite) from a supersaturated boundary layer of fluid in contact with the mineral surface. This occurs despite the bulk solution remaining undersaturated with respect to the secondary phase. The validation of such a mechanism given by the results reported here completely changes the conceptual framework concerning the mechanism of chemical weathering, and differs significantly from the concept of preferential leaching of cations postulated by most currently accepted incongruent dissolution models.

  3. Demonstration of Small Tank Tetraphenylborate Precipitation Process Using Savannah River Site High Level Waste

    SciTech Connect

    Peters, T.B.

    2001-09-10

    This report details the experimental effort to demonstrate the continuous precipitation of cesium from Savannah River Site High Level Waste using sodium tetraphenylborate. In addition, the experiments examined the removal of strontium and various actinides through addition of monosodium titanate.

  4. Modelling accumulation of marine plastics in the coastal zone; what are the dominant physical processes?

    NASA Astrophysics Data System (ADS)

    Critchell, Kay; Lambrechts, Jonathan

    2016-03-01

    Anthropogenic marine debris, mainly of plastic origin, is accumulating in estuarine and coastal environments around the world causing damage to fauna, flora and habitats. Plastics also have the potential to accumulate in the food web, as well as causing economic losses to tourism and sea-going industries. If we are to manage this increasing threat, we must first understand where debris is accumulating and why these locations are different to others that do not accumulate large amounts of marine debris. This paper demonstrates an advection-diffusion model that includes beaching, settling, resuspension/re-floating, degradation and topographic effects on the wind in nearshore waters to quantify the relative importance of these physical processes governing plastic debris accumulation. The aim of this paper is to prioritise research that will improve modelling outputs in the future. We have found that the physical characteristic of the source location has by far the largest effect on the fate of the debris. The diffusivity, used to parameterise the sub-grid scale movements, and the relationship between debris resuspension/re-floating from beaches and the wind shadow created by high islands also has a dramatic impact on the modelling results. The rate of degradation of macroplastics into microplastics also have a large influence in the result of the modelling. The other processes presented (settling, wind drift velocity) also help determine the fate of debris, but to a lesser degree. These findings may help prioritise research on physical processes that affect plastic accumulation, leading to more accurate modelling, and subsequently management in the future.

  5. Influence of oxalic acid on the agglomeration process and total soda content in precipitated Al(OH) 3

    NASA Astrophysics Data System (ADS)

    Nikolić, I.; Blec̆ić, D.; Blagojević, N.; Radmilović, V.; Kovac̆ević, K.

    2003-05-01

    Decomposition of caustic soda solutions is an important part of Bayer process for alumina production. The physico-chemical properties of precipitated Al(OH) 3 are dependent on several processes that take place simultaneously during the decomposition process and they are: nucleation, agglomeration and Al(OH) 3 crystals. An important industrial requirement is increase of Al(OH) 3 crystal grain size, and hence agglomeration and growth of Al(OH) 3 crystals become important processes and they enable increase of particle size. The influence of oxalic acid concentration on the agglomeration process and total soda content in precipitated Al(OH) 3 at different temperatures and caustic soda concentrations has been investigated. The results have shown that the agglomeration process is increased with increase of temperature and decrease of caustic soda concentration. Total soda content in precipitated Al(OH) 3 is changed in the same way. Besides, agglomeration process of Al(OH) 3 particles is favored in the presence of oxalic acid.

  6. Notice of Construction for the Magnesium Hydroxide Precipitation Process at the Plutonium Finishing Plant (PFP)

    SciTech Connect

    JANSKY, M.T.

    1999-12-01

    The following description and any attachments and references are provided to the Washington State Department of Health (WDOH), Division of Radiation Protection, Air Emissions & Defense Waste (WAC) 246-247, Radiation Protection-Air Emissions. The WAC 246-247-060, ''Applications, registration, and licensing'', states ''This section describes the information requirements for approval to construct, modify, and operate an emission unit. Any NOC requires the submittal of information listed in Appendix A.'' Appendix A (WAC 246-247-1 10) lists the requirements that must be addressed. Additionally, the following description, attachments and references are provided to the US Environmental Protection Agency (EPA) as an NOC, in accordance with Title 40, Code of Federal Regulations (CFR), Part 61, ''National Emission Standards for Hazardous Air Pollutants.'' The information required for submittal to the EPA is specified in 40 CFR 61.07. The potential emissions from this activity are estimated to provide greater than 0.1 millirem per year total effective dose equivalent (TEDE) to the hypothetical offsite maximally exposed individual (MEI), and commencement is needed within a short time. Therefore, this application also is intended to provide notification of the anticipated date of initial startup in accordance with the requirement listed in 40 CFR 61.09(a)(1), and it is requested that approval of this application also will constitute EPA acceptance of this initial startup notification. Written notification of the actual date of initial startup, in accordance with the requirement listed in 40 CFR 61.09(a)(2) will be provided at a later date. This NOC covers the activities associated with the Construction and operation activities involving the magnesium hydroxide precipitation process of plutonium solutions within the Plutonium Finishing Plant (PFP).

  7. Convective and Stratiform Precipitation Processes and their Relationship to Latent Heating

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Lang, Steve; Zeng, Xiping; Shige, Shoichi; Takayabu, Yukari

    2009-01-01

    The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of its formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the Tropics. Associated with this rainfall is a vast amount of heat, which is known as latent heat. It arises mainly due to the phase change of water vapor condensing into liquid droplets; three-fourths of the total heat energy available to the Earth's atmosphere comes from tropical rainfall. In addition, fresh water provided by tropical rainfall and its variability exerts a large impact upon the structure and motions of the upper ocean layer. An improved convective -stratiform heating (CSH) algorithm has been developed to obtain the 3D structure of cloud heating over the Tropics based on two sources of information: 1) rainfall information, namely its amount and the fraction due to light rain intensity, observed directly from the Precipitation Radar (PR) on board the TRMM satellite and 2) synthetic cloud physics information obtained from cloud-resolving model (CRM) simulations of cloud systems. The cloud simulations provide details on cloud processes, specifically latent heating, eddy heat flux convergence and radiative heating/cooling, that. are not directly observable by satellite. The new CSH algorithm-derived heating has a noticeably different heating structure over both ocean and land regions compared to the previous CSH algorithm. One of the major differences between new and old algorithms is that the level of maximum cloud heating occurs 1 to 1.5 km lower in the atmosphere in the new algorithm. This can effect the structure of the implied air currents associated with the general circulation of the atmosphere in the Tropics. The new CSH algorithm will be used provide retrieved heating data to other heating algorithms to supplement their performance.

  8. Investigation of Carbide Precipitation Process and Chromium Depletion during Thermal Treatment of Alloy 690

    NASA Astrophysics Data System (ADS)

    Jiao, S. Y.; Zhang, M. C.; Zheng, L.; Dong, J. X.

    2010-01-01

    For the purpose of studying the effect of heat treatment on carbide morphology and chromium concentration distribution, which are critical to the resistance of alloy 690 to stress corrosion cracking (SCC), a series of thermal treatments was performed. A model taking into account the intercorrelated dynamic process between the carbide precipitation and chemical diffusion of the chromium atom from matrix to grain boundary (GB) was constructed on the basis of classical nucleation theory, Kolmogorov-Johnson-Mehl-Avrami law, and diffusion theory. The validity of this model was evaluated by comparing the simulated results of the carbide average size and chromium concentration near the GB with the corresponding measured results. A discontinuous factor was introduced based on the relation linking the interdistance between the carbides and the carbide average size; thus, the carbide morphology and chromium concentration could be predicted by this model. According to the results of the experiments and simulations, a carbide discontinuous factor smaller than 2.2 together with the chromium concentration at the GB higher than a critical value (21 wt pct) were essential for the corrosion resistance ability of the alloy, and then some proper heat-treatment conditions were obtained through predicting the value of the two variables. In addition, the effects of the grain size and composition variation on the carbide discontinuous factor and chromium concentration profile were simulated. The results indicated that an intermediate grain size of approximately 31.8 to ~63.5 μm was beneficial for effectively improving the resistance of the alloy to SCC. Simultaneously, the carbon content should be adjusted near 0.02 pct, and the chromium content should be the highest possible in its chemical composition scale.

  9. Uncertainty of simulated catchment runoff response in the presence of threshold processes: Role of initial soil moisture and precipitation

    NASA Astrophysics Data System (ADS)

    Zehe, Erwin; Becker, Rolf; Bárdossy, András; Plate, Erich

    2005-12-01

    This paper examines the effect of spatially variable initial soil moisture and spatially variable precipitation on predictive uncertainty of simulated catchment scale runoff response in the presence of threshold processes. The underlying philosophy is to use a physically based hydrological model named CATFLOW as a virtual landscape, assuming perfect knowledge of the processes. The model, which in particular conceptualizes preferential flow as threshold process, was developed based on intensive process and parameter studies and has already been successfully applied to simulate flow and transport at different scales and catchments. Study area is the intensively investigated Weiherbach catchment. Numerous replicas of spatially variable initial soil moisture or spatially variable precipitation with the same geostatistical properties are conditioned to observed soil moisture and precipitation data and serve as initial and boundary conditions for the model during repeated simulations. The effect of spatially soil moisture on modeling catchment runoff response was found to depend strongly on average saturation of the catchment. Different realizations of initial soil moisture yielded strongly different hydrographs for intermediate initial soil moisture as well as in dry catchment conditions; in other states the effect was found to be much lower. This is clearly because of the threshold nature of preferential flow as well as the threshold nature of Hortonian production of overland flow. It was shown furthermore that the spatial pattern of a key parameter (macroporosity) that determined threshold behavior is of vast importance for the model response. The estimation of these patterns, which is mostly done based on sparse observations and expert knowledge, is a major source for predictive model uncertainty. Finally, it was shown that the usage of biased, i.e. spatially homogenized precipitation, input during parameter estimation yields a biased model structure, which gives

  10. Atmospheric processes sustaining a multidecadal variation in reconstructed and model-simulated Indian monsoon precipitation during the past half millennium

    NASA Astrophysics Data System (ADS)

    Wu, Qianru

    Analyses of recently reconstructed and model-simulated Indian May-September precipitation disclose a statistically significant multidecadal variation at the frequency of 40-50 year per cycle during the last half millennium. To understand the mechanism of this variation, we examined the energy and dynamic processes in the atmosphere, and the potential forcings from the sea surface temperature (SST) variations around the globe. Comparisons of paleo-SST and the paleo-precipitation simulations suggest that the SST is not a significant forcing of the multidecadal variation found in the Indian monsoon precipitation. Instead, analyses suggest that atmospheric processes characterized by phase differences between the meridional enthalpy gradient and poleward eddy enthalpy transport are important to sustain this variation. In this phase relationship, the meridional enthalpy gradient is strengthened by radiative loss in high latitudes. Driven by this enlarged gradient and associated changes in baroclinicity in the mid-latitude atmosphere, more energy is generated in the tropical and subtropical (monsoon) regions and transported poleward. The monsoon is strengthened to allow more energy being transported poleward. The increased enthalpy transport, in turn, weakens the meridional enthalpy gradient and, subsequently, softens the demand for energy production in the monsoon region. The monsoon weakens and the transport decreases. The variation in monsoon precipitation lags that in the meridional enthalpy gradient, but leads that in the poleward heat transport. This phase relationship and underlining chasing process by the heat transport to the gradient sustain this variation at the multidecadal timescale. This mechanism suggests that atmospheric circulation processes can contribute to multidecadal timescale variations in the Indian monsoon precipitation.

  11. "Physically-based" numerical experiment to determine the dominant hillslope processes during floods?

    NASA Astrophysics Data System (ADS)

    Gaume, Eric; Esclaffer, Thomas; Dangla, Patrick; Payrastre, Olivier

    2016-04-01

    To study the dynamics of hillslope responses during flood event, a fully coupled "physically-based" model for the combined numerical simulation of surface runoff and underground flows has been developed. A particular attention has been given to the selection of appropriate numerical schemes for the modelling of both processes and of their coupling. Surprisingly, the most difficult question to solve, from a numerical point of view, was not related to the coupling of two processes with contrasted kinetics such as surface and underground flows, but to the high gradient infiltration fronts appearing in soils, source of numerical diffusion, instabilities and sometimes divergence. The model being elaborated, it has been successfully tested against results of high quality experiments conducted on a laboratory sandy slope in the early eighties, which is still considered as a reference hillslope experimental setting (Abdul & Guilham). The model appeared able to accurately simulate the pore pressure distributions observed in this 1.5 meter deep and wide laboratory hillslope, as well as its outflow hydrograph shapes and the measured respective contributions of direct runoff and groundwater to these outflow hydrographs. Based on this great success, the same model has been used to simulate the response of a theoretical 100-meter wide and 10% sloped hillslope, with a 2 meter deep pervious soil and impervious bedrock. Three rain events have been tested: a 100 millimeter rainfall event over 10 days, over 1 day or over one hour. The simulated responses are hydrologically not realistic and especially the fast component of the response, that is generally observed in the real-world and explains flood events, is almost absent of the simulated response. Thinking a little about the whole problem, the simulation results appears totally logical according to the proposed model. The simulated response, in fact a recession hydrograph, corresponds to a piston flow of a relatively uniformly

  12. Comparison of precipitate behaviors in ultra-low carbon, titanium-stabilized interstitial free steel sheets under different annealing processes

    SciTech Connect

    Shi, J.; Wang, X.

    1999-12-01

    Ultra-low carbon, titanium-stabilized interstitial free (ULC Ti-IF) steel sheets are widely used in the automobile industry because of excellent deep drawability. The annealing process is critical to their final property, and there are two different annealing processes used in industrial production of interstitial free (IF) steel sheets, namely batch annealing and continuous annealing. In this study, precipitation behaviors of titanium IF steels, that is, TiN, TiS, Ti{sub 4}(CS){sub 2}, and TiC, the size and dispersion of TiN, TiS, and Ti{sub 4}(CS){sub 2} remained almost unchanged after either annealing process. Conversely, the average size of a TiC particle increased substantially after both annealing processes, while TiC after continuous annealing was larger than that after batch annealing due to the higher heating temperature of continuous annealing. Two new particles, FeTiP and (Ti, Mn)S, were also observed in the batch annealing process but not in continuous annealing. The structure of FeTiP and (Ti, Mn)S were studied, and furthermore the evolution of FeTiP precipitation was found to be closely related to recrystallization in batch annealing. Finally, the interrelation among processing parameters, precipitation behaviors, and final property was studied.

  13. The dominant processes responsible for subsidence of coastal wetlands in south Louisiana

    SciTech Connect

    Kuecher, G.J.

    1995-12-31

    Wetland loss in coastal areas of Terrebonne and Lafourche Parishes, Louisiana, largely results from two subsurface processes: (1) consolidation of recently deposited Holocene deltaic sediments and (2) active growth faulting. Locally, settlement is high where the thickness of valley fill is great and in broad interdistributary basins where the thickness of consolidation-prone, peaty soils is great. The delta cycle is identified as the fundamental sedimentologic unit that constitutes the lower delta plain. Peaty soils from the waning phase of the delta cycle are identified as the deltaic facies most subject to consolidation settlement. Data indicate direct relationships between the thickness of deltaic sediments in individual delta cycles, and the thickness of peaty soils capping these cycles, with present patterns of coastal tract land loss. In addition, active growth faulting is correlated with new areas of interior tract wetland loss. Consolidation and faulting largely explain the curious nature of wetland loss patterns in south Louisiana. Subsidence in The Netherlands has been attributed to similar causes, i.e. thick deposits of consolidation-prone sediments that accumulate on the downthrown sides of basin margin faults.

  14. A Mechanistic Treatment of the Dominant Soil Nitrogen Cycling Processes: Model Development, Testing, and Application

    SciTech Connect

    Riley, William; Maggi, F.; Gu, C.; Riley, W.J.; Hornberger, G.M.; Venterea, R.T.; Xu, T.; Spycher, N.; Steefel, C.; Miller, N.L.; Oldenburg, C.M.

    2008-05-01

    The development and initial application of a mechanistic model (TOUGHREACT-N) designed to characterize soil nitrogen (N) cycling and losses are described. The model couples advective and diffusive nutrient transport, multiple microbial biomass dynamics, and equilibrium and kinetic chemical reactions. TOUGHREACT-N was calibrated and tested against field measurements to assess pathways of N loss as either gas emission or solute leachate following fertilization and irrigation in a Central Valley, California, agricultural field as functions of fertilizer application rate and depth, and irrigation water volume. Our results, relative to the period before plants emerge, show that an increase in fertilizer rate produced a nonlinear response in terms of N losses. An increase of irrigation volume produced NO{sub 2}{sup -} and NO{sub 3}{sup -} leaching, whereas an increase in fertilization depth mainly increased leaching of all N solutes. In addition, nitrifying bacteria largely increased in mass with increasing fertilizer rate. Increases in water application caused nitrifiers and denitrifiers to decrease and increase their mass, respectively, while nitrifiers and denitrifiers reversed their spatial stratification when fertilizer was applied below 15 cm depth. Coupling aqueous advection and diffusion, and gaseous diffusion with biological processes, closely captured actual conditions and, in the system explored here, significantly clarified interpretation of field measurements.

  15. A mechanistic treatment of the dominant soil nitrogen cycling processes: Model development, testing, and application

    NASA Astrophysics Data System (ADS)

    Maggi, F.; Gu, C.; Riley, W. J.; Hornberger, G. M.; Venterea, R. T.; Xu, T.; Spycher, N.; Steefel, C.; Miller, N. L.; Oldenburg, C. M.

    2008-06-01

    The development and initial application of a mechanistic model (TOUGHREACT-N) designed to characterize soil nitrogen (N) cycling and losses are described. The model couples advective and diffusive nutrient transport, multiple microbial biomass dynamics, and equilibrium and kinetic chemical reactions. TOUGHREACT-N was calibrated and tested against field measurements to assess pathways of N loss as either gas emission or solute leachate following fertilization and irrigation in a Central Valley, California, agricultural field as functions of fertilizer application rate and depth, and irrigation water volume. Our results, relative to the period before plants emerge, show that an increase in fertilizer rate produced a nonlinear response in terms of N losses. An increase of irrigation volume produced NO2- and NO3- leaching, whereas an increase in fertilization depth mainly increased leaching of all N solutes. In addition, nitrifying bacteria largely increased in mass with increasing fertilizer rate. Increases in water application caused nitrifiers and denitrifiers to decrease and increase their mass, respectively, while nitrifiers and denitrifiers reversed their spatial stratification when fertilizer was applied below 15 cm depth. Coupling aqueous advection and diffusion, and gaseous diffusion with biological processes, closely captured actual conditions and, in the system explored here, significantly clarified interpretation of field measurements.

  16. Electrification of precipitating systems over the Amazon: Physical processes of thunderstorm development

    NASA Astrophysics Data System (ADS)

    Albrecht, Rachel I.; Morales, Carlos A.; Silva Dias, Maria A. F.

    2011-04-01

    This study investigated the physical processes involved in the development of thunderstorms over southwestern Amazon by hypothesizing causalities for the observed cloud-to-ground lightning variability and the local environmental characteristics. Southwestern Amazon experiences every year a large variety of environmental factors, such as the gradual increase in atmospheric moisture, extremely high pollution due to biomass burning, and intense deforestation, which directly affects cloud development by differential surface energy partition. In the end of the dry period it was observed higher percentages of positive cloud-to-ground (+CG) lightning due to a relative increase in +CG dominated thunderstorms (positive thunderstorms). Positive (negative) thunderstorms initiated preferentially over deforested (forest) areas with higher (lower) cloud base heights, shallower (deeper) warm cloud depths, and higher (lower) convective potential available energy. These features characterized the positive (negative) thunderstorms as deeper (relatively shallower) clouds, stronger (relatively weaker) updrafts with enhanced (decreased) mixed and cold vertically integrated liquid. No significant difference between thunderstorms (negative and positive) and nonthunderstorms were observed in terms of atmospheric pollution, once the atmosphere was overwhelmed by pollution leading to an updraft-limited regime. However, in the wet season both negative and positive thunderstorms occurred during periods of relatively higher aerosol concentration and differentiated size distributions, suggesting an aerosol-limited regime where cloud electrification could be dependent on the aerosol concentration to suppress the warm and enhance the ice phase. The suggested causalities are consistent with the invoked hypotheses, but they are not observed facts; they are just hypotheses based on plausible physical mechanisms.

  17. Use NU-WRF and GCE Model to Simulate the Precipitation Processes During MC3E Campaign

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Wu, Di; Matsui, Toshi; Li, Xiaowen; Zeng, Xiping; Peter-Lidard, Christa; Hou, Arthur

    2012-01-01

    One of major CRM approaches to studying precipitation processes is sometimes referred to as "cloud ensemble modeling". This approach allows many clouds of various sizes and stages of their lifecycles to be present at any given simulation time. Large-scale effects derived from observations are imposed into CRMs as forcing, and cyclic lateral boundaries are used. The advantage of this approach is that model results in terms of rainfall and QI and Q2 usually are in good agreement with observations. In addition, the model results provide cloud statistics that represent different types of clouds/cloud systems during their lifetime (life cycle). The large-scale forcing derived from MC3EI will be used to drive GCE model simulations. The model-simulated results will be compared with observations from MC3E. These GCE model-simulated datasets are especially valuable for LH algorithm developers. In addition, the regional scale model with very high-resolution, NASA Unified WRF is also used to real time forecast during the MC3E campaign to ensure that the precipitation and other meteorological forecasts are available to the flight planning team and to interpret the forecast results in terms of proposed flight scenarios. Post Mission simulations are conducted to examine the sensitivity of initial and lateral boundary conditions to cloud and precipitation processes and rainfall. We will compare model results in terms of precipitation and surface rainfall using GCE model and NU-WRF

  18. Precipitation and microphysical processes observed by three polarimetric X-band radars and ground-based instrumentation during HOPE

    NASA Astrophysics Data System (ADS)

    Xie, Xinxin; Evaristo, Raquel; Simmer, Clemens; Handwerker, Jan; Trömel, Silke

    2016-06-01

    This study presents a first analysis of precipitation and related microphysical processes observed by three polarimetric X-band Doppler radars (BoXPol, JuXPol and KiXPol) in conjunction with a ground-based network of disdrometers, rain gauges and vertically pointing micro rain radars (MRRs) during the High Definition Clouds and Precipitation for advancing Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE) during April and May 2013 in Germany. While JuXPol and KiXPol were continuously observing the central HOPE area near Forschungszentrum Jülich at a close distance, BoXPol observed the area from a distance of about 48.5 km. MRRs were deployed in the central HOPE area and one MRR close to BoXPol in Bonn, Germany. Seven disdrometers and three rain gauges providing point precipitation observations were deployed at five locations within a 5 km × 5 km region, while three other disdrometers were collocated with the MRR in Bonn. The daily rainfall accumulation at each rain gauge/disdrometer location estimated from the three X-band polarimetric radar observations showed very good agreement. Accompanying microphysical processes during the evolution of precipitation systems were well captured by the polarimetric X-band radars and corroborated by independent observations from the other ground-based instruments.

  19. Technical and economical assessment of formic acid to recycle phosphorus from pig slurry by a combined acidification-precipitation process.

    PubMed

    Daumer, M-L; Picard, S; Saint-Cast, P; Dabert, P

    2010-08-15

    Dissolution by acidification followed by a liquid/solid separation and precipitation of phosphorus from the liquid phase is one possibility to recycle phosphorus from livestock effluents. To avoid increase of effluent salinity by using mineral acids in the recycling process, the efficiency of two organic acids, formic and acetic acid, in dissolving the mineral phosphorus from piggery wastewater was compared. The amount of formic acid needed to dissolve the phosphorus was reduced three fold, compared to acetic acid. The amount of magnesium oxide needed for further precipitation was decreased by two with formic acid. Neither the carbon load nor the effluent salinity was significantly increased by using formic acid. An economical comparison was performed for the chemical recycling process (mineral fertilizer) vs. centrifugation (organic fertilizer) considering the centrifugation and the mineral fertilizers sold in the market. After optimisation of the process, the product could be economically competitive with mineral fertilizer as superphosphate in less than 10 years. PMID:20471746

  20. Dissolution-precipitation processes governing the carbonation and silicification of the serpentinite sole of the New Caledonia ophiolite

    NASA Astrophysics Data System (ADS)

    Ulrich, Marc; Muñoz, Manuel; Guillot, Stéphane; Cathelineau, Michel; Picard, Christian; Quesnel, Benoit; Boulvais, Philippe; Couteau, Clément

    2014-01-01

    The weathering of mantle peridotite tectonically exposed to the atmosphere leads commonly to natural carbonation processes. Extensive cryptocrystalline magnesite veins and stock-work are widespread in the serpentinite sole of the New Caledonia ophiolite. Silica is systematically associated with magnesite. It is commonly admitted that Mg and Si are released during the laterization of overlying peridotites. Thus, the occurrence of these veins is generally attributed to a per descensum mechanism that involves the infiltration of meteoric waters enriched in dissolved atmospheric CO2. In this study, we investigate serpentinite carbonation processes, and related silicification, based on a detailed petrographic and crystal chemical study of serpentinites. The relationships between serpentine and alteration products are described using an original method for the analysis of micro-X-ray fluorescence images performed at the centimeter scale. Our investigations highlight a carbonation mechanism, together with precipitation of amorphous silica and sepiolite, based on a dissolution-precipitation process. In contrast with the per descensum Mg/Si-enrichment model that is mainly concentrated in rock fractures, dissolution-precipitation process is much more pervasive. Thus, although the texture of rocks remains relatively preserved, this process extends more widely into the rock and may represent a major part of total carbonation of the ophiolite.

  1. Dissolution-precipitation processes governing the carbonation and silicification of the serpentinite sole of the New Caledonia ophiolite

    NASA Astrophysics Data System (ADS)

    Ulrich, M.; Munoz, M.; Guillot, S.; Cathelineau, M.; Picard, C.; Quesnel, B.; Boulvais, P.; Couteau, C.

    2014-12-01

    The weathering of mantle peridotite tectonically exposed to the atmosphere leads commonly to natural carbonation processes. Extensive cryptocrystalline magnesite veins and stock-work are widespread in the serpentinite sole of the New Caledonia ophiolite. Silica is systematically associated with magnesite. It is commonly admitted that Mg and Si are released during the laterization of overlying peridotites. Thus, the occurrence of these veins is generally attributed to a per descensum mechanism that involves the infiltration of meteoric waters enriched in dissolved atmospheric CO2. In this study, we investigate serpentinite carbonation processes, and related silicification, based on a detailed petrographic and crystal chemical study of serpentinites. The relationships between serpentine and alteration products are described using an original method for the analysis of micro-X-ray fluorescence images performed at the centimeter scale. Our investigations highlight a carbonation mechanism, together with precipitation of amorphous silica and sepiolite, based on a dissolution-precipitation process. In contrast with the per descensum Mg/Si-enrichment model that is mainly concentrated in rock fractures, dissolution-precipitation process is much more pervasive. Thus, although the texture of rocks remains relatively preserved, this process extends more widely into the rock and may represent a major part of total carbonation of the ophiolite.

  2. Precipitation-adsorption process for the decontamination of nuclear waste supernates

    DOEpatents

    Lee, Lien-Mow; Kilpatrick, Lester L.

    1984-01-01

    High-level nuclear waste supernate is decontaminated of cesium by precipitation of the cesium and potassium with sodium tetraphenyl boron. Simultaneously, strontium-90 is removed from the waste supernate sorption of insoluble sodium titanate. The waste solution is then filtered to separate the solution decontaminated of cesium and strontium.

  3. Precipitation-adsorption process for the decontamination of nuclear waste supernates

    DOEpatents

    Lee, L.M.; Kilpatrick, L.L.

    1982-05-19

    High-level nuclear waste supernate is decontaminated of cesium by precipitation of the cesium and potassium with sodium tetraphenyl boron. Simultaneously, strontium-90 is removed from the waste supernate sorption of insoluble sodium titanate. The waste solution is then filtered to separate the solution decontaminated of cesium and strontium.

  4. Analysis of Copper in the In-Tank Precipitation Process Caustic Samples

    SciTech Connect

    Tovo, L.L.; Boyce, W.T.

    1996-12-12

    Inductively Coupled Plasma Emission Spectroscopy (ICPES) and Inductively Coupled Plasma Mass Spectrometry (ICPMS) procedures for measuring Cu in In-Tank Precipitation (ITP) caustic samples have been tested and implemented in the Analytical Development Section at the Savannah River Technology Center.

  5. Heavy Oil Process Monitor: Automated On-Column Asphaltene Precipitation and Re-Dissolution

    SciTech Connect

    John F. Schabron; Joseph F. Rovani; Mark Sanderson

    2007-03-31

    An automated separation technique was developed that provides a new approach to measuring the distribution profiles of the most polar, or asphaltenic components of an oil, using a continuous flow system to precipitate and re-dissolve asphaltenes from the oil. Methods of analysis based on this new technique were explored. One method based on the new technique involves precipitation of a portion of residua sample in heptane on a polytetrafluoroethylene-packed (PTFE) column. The precipitated material is re-dissolved in three steps using solvents of increasing polarity: cyclohexane, toluene, and methylene chloride. The amount of asphaltenes that dissolve in cyclohexane is a useful diagnostic of the thermal history of oil, and its proximity to coke formation. For example, about 40 % (w/w) of the heptane asphaltenes from unpyrolyzed residua dissolves in cyclohexane. As pyrolysis progresses, this number decrease to below 15% as coke and toluene insoluble pre-coke materials appear. Currently, the procedure for the isolation of heptane asphaltenes and the determination of the amount of asphaltenes soluble in cyclohexane spans three days. The automated procedure takes one hour. Another method uses a single solvent, methylene chloride, to re-dissolve the material that precipitates on heptane on the PTFE-packed column. The area of this second peak can be used to calculate a value which correlates with gravimetric asphaltene content. Currently the gravimetric procedure to determine asphaltenes takes about 24 hours. The automated procedure takes 30 minutes. Results for four series of original and pyrolyzed residua were compared with data from the gravimetric methods. Methods based on the new on-column precipitation and re-dissolution technique provide significantly more detail about the polar constituent's oils than the gravimetric determination of asphaltenes.

  6. Precipitation Measurements from Space: The Global Precipitation Measurement Mission

    NASA Technical Reports Server (NTRS)

    Hou, Arthur Y.

    2007-01-01

    Water is fundamental to the life on Earth and its phase transition between the gaseous, liquid, and solid states dominates the behavior of the weather/climate/ecological system. Precipitation, which converts atmospheric water vapor into rain and snow, is central to the global water cycle. It regulates the global energy balance through interactions with clouds and water vapor (the primary greenhouse gas), and also shapes global winds and dynamic transport through latent heat release. Surface precipitation affects soil moisture, ocean salinity, and land hydrology, thus linking fast atmospheric processes to the slower components of the climate system. Precipitation is also the primary source of freshwater in the world, which is facing an emerging freshwater crisis in many regions. Accurate and timely knowledge of global precipitation is essential for understanding the behavior of the global water cycle, improving freshwater management, and advancing predictive capabilities of high-impact weather events such as hurricanes, floods, droughts, and landslides. With limited rainfall networks on land and the impracticality of making extensive rainfall measurements over oceans, a comprehensive description of the space and time variability of global precipitation can only be achieved from the vantage point of space. This presentation will examine current capabilities in space-borne rainfall measurements, highlight scientific and practical benefits derived from these observations to date, and provide an overview of the multi-national Global Precipitation Measurement (GPM) Mission scheduled to bc launched in the early next decade.

  7. The role of negative buoyancy and urbanization in warm season precipitation processes over the U. S

    NASA Astrophysics Data System (ADS)

    Ganeshan, Manisha

    This thesis investigates some important processes for better understanding and modeling warm season rainfall characteristics over the US. In the first part, the causes for commonly observed biases in the simulation of the diurnal cycle of warm season rainfall are explored. Model sensitivity analyses are carried out to identify potential deficiencies in two popular cumulus parameterization schemes, viz. Betts-Miller-Janjic (BMJ) and Kain-Fritsch (KF) schemes, considered suitable for use in mesoscale simulations. A novel approach using remote sensing observations to better understand the relevant trigger processes for convection is demonstrated. The convective trigger in both schemes is found to include weak, implicit constraints above the lifting condensation level (LCL), which may contribute to premature, light rain. In order to adjust for this behavior, a simple modification is made to the KF scheme to allow moist convection to begin only from the level of free convection (LFC). Even with the seemingly strict constraint, the scheme performs adequately in a mesoscale seasonal simulation producing an improvement in the nocturnal phase propagation of rainfall in the Central Plains region. The resolvable processes in the mesoscale model are able to overcome the negative buoyancy below the LFC, thereby reducing biases caused by sensitivity of the scheme's trigger to the grid-scale forcing at the LCL. In the future, such a modified scheme will be tested in regional and global simulations, to evaluate its robustness in varying convective regimes. In the second part of this thesis, a multi-city analysis using high-resolution surface observations over the US, investigates the impact of the Urban Heat Island (UHI) on warm season precipitation. Statistical methods are employed to study the rainfall anomalies associated with propagating and non-propagating storms. A strong variability is observed in the UHI-influence on rainfall based on geographical setting and diurnal

  8. Precipitation of iron, sodium, and potassium impurities from synthetic solutions modeling spent acid streams from a chemical coal cleaning process

    SciTech Connect

    Norton, G.A.; Richardson, R.G.; Markuszewski, R. ); Levine, A.D. . Dept. of Civil Engineering)

    1990-01-01

    This paper presents experiments on treating model spent acid streams from a chemical coal cleaning process by double salt precipitation which indicated that simple heating of solutions containing Fe{sub 2}(SO{sub 4}){sub 3}, Na{sub 2}SO{sub 4}, and K{sub 2}SO{sub 4} caused jarosite (KFe{sub 3}(SO{sub 4}){sub 2}(OH){sub 6}) to form preferentially to natrojarosite (NaFe{sub 3}(SO{sub 4}){sub 2}(OH){sub 6}), and precipitate yields were higher than when Na{sub 2}SO{sub 4} was the only alkali sulfate present. Virtually all of the K, about 90% of the Fe, and about 30% of the SO{sub 4}{sup 2 {minus}} could be precipitated at 95{degrees}C, while little or no Na was removed. However, simply heating Fe{sub 2}(SO{sub 4}){sub 3}/Na{sub 2}SO{sub 4} solution up to 95{degrees}C for {lt}12 hours did not produce adequate precipitate yields. When Na was the only alkali metal present, the Fe concentration in the solution had to be increased to avoid formation of undesirable iron compounds.

  9. Synthesis of strontium hexaferrite nanoparticles prepared using co-precipitation method and microemulsion processing

    NASA Astrophysics Data System (ADS)

    Drmota, A.; Žnidaršič, A.; Košak, A.

    2010-01-01

    Strontium hexaferrite (SrFe12O19) nanoparticles have been prepared with co-precipitation in aqueous solutions and precipitation in microemulsion system water/SDS/n-butanol/cyclohexane, using iron and strontium nitrates in different molar rations as a starting materials. The mixed Sr2+, Fe3+ hydroxide precursors obtained during the reaction between corresponding metal nitrates and tetramethylammonium hydroxide (TMAH), which served as a precipitating reagent, were calcined in a wide temperature range, from 350 °C to 1000 °C in a static air atmosphere. The influence of the Sr2+/Fe3+ molar ratio and the calcination temperature to the chemistry of the product formation, its crystallite size, morphology and magnetic properties were investigated. It was found that the formation of single phase SrFe12O19 with relatively high specific magnetization (54 Am2/kg) was achieved at the Sr2+/Fe3+ molar ration of 6.4 and calcination at 800 °C for 3h with heating/cooling rate 5 °C/min. The prepared powders were characterized using X-ray diffractometry (XRD) and specific surface area measurements (BET). The specific magnetization (DSM-10, magneto-susceptometer) of the prepared samples was measured.

  10. Processing of High Resolution, Multiparametric Radar Data for the Airborne Dual-Frequency Precipitation Radar APR-2

    NASA Technical Reports Server (NTRS)

    Tanelli, Simone; Meagher, Jonathan P.; Durden, Stephen L.; Im, Eastwood

    2004-01-01

    Following the successful Precipitation Radar (PR) of the Tropical Rainfall Measuring Mission, a new airborne, 14/35 GHz rain profiling radar, known as Airborne Precipitation Radar - 2 (APR-2), has been developed as a prototype for an advanced, dual-frequency spaceborne radar for a future spaceborne precipitation measurement mission. . This airborne instrument is capable of making simultaneous measurements of rainfall parameters, including co-pol and cross-pol rain reflectivities and vertical Doppler velocities, at 14 and 35 GHz. furthermore, it also features several advanced technologies for performance improvement, including real-time data processing, low-sidelobe dual-frequency pulse compression, and dual-frequency scanning antenna. Since August 2001, APR-2 has been deployed on the NASA P3 and DC8 aircrafts in four experiments including CAMEX-4 and the Wakasa Bay Experiment. Raw radar data are first processed to obtain reflectivity, LDR (linear depolarization ratio), and Doppler velocity measurements. The dataset is then processed iteratively to accurately estimate the true aircraft navigation parameters and to classify the surface return. These intermediate products are then used to refine reflectivity and LDR calibrations (by analyzing clear air ocean surface returns), and to correct Doppler measurements for the aircraft motion. Finally, the the melting layer of precipitation is detected and its boundaries and characteristics are identifIed at the APR-2 range resolution of 30m. The resulting 3D dataset will be used for validation of other airborne and spaceborne instruments, development of multiparametric rain/snow retrieval algorithms and melting layer characterization and statistics.

  11. CHARACTERIZATION OF A PRECIPITATE REACTOR FEED TANK (PRFT) SAMPLE FROM THE DEFENSE WASTE PROCESSING FACILITY (DWPF)

    SciTech Connect

    Crawford, C.; Bannochie, C.

    2014-05-12

    A sample of from the Defense Waste Processing Facility (DWPF) Precipitate Reactor Feed Tank (PRFT) was pulled and sent to the Savannah River National Laboratory (SRNL) in June of 2013. The PRFT in DWPF receives Actinide Removal Process (ARP)/ Monosodium Titanate (MST) material from the 512-S Facility via the 511-S Facility. This 2.2 L sample was to be used in small-scale DWPF chemical process cell testing in the Shielded Cells Facility of SRNL. A 1L sub-sample portion was characterized to determine the physical properties such as weight percent solids, density, particle size distribution and crystalline phase identification. Further chemical analysis of the PRFT filtrate and dissolved slurry included metals and anions as well as carbon and base analysis. This technical report describes the characterization and analysis of the PRFT sample from DWPF. At SRNL, the 2.2 L PRFT sample was composited from eleven separate samples received from DWPF. The visible solids were observed to be relatively quick settling which allowed for the rinsing of the original shipping vials with PRFT supernate on the same day as compositing. Most analyses were performed in triplicate except for particle size distribution (PSD), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and thermogravimetric analysis (TGA). PRFT slurry samples were dissolved using a mixed HNO3/HF acid for subsequent Inductively Coupled Plasma Atomic Emission Spectroscopy (ICPAES) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) analyses performed by SRNL Analytical Development (AD). Per the task request for this work, analysis of the PRFT slurry and filtrate for metals, anions, carbon and base were primarily performed to support the planned chemical process cell testing and to provide additional component concentrations in addition to the limited data available from DWPF. Analysis of the insoluble solids portion of the PRFT slurry was aimed at detailed characterization of these solids (TGA, PSD

  12. Pulsed-Neutron-Gamma (PNG) saturation monitoring at the Ketzin pilot site considering displacement and evaporation/precipitation processes

    NASA Astrophysics Data System (ADS)

    Baumann, Gunther; Henninges, Jan

    2013-04-01

    The storage of carbon dioxide (CO2) in saline aquifers is a promising option to reduce emissions of greenhouse gases to the atmosphere and to mitigate global climate change. During the proposed CO2 injection process, application of suitable techniques for monitoring of the induced changes in the subsurface is required. Existing models for the spreading of the CO2, as well as mixing of the different fluids associated with saturation changes or resulting issues from mutual solubility between brine and CO2, need to be checked. For well logging in cased boreholes, which would be the standard situation encountered under the given conditions, only a limited number of techniques like pulsed neutron-gamma (PNG) logging are applicable. The PNG technique uses controlled neutron bursts, which interact with the nuclei of the surrounding borehole and formation. Due to the collision with these neutrons, atoms from the surrounding environment emit gamma rays. The main PNG derived parameter is the capture cross section (Σ) which is derived from the decline of gamma rays with time from neutron capture processes. The high Σ contrast between brine and CO2 results in a high sensitivity to evaluate saturation changes. This makes PNG monitoring favourable for saturation profiling especially in time-lapse mode. Previously, the conventional PNG saturation model based on a displacement process has been used for PNG interpretation in different CO2 storage projects in saline aquifers. But in addition to the displacement process, the mutual solubility between brine and CO2 adds further complex processes like evaporation and salt precipitation, which are not considered in PNG saturation models. These evaporation and precipitation processes are relevant in the vicinity of an injection well, where dry CO2 enters the reservoir. The Σ brine value depends strongly on the brine salinity e.g. its chlorine content which makes PNG measurements suitable for evaporation and salt precipitation

  13. Nuclear criticality safety bounding analysis for the in-tank-precipitation (ITP) process, impacted by fissile isotopic weight fractions

    SciTech Connect

    Bess, C.E.

    1994-04-22

    The In-Tank Precipitation process (ITP) receives High Level Waste (HLW) supernatant liquid containing radionuclides in waste processing tank 48H. Sodium tetraphenylborate, NaTPB, and monosodium titanate (MST), NaTi{sub 2}O{sub 5}H, are added for removal of radioactive Cs and Sr, respectively. In addition to removal of radio-strontium, MST will also remove plutonium and uranium. The majority of the feed solutions to ITP will come from the dissolution of supernate that had been concentrated by evaporation to a crystallized salt form, commonly referred to as saltcake. The concern for criticality safety arises from the adsorption of U and Pt onto MST. If sufficient mass and optimum conditions are achieved then criticality is credible. The concentration of u and Pt from solution into the smaller volume of precipitate represents a concern for criticality. This report supplements WSRC-TR-93-171, Nuclear Criticality Safety Bounding Analysis For The In-Tank-Precipitation (ITP) Process. Criticality safety in ITP can be analyzed by two bounding conditions: (1) the minimum safe ratio of MST to fissionable material and (2) the maximum fissionable material adsorption capacity of the MST. Calculations have provided the first bounding condition and experimental analysis has established the second. This report combines these conditions with canyon facility data to evaluate the potential for criticality in the ITP process due to the adsorption of the fissionable material from solution. In addition, this report analyzes the potential impact of increased U loading onto MST. Results of this analysis demonstrate a greater safety margin for ITP operations than the previous analysis. This report further demonstrates that the potential for criticality in the ITP process due to adsorption of fissionable material by MST is not credible.

  14. Precipitation, dissolution, and ion exchange processes coupled with a lattice Boltzmann advection diffusion solver

    NASA Astrophysics Data System (ADS)

    Hiorth, A.; Jettestuen, E.; Cathles, L. M.; Madland, M. V.

    2013-03-01

    Pore water chemistry can dramatically affect the mechanical strength of chalk cores and the recovery of oil from them, but despite a great many core experiments, the mechanisms responsible remain unclear. This is in part because no single model is presently available that can address the changes in surface complexes and potential and mineral dissolution and precipitation that occur when fluids of different chemistry are injected. We report here the construction of a lattice Boltzmann model that includes non-linear dissolution-precipitation kinetics, surface complexation, and ion exchange. A link-based boundary condition which allows mineral boundaries to move and porosity to change is shown to converge to a correct representation of the macroscopic pore surface area. We show the chemical LB model developed predicts mineral dissolution and ion exchange similar to those predicted by PHREEQC for similar parameters, and we show how the methods developed can be applied to chalk core experiments where synthetic seawater is flooded through the core at 130 °C.

  15. Investigating dominant processes on small poorly gauged catchments: an inter-comparison approach for catchment similarity study

    NASA Astrophysics Data System (ADS)

    Crabit, Armand; Colin, François; Moussa, Roger; Lagacherie, Philippe

    2010-05-01

    Small catchment scales appear to be relevant to study and manage agricultural uses and their hydrological impacts. Mediterranean small catchment responses are characterised by short duration surface runoff due to intense rainfall events of short duration. Ephemeral streams are common fluvial systems: they are usually dry for most of the year and become particularly active during flood events. This considerably complicates hydrological analysis. Therefore, estimating and predicting runoff for small ungauged (or poorly gauged) catchments appears to be a significant challenge. It would allow to a better understanding of dominant processes in relation with catchment functions (partition, release, storage). According to many authors, classification and similarity concepts, which can be profitably used when the processes are not fully understood, could be conducted as an alternative to complex modelling. This study proposes a new methodology for small poorly gauged catchments to (i) estimate surface runoff and associated uncertainty and (ii) identify dominant functions governing hydrological responses. The work focuses on twelve small agricultural catchments, within the French Mediterranean region, with areas ranging between 0,3 and 1 km2. Water depth at the catchment's outlet and rainfall intensities have been collected at a one-minute data step, from September 2008 to September 2009. The analysis has been conducted on 120 flood events. The first step was to make an inter-catchment comparison based on limited hydrological data considering the associated uncertainty. Estimation of flow velocity for natural ephemeral channel is a difficult task. To assess catchment runoff, flow rate curves were established from water depth using Manning's equation. Innovative field and laboratory experiments have been carried out to estimate Manning's coefficient for typical Mediterranean non-aquatic vegetation types. 72 tests have been realised to analyse the effects of vegetation

  16. A new algorithm for design, operation and cost assessment of struvite (MgNH4PO4) precipitation processes.

    PubMed

    Birnhack, Liat; Nir, Oded; Telzhenski, Marina; Lahav, Ori

    2015-01-01

    Deliberate struvite (MgNH4PO4) precipitation from wastewater streams has been the topic of extensive research in the last two decades and is expected to gather worldwide momentum in the near future as a P-reuse technique. A wide range of operational alternatives has been reported for struvite precipitation, including the application of various Mg(II) sources, two pH elevation techniques and several Mg:P ratios and pH values. The choice of each operational parameter within the struvite precipitation process affects process efficiency, the overall cost and also the choice of other operational parameters. Thus, a comprehensive simulation program that takes all these parameters into account is essential for process design. This paper introduces a systematic decision-supporting tool which accepts a wide range of possible operational parameters, including unconventional Mg(II) sources (i.e. seawater and seawater nanofiltration brines). The study is supplied with a free-of-charge computerized tool (http://tx.technion.ac.il/~agrengn/agr/Struvite_Program.zip) which links two computer platforms (Python and PHREEQC) for executing thermodynamic calculations according to predefined kinetic considerations. The model can be (inter alia) used for optimizing the struvite-fluidized bed reactor process operation with respect to P removal efficiency, struvite purity and economic feasibility of the chosen alternative. The paper describes the algorithm and its underlying assumptions, and shows results (i.e. effluent water quality, cost breakdown and P removal efficiency) of several case studies consisting of typical wastewaters treated at various operational conditions. PMID:25704607

  17. Sulfur-oxidizing bacteria dominate the microbial diversity shift during the pyrite and low-grade pyrolusite bioleaching process.

    PubMed

    Han, Yifan; Ma, Xiaomei; Zhao, Wei; Chang, Yunkang; Zhang, Xiaoxia; Wang, Xingbiao; Wang, Jingjing; Huang, Zhiyong

    2013-10-01

    The microbial ecology of the pyrite-pyrolusite bioleaching system and its interaction with ore has not been well-described. A 16S rRNA gene clone library was created to evaluate changes in the microbial community at different stages of the pyrite-pyrolusite bioleaching process in a shaken flask. The results revealed that the bacterial community was disturbed after 5 days of the reaction. Phylogenetic analysis of 16S rRNA sequences demonstrated that the predominant microorganisms were members of a genus of sulfur-oxidizing bacteria, Thiomonas sp., that subsequently remained dominant during the bioleaching process. Compared with iron-oxidizing bacteria, sulfur-oxidizing bacteria were more favorable to the pyrite-pyrolusite bioleaching system. Decreased pH due to microbial acid production was an important condition for bioleaching efficiency. Iron-oxidizing bacteria competed for pyrite reduction power with Mn(IV) in pyrolusite under specific conditions. These results extend our knowledge of microbial dynamics during pyrite-pyrolusite bioleaching, which is a key issue to improve commercial applications. PMID:23673133

  18. The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Li, Xiaowen; Khain, Alexander; Matsui, Toshihisa; Lang, Stephen; Simpson, Joanne

    2012-01-01

    Recently, a detailed spectral-bin microphysical scheme was implemented into the Goddard Cumulus Ensemble (GCE) model. Atmospheric aerosols are also described using number density size-distribution functions. A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep tropical clouds in the west Pacific warm pool region and summertime convection over a mid-latitude continent with different concentrations of CCN: a low clean concentration and a high dirty concentration. The impact of atmospheric aerosol concentration on cloud and precipitation will be investigated.

  19. Development of a pilot-scale manufacturing process for protein-coated microcrystals (PCMC): mixing and precipitation - part I.

    PubMed

    König, Corinna; Bechtold-Peters, Karoline; Baum, Verena; Schultz-Fademrecht, Torsten; Bassarab, Stefan; Steffens, Klaus-Jürgen

    2012-04-01

    A novel protein-coated microcrystal (PCMC) technology offers the possibility to produce dry protein formulations suitable for inhalation or, after reconstitution, for injection. Micron-sized particles are hereby produced by co-precipitation via a rapid dehydration method. Thus, therapeutic proteins can be stabilised and immobilised on crystalline carrier surfaces. In this study, the development of a continuous manufacturing process is described, which can produce grams to kilograms of PCMC. The process chain comprises three steps: mixing/precipitation, solvent reduction (concentration) and final drying. The process is published in two parts. This part describes the mixing and precipitation performed using continuous impingement jet mixers. Mixing efficiency was improved by dividing the anti-solvent flow into two or four jets, which were combined again inside the mixer to achieve an embracing of the aqueous solution (sandwich effect). The jets provided high energy dissipation rates. The anti-solvent jets (95% of the total volume) efficiently mixed the protein-carrier containing aqueous solution (5% of the total volume), which was demonstrated with computational fluid dynamics and the Villermaux-Dushman reaction. The improved mixing performance of the double jet impingement (DJI) or the quadruple jet impingement (QJI) mixers showed a positive effect on easily crystallising carriers (e.g. dl-valine) at laminar flow rates. The mixer and outlet tube bore size was 2.0-3.2 mm, because smaller sizes showed a high tendency to block the mixer. The mixing effect by impaction was sufficiently high in the flow rate range of 250-2000 mL/min, which corresponds to the transition from laminar to turbulent flow characteristics. At lower flow rates, mixing was enhanced by ultrasound. 50-80L PCMC suspension was readily produced with the QJI mixer. PMID:22137999

  20. Precipitation-runoff processes in the Feather River basin, northeastern California, and streamflow predictability, water years 1971-97

    USGS Publications Warehouse

    Koczot, Kathryn M.; Jeton, Anne E.; McGurk, Bruce; Dettinger, Michael D.

    2005-01-01

    Precipitation-runoff processes in the Feather River Basin of northern California determine short- and long-term streamflow variations that are of considerable local, State, and Federal concern. The river is an important source of water and power for the region. The basin forms the headwaters of the California State Water Project. Lake Oroville, at the outlet of the basin, plays an important role in flood management, water quality, and the health of fisheries as far downstream as the Sacramento-San Joaquin Delta. Existing models of the river simulate streamflow in hourly, daily, weekly, and seasonal time steps, but cannot adequately describe responses to climate and land-use variations in the basin. New spatially detailed precipitation-runoff models of the basin have been developed to simulate responses to climate and land-use variations at a higher spatial resolution than was available previously. This report characterizes daily rainfall, snowpack evolution, runoff, water and energy balances, and streamflow variations from, and within, the basin above Lake Oroville. The new model's ability to predict streamflow is assessed. The Feather River Basin sits astride geologic, topographic, and climatic divides that establish a hydrologic character that is relatively unusual among the basins of the Sierra Nevada. It straddles a north-south geologic transition in the Sierra Nevada between the granitic bedrock that underlies and forms most of the central and southern Sierra Nevada and volcanic bedrock that underlies the northernmost parts of the range (and basin). Because volcanic bedrock generally is more permeable than granitic, the northern, volcanic parts of the basin contribute larger fractions of ground-water flow to streams than do the southern, granitic parts of the basin. The Sierra Nevada topographic divide forms a high altitude ridgeline running northwest to southeast through the middle of the basin. The topography east of this ridgeline is more like the rain

  1. Assessing differences in topographic form between arctic and temperate drainage basins: Possible implications for dominant erosion processes

    NASA Astrophysics Data System (ADS)

    Prancevic, J. P.; Rowland, J. C.; Wilson, C. J.; Marsh, P.; Wilson, H.

    2010-12-01

    The extent and topology of channel networks are first-order controls on the timing and magnitude of flood events, as well as the rate of landscape drainage. The latter is particularly important in arctic environments, where the release of greenhouse gases from organic-rich permafrost is partially governed by the presence of water. Recent studies are in disagreement as to whether arctic channel networks will contract or expand due to a warming climate. A challenge in predicting arctic landscape adjustment is quantifying the uncertain role permafrost and ground ice play in erosional processes. An improved understanding of the dominant geomorphic processes in low-order arctic drainage basins is required to better inform predictions of the network response to warming. In both temperate and Arctic systems, researchers often use topographic analyses to suggest scaling breaks at which there are transitions between processes. This study utilizes 2-m resolution digital elevation models to investigate divergence in topographic form between temperate systems and Trail Valley Creek basin (TVC), a 63-km2 basin in Northwest Territories, Canada that is underlain by continuous permafrost and high amounts of ground ice. The valley bottoms of the low-order basins in TVC contain vegetated swales in place of incised channels. We constructed cumulative drainage area distributions and slope-area plots in order to assess any differences in scaling breaks and network topology. We also calculated estimates of fluvial basal shear stress along flow paths with drainage areas larger than an estimated threshold (~10,000 to 20,000 m2). Our analysis includes five sub-basins within TVC, three exhibiting relatively well-developed ridge and valley topography and two less dissected landscapes that are drained by small, closely-spaced swales. The cumulative drainage area distribution curves for these sub-basins do not reveal any scaling breaks that are different from those seen in temperate regions

  2. Precipitation of jarosite-type double salts from spent acid solutions from a chemical coal cleaning process

    SciTech Connect

    Norton, G.

    1990-09-21

    The precipitation of jarosite compounds to remove Na, K, Fe, and SO{sub 4}{sup 2{minus}} impurities from spent acid solutions from a chemical coal cleaning process was studied. Simple heating of model solutions containing Fe{sub 2}(SO{sub 4}){sub 3}, Na{sub 2}SO{sub 4}, and K{sub 2}SO{sub 4} caused jarosite (KFe{sub 3}(SO{sub 4}){sub 2}(OH){sub 6}) to form preferentially to natrojarosite (NaFe{sub 3}(SO{sub 4}){sub 2}(OH){sub 6}). Virtually all of the K, about 90% of the Fe, and about 30% of the SO{sub 4}{sup 2{minus}} could be precipitated from those solutions at 95{degree}C, while little or no Na was removed. However, simple heating of model solutions containing only Fe{sub 2}(SO{sub 4}){sub 3} and Na{sub 2}SO{sub 4} up to 95{degree}C for {le}12 hours produced low yields of jarosite compounds, and the Fe concentration in the solution had to be increased to avoid the formation of undesirable Fe compounds. Precipitate yields could be increased dramatically in model solutions of Na{sub 2}SO{sub 4}/Fe{sub 2}(SO{sub 4}){sub 3} containing excess Fe by using either CaCO{sub 3}, Ca(OH){sub 2}, or ZnO to neutralize H{sub 2}SO{sub 4} released during hydrolysis of the Fe{sub 2}(SO{sub 4}){sub 3} and during the precipitation reactions. Results obtained from the studies with model solutions were applied to spent acids produced during laboratory countercurrent washing of coal which had been leached with a molten NaOH/KOH mixture. Results indicated that jarosite compounds can be precipitated effectively from spent acid solutions by heating for 6 hours at 80{degree}C while maintaining a pH of about 1.5 using CaCO{sub 3}.

  3. Activation Patterns throughout the Word Processing Network of L1-dominant Bilinguals Reflect Language Similarity and Language Decisions.

    PubMed

    Oganian, Yulia; Conrad, Markus; Aryani, Arash; Spalek, Katharina; Heekeren, Hauke R

    2015-11-01

    A crucial aspect of bilingual communication is the ability to identify the language of an input. Yet, the neural and cognitive basis of this ability is largely unknown. Moreover, it cannot be easily incorporated into neuronal models of bilingualism, which posit that bilinguals rely on the same neural substrates for both languages and concurrently activate them even in monolingual settings. Here we hypothesized that bilinguals can employ language-specific sublexical (bigram frequency) and lexical (orthographic neighborhood size) statistics for language recognition. Moreover, we investigated the neural networks representing language-specific statistics and hypothesized that language identity is encoded in distributed activation patterns within these networks. To this end, German-English bilinguals made speeded language decisions on visually presented pseudowords during fMRI. Language attribution followed lexical neighborhood sizes both in first (L1) and second (L2) language. RTs revealed an overall tuning to L1 bigram statistics. Neuroimaging results demonstrated tuning to L1 statistics at sublexical (occipital lobe) and phonological (temporoparietal lobe) levels, whereas neural activation in the angular gyri reflected sensitivity to lexical similarity to both languages. Analysis of distributed activation patterns reflected language attribution as early as in the ventral stream of visual processing. We conclude that in language-ambiguous contexts visual word processing is dominated by L1 statistical structure at sublexical orthographic and phonological levels, whereas lexical search is determined by the structure of both languages. Moreover, our results demonstrate that language identity modulates distributed activation patterns throughout the reading network, providing a key to language identity representations within this shared network. PMID:26226076

  4. Improvement for the multi-scale periodic characteristics revealing of precipitation signals and its impact assessment on soil hydrological process by combining HHT and CWT approaches

    NASA Astrophysics Data System (ADS)

    Yu, S.; Yang, J.; Liu, G.; Yao, R.; Wang, X.

    2015-03-01

    This study conducts a detailed analysis of multi-scale periodic features involved in the annual and seasonal precipitation signals at the typical coastal reclamation region in China by selecting the suitable continuous wavelet transform (CWT) and innovatively combining the improved Hilbert-Huang transform (HHT), and further deduces the precipitation trend and its impacts on the future soil hydrological process. The Morlet wavelet transform is proved suitable in revealing the precipitation signals broad-scale periodicities, however, the critical mode mixing problem in CWT causes the poor significance in the fine-scale periodicities, which cannot well match the climate background. By combining the HHT approach, the fine-scale mode mixing drawback in CWT is effectively eliminated, and the the studied precipitation signals multi-scale periodicities are accurately revealed. Consequently, an overall decreasing trend of annual and seasonal precipitation in future years is demonstrated. Furthermore, by novelly using the cross wavelet transform (XWT) and wavelet transform coherence (WTC) approaches, the prominent correlations between the precipitation dynamics and soil and groundwater salinities dynamics, it is demonstrated that the precipitation increase can effectively leach the surface soil salt downwards into the deeper soil layers and groundwater with 5-7-day lag in the new cultivated tidal land. The revealed future decreasing trend of precipitation, especially in spring and summer, may aggravate the soil salinization at the coastal reclamation region, thus some reasonable salt leaching and evaporation suppression measures need to be taken to prevent the possible soil secondary salinization process.

  5. Processing, structure and magnetic properties correlation in co-precipitated Ca-ferrite

    NASA Astrophysics Data System (ADS)

    Abasht, Behzad; Beitollahi, Ali; Mirkazemi, Seyyed Mohammad

    2016-12-01

    La-substituted hexagonal calcium ferrite, Ca1-XLaXFe12O19 (x varies from 0 to 0.6 with the step of 0.2), was synthesized by applying co-precipitation method, in which the molar ratio of Fe3+/(Ca2++La2+) was 11. The ferrite precursors were prepared from aqueous solution of calcium nitrate, ferric nitrate and lanthanum nitrate by co-precipitation of calcium, iron and lanthanum ions by using an aqueous base of sodium hydroxide (1.5 M) at the pH of 14 and at room temperature. These precursors were calcinated with different amount of La at different temperature of 700, 1100 and 1200 °C for constant calcination time of 1 h in a static air atmosphere. Some tests such as simultaneous thermal analysis (STA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) were carried out to investigate the thermal behavior, crystallographic properties, morphology and magnetic properties of the precursor powders which were calcinated at different temperatures. The powder XRD patterns of samples which consisted of La as dopant and were calcinated at 1200 °C for 1 h, indicates the formation of calcium hexaferrite and also α-Fe2O3 besides Magnetoplumbite-phase (M-phase). However, the results showed that CaFe4O7 and α-Fe2O3 phases were formed in the sample with the same condition but without using any dopant. The results of SEM showed that the calcium hexaferrite particle were regular hexagonal platelets with the size range of 1-2 μm. The magnetic properties such as maximum magnetization (MMax), remanent magnetization (Mr) and coercivity (Hc) were measured from the hysteresis loops. Low values of coercive field (16.3 kA m-1) and maximum magnetization (50.6 A m2 kg-1) were obtained from calcium hexaferrite particle in optimum amount of La (X=0.4) which calcinated at the temperature of 1200 °C.

  6. New, Improved Bulk-microphysical Schemes for Studying Precipitation Processes in WRF. Part 1; Comparisons with Other Schemes

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Shi, J.; Chen, S. S> ; Lang, S.; Hong, S.-Y.; Thompson, G.; Peters-Lidard, C.; Hou, A.; Braun, S.; Simpson, J.

    2007-01-01

    Advances in computing power allow atmospheric prediction models to be mn at progressively finer scales of resolution, using increasingly more sophisticated physical parameterizations and numerical methods. The representation of cloud microphysical processes is a key component of these models, over the past decade both research and operational numerical weather prediction models have started using more complex microphysical schemes that were originally developed for high-resolution cloud-resolving models (CRMs). A recent report to the United States Weather Research Program (USWRP) Science Steering Committee specifically calls for the replacement of implicit cumulus parameterization schemes with explicit bulk schemes in numerical weather prediction (NWP) as part of a community effort to improve quantitative precipitation forecasts (QPF). An improved Goddard bulk microphysical parameterization is implemented into a state-of the-art of next generation of Weather Research and Forecasting (WRF) model. High-resolution model simulations are conducted to examine the impact of microphysical schemes on two different weather events (a midlatitude linear convective system and an Atllan"ic hurricane). The results suggest that microphysics has a major impact on the organization and precipitation processes associated with a summer midlatitude convective line system. The 31CE scheme with a cloud ice-snow-hail configuration led to a better agreement with observation in terms of simulated narrow convective line and rainfall intensity. This is because the 3ICE-hail scheme includes dense ice precipitating (hail) particle with very fast fall speed (over 10 m/s). For an Atlantic hurricane case, varying the microphysical schemes had no significant impact on the track forecast but did affect the intensity (important for air-sea interaction)

  7. HEAVY OIL PROCESS MONITOR: AUTOMATED ON-COLUMN ASPHALTENE PRECIPITATION AND RE-DISSOLUTION

    SciTech Connect

    John F. Schabron; Joseph F. Rovani Jr; Mark Sanderson

    2006-06-01

    About 37-50% (w/w) of the heptane asphaltenes from unpyrolyzed residua dissolve in cyclohexane. As pyrolysis progresses, this number decrease to below 15% as coke and toluene insoluble pre-coke materials appear. This solubility measurement can be used after coke begins to form, unlike the flocculation titration, which cannot be applied to multi-phase systems. Currently, the procedure for the isolation of heptane asphaltenes and the determination of the amount of asphaltenes soluble in cyclohexane spans three days. A more rapid method to measure asphaltene solubility was explored using a novel on-column asphaltene precipitation and re-dissolution technique. This was automated using high performance liquid chromatography (HPLC) equipment with a step gradient sequence using the solvents: heptane, cyclohexane, toluene:methanol (98:2). Results for four series of original and pyrolyzed residua were compared with data from the gravimetric method. The measurement time was reduced from three days to forty minutes. The separation was expanded further with the use of four solvents: heptane, cyclohexane, toluene, and cyclohexanone or methylene chloride. This provides a fourth peak which represents the most polar components, in the oil.

  8. Usage of multivariate geostatistics in interpolation processes for meteorological precipitation maps

    NASA Astrophysics Data System (ADS)

    Gundogdu, Ismail Bulent

    2015-09-01

    Long-term meteorological data are very important both for the evaluation of meteorological events and for the analysis of their effects on the environment. Prediction maps which are constructed by different interpolation techniques often provide explanatory information. Conventional techniques, such as surface spline fitting, global and local polynomial models, and inverse distance weighting may not be adequate. Multivariate geostatistical methods can be more significant, especially when studying secondary variables, because secondary variables might directly affect the precision of prediction. In this study, the mean annual and mean monthly precipitations from 1984 to 2014 for 268 meteorological stations in Turkey have been used to construct country-wide maps. Besides linear regression, the inverse square distance and ordinary co-Kriging (OCK) have been used and compared to each other. Also elevation, slope, and aspect data for each station have been taken into account as secondary variables, whose use has reduced errors by up to a factor of three. OCK gave the smallest errors (1.002 cm) when aspect was included.

  9. Precipitation Processes Derived from TRMM Satellite Data, Cloud Resolving Model and Field Campaigns

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Rainfall is a key link in the hydrologic cycle and is a primary heat source for the atmosphere. The vertical distribution of latent-heat release, which is accompanied by rainfall, modulates the large-scale circulations of the tropics and in turn can impact midlatitude weather. This latent heat release is a consequence of phase changes between vapor, liquid. and solid water. Present large-scale weather and climate models can simulate cloud latent heat release only crudely thus reducing their confidence in predictions on both global and regional scales. In this paper, NASA Tropical Rainfall Measuring (TRMM) precipitation radar (PR) derived rainfall information and the Goddard Convective and Stratiform Heating (CSH) algorithm used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to October 2000. Rainfall latent heating and radar reflectively structure between ENSO (1997-1998 winter) and non-ENSO (1998-1999 winter) periods are examined and compared. The seasonal variation of heating over various geographic locations (i.e. Indian ocean vs west Pacific; Africa vs S. America) are also analyzed. In addition, the relationship between rainfall latent heating maximum heating level), radar reflectively and SST are examined.

  10. Modern sedimentation processes in a wave-dominated coastal embayment: Espírito Santo Bay, southeast Brazil

    NASA Astrophysics Data System (ADS)

    Bastos, Alex Cardoso; Costa Moscon, Daphnne Moraes; Carmo, Dannilo; Neto, José Antonio Baptista; da Silva Quaresma, Valéria

    2015-02-01

    Sediment dynamics in wave-dominated coastal embayments are generally controlled by seasonal meteorological conditions, storms having a particularly strong influence. In the present study, such hydrodynamic processes and associated deposits have been investigated in a coastal embayment located along the southeast coast of Brazil, i.e. Espírito Santo Bay, in the winter (June/July) of 2008. The bay has undergone a series of human interventions that have altered the local hydrodynamic processes and, consequently, the sediment transport patterns. Facies distribution and sediment dynamics were examined by acoustic seabed mapping, sediment and core sampling, hydrodynamic measurements and sand transport modelling. The results show that sediment distribution can be described in terms of nearshore and offshore zones. The offshore bay sector is predominantly composed of "palimpsest" lithoclastic medium-coarse sands deposited in the course of the early Holocene transgression that peaked about 5,000 years ago. In the inner bay or nearshore zone (up to depths of 4-8 m), these older transgressive deposits are today overlain by a thin (up to 30-cm-thick) and partly patchy blanket of younger regressive fine sand/muddy fine sands. Both coarse- and fine-grained facies are being reworked during high-energy events (Hs>1.5 m) when fine sediment is resuspended, weak tide-induced drift currents causing the sand patches to be displaced. The coarser sediment, by contrast, is mobilized as bedload to produce wave ripples with spacings of up to 1.2 m. These processes lead to a sharp spatial delimitation between a fine sand/mud facies and a rippled coarse sand facies. The fine sand patches have a relief of about 20-30 cm and reveal a typical internal tempestite depositional sequence. Fair-weather wave-induced sediment transport (Hs<1 m), supported by weak tidal currents, seems to only affect the fine sediment facies. Sediment dynamics in Espírito Santo Bay is thus essentially controlled by

  11. Molecular analysis of dominant species in Listeria monocytogenes-positive biofilms in the drains of food processing facilities.

    PubMed

    Liu, Yanlan; Zhang, Hongmei; Wu, Changli; Deng, Wenjia; Wang, Dong; Zhao, Guifen; Song, Jiankun; Jiang, Yan

    2016-04-01

    Listeria monocytogenes exhibits symbiotic codependence with the dominant commensal bacteria, which may help it avoid being removed or inactivated by disinfectants in local environments. In this study, we investigated L. monocytogenes-positive biofilms at food production facilities, and the dominant bacterial species of the biofilms were identified to determine the properties of the microbiological background. For this purpose, the ISO 11290 method was used for the detection and isolation of L. monocytogenes, and the species were further identified based on 16S rRNA and hly genes. 16S rRNA gene-based cloning, terminal restriction fragment length polymorphism, and denaturing gradient gel electrophoresis were combined to evaluate the dominant bacteria of the drain biofilms. Out of 100 drain samples, 8 were naturally contaminated with L. monocytogenes. Three molecular methods consistently showed that Pseudomonas psychrophila, Pseudomonas sp., and Klebsiella oxytoca were dominant species in 3Q, 5Q, and 6Q samples; Aeromonas hydrophila and Klebsiella sp. were significantly dominant in 1-2, 1-3, and 3-2 samples; A. hydrophila and K. oxytoca were dominant in the 2-3 sample; and A. hydrophila and Pseudomonas sp. were prominent in the 3-3 sample. Different biofilms from the same plant shared common bands, suggesting that similar bacteria can be found and can be dominant in different biofilms. This study provides a better understanding of the dominant compositions in these bacterial communities. Further studies to determine the mechanism of co-culture with L. monocytogenes will be of critical importance in predicting effective disinfection strategies. PMID:26658820

  12. Insights Into Precipitation Processes As Revealed By Profiling Radar, Disdrometer and Aircraft Observations During The MC3E Campaign.

    NASA Astrophysics Data System (ADS)

    Giangrande, S. E.; Toto, T.; Mishra, S.; Ryzhkov, A.; Bansemer, A.; Kumjian, M.

    2014-12-01

    The Midlatitude Continental Convective Clouds Experiment (MC3E) was a collaborative campaign led by the National Aeronautic and Space Administration's (NASA's) Global Precipitation Measurement (GPM) mission and the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program. This campaign was held at the DOE ARM Southern Great Plains (SGP) Central Facility (CF) in north-central Oklahoma, with the programs joining forces to deploy an extensive array of airborne, radiosonde and ground-based instrumentation towards an unprecedented set of deep convective environment and cloud property observations. An overarching motivation was to capitalize on the wealth of aircraft observations and new multi-frequency dual-polarization radars to provide insights for improving the treatments of cloud processes in convective models. This study considers a coupled aircraft, radar and surface disdrometer approach for identifying key cloud processes and linking those to possible radar-based microphysical fingerprints and/or cloud properties. Our emphasis is on the MC3E observations collected during aircraft spirals over the column of the ARM CF. We focus on those spirals associated with radar 'bright band' signatures and Doppler spectral anomalies observed within trailing stratifrom precipitation. Two cases are highlighted, one following a weaker convective event, and one following a stronger squall line. For each event, we investigate the usefulness of radar to inform on processes including aggregation and riming as viewed by the vertically-pointing ARM wind profiler (915 MHz) and cloud radar Doppler spectral observations (35 GHz). Matching dual-polarization radar signatures from nearby cm-wavelength radar are also consulted for complementary insights. For one event, the successive Citation II aircraft spirals through the melting layer and associated ground observations indicate a fortunate capture of the transition from a region of riming to one favoring aggregation

  13. Insights into riming and aggregation processes as revealed by aircraft, radar, and disdrometer observations for a 27 April 2011 widespread precipitation event: Insights into Riming and Aggregation

    DOE PAGESBeta

    Giangrande, Scott E.; Toto, Tami; Bansemer, Aaron; Kumjian, Matthew R.; Mishra, Subhashree; Ryzhkov, Alexander V.

    2016-05-19

    Our study presents aircraft spiral ascent and descent observations intercepting a transition to riming processes during widespread stratiform precipitation. The sequence is documented using collocated scanning and profiling radar, including longer-wavelength dual polarization measurements and shorter-wavelength Doppler spectra. Riming regions are supported using aircraft measurements recording elevated liquid water concentrations, spherical particle shapes, and saturation with respect to water. Profiling cloud radar observations indicate riming regions during the event as having increasing particle fall speeds, rapid time-height changes, and bimodalities in Doppler spectra. These particular riming signatures are coupled to scanning dual polarization radar observations of higher differential reflectivity (ZDR)more » aloft. Moreover, reduced melting layer enhancements and delayed radar bright-band signatures in the column are also observed during riming periods, most notably with the profiling radar observations. The bimodal cloud radar Doppler spectra captured near riming zones indicate two time-height spectral ice peaks, one rimed particle peak, and one peak associated with pristine ice needle generation and/or growth between -4°C and -7°C also sampled by aircraft probes. We observe this pristine needle population near the rimed particle region which gives a partial explanation for the enhanced ZDR. The riming signatures aloft and radar measurements within the melting level are weakly lag correlated (r~0.6) with smaller median drop sizes at the surface, as compared with later times when aggregation of larger particle sizes was believed dominant.« less

  14. Screening of bacteria for self-healing of concrete cracks and optimization of the microbial calcium precipitation process.

    PubMed

    Zhang, J L; Wu, R S; Li, Y M; Zhong, J Y; Deng, X; Liu, B; Han, N X; Xing, F

    2016-08-01

    A novel high-throughput strategy was developed to determine the calcium precipitation activity (CPA) of mineralization bacteria used for self-healing of concrete cracks. A bacterial strain designated as H4 with the highest CPA of 94.8 % was screened and identified as a Bacillus species based on 16S rDNA sequence and phylogenetic tree analysis. Furthermore, the effects of certain influential factors on the microbial calcium precipitation process of H4 were evaluated. The results showed that lactate and nitrate are the best carbon and nitrogen sources, with optimal concentrations of approximately 25 and 18 mM, respectively. The H4 strain is able to maintain a high CPA in the pH range of 9.5-11.0, and a suitable initial spore concentration is 4.0 × 10(7) spores/ml. Moreover, an ambient Ca(2+) concentration greater than 60 mM resulted in a serious adverse impact not only on the CPA but also on the growth of H4, suggesting that the maintenance of the Ca(2+) concentration at a low level is necessary for microbial self-healing of concrete cracks. PMID:26883348

  15. A Coupled GCM-Cloud Resolving Modeling System, and a Regional Scale Model to Study Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2007-01-01

    Recent GEWEX Cloud System Study (GCSS) model comparison projects have indicated that cloud-resolving models (CRMs) agree with observations better than traditional single-column models in simulating various types of clouds and cloud systems from different geographic locations. Current and future NASA satellite programs can provide cloud, precipitation, aerosol and other data at very fine spatial and temporal scales. It requires a coupled global circulation model (GCM) and cloud-scale model (termed a superparameterization or multi-scale modeling framework, MMF) to use these satellite data to improve the understanding of the physical processes that are responsible for the variation in global and regional climate and hydrological systems. The use of a GCM will enable global coverage, and the use of a CRM will allow for better and more sophisticated physical parameterization. NASA satellite and field campaign cloud related datasets can provide initial conditions as well as validation for both the MMF and CRMs. The Goddard MMF is based on the 2D Goddard Cumulus Ensemble (GCE) model and the Goddard finite volume general circulation model (fvGCM), and it has started production runs with two years results (1998 and 1999). Also, at Goddard, we have implemented several Goddard microphysical schemes (2ICE, several 31CE), Goddard radiation (including explicitly calculated cloud optical properties), and Goddard Land Information (LIS, that includes the CLM and NOAH land surface models) into a next generatio11 regional scale model, WRF. In this talk, I will present: (1) A brief review on GCE model and its applications on precipitation processes (microphysical and land processes), (2) The Goddard MMF and the major difference between two existing MMFs (CSU MMF and Goddard MMF), and preliminary results (the comparison with traditional GCMs), and (3) A discussion on the Goddard WRF version (its developments and applications).

  16. A Coupled GCM-Cloud Resolving Modeling System, and a Regional Scale Model to Study Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2006-01-01

    Recent GEWEX Cloud System Study (GCSS) model comparison projects have indicated that cloud-resolving models (CRMs) agree with observations better than traditional single-column models in simulating various types of clouds and cloud systems from different geographic locations. Current and future NASA satellite programs can provide cloud, precipitation, aerosol and other data at very fine spatial and temporal scales. It requires a coupled global circulation model (GCM) and cloud-scale model (termed a super-parameterization or multi-scale modeling framework, MMF) to use these satellite data to improve the understanding of the physical processes that are responsible for the variation in global and regional climate and hydrological systems. The use of a GCM will enable global coverage, and the use of a CRM will allow for better and more sophisticated physical parameterization. NASA satellite and field campaign cloud related datasets can provide initial conditions as well as validation for both the MMF and CFWs. The Goddard MMF is based on the 2D Goddard Cumulus Ensemble (GCE) model and the Goddard finite volume general circulation model (fvGCM), and it has started production runs with two years results (1 998 and 1999). In this talk, I will present: (1) A brief review on GCE model and its applications on precipitation processes (microphysical and land processes), (2) The Goddard MMF and the major difference between two existing MMFs (CSU MMF and Goddard MMF), and preliminary results (the comparison with traditional GCMs), and (3) A discussion on the Goddard WRF version (its developments and applications).

  17. A Coupled GCM-Cloud Resolving Modeling System, and A Regional Scale Model to Study Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2006-01-01

    Recent GEWEX Cloud System Study (GCSS) model comparison projects have indicated that cloud-resolving models (CRMs) agree with observations better than traditional single-column models in simulating various types of clouds and cloud systems from different geographic locations. Current and future NASA satellite programs can provide cloud, precipitation, aerosol and other data at very fine spatial and temporal scales. It requires a coupled global circulation model (GCM) and cloud-scale model (termed a super-parameterization or multi-scale modeling framework, MMF) to use these satellite data to improve the understanding of the physical processes that are responsible for the variation in global and regional climate and hydrological systems. The use of a GCM will enable global coverage, and the use of a CRM will allow for better and more sophisticated physical parameterization. NASA satellite and field campaign cloud related datasets can provide initial conditions as well as validation for both the MMF and CRMs. The Goddard MMF is based on the 2D Goddard Cumulus Ensemble (GCE) model and the Goddard finite volume general circulation model (fvGCM), and it has started production runs with two years results (1998 and 1999). Also, at Goddard, we have implemented several Goddard microphysical schemes (21CE, several 31CE), Goddard radiation (including explicitly calculated cloud optical properties), and Goddard Land Information (LIS, that includes the CLM and NOAH land surface models) into a next generation regional scale model, WRF. In this talk, I will present: (1) A brief review on GCE model and its applications on precipitation processes (microphysical and land processes), (2) The Goddard MMF and the major difference between two existing MMFs (CSU MMF and Goddard MMF), and preliminary results (the comparison with traditional GCMs), and (3) A discussion on the Goddard WRF version (its developments and applications).

  18. A stepwise recovery of metals from hybrid cathodes of spent Li-ion batteries with leaching-flotation-precipitation process

    NASA Astrophysics Data System (ADS)

    Huang, Yanfang; Han, Guihong; Liu, Jiongtian; Chai, Wencui; Wang, Wenjuan; Yang, Shuzhen; Su, Shengpeng

    2016-09-01

    The recovering of valuable metals in spent lithium-ion battery cathodes brings about economic and environmental benefits. A stepwise leaching-flotation-precipitation process is adopted to separate and recover Li/Fe/Mn from the mixed types of cathode materials (hybrid wastes of LiFePO4 and LiMn2O4). The optimal operating conditions for the stepwise recovery process are determined and analyzed by factorial design, thermodynamics calculation, XRD and SEM characterization in this study. First, Li/Fe/Mn ions are released from the cathode using HCl assisted with H2O2 in the acid leaching step. The leachability of metals follows the series Li > Fe > Mn in the acidic environment. Then Fe3+ ions are selectively floated and recovered as FeCl3 from the leachate in the flotation step. Finally, Mn2+/Mn3+ and Li+ ions are sequentially precipitated and separated as MnO2/Mn2O3 and Li3PO4 using saturated KMnO4 solution and hot saturated Na3PO4 solution, respectively. Under the optimized and advisable conditions, the total recovery of Li, Fe and Mn is respectively 80.93 ± 0.16%, 85.40 ± 0.12% and 81.02 ± 0.08%. The purity for lithium, ferrum and manganese compounds is respectively 99.32 ± 0.07%, 97.91 ± 0.05% and 98.73 ± 0.05%. This stepwise process could provide an alternative way for the effective separation and recovery of metal values from spent Li-ion battery cathodes in industry.

  19. Precipitation and dissolution of calcium carbonate: key processes bridging the bio- and geosciences (Vladimir Ivanovich Vernadsky Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Gattuso, J.-P.

    2012-04-01

    In this Vladimir Ivanovich Vernadsky medal lecture, I will focus on the biogeochemical cycle of calcium carbonate (CaCO3) which is arguably one of the best example of a set processes that bridge the bio- and geosciences. The main reactions involved are calcification and dissolution that, respectively, manufacture and destroy calcium carbonate. Biology is intimately involved in these two processes which are key controls of the Earth's climate and leave remains that are of great use to human societies (as building materials) and geoscientists. I will illustrate the bridge between the bio- and geosciences by providing brief examples for each of the following four issues. (1) The marine cycle of CaCO3 and its relationship with climate. The release of CO2 by the precipitation of calcium carbonate and the uptake of CO2 by its dissolution are important controls of atmospheric CO2 and climate. The vertical distribution of Ψ, the ratio of CO2 released/used per CaCO3 precipitated/dissolved in the ocean will be shown to be consistent with the Högbom-Urey reactions. (2) The use of CaCO3 in paleooceanography. The remains of calcium carbonate shells and skeletons are wonderful archives of past environmental changes. Their isotopic composition and the concen-tration of trace elements are invaluable in the reconstruction of past climate. I will address the challenge of calibrating one of the proxies used to reconstruct past ocean pH. (3) The challenge of understanding calcification. Despite having been investigated for decades, many aspects of the physiological and molecular processes involved in calcification by marine organisms remain obscure. Recent breakthroughs, mostly on reef-building corals, will be briefly reviewed. (4) The response of calcification and dissolution to environmental change. The critical importance of CaCO3 precipitation and dissolution as climate controls makes it vital to understand their response to global environmental changes such as ocean warming and

  20. Microbially induced carbonate precipitation (MICP) by denitrification as ground improvement method - Process control in sand column experiments

    NASA Astrophysics Data System (ADS)

    Pham, Vinh; van Paassen, Leon; Nakano, Akiko; Kanayama, Motohei; Heimovaara, Timo

    2013-04-01

    Calcite precipitation induced by microbes has been proven to be efficient in stabilizing granular soils, especially with urea hydrolysis, as it has been successfully demonstrated in a pilot application 2010. However, as a byproduct highly concentrated ammonium chloride (NH4Cl) solution is produced, which has to be removed and disposed and forms a significant disadvantage of the technique that makes an alternative process like denitrification preferred. The proof of principle of microbially induced calcite precipitation (MICP) by denitrification has been demonstrated by Van Paassen et al (2010) who suggested that instead of producing waste as a byproduct, different pre-treated waste streams could be used as substrates for in situ growth of denitrifying bacteria and simultaneous cementation without producing waste to be removed. In this study sand column experiments are performed in which calcium carbonate was successfully precipitated by indigenous denitrifying micro-organisms, which were supplied weekly with a pulse of a substrate solution containing calcium acetate and calcium nitrate. Besides the production of calcite and the growth of bacteria in biofilms, the reduction of nitrate resulted in the production of (nitrogen) gas. It was observed that this gas partly fills up the pore space and consequently contributed to a reduction of the permeability of the treated sand. The presence of gas in the pore space affected the flow of the injected substrates and influenced to the distribution of calcium carbonate. The effect of the mean particle size (D50) on the flow and transport of solutes and gas in the porous media has been evaluated by treating several columns with varying grain size distribution and comparing the change in permeability after each incubation period and analyzing the distribution of the gas throughout the columns using X-ray computed tomography (CT) scanning. The present results show that there is a considerable decrease of permeability - a

  1. Characteristics of the precipitation recycling ratio and its relationship with regional precipitation in China

    NASA Astrophysics Data System (ADS)

    Hua, Lijuan; Zhong, Linhao; Ke, Zongjian

    2015-10-01

    A dynamic recycling model (DRM) with an analytical moisture trajectory tracking method, together with Japan Meteorological Agency 25-year reanalysis data, is used to study the regional precipitation recycling process across China, by calculating the regional recycling ratio (ρ r ) at the daily time scale during 1979-2010. The distribution of ρ r shows that, in western China, especially the Tibetan Plateau and its surrounding areas, precipitation is strongly dependent on the recycling process associated with regional evaporation. In Southeast China, however, the contribution from the recycling processes is much smaller due to the influence of the summer monsoon. A precipitation threshold value of about 4 mm/day is obtained from detailed analysis of both extreme and all-range ρ r years. According to this threshold, China is classified into three types of sub-regions: low-precipitation sub-regions (mainly in the northwest), high-precipitation sub-regions (mainly in the south), and medium-precipitation sub-regions (mainly in the northeast). It is found that ρ r correlates positively with precipitation, as well as convective precipitation (P CP) and large-scale precipitation (P LP) in the low-precipitation sub-regions. However, negative ρ r ˜ P LP correlations are found in the high-precipitation sub-regions and nonsignificant correlations exist in the medium-precipitation sub-regions. As P CP is mainly locally generated due to mid-latitude mesoscale systems and the cumulus parameterization used in producing the reanalysis, the recycling ratio positively correlates to the ratio P CP/P LP in almost all sub-regions, particularly in the Tibetan Plateau and its surrounding areas. The correlation between radiation flux and ρ r suggests more net radiation supports more evaporation and higher ρ r , especially in the high-precipitation sub-regions. The influence of clouds on shortwave radiation is crucial, since evaporation is suppressed when the amount of cloudiness

  2. Laboratory Tests on Post-Filtration Precipitation in the WTP Pretreatment Process

    SciTech Connect

    Russell, Renee L.; Peterson, Reid A.; Rinehart, Donald E.; Crum, Jarrod V.

    2009-11-20

    Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed, and operated as part of a plan to respond to issue M12, "Undemonstrated Leaching Processes," of the External Flowsheet Review Team (EFRT) issue response plan (Barnes et al. 2006). The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. A simplified flow diagram of the PEP system is shown in Figure 1.1. Two operating scenarios are currently being evaluated for the ultrafiltration process (UFP) and leaching operations. The first scenario has caustic leaching performed in the UFP-2 ultrafiltration feed vessels (i.e., vessel UFP-VSL-T02A in the PEP; and vessels UFP-VSL-00002A and B in the WTP PTF). The second scenario has caustic leaching conducted in the UFP-1 ultrafiltration feed preparation vessels (i.e., vessels UFP-VSL-T01A and B in the PEP; vessels UFP-VSL-00001A and B in the WTP PTF).

  3. High-frequency monitoring reveals nutrient sources and transport processes in an agriculture-dominated lowland water system

    NASA Astrophysics Data System (ADS)

    van der Grift, Bas; Broers, Hans Peter; Berendrecht, Wilbert; Rozemeijer, Joachim; Osté, Leonard; Griffioen, Jasper

    2016-05-01

    Many agriculture-dominated lowland water systems worldwide suffer from eutrophication caused by high nutrient loads. Insight in the hydrochemical functioning of embanked polder catchments is highly relevant for improving the water quality in such areas or for reducing export loads to downstream water bodies. This paper introduces new insights in nutrient sources and transport processes in a polder in the Netherlands situated below sea level using high-frequency monitoring technology at the outlet, where the water is pumped into a higher situated lake, combined with a low-frequency water quality monitoring programme at six locations within the drainage area. Seasonal trends and short-scale temporal dynamics in concentrations indicated that the NO3 concentration at the pumping station originated from N loss from agricultural lands. The NO3 loads appear as losses via tube drains after intensive rainfall events during the winter months due to preferential flow through the cracked clay soil. Transfer function-noise modelling of hourly NO3 concentrations reveals that a large part of the dynamics in NO3 concentrations during the winter months can be related to rainfall. The total phosphorus (TP) concentration and turbidity almost doubled during operation of the pumping station, which points to resuspension of particulate P from channel bed sediments induced by changes in water flow due to pumping. Rainfall events that caused peaks in NO3 concentrations did not results in TP concentration peaks. The rainfall induced and NO3 enriched quick interflow, may also be enriched in TP but retention of TP due to sedimentation of particulate P then results in the absence of rainfall induced TP concentration peaks. Increased TP concentrations associated with run-off events is only observed during a rainfall event at the end of a freeze-thaw cycle. All these observations suggest that the P retention potential of polder water systems is primarily due to the artificial pumping regime

  4. High-frequency monitoring reveals nutrient sources and transport processes in an agriculture-dominated lowland water system

    NASA Astrophysics Data System (ADS)

    van der Grift, B.; Broers, H. P.; Berendrecht, W. L.; Rozemeijer, J. C.; Osté, L. A.; Griffioen, J.

    2015-08-01

    Many agriculture-dominated lowland water systems worldwide suffer from eutrophication caused by high nutrient loads. Insight in the hydrochemical functioning of embanked polder catchments is highly relevant for improving the water quality in such areas. This paper introduces new insights in nutrient sources and transport processes in a low elevated polder in the Netherlands using high-frequency monitoring technology at the outlet, where the water is pumped into a higher situated lake, combined with a low-frequency water quality monitoring program at six locations within the drainage area. Seasonal trends and short scale temporal dynamics in concentrations indicated that the NO3 concentration at the pumping station originated from N-loss from agricultural lands. The NO3 loads appear as losses with drain water discharge after intensive rainfall events during the winter months due to preferential flow through the cracked clay soil. Transfer function-noise modelling of hourly NO3 concentrations reveals that a large part of the dynamics in NO3 concentrations during the winter months can be related to rainfall. The total phosphorus (TP) concentration almost doubled during operation of the pumping station which points to resuspension of particulate P from channel bed sediments induced by changes in water flow due to pumping. Rainfall events that caused peaks in NO3 concentrations did not results in TP concentration peaks. The by rainfall induced and NO3 enriched quick interflow, may also be enriched in TP but this is then buffered in the water system due to sedimentation of particulate P. Increased TP concentrations associated with run-off events is only observed during a rainfall event at the end of a freeze-thaw cycle. All these observations suggest that the P retention potential of polder water systems is highly due to the artificial pumping regime that buffers high flows. As the TP concentration is affected by operation of the pumping station, timing of sampling

  5. K Basin Sludge Conditioning Process Testing Partitioning of PCBs in Dissolver Solution After Neutralization/Precipitation (Caustic Adjustment)

    SciTech Connect

    Schmidt, A.J.; Thornton, B.M.; Hoppe, E.W.; Mong, G.M.; Silvers, K.L.; Slate, S.O.

    1999-01-04

    The purpose of the work described in this report was to gain a better understanding of how PCB congeners present in a simulated K Basin sludge dissolver solution will partition upon neutralization and precipitation (i.e., caustic adjustment). In a previous study (Mong et al. 1998),the entire series of sludge conditioning steps (acid dissolution, filtration, and caustic adjustment) were examined during integrated testing. In the work described here, the caustic adjustment step was isolated to examine the fate of PCBs in more detail within this processing step. For this testing, solutions of dissolver simulant (containing no solids) with a known initial concentration of PCB congeners were neutralized with caustic to generate a clarified supernatant and a settled sludge phase. PCBs were quantified in each phase (including the PCBs associated with the test vessel rinsates), and material balance information was collected.

  6. The Discernment Process of the Sisters of Saint Dominic regarding the Continued Sponsorship of Its Secondary Schools

    ERIC Educational Resources Information Center

    Tavis, Patricia

    2010-01-01

    The purpose of this dissertation was to examine the factors that a congregation of women religious, the Sisters of Saint Dominic of Caldwell, New Jersey, must consider in order to continue its sponsored relationship and the extent of this sponsored relationship with its secondary educational ministries for the future. This descriptive and…

  7. Separation of particles precipitated from (U,RE){sub 3}O{sub 8} powder oxidation by dry process

    SciTech Connect

    Lee Jae Won; Lee Jung Won; Yang Myung Seung; Song Kee Chan; Park Geun Il

    2007-07-01

    The phase separation characteristics of RE elements from SIMFUEL (simulated spent fuel) was investigated by a high temperature oxidation at 1174{approx}1673 K using a fuel powder of (U,RE){sub 3}O{sub 8} in a single RE element system. A typical oxidation and reduction treatment followed by a dry milling process was introduced and investigated for a separation of the precipitated RE-rich (U{sub 1-y}RE{sub y})O{sub 2+z} particles and RE-poor U{sub 3}O{sub 8} particles formed by a high temperature oxidation. The XRD and SEM results indicate that an increase of the oxidation temperature increases the amount of the (U{sub 1-y}RE{sub y})O{sub 2+z} phase, while decreasing that of the RE-poor U{sub 3}O{sub 8}-type phase. Since the solubility of RE in the U{sub 3}O{sub 8}-type phase was almost constant regardless of the oxidation temperature, the decrease of the RE concentration in the RE-rich (U{sub 1-y}RE{sub y})O{sub 2+z} phase with an increasing oxidation temperature seems to be due to a diffusion of the U ion from the RE-poor U{sub 3}O{sub 8}-type phase to the RE-rich (U{sub 1-y}RE{sub y})O{sub 2+z} phase. The RE-rich (U{sub 1-y}RE{sub y})O{sub 2+z} particle precipitated from the RE-poor U{sub 3}O{sub 8} particle is mostly separated by a reduction and oxidation treatment at a typical temperature of the powdering process of uranium dioxide and completely separated by a dry milling. (authors)

  8. Modelling evapotranspiration during precipitation deficits: Identifying critical processes in a land surface model

    DOE PAGESBeta

    Ukkola, Anna M.; Pitman, Andy J.; Decker, Mark; De Kauwe, Martin G.; Abramowitz, Gab; Kala, Jatin; Wang, Ying -Ping

    2016-06-21

    Surface fluxes from land surface models (LSMs) have traditionally been evaluated against monthly, seasonal or annual mean states. The limited ability of LSMs to reproduce observed evaporative fluxes under water-stressed conditions has been previously noted, but very few studies have systematically evaluated these models during rainfall deficits. We evaluated latent heat fluxes simulated by the Community Atmosphere Biosphere Land Exchange (CABLE) LSM across 20 flux tower sites at sub-annual to inter-annual timescales, in particular focusing on model performance during seasonal-scale rainfall deficits. The importance of key model processes in capturing the latent heat flux was explored by employing alternative representations of hydrology, leafmore » area index, soil properties and stomatal conductance. We found that the representation of hydrological processes was critical for capturing observed declines in latent heat during rainfall deficits. By contrast, the effects of soil properties, LAI and stomatal conductance were highly site-specific. Whilst the standard model performs reasonably well at annual scales as measured by common metrics, it grossly underestimates latent heat during rainfall deficits. A new version of CABLE, with a more physically consistent representation of hydrology, captures the variation in the latent heat flux during seasonal-scale rainfall deficits better than earlier versions, but remaining biases point to future research needs. Lastly, our results highlight the importance of evaluating LSMs under water-stressed conditions and across multiple plant functional types and climate regimes.« less

  9. A Robust Multi-Scale Modeling System for the Study of Cloud and Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2012-01-01

    During the past decade, numerical weather and global non-hydrostatic models have started using more complex microphysical schemes originally developed for high resolution cloud resolving models (CRMs) with 1-2 km or less horizontal resolutions. These microphysical schemes affect the dynamic through the release of latent heat (buoyancy loading and pressure gradient) the radiation through the cloud coverage (vertical distribution of cloud species), and surface processes through rainfall (both amount and intensity). Recently, several major improvements of ice microphysical processes (or schemes) have been developed for cloud-resolving model (Goddard Cumulus Ensemble, GCE, model) and regional scale (Weather Research and Forecast, WRF) model. These improvements include an improved 3-ICE (cloud ice, snow and graupel) scheme (Lang et al. 2010); a 4-ICE (cloud ice, snow, graupel and hail) scheme and a spectral bin microphysics scheme and two different two-moment microphysics schemes. The performance of these schemes has been evaluated by using observational data from TRMM and other major field campaigns. In this talk, we will present the high-resolution (1 km) GeE and WRF model simulations and compared the simulated model results with observation from recent field campaigns [i.e., midlatitude continental spring season (MC3E; 2010), high latitude cold-season (C3VP, 2007; GCPEx, 2012), and tropical oceanic (TWP-ICE, 2006)].

  10. Modelling evapotranspiration during precipitation deficits: identifying critical processes in a land surface model

    NASA Astrophysics Data System (ADS)

    Ukkola, A.; Pitman, A.; Decker, M. R.; De Kauwe, M. G.; Abramowitz, G.; Wang, Y.; Kala, J.

    2015-12-01

    Surface fluxes from land surface models (LSM) have traditionally been evaluated against monthly, seasonal or annual mean states. Previous studies have noted the limited ability of LSMs to reproduce observed evaporative fluxes under water-stressed conditions but very few studies have systematically evaluated LSMs during rainfall deficits. We investigate the performance of the Community Atmosphere Biosphere Land Exchange (CABLE) LSM in simulating latent heat fluxes in offline mode. CABLE is evaluated against eddy covariance measurements of latent heat flux across 20 flux tower sites at sub-annual to inter-annual time scales, with a focus on model performance during seasonal-scale rainfall deficits. The importance of key model processes in capturing the latent heat flux is explored by employing alternative representations of hydrology, soil properties, leaf area index and stomatal conductance. We demonstrate the critical role of hydrological processes for capturing observed declines in latent heat. The effects of soil, LAI and stomatal conductance are shown to be highly site-specific. The default CABLE performs reasonably well at annual scales despite grossly underestimating latent heat during rainfall deficits, highlighting the importance for evaluating models explicitly under water-stressed conditions across multiple vegetation and climate regimes. A new version of CABLE, with a more physically consistent representation of hydrology, captures the variation in the latent heat flux during seasonal-scale rainfall deficits better than earlier versions but remaining deficiencies point to future research needs.

  11. Modelling evapotranspiration during precipitation deficits: identifying critical processes in a land surface model

    NASA Astrophysics Data System (ADS)

    Ukkola, A. M.; Pitman, A. J.; Decker, M.; De Kauwe, M. G.; Abramowitz, G.; Kala, J.; Wang, Y.-P.

    2015-10-01

    Surface fluxes from land surface models (LSM) have traditionally been evaluated against monthly, seasonal or annual mean states. The limited ability of LSMs to reproduce observed evaporative fluxes under water-stressed conditions has been previously noted, but very few studies have systematically evaluated these models during rainfall deficits. We evaluated latent heat flux simulated by the Community Atmosphere Biosphere Land Exchange (CABLE) LSM across 20 flux tower sites at sub-annual to inter-annual time scales, in particular focusing on model performance during seasonal-scale rainfall deficits. The importance of key model processes in capturing the latent heat flux are explored by employing alternative representations of hydrology, leaf area index, soil properties and stomatal conductance. We found that the representation of hydrological processes was critical for capturing observed declines in latent heat during rainfall deficits. By contrast, the effects of soil properties, LAI and stomatal conductance are shown to be highly site-specific. Whilst the standard model performs reasonably well at annual scales as measured by common metrics, it grossly underestimates latent heat during rainfall deficits. A new version of CABLE, with a more physically consistent representation of hydrology, captures the variation in the latent heat flux during seasonal-scale rainfall deficits better than earlier versions but remaining biases point to future research needs. Our results highlight the importance of evaluating LSMs under water-stressed conditions and across multiple plant functional types and climate regimes.

  12. Modelling evapotranspiration during precipitation deficits: identifying critical processes in a land surface model

    NASA Astrophysics Data System (ADS)

    Ukkola, Anna M.; Pitman, Andy J.; Decker, Mark; De Kauwe, Martin G.; Abramowitz, Gab; Kala, Jatin; Wang, Ying-Ping

    2016-06-01

    Surface fluxes from land surface models (LSMs) have traditionally been evaluated against monthly, seasonal or annual mean states. The limited ability of LSMs to reproduce observed evaporative fluxes under water-stressed conditions has been previously noted, but very few studies have systematically evaluated these models during rainfall deficits. We evaluated latent heat fluxes simulated by the Community Atmosphere Biosphere Land Exchange (CABLE) LSM across 20 flux tower sites at sub-annual to inter-annual timescales, in particular focusing on model performance during seasonal-scale rainfall deficits. The importance of key model processes in capturing the latent heat flux was explored by employing alternative representations of hydrology, leaf area index, soil properties and stomatal conductance. We found that the representation of hydrological processes was critical for capturing observed declines in latent heat during rainfall deficits. By contrast, the effects of soil properties, LAI and stomatal conductance were highly site-specific. Whilst the standard model performs reasonably well at annual scales as measured by common metrics, it grossly underestimates latent heat during rainfall deficits. A new version of CABLE, with a more physically consistent representation of hydrology, captures the variation in the latent heat flux during seasonal-scale rainfall deficits better than earlier versions, but remaining biases point to future research needs. Our results highlight the importance of evaluating LSMs under water-stressed conditions and across multiple plant functional types and climate regimes.

  13. An Improved Bulk Microphysical Scheme for Studying Precipitation Processes: Comparisons with Other Schemes

    NASA Technical Reports Server (NTRS)

    Tao, W. K.; Shi, J. J.; Lang, S.; Chen, S.; Hong, S-Y.; Peters-Lidard, C.

    2007-01-01

    Cloud microphysical processes play an important role in non-hydrostatic high-resolution simulations. Over the past decade both research and operational numerical weather prediction models have started using more complex cloud microphysical schemes that were originally developed for high-resolution cloud-resolving models. An improved bulk microphysical parameterization (adopted from the Goddard microphysics schemes) has recently implemented into the Weather Research and Forecasting (WRF) model. This bulk microphysical scheme has three different options --- 2ICE (cloud ice & snow), 3ICE-graupel (cloud ice, snow & graupel) and 3ICE-hail (cloud ice, snow & hail). High-resolution model simulations are conducted to examine the impact of microphysical schemes on two different weather events (a midlatitude linear convective system and an Atlantic hurricane). In addition, this bulk microphysical parameterization is compared with WIRF's three other bulk microphysical schemes.

  14. The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Li, X.; Khain, A.; Simpson, S.

    2005-01-01

    Cloud microphysics are inevitable affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds, Therefore, size distributions parameterized as spectral bin microphysics are needed to explicitly study the effect of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates for convective clouds. Recently, a detailed spectral-bin microphysical scheme was implemented into the the Goddard Cumulus Ensemble (GCE) model. The formulation for the explicit spectral-bim microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e., pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), graupel and frozen drops/hail]. Each type is described by a special size distribution function containing many categories (i.e., 33 bins). Atmospheric aerosols are also described using number density size-distribution functions.

  15. Layer-by-layer modification of high surface curvature nanoparticles with weak polyelectrolytes using a multiphase solvent precipitation process.

    PubMed

    Nagaraja, Ashvin T; You, Yil-Hwan; Choi, Jeong-Wan; Hwang, Jin-Ha; Meissner, Kenith E; McShane, Michael J

    2016-03-15

    The layer-by-layer modification of ≈5 nm mercaptocarboxylic acid stabilized gold nanoparticles was studied in an effort to illustrate effective means to overcome practical issues in handling and performing surface modification of such extremely small materials. To accomplish this, each layer deposition cycle was separated into a multi-step process wherein solution pH was controlled in two distinct phases of polyelectrolyte adsorption and centrifugation. Additionally, a solvent precipitation step was introduced to make processing more amenable by concentrating the sample and exchanging solution pH before ultracentrifugation. The pH-dependent assembly on gold nanoparticles was assessed after each layer deposition cycle by monitoring the plasmon peak absorbance location, surface charge, and the percentage of nanoparticles recovered. The selection of solution pH during the adsorption phase was found to be a critical parameter to enhance particle recovery and maximize surface charge when coating with weak polyelectrolytes. One bilayer was deposited with a high yield and the modified particles exhibited enhanced colloidal stability across a broad pH range and increased ionic strength. These findings support the adoption of this multi-step processing approach as an effective and generalizable approach to improve stability of high surface curvature particles. PMID:26771506

  16. Reconstructing climate processes driving variability in precipitation sources from mid to late Holocene speleothem δ18O records from the Southwest US

    NASA Astrophysics Data System (ADS)

    Wong, C. I.; Nusbaumer, J. M.; Banner, J.

    2015-12-01

    Independent co-variation of speleothem δ18O values and other moisture-sensitive speleothem proxies (e.g., growth rate, trace element concentrations) in recently published Holocene stalagmite records from Texas and New Mexico suggest a decoupling between precipitation amounts and precipitation sources over the southwest US. There is, however, limited understanding of the relation between precipitation sources and precipitation amounts and the climate processes governing variability in the region's precipitation sources. To address this, we use source water tags to track precipitation derived from Pacific and Atlantic Oceans during a simulation of modern (1975-2013) climate. We find distinct patterns in the spatial distribution of the fraction of Pacific-derived winter precipitation are associated with unique atmospheric states. High pressure ridging reflected by 500 hPa geopotential heights result in weaker zonal winds and stronger northerly winds over the western US. Under these conditions, Pacific-derived moisture propagates further to the east, and Atlantic-derived moisture is suppressed over southern US. Conversely, 500 hPa geopotential heights that are latitudinally streamline result in strong zonal winds across the entire US. Under these conditions, the fraction of West Pacific-derived precipitation is limited to higher latitudes, and the fraction of far East Pacific- and Atlantic-derived precipitation is enhanced across the Southwest and Southern US, respectively. Further analysis of this data set will assess the teleconnections that link the distinct atmospheric conditions over the US with the state of the ocean and atmosphere over the Pacific and Atlantic Oceans. The results will be applied to reconstructing variability in the climate dynamics governing moisture transport to the southwest US during the mid to late Holocene as reflected by speleothem δ18O records in the region.

  17. Scale appropriate modelling to represent dominant pollution processes in agricultural catchments, to underpin management and policy decisions

    NASA Astrophysics Data System (ADS)

    Adams, Russell; Quinn, Paul

    2014-05-01

    We present the development of scale appropriate modelling techniques to represent dominant pollution processes in agricultural catchments to underpin catchment management and its implications on policy. A quasi-physically based, spatially lumped macro-model (CRAFT), has been developed to assess mitigation options for nitrogen and phosphorus. CRAFT has been developed to use daily time series data of rainfall, stream flow and nutrient concentration data, and can be applied to catchments varying in size from a few hectares to 100s of square kilometres. If stream flow routing is added to the model then potentially larger catchments and sub-daily time steps could be represented. There are two key issues addressed here. Firstly, the model can be used to assess the usefulness of monitoring data collected at a high temporal resolution at considerable expense compared to routine grab sampling. An earlier study in the Frome catchment in southern England collected sub-daily water quality data for more than 12 months at the catchment outlet, comprising: total oxidised nitrogen (TON); soluble reactive phosphorus (SRP) and total phosphorus (TP) concentrations. The three data sets have quite different temporal signals relating to flow pathways with different residence times and the importance of runoff events in generating acute pollution. The flexible model structure was therefore developed to include different sources of runoff including overland flow from impervious areas in the catchment, where pollution hotspots will be located (e.g. farmyards). The model has been used to assess the value of collecting high resolution monitoring data, in this case by resampling the Frome sub-daily data to a daily timestep, and comparing these model simulations against those calibrated using all the samples. The usefulness of the high resolution data can be assessed on whether a daily model would undepredict (for example) high nutrient concentrations that can be identified in the sub

  18. Nitrate-nitrogen and oxygen isotope ratios for identification of nitrate sources and dominant nitrogen cycle processes in a tile-drained dryland agricultural field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural systems are a leading source of reactive nitrogen to aquatic and atmospheric ecosystems. Natural d15Nnitrate and d18Onitrate are used to identify the dominant nitrogen cycle processes and sources of NO3- leached from a tile-drained, dryland agricultural field. Tile-drain water discharge...

  19. The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Li, X.; Khain, A.; Simpson, S.; Johnson, D.; Remer, L.

    2004-01-01

    Cloud microphysics is inevitably affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distributions parameterized as spectral bin microphysics are needed to explicitly study the effects of atmospheric aerosol concentration on cloud development, r d a U production, and rainfall rates for convective clouds. Recently, two detailed spectral-bin microphysical schemes were implemented into the Goddard Cumulus Ensembe1 (GCE) model. The formulation for the explicit spectral-bin microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e. pristine ice crystals (columnar and platelike), snow (dendrites and aggregates), graupel and frozen drops/hail]. Each type is described by a special size distribution function containing many categories (i.e. 33 bins). Atmospheric aerosols are also described using number density size-distribution functions. A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep tropical clouds in the west Pacific warm pool region and in the mid-latitude continent with different concentrations of CCN: a low "c1ean"concentration and a high "dirty" concentration. In addition, differences and similarities between bulk microphysics and spectral-bin microphysical schemes will be examined and discussed.

  20. The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Li, X.; Khain, A.; Simpson, S.

    2004-01-01

    Cloud microphysics are inevitably affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distributions parameterized as spectral bin microphysics are needed to explicitly study the effects of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates for convective clouds. Recently, two detailed spectral-bin microphysical schemes were implemented into the Goddard Cumulus Ensemble (GCE) model. The formulation for the explicit spectral-bin microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles (i.e., pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), graupel and frozen drops/hail). Each type is described by a special size distribution function containing many categories (i.e. 33 bins). Atmospheric aerosols are also described using number density size-distribution functions. A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep cloud systems in the west Pacific warm pool region, in the sub-tropics (Florida) and in the mid-latitude using identical thermodynamic conditions but with different concentrations of CCN: a low 'clean' concentration and a high 'dirty' concentration.

  1. The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Li, X.; Khain, A.; Simpson, S.; Johnson, D.; Remer, L.

    2004-01-01

    Cloud microphysics is inevitably affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distributions parameterized as spectral bin microphysics are needed to explicitly study the effects of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates for convective clouds. Recently, two detailed spectral-bin microphysical schemes were implemented into the Goddard Cumulus Ensembel (GCE) model. The formulation for the explicit spectral-bin microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e. pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), graupel and frozen drops/hail]. Each type is described by a special size distribution function containing many categories (i.e. 33 bins). Atmospheric aerosols are also described using number density size distribution functions. A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep tropical clouds in the west Pacific warm pool region and in the mid-latitude continent with different concentrations of CCN: a low "c1ean"concentration and a high "dirty" concentration. In addition, differences and similarities between bulk microphysics and spectral-bin microphysical schemes will be examined and discussed.

  2. Dissolution-precipitation processes in tank experiments for testing numerical models for reactive transport calculations: Experiments and modelling

    NASA Astrophysics Data System (ADS)

    Poonoosamy, Jenna; Kosakowski, Georg; Van Loon, Luc R.; Mäder, Urs

    2015-06-01

    In the context of testing reactive transport codes and their underlying conceptual models, a simple 2D reactive transport experiment was developed. The aim was to use simple chemistry and design a reproducible and fast to conduct experiment, which is flexible enough to include several process couplings: advective-diffusive transport of solutes, effect of liquid phase density on advective transport, and kinetically controlled dissolution/precipitation reactions causing porosity changes. A small tank was filled with a reactive layer of strontium sulfate (SrSO4) of two different grain sizes, sandwiched between two layers of essentially non-reacting quartz sand (SiO2). A highly concentrated solution of barium chloride was injected to create an asymmetric flow field. Once the barium chloride reached the reactive layer, it forced the transformation of strontium sulfate into barium sulfate (BaSO4). Due to the higher molar volume of barium sulfate, its precipitation caused a decrease of porosity and lowered the permeability. Changes in the flow field were observed with help of dye tracer tests. The experiments were modelled using the reactive transport code OpenGeosys-GEM. Tests with non-reactive tracers performed prior to barium chloride injection, as well as the density-driven flow (due to the high concentration of barium chloride solution), could be well reproduced by the numerical model. To reproduce the mineral bulk transformation with time, two populations of strontium sulfate grains with different kinetic rates of dissolution were applied. However, a default porosity permeability relationship was unable to account for measured pressure changes. Post mortem analysis of the strontium sulfate reactive medium provided useful information on the chemical and structural changes occurring at the pore scale at the interface that were considered in our model to reproduce the pressure evolution with time.

  3. Dissolution-precipitation processes in tank experiments for testing numerical models for reactive transport calculations: Experiments and modelling.

    PubMed

    Poonoosamy, Jenna; Kosakowski, Georg; Van Loon, Luc R; Mäder, Urs

    2015-01-01

    In the context of testing reactive transport codes and their underlying conceptual models, a simple 2D reactive transport experiment was developed. The aim was to use simple chemistry and design a reproducible and fast to conduct experiment, which is flexible enough to include several process couplings: advective-diffusive transport of solutes, effect of liquid phase density on advective transport, and kinetically controlled dissolution/precipitation reactions causing porosity changes. A small tank was filled with a reactive layer of strontium sulfate (SrSO4) of two different grain sizes, sandwiched between two layers of essentially non-reacting quartz sand (SiO2). A highly concentrated solution of barium chloride was injected to create an asymmetric flow field. Once the barium chloride reached the reactive layer, it forced the transformation of strontium sulfate into barium sulfate (BaSO4). Due to the higher molar volume of barium sulfate, its precipitation caused a decrease of porosity and lowered the permeability. Changes in the flow field were observed with help of dye tracer tests. The experiments were modelled using the reactive transport code OpenGeosys-GEM. Tests with non-reactive tracers performed prior to barium chloride injection, as well as the density-driven flow (due to the high concentration of barium chloride solution), could be well reproduced by the numerical model. To reproduce the mineral bulk transformation with time, two populations of strontium sulfate grains with different kinetic rates of dissolution were applied. However, a default porosity permeability relationship was unable to account for measured pressure changes. Post mortem analysis of the strontium sulfate reactive medium provided useful information on the chemical and structural changes occurring at the pore scale at the interface that were considered in our model to reproduce the pressure evolution with time. PMID:25805363

  4. Biosynthesis, targeting, and processing of lysosomal proteins: pulse-chase labeling and immune precipitation.

    PubMed

    Pohl, Sandra; Hasilik, Andrej

    2015-01-01

    Incorporation of radioactive precursors of amino acids and/or modifier groups into proteins, isolation and sizing of polypeptide species of interest, and finally their detection and characterization provide a robust handle to examine the life cycle and varied modifications of any protein. A prerequisite in application of these techniques to lysosomal enzymes is the availability of an avid and specific antibody, because lysosomal proteins represent a very minor fraction of the cellular protein and must be purified without a significant loss many 1000-fold as conveniently as possible. Pulse-chase labeling and good knowledge on organelle-specific modifications of lysosomal proteins may enhance the information that can be obtained from such experiments. We describe procedures for pulse-chase labeling experiments that have proven to work with a commercially available antibody against a mouse and a human lysosomal protease and can be used as a reference in establishing the technique in any laboratory that has an access to a certified isotope facility and the knowledge to handle radioactivity safely. We discuss the crucial steps and refer to alternatives described in the literature. The present model protein cathepsin Z is synthesized as a larger proenzyme that contains two N-linked oligosaccharides and matures to a shorter single chain enzyme retaining the processed oligosaccharides. A pulse-chase experiment demonstrates the conversion of the precursor into the mature form. In addition, results on deglycosylation of metabolically labeled cathepsin Z are shown and the alterations in the apparent size of the glycopeptides are explained. PMID:25665441

  5. The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

    NASA Astrophysics Data System (ADS)

    Tao, W.; Li, X.; Khain, A.; Simpson, J.

    2004-12-01

    Cloud microphysics are inevitably affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distributions parameterized as spectral bin microphysics are needed to explicitly study the effects of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates for convective clouds. Recently, two detailed spectral-bin microphysical schemes were implemented into the Goddard Cumulus Ensemble (GCE) model. The formulation for the explicit spectral-bin microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e. pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), graupel and frozen drops/hail]. Each type is described by a special size distribution function containing many categories (i.e. 33 bins). Atmospheric aerosols are also described using number density size-distribution functions. A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep cloud systems in the west Pacific warm pool region, in the sub-tropics (Florida) and in the mid-latitude using identical thermodynamic conditions but with different concentrations of CCN: a low "clean" concentration and a high "dirty" concentration. Besides the initial differences in aerosol concentration, preliminary results indicate that the low CCN concentration case produces rainfall at the surface sooner than the high CCN case but has less cloud water mass aloft. Because the spectral-bin model explicitly calculates and allows for the examination of both the mass and number concentration of species in each size category, a detailed analysis of the instantaneous size spectrum can be obtained for the two

  6. The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Khain, A.; Simpson, S.; Johnson, D.; Li, X.; Remer, L.

    2003-01-01

    Cloud microphysics are inevitable affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distribution parameterized as spectral bin microphysics are needed to explicitly study the effect of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates convective clouds. Recently, two detailed spectral-bin microphysical schemes were implemented into the Goddard Cumulus Ensembel (GCE) model. The formulation for the explicit spectral-bim microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e., pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), groupel and frozen drops/hall] Each type is described by a special size distribution function containing many categories (i.e., 33 bins). Atmospheric aerosols are also described using number density size-distribution functions.A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep cloud systems in the west Pacific warm pool region and in the mid-latitude using identical thermodynamic conditions but with different concentrations of CCN: a low "clean" concentration and a high "dirty" concentration. Besides the initial differences in aerosol concentration, preliminary results indicate that the low CCN concentration case produces rainfall at the surface sooner than the high CCN case but has less cloud water mass aloft. Because the spectral-bim model explicitly calculates and allows for the examination of both the mass and number concentration of cpecies in each size category, a detailed analysis of the instantaneous size spectrum can be obtained for the two cases. It is shown that since the low

  7. The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Khain, A.; Simpson, S.; Johnson, D.; Li, X.; Remer, L.

    2003-01-01

    Cloud microphysics are inevitably affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distributions parameterized as spectral bin microphysics are needed to explicitly study the effects of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates for convective clouds. Recently, two detailed spectral-bin microphysical schemes were implemented into the Goddard Cumulus Ensemble (GCE) model. The formulation for the explicit spectral-bin microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e.,pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), graupel and frozen drops/hail]. Each type is described by a special size distribution function containing many categories (i.e. 33 bins). Atmospheric aerosols are also described using number density size-distribution functions.A spectral-bin microphysical model is very expensive from a from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep tropical clouds in the west Pacific warm pool region using identical thermodynamic conditions but with different concentrations of CCN: a low "clean" concentration and a high "dirty" concentration. Besides the initial differences in aerosol concentration, preliminary results indicate that the low CCN concentration case produces rainfall at the surface sooner than the high CCN case but has less cloud water mass aloft. Because the spectral-bin model explicitly calculates and allows for the examination of both the mass and number concentration of species in each size categor, a detailed analysis of the instantaneous size spectrum can be obtained for the two cases. It is shown that since the low CCN case

  8. Fearless Dominance and reduced feedback-related negativity amplitudes in a time-estimation task – Further neuroscientific evidence for dual-process models of psychopathy☆

    PubMed Central

    Schulreich, Stefan; Pfabigan, Daniela M.; Derntl, Birgit; Sailer, Uta

    2013-01-01

    Dual-process models of psychopathy postulate two etiologically relevant processes. Their involvement in feedback processing and its neural correlates has not been investigated so far. Multi-channel EEG was collected while healthy female volunteers performed a time-estimation task and received negative or positive feedback in form of signs or emotional faces. The affective-interpersonal factor Fearless Dominance, but not Self-Centered Impulsivity, was associated with reduced feedback-related negativity (FRN) amplitudes. This neural dissociation extends previous findings on the impact of psychopathy on feedback processing and further highlights the importance of distinguishing psychopathic traits and extending previous (neuroscientific) models of psychopathy. PMID:23607997

  9. Interface-coupled dissolution-precipitation processes allow a photonic crystal to replace an ionic crystal along lattice planes

    NASA Astrophysics Data System (ADS)

    Liesegang, Moritz; Milke, Ralf

    2015-04-01

    Nanocolloidal amorphous silica (SiO2×nH2O) is a major component of environmental aqueous solutions and surface coatings on rocks or mineral grains. Detailed knowledge of amorphous silica formation is indispensable for a better understanding of silicate rock alteration and diagenetic processes. We analyzed a wide range of samples from the Australian precious opal fields in South Australia and Queensland using petrographic microscopy, XRPD, SEM, and EPMA to characterize opaline silica, the mineral assemblage, and the host rock. Over the past 90 Ma the Lower Cretaceous lithologies of central Australia have undergone a weathering regime ranging from sub-tropical to arid, in which pH fluctuated from alkaline to acidic. The prolonged chemical alteration of sedimentary rocks derived from andesitic volcaniclastics and organic matter liberated large volumes of silica into solution, eventually leading to precipitation of nanocolloidal amorphous silica and formation of opal-A. A regular arrangement of close-packed uniform (monodisperse) spheres permits diffraction of white light and gives rise to the famous play-of-color. The opals in this study consist of silica spheres with an average diameter of 100-320 nm and often show a prominent core-shell structure. Two groups are separated by their relative standard deviation (RSD): monodisperse spheres (RSD<6%) and polydisperse spheres (RDS>10%). Monodisperse and polydisperse spheres are separated by their Na/K ratio, restricting the appearance of monodisperse spheres to values <1.2 and polydisperse spheres to values >3.0. We suggest that the Na/K ratio represents significant differences in the overall solution characteristics. The associated minerals (e.g., alunite, gypsum, kaolinite, K feldspar) indicate large variations of fluid composition and pH. Probably, uniform spheres grew at acidic pH, with repulsive forces large enough to arrange them in an ordered array prior to the evaporation of interstitial fluids. The investigation

  10. The evolution of dominance.

    PubMed

    Bourguet, D

    1999-07-01

    The evolution of dominance has been subject to intensive debate since Fisher first argued that modifiers would be selected for if they made wild-type alleles more dominant over mutant alleles. An alternative explanation, put forward by Wright, is that the commonly observed dominance of wild-type alleles is simply a physiological consequence of metabolic pathways. Wright's explanation has gained support over the years, largely ending the debate over the general recessivity of deleterious mutations. Nevertheless there is reason to believe that dominance relationships have been moulded by natural selection to some extent. First, the metabolic pathways are themselves products of evolutionary processes that may have led them to be more stable to perturbations, including mutations. Secondly, theoretical models and empirical experiments suggest that substantial selection for dominance modifiers exists during the spread of adaptive alleles or when a polymorphism is maintained either by overdominant selection or by migration-selection balance. PMID:10447697

  11. On scaling in spatial precipitation from radar

    NASA Astrophysics Data System (ADS)

    Paschalis, Athanasios; Molnar, Peter; Burlando, Paolo

    2013-04-01

    The topic of self-similarity in precipitation in time and space has been prominent in precipitation research for at least the last 3 decades. Data analysts have explored evidence for self-similarity and reported departures from it. Modellers have developed stochastic models that are based on self-similarity concepts or at least reproduce the observed scaling behaviour. Physicists and meteorologists have argued why scale invariance should, or should not, exist in precipitation. Although there appears to be consensus between these communities that precipitation may exhibit scale invariance in some range of scales, most of us would probably also agree that the scaling properties are connected to the precipitation generation mechanisms (e.g. convection, orographic enhancement, etc.) and are not generally valid. The demonstration of this variability in scaling properties of precipitation and their relation to possible precipitation generating mechanisms is the focus of this paper. We analyse the spatial structure of radar precipitation for the orographically complex environment of the Swiss Alps as a multi-scaling process. A reliable 7 year long, high quality precipitation radar dataset, derived from the operational weather radars of MeteoSwiss is used to conduct a comprehensive data analysis and to reveal potential connections of the scaling processes of the precipitation structure and its respective generating mechanisms. We use different analysis techniques to quantify scale-dependent properties, from spectral analysis to multiplicative random cascades, employing estimation techniques spanning from traditional moment scaling to wavelet based estimators. We compare the results seasonally for radars in two different locations, one north and one south of the main Alpine divide, with very different topography. The main result is that distinct seasonal and spatial patterns in precipitation scaling properties exist which highlight the effect of topography on precipitation

  12. Massive barite deposits and carbonate mineralization in the Derugin Basin, Sea of Okhotsk: precipitation processes at cold seep sites

    NASA Astrophysics Data System (ADS)

    Greinert, Jens; Bollwerk, Sandra M.; Derkachev, Alexander; Bohrmann, Gerhard; Suess, Erwin

    2002-10-01

    An area of massive barite precipitations was studied at a tectonic horst in 1500 m water depth in the Derugin Basin, Sea of Okhotsk. Seafloor observations and dredge samples showed irregular, block- to column-shaped barite build-ups up to 10 m high which were scattered over the seafloor along an observation track 3.5 km long. High methane concentrations in the water column show that methane expulsion and probably carbonate precipitation is a recently active process. Small fields of chemoautotrophic clams ( Calyptogena sp., Acharax sp.) at the seafloor provide additional evidence for active fluid venting. The white to yellow barites show a very porous and often layered internal fabric, and are typically covered by dark-brown Mn-rich sediment; electron microprobe spectroscopy measurements of barite sub-samples show a Ba substitution of up to 10.5 mol% of Sr. Rare idiomorphic pyrite crystals (˜1%) in the barite fabric imply the presence of H 2S. This was confirmed by clusters of living chemoautotrophic tube worms (1 mm in diameter) found in pores and channels within the barite. Microscopic examination showed that micritic aragonite and Mg-calcite aggregates or crusts are common authigenic precipitations within the barite fabric. Equivalent micritic carbonates and barite carbonate cemented worm tubes were recovered from sediment cores taken in the vicinity of the barite build-up area. Negative δ 13C values of these carbonates (>-43.5‰ PDB) indicate methane as major carbon source; δ 18O values between 4.04 and 5.88‰ PDB correspond to formation temperatures, which are certainly below 5°C. One core also contained shells of Calyptogena sp. at different core depths with 14C-ages ranging from 20 680 to >49 080 yr. Pore water analyses revealed that fluids also contain high amounts of Ba; they also show decreasing SO 42- concentrations and a parallel increase of H 2S with depth. Additionally, S and O isotope data of barite sulfate (δ 34S: 21.0-38.6‰ CDT; δ 18O

  13. Selective Precipitation of Proteins.

    PubMed

    Matulis, Daumantas

    2016-01-01

    Selective precipitation of proteins can be used as a bulk method to recover the majority of proteins from a crude lysate, as a selective method to fractionate a subset of proteins from a protein solution, or as a very specific method to recover a single protein of interest from a purification step. This unit describes a number of methods suitable for selective precipitation. In each of the protocols that are outlined, the physical or chemical basis of the precipitation process, the parameters that can be varied for optimization, and the basic steps for developing an optimized precipitation are described. PMID:26836410

  14. Effects of caustic sodium concentration and molecular ratio of Na2O to Al2O3 on agglomeration in the precipitation process

    NASA Astrophysics Data System (ADS)

    Liu, Zhanwei; Chen, Wenmi; Li, Wangxing

    2010-11-01

    The supersaturation of sodium aluminate solution (liquor) is a prerequisite for agglomeration and the key factors that determine supersaturation of liquor are caustic sodium concentration (Nk) and molecular ratio of Na2O to Al2O3 (αk). In this paper, the effects of Nk and αk on the agglomeration process of seeded precipitation were studied. The results show that the Nk plays an important role in the agglomeration process. The supersaturation of liquor decreases with the increasing of Nk and so not only does the precipitation ratio of liquor decrease but also the particle size of agglomerate decreases. The supersaturation of liquor decreases with the increasing of αk and so the precipitation rate and depth of liquor decrease and thus the agglomeration of fine particles is weakened.

  15. Post-processing ECMWF precipitation and temperature ensemble reforecasts for operational hydrologic forecasting at various spatial scales

    NASA Astrophysics Data System (ADS)

    Verkade, J. S.; Brown, J. D.; Reggiani, P.; Weerts, A. H.

    2013-09-01

    The ECMWF temperature and precipitation ensemble reforecasts are evaluated for biases in the mean, spread and forecast probabilities, and how these biases propagate to streamflow ensemble forecasts. The forcing ensembles are subsequently post-processed to reduce bias and increase skill, and to investigate whether this leads to improved streamflow ensemble forecasts. Multiple post-processing techniques are used: quantile-to-quantile transform, linear regression with an assumption of bivariate normality and logistic regression. Both the raw and post-processed ensembles are run through a hydrologic model of the river Rhine to create streamflow ensembles. The results are compared using multiple verification metrics and skill scores: relative mean error, Brier skill score and its decompositions, mean continuous ranked probability skill score and its decomposition, and the ROC score. Verification of the streamflow ensembles is performed at multiple spatial scales: relatively small headwater basins, large tributaries and the Rhine outlet at Lobith. The streamflow ensembles are verified against simulated streamflow, in order to isolate the effects of biases in the forcing ensembles and any improvements therein. The results indicate that the forcing ensembles contain significant biases, and that these cascade to the streamflow ensembles. Some of the bias in the forcing ensembles is unconditional in nature; this was resolved by a simple quantile-to-quantile transform. Improvements in conditional bias and skill of the forcing ensembles vary with forecast lead time, amount, and spatial scale, but are generally moderate. The translation to streamflow forecast skill is further muted, and several explanations are considered, including limitations in the modelling of the space-time covariability of the forcing ensembles and the presence of storages.

  16. PRECIPITATION OF PROTACTINIUM

    DOEpatents

    Moore, R.L.

    1958-07-15

    An lmprovement in the separation of protactinium from aqueous nitric acid solutions is described. 1t covers the use of lead dioxide and tin dioxide as carrier precipitates for the protactinium. In carrying out the process, divalent lead or divalent tin is addcd to the solution and oxidized, causing formation of a carrier precipitate of lead dioxide or stannic oxide, respectively.

  17. Auger recombination as the dominant recombination process in indium nitride at low temperatures during steady-state photoluminescence

    SciTech Connect

    Seetoh, I. P.; Soh, C. B.; Fitzgerald, E. A.; Chua, S. J.

    2013-03-11

    Auger recombination in InN films grown by metal-organic chemical vapor deposition was studied by steady-state photoluminescence at different laser excitation powers and sample temperatures. It was dominant over radiative recombination and Shockley-Read-Hall recombination at low temperatures, contributing to the sub-linear relationship between the integrated photoluminescence intensity and laser excitation power. Auger recombination rates increased gradually with temperature with an activation energy of 10-17 meV, in good agreement with values from transient photoluminescence reported in literature. As the Auger recombination rates were independent of material quality, they may form an upper limit to the luminous efficiency of InN.

  18. Auger recombination as the dominant recombination process in indium nitride at low temperatures during steady-state photoluminescence

    NASA Astrophysics Data System (ADS)

    Seetoh, I. P.; Soh, C. B.; Fitzgerald, E. A.; Chua, S. J.

    2013-03-01

    Auger recombination in InN films grown by metal-organic chemical vapor deposition was studied by steady-state photoluminescence at different laser excitation powers and sample temperatures. It was dominant over radiative recombination and Shockley-Read-Hall recombination at low temperatures, contributing to the sub-linear relationship between the integrated photoluminescence intensity and laser excitation power. Auger recombination rates increased gradually with temperature with an activation energy of 10-17 meV, in good agreement with values from transient photoluminescence reported in literature. As the Auger recombination rates were independent of material quality, they may form an upper limit to the luminous efficiency of InN.

  19. Spatial dependences among precipitation maxima over Belgium

    NASA Astrophysics Data System (ADS)

    Vannitsem, S.; Naveau, P.

    2007-09-01

    For a wide range of applications in hydrology, the probability distribution of precipitation maxima represents a fundamental quantity to build dykes, propose flood planning policies, or more generally, to mitigate the impact of precipitation extremes. Classical Extreme Value Theory (EVT) has been applied in this context by usually assuming that precipitation maxima can be considered as Independent and Identically Distributed (IID) events, which approximately follow a Generalized Extreme Value distribution (GEV) at each recording site. In practice, weather stations records can not be considered as independent in space. Assessing the spatial dependences among precipitation maxima provided by two Belgium measurement networks is the main goal of this work. The pairwise dependences are estimated by a variogram of order one, also called madogram, that is specially tailored to be in compliance with spatial EVT and to capture EVT bivariate structures. Our analysis of Belgium precipitation maxima indicates that the degree of dependence varies greatly according to three factors: the distance between two stations, the season (summer or winter) and the precipitation accumulation duration (hourly, daily, monthly, etc.). Increasing the duration (from one hour to 20 days) strengthens the spatial dependence. The full independence is reached after about 50 km (100 km) for summer (winter) for a duration of one hour, while for long durations only after a few hundred kilometers. In addition this dependence is always larger in winter than in summer whatever is the duration. An explanation of these properties in terms of the dynamical processes dominating during the two seasons is advanced.

  20. A Coupled GCM-Cloud Resolving Modeling System, and A Regional Scale Model to Study Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2006-01-01

    Recent GEWEX Cloud System Study (GCSS) model comparison projects have indicated that cloud-resolving models (CRMs) agree with observations better than traditional single-column models in simulating various types of clouds and cloud systems from different geographic locations. Current and future NASA satellite programs can provide cloud, precipitation, aerosol and other data at very fine spatial and temporal scales. It requires a coupled global circulation model (GCM) and cloud-scale model (termed a super-parameterization or multi-scale modeling framework, MMF) to use these satellite data to improve the understanding of the physical processes that are responsible for the variation in global and regional climate and hydrological systems. The use of a GCM will enable global coverage, and the use of a CRM will allow for better and more sophisticated physical parameterization. NASA satellite and field campaign cloud related datasets can provide initial conditions as well as validation for both the MMF and CRMs. The Goddard MMF is based on the 2D Goddard Cumulus Ensemble (GCE) model and the Goddard finite volume general circulation model (fvGCM), and it has started production runs with two years results (1 998 and 1999).

  1. Precipitation processes developed during TOGA COARE (1992), GATE (1974), SCSMEX (1998), and KWAJEX (1999): 3D Cloud Resolving Model Simulation

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.

    2006-01-01

    Real clouds and cloud systems are inherently three-dimensional (3D). Because of the limitations in computer resources, however, most cloud-resolving models (CRMs) today are still two-dimensional (2D). A few 3D CRMs have been used to study the response of clouds to large-scale forcing. In these 3D simulations, the model domain was small, and the integration time was 6 hours. Only recently have 3D experiments been performed for multi-day periods for tropical cloud systems with large horizontal domains at the National Center for Atmospheric Research (NCAR), NOAA GFDL, the U.K. Met. Office, Colorado State University and NASA Goddard Space Flight Center. An improved 3D Goddard Cumulus Ensemble (GCE) model was recently used to simulate periods during TOGA COARE (December 19-27, 1992), GATE (september 1-7, 1974), SCSMEX (May 18-26, June 2-11, 1998) and KWAJEX (August 7-13, August 18-21, and August 29-September 12, 1999) using a 512 by 512 km domain and 41 vertical layers. The major objectives of this paper are: (1) to identify the differences and similarities in the simulated precipitation processes and their associated surface and water energy budgets in TOGA COARE, GATE, KWAJEX, and SCSMEX, and (2) to asses the impact of microphysics, radiation budget and surface fluxes on the organization of convection in tropics.

  2. Microbial precipitation of dolomite in methanogenic groundwater

    NASA Astrophysics Data System (ADS)

    Roberts, Jennifer A.; Bennett, Philip C.; González, Luis A.; MacPherson, G. L.; Milliken, Kitty L.

    2004-04-01

    We report low-temperature microbial precipitation of dolomite in dilute natural waters from both field and laboratory experiments. In a freshwater aquifer, microorganisms colonize basalt and nucleate nonstoichiometric dolomite on cell walls. In the laboratory, ordered dolomite formed at near-equilibrium conditions from groundwater with molar Mg:Ca ratios of <1; dolomite was absent in sterile experiments. Geochemical and microbiological data suggest that methanogens are the dominant metabolic guild in this system and are integral to dolomite precipitation. We hypothesize that the attached microbial consortium reacts with the basalt surface, releasing Mg and Ca into solution, which drives dolomite precipitation via nucleation on the cell wall. These findings provide insight into the long-standing dolomite problem and suggest a fundamental role for microbial processes in the formation of dolomite across a wide range of environmental conditions.

  3. A framework for process-based assessment of regional climate model experiments: applied to projections of southern African precipitation

    NASA Astrophysics Data System (ADS)

    James, Rachel; Washington, Richard; Jones, Richard

    2015-04-01

    There is a demand from adaptation planners for regional climate change projections, particularly the finer resolution data delivered by regional models. However, climate models are subject to important uncertainties, and their projections diverge substantially, particularly for precipitation. So how should decision makers know which futures to consider and which to disregard? Model evaluation is clearly a priority. The majority of studies seeking to assess the validity of projections are based on comparison of the models' twentieth century climatologies with observations or reanalysis. Whilst this work is very important, examination of the modelled mean state it is not sufficient to assess the credibility of modelled changes. Direct investigation of the mechanisms for change is also vital. In this study, a framework for process-based analysis of projections is presented, whereby circulation changes accompanying future responses are examined, and then compared to atmospheric dynamics during historical years in models and reanalyses. This framework has previously been applied to investigate a drying signal in West Africa, and will here be used to examine projected precipitation change in southern Africa. An ensemble of five global and regional model experiments will be employed, consisting of five perturbed versions of HadCM3 and five corresponding runs of HadRM3P (PRECIS), run over the CORDEX Africa domain. The global and regional model runs show contrasting future responses: there is a strong drying in the global models over southern Africa during the rainy season, but the regional models show drying over Madagascar and the south west Indian Ocean. Circulation changes associated with these projections will be presented as a first step towards understanding the mechanisms for change and the reasons for difference between the global and regional models. The interannual variability will also be examined and compared to reanalysis to explore how well the models

  4. Changes in extreme precipitation and their dependence on temporal resolution and precipitation classification

    NASA Astrophysics Data System (ADS)

    Berg, Peter; Haerter, Jan; Hagemann, Stefan

    2010-05-01

    At short temporal resolutions it has been found in the literature that the rate of increase of heavy precipitation with temperature may well exceed the increase of moisture holding capacity of the atmosphere, as described by the Clausius-Clapeyron relation. While this may point towards strong dynamical processes in the atmosphere leading to dramatic moisture convergence and subsequent rapid lifting of moist air, the explanation may also lie in a statistical superposition of distinct meteorological phenomena, namely the dominance of large-scale (frontal) precipitation at lower temperatures and in the winter months, and convective (thunderstorm like) events at high temperatures. A high resolution data set of precipitation measurements are used to study the scaling relations of probability distributions of precipitation intensity and the dependence on the temporal resolution of the data. We use a data set of five-minute resolution precipitation observations from six German stations, each with over 30 year long measurement records. In a first step, a cascade of averaging intervals is computed to obtain the behaviour of precipitation intensity from the instantaneous to the daily resolution. While the distribution of the shortest timescale displays a strict power-law tail, it acquires a more elaborate scaling when precipitation and dry periods are mixed at longer averaging intervals. The typical event size of all events are found to be between 30 and 60 minutes. Next, the precipitation data is classified into stratiform and convective precipitation types using the EECRA data base of WMO station synoptic observations, corresponding to the exact locations of our precipitation data. The synoptic observations are available at three hourly time steps, and the classification is assumed to be valid for one hour before and after the time of the observation. Statistical properties - such as the probability density function for precipitation intensities and event statistics and

  5. A Guide for Developing Standard Operating Job Procedures for the Tertiary Chemical Treatment - Lime Precipitation Process Wastewater Treatment Facility. SOJP No. 6.

    ERIC Educational Resources Information Center

    Petrasek, Al, Jr.

    This guide describes the standard operating job procedures for the tertiary chemical treatment - lime precipitation process of wastewater treatment plants. Step-by-step instructions are given for pre-start up, start-up, continuous operation, and shut-down procedures. In addition, some theoretical material is presented along with some relevant…

  6. Dominant mixed QCD-electroweak O (αs α) corrections to Drell-Yan processes in the resonance region

    NASA Astrophysics Data System (ADS)

    Dittmaier, Stefan; Huss, Alexander; Schwinn, Christian

    2016-03-01

    A precise theoretical description of W- and Z-boson production in the resonance region is essential for the correct interpretation of high-precision measurements of the W-boson mass and the effective weak mixing angle. Currently, the largest unknown fixed-order contribution is given by the mixed QCD-electroweak corrections of O (αs α) . We argue, using the framework of the pole expansion for the NNLO QCD-electroweak corrections established in a previous paper, that the numerically dominant corrections arise from the combination of large QCD corrections to the production with the large electroweak corrections to the decay of the W / Z boson. We calculate these so-called factorizable corrections of "initial-final" type and estimate the impact on the W-boson mass extraction. We compare our results to simpler approximate combinations of electroweak and QCD corrections in terms of naive products of NLO QCD and electroweak correction factors and using leading-logarithmic approximations for QED final-state radiation as provided by the structure-function approach or QED parton-shower programs. We also compute corrections of "final-final" type, which are given by finite counterterms to the leptonic vector-boson decays and are found to be numerically negligible.

  7. Warming and increased precipitation frequency on the Colorado Plateau: Implications for biological soil crusts and soil processes

    SciTech Connect

    Zelikova TJ; Hosman DC; Grote EE; Neher DA; Belnap J

    2011-03-21

    Frequent hydration and drying of soils in arid systems can accelerate desert carbon and nitrogen mobilization due to respiration, microbial death, and release of intracellular solutes. Because desert microinvertebrates can mediate nutrient cycling, and the autotrophic components of crusts are known to be sensitive to rapid desiccation due to elevated temperatures after wetting events, we studied whether altered soil temperature and frequency of summer precipitation can also affect the composition of food web consumer functional groups. We conducted a two-year field study with experimentally-elevated temperature and frequency of summer precipitation in the Colorado Plateau desert, measuring the change in abundance of nematodes, protozoans, and microarthropods. We hypothesized that microfauna would be more adversely affected by the combination of elevated temperature and frequency of summer precipitation than either effect alone, as found previously for phototrophic crust biota. Microfauna experienced normal seasonal fluctuations in abundance, but the effect of elevated temperature and frequency of summer precipitation was statistically non-significant for most microfaunal groups, except amoebae. The seasonal increase in abundance of amoebae was reduced with combined elevated temperature and increased frequency of summer precipitation compared to either treatment alone, but comparable with control (untreated) plots. Based on our findings, we suggest that desert soil microfauna are relatively more tolerant to increases in ambient temperature and frequency of summer precipitation than the autotrophic components of biological soil crust at the surface.

  8. Cell Death Processes during Expression of Hybrid Lethality in Interspecific F1 Hybrid between Nicotiana gossei Domin and Nicotiana tabacum

    PubMed Central

    Mino, Masanobu; Maekawa, Kenji; Ogawa, Ken'ichi; Yamagishi, Hiroshi; Inoue, Masayoshi

    2002-01-01

    Hybrid lethality, a type of reproductive isolation, is a genetically controlled event appearing at the seedling stage in interspecific hybrids. We characterized the lethality of F1 hybrid seedlings from Nicotiana gossei Domin and Nicotiana tabacum cv Bright-Yellow 4 using a number of traits including growth rate, microscopic features of tissues and cells, ion leakage, DNA degradation, reactive oxygen intermediates including superoxide radical (O2−) and hydrogen peroxide (H2O2), and expression of stress response marker genes. Lethal symptoms appeared at 4 d after germination in the basal hypocotyl and extended toward both the hypocotyl and root of the plants grown at 26°C. Microscopic analysis revealed a prompt lysis of cell components during cell death. Membrane disruption and DNA degradation were found in the advanced stage of the lethality. The death of mesophyll cells in the cotyledon was initiated by the vascular bundle, suggesting that a putative factor inducing cell death diffused into surrounding cells from the vascular tissue. In contrast, these symptoms were not observed in the plants grown at 37°C. Seedlings grown at 26°C generated larger amounts of reactive oxygen intermediate in the hypocotyl than those grown at 37°C. A number of stress response marker genes were expressed at 26°C but not at 37°C. We proposed that a putative death factor moving systemically through the vascular system induced a prompt and successive lysis of the cytoplasm of cells and that massive cell death eventually led to the loss of the hybrid plant. PMID:12481061

  9. On the complex conductivity signatures of calcite precipitation

    SciTech Connect

    Wu, Yuxin; Hubbard, Susan; Williams, Kenneth Hurst; Ajo-Franklin, Jonathan

    2009-11-01

    Calcite is a mineral phase that frequently precipitates during subsurface remediation or geotechnical engineering processes. This precipitation can lead to changes in the overall behavior of the system, such as flow alternation and soil strengthening. Because induced calcite precipitation is typically quite variable in space and time, monitoring its distribution in the subsurface is a challenge. In this research, we conducted a laboratory column experiment to investigate the potential of complex conductivity as a mean to remotely monitor calcite precipitation. Calcite precipitation was induced in a glass bead (3 mm) packed column through abiotic mixing of CaCl{sub 2} and Na{sub 2}CO{sub 3} solutions. The experiment continued for 12 days with a constant precipitation rate of {approx}0.6 milimole/d. Visual observations and scanning electron microscopy imaging revealed two distinct phases of precipitation: an earlier phase dominated by well distributed, discrete precipitates and a later phase characterized by localized precipitate aggregation and associated pore clogging. Complex conductivity measurements exhibited polarization signals that were characteristic of both phases of calcite precipitation, with the precipitation volume and crystal size controlling the overall polarization magnitude and relaxation time constant. We attribute the observed responses to polarization at the electrical double layer surrounding calcite crystals. Our experiment illustrates the potential of electrical methods for characterizing the distribution and aggregation state of nonconductive minerals like calcite. Advancing our ability to quantify geochemical transformations using such noninvasive methods is expected to facilitate our understanding of complex processes associated with natural subsurface systems as well as processes induced through engineered treatments (such as environmental remediation and carbon sequestration).

  10. Numerical Simulations of Precipitation Processes, Microphysics, and Microwave Radiative Properties of flood Producing Storms in Mediterranean & Adriatic Basins

    NASA Technical Reports Server (NTRS)

    Smith, Eric A.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    A comprehensive understanding of the meteorological and microphysical nature of Mediterranean storms requires a combination of in situ data analysis, radar data analysis, and satellite data analysis, effectively integrated with numerical modeling studies at various scales. An important aspect of understanding microphysical controls of severe storms, is first understanding the meteorological controls under which a storm has evolved, and then using that information to help characterize the dominant microphysical processes. For hazardous Mediterranean storms, highlighted by the October 5-6, 1998 Friuli flood event in northern Italy, a comprehensive microphysical interpretation requires an understanding of the multiple phases of storm evolution. This involves intense convective development, Sratiform decay, orographic lifting, and sloped frontal lifting processes, as well as the associated vertical motions and thermodynamical instabilities governing physical processes that effect details of the size distributions and fall rates of the various types of hydrometeors found within the storm environment. This talk overviews the microphysical elements of a severe Mediterranean storm in such a context, investigated with the aid of TRMM satellite and other remote sensing measurements, but guided by a nonhydrostatic mesoscale model simulation of the Friuli flood event. The data analysis for this paper was conducted by my research groups at the Global Hydrology and Climate Center in Huntsville, AL and Florida State University in Tallahassee, and in collaboration with Dr. Alberto Mugnai's research group at the Institute of Atmospheric Physics in Rome. The numerical modeling was conducted by Professor Oreg Tripoli and Ms. Giulia Panegrossi at the University of Wisconsin in Madison, using Professor Tripoli's nonhydrostatic modeling system (NMS). This is a scalable, fully nested mesoscale model capable of resolving nonhydrostatic circulations from regional scale down to cloud scale

  11. Permeability Reduction in Passively Degassing Seawater-dominated Volcanic-hydrothermal systems: Processes and Perils on Raoul Island, Kermadecs (NZ)

    NASA Astrophysics Data System (ADS)

    Christenson, B. W.; Reyes, A. G.

    2014-12-01

    The 2006 eruption from Raoul Island occurred apparently in response to local tectonic swarm activity, but without any precursory indication of volcanic unrest within the hydrothermal system on the island. The eruption released some 200 T of SO2, implicating the involvement of a deep magmatic vapor input into the system during/prior to the event. In the absence of any recognized juvenile material in the eruption products, previous explanations for this eruptive event focused on this vapor being a driving force for the eruption. In 2004, at least 80 T/d of CO2 was escaping from the hydrothermal system, but mainly through areas that did not correspond to the 2006 eruption vents. The lack of a pre-eruptive hydrothermal system response related to the seismic event in 2006 can be explained by the presence of a hydrothermal mineralogic seal in the vent area of the volcano. Evidence for the existence of such a seal was found in eruption deposits in the form of massive fracture fillings of aragonite, calcite and anhydrite. Fluid inclusion homogenization temperatures in these phases range from ca. 140 °C to 220 °C which, for pure water indicate boiling point depths of between 40 and 230 m assuming a cold hydrostatic pressure constraint. Elevated pressures behind this seal are consistent with the occurrence of CO2 clathrates in some inclusion fluids, indicating CO2 concentrations approaching 1 molal in the parent fluids. Reactive transport modeling of magmatic volatile inputs into what is effectively a seawater-dominated hydrothermal system provide valuable insights into seal formation. Carbonate mineral phases ultimately come to saturation along this flow path, but we suggest that focused deposition of the observed massive carbonate seal is facilitated by near-surface boiling of these CO2-enriched altered seawaters, leading to large degrees of supersaturation which are required for the formation of aragonite. As the seal grew and permeability declined, pore pressures

  12. Influence of Microscopic Diffusive Process on Uranyl Precipitation and Dissolution in Subsurface Sediments at Hanford Site, USA

    SciTech Connect

    Liu, Chongxuan; Zachara, John M.; McKinley, James P.; Wang, Zheming; Majors, Paul D.

    2004-03-29

    Uranium in DOE Hanford sediments was found to be distributed as uranyl silicate precipitates almost exclusively within interiors of sediment grains. The precipitates were minute, generally 1-3 {micro}m across in either radiating or parallel arrays in intraparticle microfractures of a few microns width and variable connectivity to particle surfaces. Grain-scale porosity, tortuosity and diffusivity of tracer (H2O) and U(VI) were measured and imaged using various spectroscopic techniques. Simulations using a microscopic reactive diffusion model suggested that diffusion-limited mass transport generated a favorable thermodynamic condition within the grain microfractures for precipitation and concentration of uranium from waste plumes. The rate and extent of uranyl precipitate dissolution were studied in various electrolytes with variable pH under ambient CO2 pressure. Uranium speciation and distribution before and after dissolution were monitored by spectroscopic and imaging techniques . Experimental, spectroscopic and modeling results collectively indicated that dissolution of uranyl precipitates was controlled by diffusion-limited dissolution kinetics.

  13. Sex-linked dominant

    MedlinePlus

    Inheritance - sex-linked dominant; Genetics - sex-linked dominant; X-linked dominant; Y-linked dominant ... one of the sex chromosomes, which are the X and Y chromosomes. Dominant inheritance occurs when an ...

  14. Co-variability of spring and autumn precipitation over France: Evidence of missing processes in current climate models?

    NASA Astrophysics Data System (ADS)

    Hirschi, M.; Seneviratne, S. I.

    2009-04-01

    In a previous paper, negative correlations between domain-averaged spring and autumn precipitation of the same year were found in two domains covering France and Central Europe for the period 1972-1990 (Hirschi et al. 2007). Here we further investigate this link and its temporal evolution over France during the 20th century and relate it to the atmospheric circulation. The link is analyzed using observational data sets of precipitation, mean sea level pressure and teleconnection patterns. Moreover, we analyze various global and regional climate models in terms of this phenomenon. The temporal evolution of the described link in precipitation over France is analyzed over the 20th century by means of a running correlation with a 30-year time window. The investigation of various observational precipitation data sets reveals a decreasing trend in the spring to autumn correlations, which become significantly negative in the second half of the last century. These negative correlations can be explained by significantly negative spring to autumn correlations in observed mean sea level pressure, and by the significantly negatively correlated spring East Atlantic and autumn Scandinavian teleconnection patterns. Except for the ERA-40 driven regional climate models from ENSEMBLES, the analyzed regional and global climate models, including IPCC AR4 simulations, do not capture this observed variability in precipitation. This is associated with a failure of most models in simulating the observed correlations between spring and autumn mean sea level pressure. References: Hirschi, M., S. I. Seneviratne, S. Hagemann, and C. Schär (2007). Analysis of seasonal terrestrial water storage variations in regional climate simulations over Europe. J. Geophys. Res., 112(D22109):doi:10.1029/2006JD008338.

  15. Cloud and Precipitation Radar

    NASA Astrophysics Data System (ADS)

    Hagen, Martin; Höller, Hartmut; Schmidt, Kersten

    Precipitation or weather radar is an essential tool for research, diagnosis, and nowcasting of precipitation events like fronts or thunderstorms. Only with weather radar is it possible to gain insights into the three-dimensional structure of thunderstorms and to investigate processes like hail formation or tornado genesis. A number of different radar products are available to analyze the structure, dynamics and microphysics of precipitation systems. Cloud radars use short wavelengths to enable detection of small ice particles or cloud droplets. Their applications differ from weather radar as they are mostly orientated vertically, where different retrieval techniques can be applied.

  16. Effects of variation in precipitation on the distribution of soil bacterial diversity in the primitive Korean pine and broadleaved forests.

    PubMed

    Wang, Nannan; Wang, Meiju; Li, Shilan; Sui, Xin; Han, Shijie; Feng, Fujuan

    2014-11-01

    Patterns of precipitation have changed as a result of climate change and will potentially keep changing in the future. Therefore, it is critical to understand how ecosystem processes will respond to the variation of precipitation. However, compared to aboveground processes, the effects of precipitation change on soil microorganisms remain poorly understood. Changbai Mountain is an ideal area to study the responses of temperate forests to the variations in precipitation. In this study, we conducted a manipulation experiment to simulation variation of precipitation in the virgin, broad-leaved Korean pine mixed forest in Changbai Mountain. Plots were designed to increase precipitation by 30 % [increased (+)] or decrease precipitation by 30 % [decreased (-)]. We analyzed differences in the diversity of the bacterial community in surface bulk soils (0-5 and 5-10 cm) and rhizosphere soils between precipitation treatments, including control. Bacteria were identified using the high-throughput 454 sequencing method. We obtained a total 271,496 optimized sequences, with a mean value of 33,242 (±1,412.39) sequences for each soil sample. Being the same among the sample plots with different precipitation levels, the dominant bacterial communities were Proteobacteria, Acidobacteria, Actinobacteria, Planctomycetes, and Chloroflexi. Bacterial diversity and abundance declined with increasing soil depth. In the bulk soil of 0-5 cm, the bacterial diversity and abundance was the highest in the control plots and the lowest in plots with reduced precipitation. However, in the soil of 5-10 cm, the diversity and abundance of bacteria was the highest in the plots of increased precipitation and the lowest in the control plots. Bacterial diversity and abundance in rhizosphere soils decreased with increased precipitation. This result implies that variation in precipitation did not change the composition of the dominant bacterial communities but affected bacterial abundance and the response

  17. Evaluation of moist processes during intense precipitation in km-scale NWP models using remote sensing and in-situ data: Impact of microphysics size distribution assumptions

    SciTech Connect

    Van Weverberg, K.; van Lipzig, N. P. M.; Delobbe, L.

    2011-02-01

    This study investigates the sensitivity of moist processes and surface precipitation during three extreme precipitation events over Belgium to the representation of rain, snow and hail size distributions in a bulk one-moment microphysics parameterisation scheme. Sensitivities included the use of empirically derived relations to calculate the slope parameter and diagnose the intercept parameter of the exponential snow and rain size distributions and sensitivities to the treatment of hail/graupel. A detailed evaluation of the experiments against various high temporal resolution and spatially distributed observational data was performed to understand how moist processes responded to the implemented size distribution modifications. Net vapor consumption by microphysical processes was found to be unaffected by snow or rain size distribution modifications, while it was reduced replacing formulations for hail by those typical for graupel, mainly due to intense sublimation of graupel. Cloud optical thickness was overestimated in all experiments and all cases, likely due to overestimated snow amounts. The overestimation slightly deteriorated by modifying the rain and snow size distributions due to increased snow depositional growth, while it was reduced by including graupel. The latter was mainly due to enhanced cloud water collection by graupel and reduced snow depositional growth. Radar reflectivity and cloud optical thickness could only be realistically represented by inclusion of graupel during a stratiform case, while hail was found indispensable to simulate the vertical reflectivity profile and the surface precipitation structure. Precipitation amount was not much altered by any of the modifications made and the general overestimation was only decreased slightly during a supercell convective case.

  18. Heavy warm season precipitation events in northern Spain: ¿mediterranean processes in an oceanic temperate region?

    NASA Astrophysics Data System (ADS)

    García Codrón, J. C.; Rasilla Álvarez, D.; Garmendia Pedraja, C.

    2009-09-01

    The northern coast of the Iberian Peninsula is one of the wettest areas of Europe. Most of the coastal observatories receive exceed 1000mm, and the rainfall is higher than 1700mm along the basque coast. The contribution of late summer-early fall precipitation is remarkable (about 25 %), unusual taking in account the southern latitude of the region at continental scale (Cfb climate, following Köppen’s notation). One of the causes of this summertime wetness are the frequent heavy rainfall events, historically responsible of the most damaging floods in the region. The aim of this paper is to identify and investigate the spatial and temporal characteristics of those heavy rain events, improving the understanding of the dynamical mechanisms by means of a classification of the related atmospheric patterns. The role of the exchange of heat fluxes from a very warm pool of water around the vertex of the Gulf of Biscay, feeding the lowest atmospheric layers, is also discussed. Heavy rainfall events were analyzed using long-term daily rainfall records from 22 stations belonging to the spanish, portuguese and french meteorological networks. The 1000 hPa and 500 hPa geopotential heights (hereafter Z1000 and Z500), as well as the 850 hPa temperature (T850) were utilized to derive a typology of circulation pattern, combining principal components analysis (PCA) and cluster analysis (CA). Results show that most of those heavy precipitation events, whose atmospheric environment and spatial impacts remember some of the typical features of the heavy precipitation events in the Spanish Mediterranean coast, implicate convective systems, associated to upper level stationary disturbances ("cold lows"), which trigger a thermodynamic instability. Most of them affect a relatively restricted area, from Cantabria to the Basque Country, and, even within this area, most of the precipitation falls in the shorelines and the first orographic ridges. Finally, it is worth to mention that the

  19. Microbial processes dominate P fluxes in a low-phosphorus temperate forest soil: insights provided by 33P and 18O in phosphate

    NASA Astrophysics Data System (ADS)

    Pistocchi, Chiara; Tamburini, Federica; Bünemann, Else; Mészáros, Éva; Frossard, Emmanuel

    2016-04-01

    The classical view of the P cycle in forests is that trees and mycorrhizal fungi associated with them take up most of their phosphorus as phosphate (P) from the soil solution. The soil solution is then replenished by the release of P from sorbed phases, by the dissolution of P containing minerals or by biological mineralization and/or enzymatic hydrolysis of organic P compounds. Direct insight into the processes phosphate goes through at the ecosystem level is, however, missing. Assessing the relevance of inorganic and biological processes controlling P cycling requires the use of appropriate approaches and tracers. Within the German Priority Program "Ecosystem Nutrition: Forest Strategies for limited Phosphorus Resources" we studied P forms and dynamics in organic horizons (Of/Oh) of temperate beech forest soils in Germany with contrasting soil P availability (P-poor and P-rich). We followed the fate of P from the litter into the soil pools, using isotopes as tracers (stable oxygen isotopes in water and phosphate and 33P) and relied on measurements in experimental forest sites and a three-months incubation experiment with litter addition. Using an isotopic dilution approach we were able to estimate gross (7 mg P kg‑1 d‑1 over the first month) and net mineralization rates (about 5 mg P kg‑1 d‑1 over the first 10 days) in the P-poor soil. In this soil the immobilization of P in the microbial biomass ranged from 20 to 40% of gross mineralization during the incubation, meaning that a considerable part of mineralized P contributed to replenish the available P pool. In the P-rich soil, physicochemical processes dominated exchangeable P to the point that the contribution of biological/biochemical processes was non-detectable. Oxygen isotopes in phosphate elucidated that organic P mineralization by enzymatic hydrolysis gains more importance with decreasing P availability, both under controlled and under field conditions. In summary, microbial processes dominated P

  20. Using Nitrate N and O Isotope Ratios to Identify Nitrate Sources and Dominant Nitrogen Cycling Processes in a 12ha Tile Drained Dryland Agricultural Field in the Palouse Basin of Eastern Washington State

    NASA Astrophysics Data System (ADS)

    Kelley, C. J.; Keller, C. K.; Evans, R. D.; Orr, C. H.; Smith, J. L.

    2010-12-01

    Agricultural systems are a leading source of reactive nitrogen to aquatic and atmospheric ecosystem. Understanding how anthropogenic nitrogen sources are cycled during transport from agricultural systems to aquatic and atmospheric systems is essential to identify the sink(s) of missing nitrogen and improve nitrogen management. Here we use natural nitrate 15N and 18O isotope abundances to determine the timing of nitrogen cycling process and to identify the source of nitrate discharged from a tile drained section of the WSU Cook Agronomy Farm. Previous research at the Cook Farm has shown that 5% to 20% of fertilizer nitrogen leaves the system as nitrate through the tile-drain. Identifying the timing of nitrogen cycling events and identifying the source(s) of tile drain nitrate is the first step to reduce nitrogen loss to aquatic systems bordering agricultural land. Throughout the 5 year study period δ18Onitrate averaged -1.26±1.48‰, indicating that nitrate-oxygen isotopes were not being enriched. Tile drain nitrate δ15N varied seasonally from -0.48‰ in the winter to +9.24‰ during the summer with an average of +3.19±2.62‰. The lack of nitrate-oxygen enrichment during the study period indicates that nitrification is the dominant nitrogen cycling process in the tile drained soil. The expected δ18Onitrate from nitrification based on the nitrification equation is -2.0‰, also supporting the claim that nitrification is the dominant nitrogen cycling process in the soil drained by the tile drain system. The large range of nitrate δ15N overlaps the expected isotope values for nitrate from nitrified synthetic nitrogen fertilizers and soil organic nitrogen. Nitrate-nitrogen and nitrate-oxygen isotope abundances have shown that nitrate in high nitrate concentration TD discharge originates from nitrification of reduced nitrogen fertilizers and nitrate in low nitrate concentration TD discharge originates from nitrification of; 1) soil organic nitrogen, 2) biotically

  1. Simultaneous removal of ammonia, P and COD from anaerobically digested piggery wastewater using an integrated process of chemical precipitation and air stripping.

    PubMed

    Quan, Xuejun; Ye, Changying; Xiong, Yanqi; Xiang, Jinxin; Wang, Fuping

    2010-06-15

    The paper presented an efficient integrated physicochemical process, which consists of chemical precipitation and air stripping, for the simultaneous removal of NH(3)-N, total P and COD from anaerobically digested piggery wastewater. In the integrated process, Ca(OH) (2) was used as the precipitant for NH(4)(+), PO(4)(3-) and organic phosphorous compounds, and as the pH adjuster for the air stripping of residual ammonia. The possibility of the suggested process and the related mechanisms were first investigated through a series of equilibrium tests. Laboratory scale tests were carried out to validate the application possibility of the integrated process using a new-patented water sparged aerocyclone reactor (WSA). The WSA could be effectively used for the simultaneous removal of NH(3)-N, total P and COD. 3g/L of Ca(OH) (2) is a proper dosage for the simultaneous removal. The simultaneous removal of NH(3)-N, total P and COD in the WSA reactor could be easily optimized by selecting a proper air inlet velocity and a proper jet velocity of the liquid phase. In all the cases, the removal efficiencies of the NH(3)-N, total P and COD were over 91%, 99.2% and 52% for NH(3)-N, total P and COD, respectively. The formed precipitates in the process could be easily settled down from the suspension system. Therefore, the integrated process provided an efficient alternative for the simultaneous removal of NH(3)-N, total P and COD from the wastewater. PMID:20189301

  2. Effect of rapid thermal processing on copper precipitation in p/p{sup +} silicon epitaxial wafers with heavily boron-doped substrates

    SciTech Connect

    Xu, Jin; Ji, Chuan; Zhang, Guangchao

    2014-01-14

    The effect of rapid thermal processing (RTP) on the formation of copper precipitation in p/p{sup +} silicon (Si) epitaxial wafers was systematically investigated by defect etching and optical microscopy. After RTP preannealing at high temperature (1250 °C/60 s, with cooling rate 30 K/s) followed by the 750 °C/8 h + 1050 °C/16 h low-high (L-H) two-step annealing, it was revealed that the bulk microdefects were found only inside the p{sup +} substrate, manifesting no defects generated in the epitaxial layer. However, it was found that the width of denude zone (DZ) in samples only subjected to L-H two-step annealing was narrower than that of epitaxial layer, which meant that oxygen precipitation was formed in epitaxial layer. It can be concluded that RTP was beneficial to the formation of DZ. Additionally, it was found that the width of DZ has a sharp dependence on the introducing temperature of copper contamination, that is, the corresponding equilibrium concentration of interstitial copper in the Si influence the thermodynamics and kinetics process of the formation of copper precipitation significantly.

  3. Nutrient removal and energy production in a urine treatment process using magnesium ammonium phosphate precipitation and a microbial fuel cell technique.

    PubMed

    Zang, Guo-Long; Sheng, Guo-Ping; Li, Wen-Wei; Tong, Zhong-Hua; Zeng, Raymond J; Shi, Chen; Yu, Han-Qing

    2012-02-14

    Urine pretreatment has attracted increasing interest as it is able to relieve the nitrogen and phosphorus overloading problems in municipal wastewater treatment plants. In this study, an integrated process, which combines magnesium ammonium phosphate (MAP) precipitation with a microbial fuel cell (MFC), is proposed for the recovery of a slow-release fertilizer and electricity from urine. In such a two-step process, both nitrogen and phosphorus are recovered through the MAP process, and organic matters in the urine are converted into electricity in the MFCs. With this integrated process, when the phosphorus recovery is maximized without a dose of PO(4)(3-)-P in the MAP precipitation process, removal efficiencies for PO(4)(3)-P and NH(4)(+)-N of 94.6% and 28.6%, respectively, were achieved with a chemical oxygen demand (COD) of 64.9% accompanied by a power output of 2.6 W m(-3). Whereas removal efficiencies for PO(4)(3)-P and NH(4)(+)-N of 42.6% and 40%, respectively, and a COD of 62.4% and power density of 0.9 W m(-3) were obtained if simultaneous recovery of phosphorus and nitrogen was required through dosing with 620 mg L(-1) of PO(4)(3-)-P in the MAP process. This work provides a new sustainable approach for the efficient and cost-effective treatment of urine with the recovery of energy and resources. PMID:22234416

  4. Precipitation intensity and vegetation controls on geomorphology of the central Andes

    NASA Astrophysics Data System (ADS)

    Jeffery, M. L.; Poulsen, C. J.; Ehlers, T. A.; Yanites, B. J.

    2012-12-01

    Field observations and landscape evolution models indicate that landscape processes in active mountain belts are strongly dependent on vegetation and climate. In fluvial landscapes, erosional efficiency is commonly thought to depend on the intensity, frequency, and duration of precipitation events. We use Tropical Rainfall Measuring Mission (TRMM) observations to test the importance of precipitation intensity in determining geomorphology at the mountain belt scale. Precipitation metrics, including mean annual precipitation, and the mean intensity, duration, and frequency of precipitation events, are derived from the TRMM 3B42v7 product. The new precipitation datasets are then compared with different topographic metrics of the central Andes. Statistical analyses, including multiple linear regression, are used to quantify the importance of different precipitation metrics in controlling the regional topographic characteristics. In addition to climate properties, spatial variations in tectonic regime, bedrock lithology, and the amount and type of vegetation cover are accounted for in the statistical analyses. Our analysis indicates that in regions with high vegetation cover (>80%), mean precipitation intensity and mean interval correlate most strongly with mean hillslope (r = -0.51 and r = -0.66 respectively). In these regions, mean hillslope decreases from ~25° to ~ 10° with increasing mean event precipitation intensity (from 10 to 40 mm/day). In contrast, in sparsely vegetated (<40%) or shrub-dominated landscapes, precipitation intensity does not correlate with mean hillslope (r < 0.1). In regions with high vegetation cover, mean annual precipitation is weakly correlated with mean hillslope (r = 0.24). However, mean hillslope increases with increasing mean annual precipitation (r = 0.52) when all vegetation cover is considered. We interpret the results as evidence that vegetation is a key control on critical erosion thresholds at the landscape scale. Furthermore

  5. Sex-linked dominant

    MedlinePlus

    Inheritance - sex-linked dominant; Genetics - sex-linked dominant; X-linked dominant; Y-linked dominant ... type of chromosome that is affected (autosomal or sex chromosome). It also depends on whether the trait ...

  6. Discontinuous Precipitation in Ni-Base Superalloys During Solution Heat Treatment

    NASA Astrophysics Data System (ADS)

    Welton, D.; D'Souza, N.; Kelleher, J.; Gardner, S.; Dong, Z. H.; West, G. D.; Dong, Hongbiao

    2015-09-01

    Discontinuous precipitation in single-crystal Ni-base superalloys during solution heat treatment has been studied. It is found that discontinuous precipitation occurs at temperatures approaching the solvus, where volume diffusion is dominant. Diffusion of Al ahead of the boundary leads to gamma prime precipitation and is accompanied by a loss in the driving force available for advancement of the grain boundary. The rate of gamma prime precipitation was tracked using in situ neutron diffraction during isothermal hold. Gamma prime precipitation is accompanied by super-saturation of Cr and W within the channels ahead of the interface. The driving force calculated for the initial stages of DP was [10-5 to 10-4] N/[ μm2 of the grain boundary]. The results provide an insight into discontinuous precipitation during solution heat treatment of Ni-base single-crystal alloys and are useful in optimizing the heat treatment process to avoid surface defect formation.

  7. A new combined process for efficient removal of Cu(II) organic complexes from wastewater: Fe(III) displacement/UV degradation/alkaline precipitation.

    PubMed

    Xu, Zhe; Gao, Guandao; Pan, Bingcai; Zhang, Weiming; Lv, Lu

    2015-12-15

    Efficient removal of heavy metals complexed with organic ligands from water is still an important but challenging task now. Herein, a novel combined process, i.e., Fe(III)-displacement/UV degradation/alkaline precipitation (abbreviated as Fe(III)/UV/OH) was developed to remove copper-organic complexes from synthetic solution and real electroplating effluent, and other processes including alkaline precipitation, Fe(III)/OH, UV/OH were employed for comparison. By using the Fe(III)/UV/OH process, some typical Cu(II) complexes, such as Cu(II)-ethylenediaminetetraacetic acid (EDTA), Cu(II)-nitrilotriacetic acid (NTA), Cu(II)-citrate, Cu(II)-tartrate, and Cu(II)-sorbate, each at 19.2 mg Cu/L initially, were efficiently removed from synthetic solution with the residual Cu below 1 mg/L. Simultaneously, 30-48% of total organic carbon was eliminated with exception of Cu(II)-sorbate. Comparatively, the efficiency of other processes was much lower than the Fe(III)/UV/OH process. With Cu(II)-citrate as the model complex, the optimal conditions for the combined process were obtained as: initial pH for Fe(III) displacement, 1.8-5.4; molar ratio of [Fe]/[Cu], 4:1; UV irradiation, 10 min; precipitation pH, 6.6-13. The mechanism responsible for the process involved the liberation of Cu(II) ions from organic complexes as a result of Fe(III) displacement, decarboxylation of Fe(III)-ligand complexes subjected to UV irradiation, and final coprecipitation of Cu(II) and Fe(II)/Fe(III) ions. Up to 338.1 mg/L of Cu(II) in the electroplating effluent could be efficiently removed by the process with the residual Cu(II) below 1 mg/L and the removal efficiency of ∼99.8%, whereas direct precipitation by using NaOH could only result in total Cu(II) removal of ∼8.6%. In addition, sunlight could take the place of UV to achieve similar removal efficiency with longer irradiation time (90 min). PMID:26454633

  8. Precipitation Matters

    ERIC Educational Resources Information Center

    McDuffie, Thomas

    2007-01-01

    Although weather, including its role in the water cycle, is included in most elementary science programs, any further examination of raindrops and snowflakes is rare. Together rain and snow make up most of the precipitation that replenishes Earth's life-sustaining fresh water supply. When viewed individually, raindrops and snowflakes are quite…

  9. Precipitation Recycling in India during South West Monsoon

    NASA Astrophysics Data System (ADS)

    Pathak, A.; Ghosh, S.; Kumar, P.

    2012-12-01

    The summer monsoon (June to September, JJAS) rainfall over India is dominated by oceanic forcing but the land surface hydrology may also have significant role in generation of precipitation over the Indian subcontinent. The present study aims to investigate the role of land surface processes in rainfall through evapotranspiration. As monsoon progresses in Indian subcontinent, the rainfall enhances the soil moisture and vegetation cover. Though the humidity is high during monsoon; very high wind speed, large availability of water surface area, and vegetation cover intensifies the evapotranspiration process. The evapotranspiration over a region in the summer monsoon months supplies the moisture to the atmosphere which may also lead to precipitation other than oceanic sources. However, it is the interaction between land surface and atmosphere that determines the fate of evapotranspirated water molecule. The fraction of precipitation generated because of local evapotranspiration is known as recycled precipitation and this phenomenon is known as precipitation recycling. The precipitation recycling is quantified by recycling ratio which is equal to ratio of recycled precipitation to total precipitation. The estimates of precipitation recycling provide a clear picture of interactions between land and atmosphere for any region and may help in understanding the mechanism behind precipitation. The objective of this work is to study the impact of precipitation recycling on Indian southwest monsoon rainfall. In the present work, daily dataset from National Centers for Environmental Prediction (NCEP) and Climate Forecast System Reanalysis (CFSR), for the period of 1980 to 2001, at a spatial resolution of 0.5o x 0.5o, is used. In order to study the impact of recycling process on monsoon rainfall, dynamic recycling model is used and the regional recycling ratio values for entire Indian sub-continental land region are estimated. It is observed that precipitation recycling is

  10. Production and characterization of poly(3-hydroxybutyrate) generated by Alcaligenes latus using lactose and whey after acid protein precipitation process.

    PubMed

    Berwig, Karina Hammel; Baldasso, Camila; Dettmer, Aline

    2016-10-01

    Whey after acid protein precipitation was used as substrate for PHB production in orbital shaker using Alcaligenes latus. Statistical analysis determined the most appropriate hydroxide for pH neutralization of whey after protein precipitation among NH4OH, KOH and NaOH 10%w/v. The results were compared to those of commercial lactose. A scale-up test in a 4L bioreactor was done at 35°C, 750rpm, 7L/min air flow, and 6.5 pH. The PHB was characterized through Fourier Transform Infrared Spectroscopy, thermogravimetry and differential scanning calorimetry. NH4OH provided the best results for productivity (p), 0.11g/L.h, and for polymer yield, (YP/S), 1.08g/g. The bioreactor experiment resulted in lower p and YP/S. PHB showed maximum degradation temperature (291°C), melting temperature (169°C), and chemical properties similar to those of standard PHB. The use of whey as a substrate for PHB production did not affect significantly the final product quality. PMID:27347795

  11. Extreme Precipitation in a Multi-Scale Modeling Framework

    NASA Astrophysics Data System (ADS)

    Phillips, M.; Denning, S.; Arabi, M.

    2015-12-01

    Extreme precipitation events are characterized by infrequent but large magnitude accummulatations that generally occur on scales belowthat resolved by the typical Global Climate Model. The Multi-scale Modeling Framework allows for information about the precipitation on these scales to be simulated for long periods of time without the large computational resources required for the use of a full cloud permitting model. The Community Earth System Model was run for 30 years in both its MMF and GCM modes, and the annual maximum series of 24 hour precipitation accumulations were used to estimate the parameters of statistical distributions. The distributions generated from model ouput were then t to a General Extreme Value distribution and evaluated against observations. These results indicate that the MMF produces extreme precipitation with a statistical distribution that closely resembles that of observations and motivates the continued use of the MMF for analysis of extreme precipitation, and shows an improvement over the traditional GCM. The improvement in statistical distributions of annual maxima is greatest in regions that are dominated by convective precipitation where the small-scale information provided by the MMF heavily influences precipitation processes.

  12. Effects of the fabrication process parameters on the precipitates and mechanical properties of a 9Cr-2W-V-Nb steel

    NASA Astrophysics Data System (ADS)

    Kim, Tae Kyu; Baek, Jong Hyuk; Han, Chang Hee; Kim, Sung Ho; Lee, Chan Bock

    2009-06-01

    The effects of the fabrication process parameters such as a tempering temperature, cold rolling and annealing condition on the precipitates and mechanical properties of a normalized 9Cr-2W-V-Nb steel were evaluated. Nb-rich MX precipitates were found in the specimen tempered at 550 °C while M 23C 6, Nb- and V-rich MX ones were observed in the specimen tempered at 750 °C. A cold rolling and an annealing at 750 °C of the specimen tempered at 550 °C induced the formation of large inhomogeneous M 23C 6 carbides, causing a reduced tensile strength. However, the cold rolling of the specimen tempered at 750 °C provided fine precipitates due to a fragmentation of some of the M 23C 6 carbides, and an annealing at 700 °C for 30 min was found to be suitable to recover the degraded mechanical properties from a cold working.

  13. DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES

    DOEpatents

    Fries, B.A.

    1959-11-10

    A plutonium separatory ore concentration procedure involving the use of a fluoride type of carrier is presented. An improvement is given in the derivation step in the process for plutonium recovery by carrier precipitation of plutonium values from solution with a lanthanum fluoride carrier precipitate and subsequent derivation from the resulting plutonium bearing carrier precipitate of an aqueous acidic plutonium-containing solution. The carrier precipitate is contacted with a concentrated aqueous solution of potassium carbonate to effect dissolution therein of at least a part of the precipitate, including the plutonium values. Any remaining precipitate is separated from the resulting solution and dissolves in an aqueous solution containing at least 20% by weight of potassium carbonate. The reacting solutions are combined, and an alkali metal hydroxide added to a concentration of at least 2N to precipitate lanthanum hydroxide concomitantly carrying plutonium values.

  14. Acidic precipitation

    SciTech Connect

    Martin, H.C.

    1987-01-01

    At the International Symposium on Acidic Precipitation, over 400 papers were presented, and nearly 200 of them are included here. They provide an overview of the present state of the art of acid rain research. The Conference focused on atmospheric science (monitoring, source-receptor relationships), aquatic effects (marine eutrophication, lake acidification, impacts on plant and fish populations), and terrestrial effects (forest decline, soil acidification, etc.).

  15. Near-Infrared Spectroscopy as an Analytical Process Technology for the On-Line Quantification of Water Precipitation Processes during Danhong Injection

    PubMed Central

    Liu, Xuesong; Wu, Chunyan; Geng, Shu; Jin, Ye; Luan, Lianjun; Chen, Yong; Wu, Yongjiang

    2015-01-01

    This paper used near-infrared (NIR) spectroscopy for the on-line quantitative monitoring of water precipitation during Danhong injection. For these NIR measurements, two fiber optic probes designed to transmit NIR radiation through a 2 mm flow cell were used to collect spectra in real-time. Partial least squares regression (PLSR) was developed as the preferred chemometrics quantitative analysis of the critical intermediate qualities: the danshensu (DSS, (R)-3, 4-dihydroxyphenyllactic acid), protocatechuic aldehyde (PA), rosmarinic acid (RA), and salvianolic acid B (SAB) concentrations. Optimized PLSR models were successfully built and used for on-line detecting of the concentrations of DSS, PA, RA, and SAB of water precipitation during Danhong injection. Besides, the information of DSS, PA, RA, and SAB concentrations would be instantly fed back to site technical personnel for control and adjustment timely. The verification experiments determined that the predicted values agreed with the actual homologic value. PMID:26839549

  16. The Kongsfjorden Channel System offshore NW Spitsbergen, European Arctic: evidence of down-slope processes in a contour-current dominated setting on the continental margin

    NASA Astrophysics Data System (ADS)

    Forwick, Matthias; Sverre Laberg, Jan; Hass, H. Christian; Osti, Giacomo

    2016-04-01

    The Kongsfjorden Channel System (KCS) is located on the continental slope in the eastern Fram Strait, off northwest Spitsbergen. It provides evidence that the influence of down-slope sedimentary processes locally exceeds regional along-slope sedimentation. Compared to other submarine channel systems on and off glaciated continental margins, it is a relatively short system (~120 km) occurring at a large range of water depths (~250-4000 m). It originates with multiple gullies on the Kongsfjorden Trough Mouth Fan merging to small channels that further downslope merge to a main channel. The overall location of the channel system is controlled by variations in slope gradients (0-20°) and the ambient regional bathymetry: widest and deepest incisions occur in areas of steepest slope gradients. The KCS has probably been active since ~1 Ma when glacial activity on Svalbard increased and grounded ice expanded to the shelf break off Kongsfjorden repeatedly. Activity within the system was probably highest during glacials. However, reduced activity presumably took place also during interglacials. The presentation summarizes the work of Forwick et al. (2015). Reference: Forwick, M., Laberg, J.S., Hass, H.C. & Osti, C., 2015. The Kongsfjorden Channel System offshore NW Svalbard: downslope sedimentary processes in a contour-current-dominated setting. Arktos 1, DOI: 10.1007/s41063-015-0018-4.

  17. Precipitation, pH and metal load in AMD river basins: an application of fuzzy clustering algorithms to the process characterization.

    PubMed

    Grande, J A; Andújar, J M; Aroba, J; de la Torre, M L; Beltrán, R

    2005-04-01

    In the present work, Acid Mine Drainage (AMD) processes in the Chorrito Stream, which flows into the Cobica River (Iberian Pyrite Belt, Southwest Spain) are characterized by means of clustering techniques based on fuzzy logic. Also, pH behavior in contrast to precipitation is clearly explained, proving that the influence of rainfall inputs on the acidity and, as a result, on the metal load of a riverbed undergoing AMD processes highly depends on the moment when it occurs. In general, the riverbed dynamic behavior is the response to the sum of instant stimuli produced by isolated rainfall, the seasonal memory depending on the moment of the target hydrological year and, finally, the own inertia of the river basin, as a result of an accumulation process caused by age-long mining activity. PMID:15798799

  18. Microstructural record of cataclastic and dissolution-precipitation processes from shallow crustal carbonate strike-slip faults, Northern Calcareous Alps (Austria)

    NASA Astrophysics Data System (ADS)

    Bauer, Helene; Grasemann, Bernhard; Decker, Kurt

    2015-04-01

    The concept of coseismic slip and aseismic creep deformation along faults is supported by the variability of natural fault rocks and their microstructures. Faults in carbonate rocks are characterized by very narrow principal slip zones (cm to mm wide) containing (ultra)cataclastic fault rocks that accommodate most of the fault displacement. Fluidization of ultracataclastic sub layers and thermal decomposition of calcite due to frictional heating have been proposed as possible indicators for seismic slip. Dissolution-precipitation (DP) processes are possible mechanism of aseismic sliding, resulting in spaced cleavage solution planes and associated veins, indicating diffusive mass transfer and precipitation in pervasive vein networks. We investigated exhumed, sinistral strike-slip faults in carbonates of the Northern Calcareous Alps. The study presents microstructural investigations of natural carbonate fault rocks that formed by cataclastic and dissolution-precipitation related deformation processes. Faults belong to the eastern segment of the Salzachtal-Ennstal-Mariazell-Puchberg (SEMP) fault system that was formed during eastward lateral extrusion of the Eastern Alps in Oligocene to Lower Miocene. The investigated faults accommodated sinistral slip between several tens and few hundreds of meters. Microstructural analysis of fault rocks was done with scanning electron microscopy and optical microscopy. Deformation experiments of natural fault rocks are planned to be conducted at the Sapienza University of Roma and should be available at the meeting. The investigated fault rocks give record of alternating cataclastic deformation and DP creep. DP fault rocks reveal various stages of evolution including early stylolites, pervasive pressure solution seams and cleavage, localized shear zones with syn-kinematic calcite fibre growth and mixed DP/cataclastic microstructures, involving pseudo sc- and scc'-fabrics. Pressure solution seams host fine grained kaolinit, chlorite

  19. Impact on watershed resilience due to variation of precipitation

    NASA Astrophysics Data System (ADS)

    Kaur, H.; Kumar, P.

    2013-12-01

    This study presents the variation of magnitude of precipitation as well as its seasonal distribution in Minnesota River Basin. The motivation for the study is the sediment increment in Minnesota River. The human, external and climatic changes are affecting the dynamics of Minnesota River Basin, a 44,000 km2 agriculturally-dominated watershed in the upper Midwest. The fluctuations in anthropogenic or climatic factors can influence the dynamics of watershed. We are analyzing the variation in precipitation over 110 years from 1900-2010. The hydrologic daily data is obtained from 22 gages distributed across the Minnesota River Basin. In this study we are trying to understand the shifting precipitation patterns and increase in heavy rainfall events. Soil erosion is affected by the increase in frequency and intensity of precipitation events. The variation in precipitation pattern can be the factor responsible for sediment increment and can disturb the resilience of watershed. The precipitation is considered as the Dichotomous Markov Noise with its two values as the day with precipitation and without precipitation. The transition rates for precipitation from one value to another value are obtained for 11 decades throughout the period. The probability of occurrence of precipitation event is also compared for 11 decades. The outlier precipitation events are categorized into different months for each decade. The year is divided into four seasons and all the comparisons are made seasonal as well as yearly. The low dimensional catastrophic shift model of sediment dynamics will be framed. This model will show the increase rate in sediment depending on the environmental processes such as erosion, deposition or bio stabilization. Single or multiple stable states can be obtained with this catastrophic shift model. The precipitation will act as a Dichotomous Markov Noise in affecting the sediment dynamics. The switches between the stable states can be observed depending on the

  20. Behavioral evidence of the dominant radicals and intermediates involved in bisphenol A degradation using an efficient Co2+/PMS oxidation process.

    PubMed

    Huang, Yi-Fong; Huang, Yao-Hui

    2009-08-15

    This study investigated the degradation and mineralization of Bisphenol A (BPA) at pH 7, taken as a model compound in the presence of the trace metal-ions, Co(2+), and peroxymonosulfate (Oxone: PMS). We took advantage of the high oxidation-reduction potential of hydroxyl and sulfite radicals transformed from PMS as the oxidants to oxidize BPA to less complex compounds (stoichiometric ratio: [PMS](0)/[BPA](0)=2). Afterwards, the expected radicals were used to mineralize those compounds more efficiently (TOC removal approximately 40%) as compared to the 1% removal demonstrated in the UV/persulfate system in our previous study. To the best of our knowledge, this is the first attempt to evidence that the dominant behavior of radicals in a (bi)sulfite process is very different from that in a persulfate process. Additionally, the utilization of extremely small amounts of activator and oxidant for the complete degradation of BPA was achieved. The BPA degradation in this Co(2+)/PMS process formulated a pseudo-first-order kinetic model well over a practicable range of 25-45 degrees C. The activation energy (DeltaE=57.6 kJ mol(-1)) was calculated under different conditions, and the detailed discussion indicates that the activity of BPA degradation is not obviously dependent on the PMS concentration, but rather is related to Co(2+) dosage. Possible BPA side-chain oxidative metabolic pathways are suggested based on experimental results incorporating the evidence from EPR (electron paramagnetic resonance) and analysis from GC-MS (gas chromatography-mass spectrometry). PMID:19216025

  1. Natural acidity of waters in podzolized soils and potential impacts from acid precipitation

    SciTech Connect

    Stednick, J.D.; Johnson, D.W.

    1982-01-01

    Nutrient movements through sites in southeast Alaska and Washington were documented to determine net changes in chemical composition of precipitation water as it passed through a forest soil and became stream-flow. These sites were not subject to acid precipitation (rainfall pH 5.8 to 7.2), yet soil water was acidified to 4.2 by natural organic acid-forming processes in the podzol soils. Organic acids precipitated in the subsoils, allowing a pH increase. Streamwater pH ranged from 6.5 to 7.2 indicating a natural buffering capacity that may exceed any additional acid input from acid rain. Precipitation composition was dominated by calcium, magnesium, sodium, and chloride due to the proximity of the ocean at the southeast Alaska site. Anionic constituents of the precipitation were dominated by bicarbonate at the Washington site. Soil podzolization processes concurrently increased solution color and iron concentrations in the litter and surface horizons leachates. The anion flux through the soil profile was dominated by chloride and sulfate at the southeast Alaska site, whereas at the Washington site anion flux appeared to be dominated by organic acids. Electroneutrality calculations indicated a cation deficit for the southeast Alaska site.

  2. Natural acidity of waters in podzolized soils and potential impacts from acid precipitation

    SciTech Connect

    Stednick, J.D.; Johnson, D.W.

    1982-01-01

    Nutrient movements through sites in southeast Alaska and Washington were documented to determine net changes in chemical composition of precipitation water as it passed through a forest soil and became stream flow. These sites were not subject to acid precipitation (rainfall pH 5.8 to 7.2), yet soil water was acidified to 4.2 by natural organic acid forming processes in the podzol soils. Organic acids precipitated in the subsoils, allowing a pH increase. Stream water pH ranged from 6.5 to 7.2 indicating a natural buffering capacity that may exceed any additional acid input from acid rain. Precipitation composition was dominated by magnesium, sodium, and chloride due to the proximity of the ocean at the southeast Alaska site. Anionic constituents of the precipitation were dominated by bicarbonate at the Washington site. Soil podzolization processes concurrently increased solution color and iron concentrations in the litter and surface horizons leachates. The anion flux through the soil profile was dominated by chloride and sulfate at the southwast Alaska site, whereas at the Washington site anion flux appeared to be dominated by organic acids. Electroneutrality calculations indicated a cation deficit for the southeast Alaska site. 10 references, 2 tables.

  3. Ecohydrologic relationships of two juniper woodlands with different precipitation regimes

    NASA Astrophysics Data System (ADS)

    Ochoa, C. G.; Guldan, S. J.; Deboodt, T.; Fernald, A.; Ray, G.

    2015-12-01

    The significant expansion of juniper (Juniperus spp.) woodlands throughout the western U.S. during the last two centuries has disrupted important ecological functions and hydrologic processes. The relationships between water and vegetation distribution are highly impacted by the ongoing shift from shrub steppe and grassland to woodland-dominated landscapes. We investigated vegetation dynamics and hydrologic processes occurring in two distinct juniper landscapes with different precipitation regimes in the Intermountain West region: A winter snow-dominated (Oregon) and a summer rain-dominated with some winter precipitation (New Mexico) landscape. Results from the Oregon site showed marginal differences (1-2%) in soil moisture in treated vs untreated watersheds throughout the dry and wet seasons. In general, soil moisture was greater in the treated watershed in both seasons. Canopy cover affected soil moisture over time. Perennial grass cover was positively correlated with changes in soil moisture, whereas juniper cover was negatively correlated with changes in soil moisture. Shallow groundwater response observed in upland and valley monitoring wells indicate there are temporary hydrologic connections between upland and valley locations during the winter precipitation season. Results from the New Mexico site provided valuable information regarding timing and intensity of monsoon-driven precipitation and the rainfall threshold (5 mm/15 min) that triggers runoff. Long-term vegetation dynamics and hydrologic processes were evaluated based on pre- and post-juniper removal (70%) in three watersheds. In general, less runoff and greater forage response was observed in the treated watersheds. During rainfall events, soil moisture was less under juniper canopy compared with inter-canopy; this difference in soil moisture was intensified during high intensity, short duration rainstorms in the summer months. We found that winter snow precipitation helped recharge soil moisture

  4. Precipitation of CaCO3 in pressure solution experiments: The importance of damage and stress

    NASA Astrophysics Data System (ADS)

    Laronne Ben-Itzhak, L.; Erez, J.; Aharonov, E.

    2016-01-01

    Pressure solution (PS) is a widespread phenomenon in the Earth's upper crust, which influences many important natural processes, including porosity evolution of sedimentary rocks and fault healing. PS is a creep process effecting porous rocks, involving microscale dissolution and precipitation reactions mediated by diffusion of solutes in the fluid phase. This paper presents an experimental study in carbonates, aiming to advance basic understanding of the physical chemistry controlling PS. The experiments utilize a newly developed method which enables imaging the precipitation stage of PS with a confocal microscope, via a fluorescent marker that binds to precipitating carbonate. We use this method to study the relative role of the various driving forces and the dominant mechanisms controlling the amount and spatial distribution of precipitation in carbonates undergoing PS. Using a clamping apparatus we performed dozens of experiments in which carbonate samples were indented by quartz grains in the presence of water. Carbonate precipitation was observed to occur relatively fast (hours-days), within and around all indented pits, irrespective of the imposed experimental conditions such as stress and fluid saturation, yet the amount and distribution of the precipitation varies between experiments. Two major factors were found to control the amount of precipitation: degree of damage inflicted by pitting and the application of stress. Fluid saturation was seen to affect the spatial distribution of precipitates. In light of these results, we reexamine the traditional chemical potential equations of PS in order to explain the comparable effects of damage and stress on precipitation.

  5. Variation of Ground GPS Integrated Precipitable Water Vapor Estimates among GPS Processing Packages and Strategies in the Context of Forecaster Situational Awareness

    NASA Astrophysics Data System (ADS)

    Moore, A. W.; Haase, J. S.; Bock, Y.; Gutman, S. I.; Laber, J. L.; Small, I. J.; Dumas, J. L.; Holub, K.; Jackson, M. E.

    2015-12-01

    Integrated precipitable water vapor (PW) estimated from ground GPS has for many years been assimilated into operational weather models, and under a NASA AIST project, our collaboration of JPL, SIO, NOAA Weather Forecasting Offices in southern California, and NOAA's Earth System Research Laboratory demonstrated that GPS PW estimates enhance forecaster situational awareness during North American Monsoon events. However, during a rigorous investigation of operational near real-time processing, we discovered some interesting discrepancies between ESRL GAMIT 30-minute and JPL GIPSY 5-minute zenith delay and PW solutions. Exploring this more deeply, we observed that PW timeseries determined with various GPS software packages and mapping functions have variations that manifest themselves on seasonal timescales. We use radiosonde, water vapor radiometer (WVR), and weather model data to explore the underlying cause of the differences, with particular attention to processing artifacts that could lend themselves to misinterpretation in subjective forecasting.

  6. Seasonal variations in energy levels and metabolic processes of two dominant Acropora species ( A. spicifera and A. digitifera) at Ningaloo Reef

    NASA Astrophysics Data System (ADS)

    Hinrichs, S.; Patten, N. L.; Allcock, R. J. N.; Saunders, S. M.; Strickland, D.; Waite, A. M.

    2013-09-01

    Seasonal variations in coral health indices reflecting autotrophic activity (chlorophyll a and zooxanthellae density), metabolic rates (RNA/DNA ratio and protein) and energy storage (ratio of storage: structural lipids or lipid ratios) were examined for two dominant Acropora species [ Acropora digitifera ( AD) and Acropora spicifera ( AS)] at Ningaloo Reef (north-western Australia). Such detailed investigation of metabolic processes is important background, with regard to understanding the vulnerability of corals to environmental change. Health indices in AD and AS were measured before and after spawning in austral autumn and winter 2010, and austral summer 2011 at six stations. Health indices showed seasonal and species-specific differences but negligible spatial differences across a reef section. For AD, autotrophic indices were negatively correlated with lipid ratios and metabolic indices. Metabolic indices were significantly higher in AS than AD. No correlation was observed between RNA/DNA ratios and lipid ratios with any autotrophic indices for AS. Lipid ratios were stable throughout the year for AS while they changed significantly for AD. For both species, indices of metabolic activity were highest during autumn, while autotrophic indices were highest in winter and summer. Results suggest that the impact of the broadcast spawning event on coral health indices at Ningaloo Reef occurred only as a backdrop to massive seasonal changes in coral physiology. The La Niña summer pattern resulted in high autotrophic indices and low metabolic indices and energy stores. Our results imply different metabolic processes in A. digitifera and A. spicifera as well as a strong impact of extreme events on coral physiology.

  7. The effect of using citric or acetic acid on survival of Listeria monocytogenes during fish protein recovery by isoelectric solubilization and precipitation process.

    PubMed

    Otto, R A; Beamer, S; Jaczynski, J; Matak, K E

    2011-10-01

    Isoelectric solubilization and precipitation (ISP) is a protein recovery process effective at reducing Listeria innocua, a nonpathogenic bacterium typically used as a surrogate for L. monocytogenes in recovered trout protein. The response of L. monocytogenes to ISP processing was determined and compared to the response of L. innocua. Headed and gutted rainbow trout were inoculated with L. monocytogenes (10.16 log CFU/g), homogenized, and pH-adjusted with granular citric acid (pH 2.0 and 2.5) or glacial acetic acid (pH 3.0 and 3.5). Proteins were solubilized and centrifugation was used to remove insoluble components (skin, insoluble protein, so on). The supernatant was returned to the protein isoelectric point (pH 5.5) with NaOH and centrifuged to remove precipitated protein. Microbial load was enumerated on both growth and selective media; recovery was not significantly different (P > 0.05). Surviving cells from each component (protein, insoluble, and water) were compared to initial inoculum numbers. Significant reductions were detected at all pH (P < 0.05). The greatest reductions were at pH 3.0 with acetic acid, with a mean log reduction of 3.03 in the combined components, and a 3.53 log reduction in the protein portion. Data were compared to results from a previous study using L. innocua. Significant differences (P < 0.05) in recovery were found between the 2 species at pH 2.0 and 3.0 with greater recovery of L. monocytogenes, regardless of processing pH or acid type. These results demonstrate the variability in resistance between species and indicate that L. innocua is not an appropriate surrogate for L. monocytogenes for ISP processing with organic acids. PMID:21913922

  8. Resistivity Problems in Electrostatic Precipitation

    ERIC Educational Resources Information Center

    White, Harry J.

    1974-01-01

    The process of electrostatic precipitation has ever-increasing application in more efficient collection of fine particles from industrial air emissions. This article details a large number of new developments in the field. The emphasis is on high resistivity particles which are a common cause of poor precipitator performance. (LS)

  9. Fast and slow precipitation responses to individual climate forcers: A PDRMIP multimodel study

    NASA Astrophysics Data System (ADS)

    Samset, B. H.; Myhre, G.; Forster, P. M.; Hodnebrog, Ø.; Andrews, T.; Faluvegi, G.; Fläschner, D.; Kasoar, M.; Kharin, V.; Kirkevâg, A.; Lamarque, J.-F.; Olivié, D.; Richardson, T.; Shindell, D.; Shine, K. P.; Takemura, T.; Voulgarakis, A.

    2016-03-01

    Precipitation is expected to respond differently to various drivers of anthropogenic climate change. We present the first results from the Precipitation Driver and Response Model Intercomparison Project (PDRMIP), where nine global climate models have perturbed CO2, CH4, black carbon, sulfate, and solar insolation. We divide the resulting changes to global mean and regional precipitation into fast responses that scale with changes in atmospheric absorption and slow responses scaling with surface temperature change. While the overall features are broadly similar between models, we find significant regional intermodel variability, especially over land. Black carbon stands out as a component that may cause significant model diversity in predicted precipitation change. Processes linked to atmospheric absorption are less consistently modeled than those linked to top-of-atmosphere radiative forcing. We identify a number of land regions where the model ensemble consistently predicts that fast precipitation responses to climate perturbations dominate over the slow, temperature-driven responses.

  10. Fast and Slow Precipitation Responses to Individual Climate Forcers: A PDRMIP Multimodel Study

    NASA Technical Reports Server (NTRS)

    Samset, B. H.; Myhre, G.; Forster, P.M.; Hodnebrog, O.; Andrews, T.; Faluvegi, G.; Flaschner, D.; Kasoar, M.; Kharin, V.; Kirkevag, A.; Shindell, D.; Voulgarakis, A.

    2016-01-01

    Precipitation is expected to respond differently to various drivers of anthropogenic climate change. We present the first results from the Precipitation Driver and Response Model Intercomparison Project (PDRMIP), where nine global climate models have perturbed CO2, CH4, black carbon, sulfate, and solar insolation. We divide the resulting changes to global mean and regional precipitation into fast responses that scale with changes in atmospheric absorption and slow responses scaling with surface temperature change. While the overall features are broadly similar between models, we find significant regional intermodel variability, especially over land. Black carbon stands out as a component that may cause significant model diversity in predicted precipitation change. Processes linked to atmospheric absorption are less consistently modeled than those linked to top-of-atmosphere radiative forcing. We identify a number of land regions where the model ensemble consistently predicts that fast precipitation responses to climate perturbations dominate over the slow, temperature-driven responses.

  11. Continuous Precipitation of Ceria Nanoparticles from a Continuous Flow Micromixer

    SciTech Connect

    Tseng, Chih Heng; Paul, Brian; Chang, Chih-hung; Engelhard, Mark H.

    2013-01-01

    Cerium oxide nanoparticles were continuously precipitated from a solution of cerium(III) nitrate and ammonium hydroxide using a micro-scale T-mixer. Findings show that the method of mixing is important in the ceria precipitation process. In batch mixing and deposition, disintegration and agglomeration dominates the deposited film. In T-mixing and deposition, more uniform nanorod particles are attainable. In addition, it was found that the micromixing approach reduced the exposure of the Ce(OH)3 precipates to oxygen, yielding hydroxide precipates in place of CeO2 precipitates. Advantages of the micro-scale T-mixing approach include shorter mixing times, better control of nanoparticle shape and less agglomeration.

  12. Reliable solution processed planar perovskite hybrid solar cells with large-area uniformity by chloroform soaking and spin rinsing induced surface precipitation

    NASA Astrophysics Data System (ADS)

    Chern, Yann-Cherng; Wu, Hung-Ruei; Chen, Yen-Chu; Zan, Hsiao-Wen; Meng, Hsin-Fei; Horng, Sheng-Fu

    2015-08-01

    A solvent soaking and rinsing method, in which the solvent was allowed to soak all over the surface followed by a spinning for solvent draining, was found to produce perovskite layers with high uniformity on a centimeter scale and with much improved reliability. Besides the enhanced crystallinity and surface morphology due to the rinsing induced surface precipitation that constrains the grain growth underneath in the precursor films, large-area uniformity with film thickness determined exclusively by the rotational speed of rinsing spinning for solvent draining was observed. With chloroform as rinsing solvent, highly uniform and mirror-like perovskite layers of area as large as 8 cm × 8 cm were produced and highly uniform planar perovskite solar cells with power conversion efficiency of 10.6 ± 0.2% as well as much prolonged lifetime were obtained. The high uniformity and reliability observed with this solvent soaking and rinsing method were ascribed to the low viscosity of chloroform as well as its feasibility of mixing with the solvent used in the precursor solution. Moreover, since the surface precipitation forms before the solvent draining, this solvent soaking and rinsing method may be adapted to spinless process and be compatible with large-area and continuous production. With the large-area uniformity and reliability for the resultant perovskite layers, this chloroform soaking and rinsing approach may thus be promising for the mass production and commercialization of large-area perovskite solar cells.

  13. Reliable solution processed planar perovskite hybrid solar cells with large-area uniformity by chloroform soaking and spin rinsing induced surface precipitation

    SciTech Connect

    Chern, Yann-Cherng; Wu, Hung-Ruei; Chen, Yen-Chu; Horng, Sheng-Fu; Zan, Hsiao-Wen; Meng, Hsin-Fei

    2015-08-15

    A solvent soaking and rinsing method, in which the solvent was allowed to soak all over the surface followed by a spinning for solvent draining, was found to produce perovskite layers with high uniformity on a centimeter scale and with much improved reliability. Besides the enhanced crystallinity and surface morphology due to the rinsing induced surface precipitation that constrains the grain growth underneath in the precursor films, large-area uniformity with film thickness determined exclusively by the rotational speed of rinsing spinning for solvent draining was observed. With chloroform as rinsing solvent, highly uniform and mirror-like perovskite layers of area as large as 8 cm × 8 cm were produced and highly uniform planar perovskite solar cells with power conversion efficiency of 10.6 ± 0.2% as well as much prolonged lifetime were obtained. The high uniformity and reliability observed with this solvent soaking and rinsing method were ascribed to the low viscosity of chloroform as well as its feasibility of mixing with the solvent used in the precursor solution. Moreover, since the surface precipitation forms before the solvent draining, this solvent soaking and rinsing method may be adapted to spinless process and be compatible with large-area and continuous production. With the large-area uniformity and reliability for the resultant perovskite layers, this chloroform soaking and rinsing approach may thus be promising for the mass production and commercialization of large-area perovskite solar cells.

  14. CONCENTRATION OF Pu USING AN IODATE PRECIPITATE

    DOEpatents

    Fries, B.A.

    1960-02-23

    A method is given for separating plutonium from lanthanum in a lanthanum fluoride carrier precipitation process for the recovery of plutonium values from an aqueous solution. The carrier precipitation process includes the steps of forming a lanthanum fluoride precipi- . tate, thereby carrying plutonium out of solution, metathesizing the fluoride precipitate to a hydroxide precipitate, and then dissolving the hydroxide precipitate in nitric acid. In accordance with the invention, the nitric acid solution, which contains plutonium and lanthanum, is made 0.05 to 0.15 molar in potassium iodate. thereby precipitating plutonium as plutonous iodate and the plutonous iodate is separated from the lanthanum- containing supernatant solution.

  15. Understanding the relationship between DOC and nitrate export and dominant rainfall-runoff processes through long-term high frequency measurements

    NASA Astrophysics Data System (ADS)

    Schwab, Michael; Klaus, Julian; Pfister, Laurent; Weiler, Markus

    2016-04-01

    Over the past decades, stream sampling protocols for hydro-geochemical parameters were often limited by logistical and technological constraints. While long-term monitoring protocols were typically based on weekly sampling intervals, high frequency sampling was commonly limited to a few single events. In our study, we combined high frequency and long-term measurements to understand the DOC and nitrate behaviour and dynamics for different runoff events and seasons. Our study area is the forested Weierbach catchment (0.47 km2) in Luxembourg. The fractured schist bedrock is covered by cambisol soils. The runoff response of the catchment is characterized by a double peak behaviour. A first discharge peak occurs during or right after a rainfall event (triggered by fast near surface runoff generation processes), while a second delayed peak lasts several days (generated by subsurface flow/ shallow groundwater flow). Peaks in DOC concentrations are closely linked to the first discharge peak, whereas nitrate concentrations follow the second peak. Our observations were carried out with the field deployable instrument spectro::lyser (scan Messtechnik GmbH). This instrument relies on the principles of UV-Vis spectrometry and measures DOC and nitrate concentrations. The measurements were carried out at a high frequency of 15 minutes in situ in the Weierbach creek for more than two years. In addition, a long-term validation was carried out with data obtained from the analysis of water collected with automatic samplers. The long-term, high-frequency measurements allowed us to calculate a complete and detailed balance of DOC and nitrate export over two years. Transport behaviour of the DOC and nitrate showed different dynamics between the first and second hydrograph peaks. DOC is mainly exported during first peaks, while nitrate is mostly exported during the delayed second peaks. In combination with other measurements in the catchment, the long and detailed observations have

  16. Role of Carbide Precipitates and Process Parameters on Achieving Grain Boundary Engineered Microstructure in a Ni-Based Superalloy

    NASA Astrophysics Data System (ADS)

    Katnagallu, Shyam Swaroop; Mandal, Sumantra; Cheekur Nagaraja, Athreya; de Boer, Bernd; Vadlamani, Subramanya Sarma

    2015-10-01

    Thermo-mechanical processing (one-step and iterative) comprising strain (5, 10, and 15 pct cold rolling) and annealing [at 1273 K, 1323 K, and 1373 K (1000 °C, 1050 °C, and 1100 °C) for different times of 30 minutes, 1 and 2 hours] were employed to realize a grain boundary engineered (GBE) microstructure in alloy 617. Among the single-step routes, the process employing 15 pct cold reduction and annealing at 1373 K (1100 °C) for 1 hour was found to be effective in increasing the fraction of Σ3 boundaries; however, it also induced partial recrystallization. The iterative processing employing lower reductions and higher annealing temperatures failed to realize GBE microstructure. The second-phase carbides in this material effectively pin the boundaries thus requiring higher pre-strain to initiate the boundary migration and subsequent multiple twinning events. The iterative processing designed based on the outcomes of the single step route resulted in GBE microstructure by significantly increasing the Σ3 fraction and substantially disrupting the random high-angle grain boundaries connectivity. The newly added Σ3 boundaries in the GBE microstructure predominantly terminated on (111) plane indicating that they have low-energy configuration. The GBE specimen has shown remarkable resistance to intergranular corrosion as compared to the as-received condition.

  17. Non-growing-season soil respiration is controlled by freezing and thawing processes in the summer monsoon-dominated Tibetan alpine grassland

    NASA Astrophysics Data System (ADS)

    Wang, Yonghui; Liu, Huiying; Chung, Haegeun; Yu, Lingfei; Mi, Zhaorong; Geng, Yan; Jing, Xin; Wang, Shiping; Zeng, Hui; Cao, Guangmin; Zhao, Xinquan; He, Jin-Sheng

    2014-10-01

    The Tibetan alpine grasslands, sharing many features with arctic tundra ecosystems, have a unique non-growing-season climate that is usually dry and without persistent snow cover. Pronounced winter warming recently observed in this ecosystem may significantly alter the non-growing-season carbon cycle processes such as soil respiration (Rs), but detailed measurements to assess the patterns, drivers of, and potential feedbacks on Rs have not been made yet. We conducted a 4 year study on Rs using a unique Rs measuring system, composed of an automated soil CO2 flux sampling system and a custom-made container, to facilitate measurements in this extreme environment. We found that in the nongrowing season, (1) cumulative Rs was 82-89 g C m-2, accounting for 11.8-13.2% of the annual total Rs; (2) surface soil freezing controlled the diurnal pattern of Rs and bulk soil freezing induced lower reference respiration rate (R0) and temperature sensitivity (Q10) than those in the growing season (0.40-0.53 versus 0.84-1.32 µmol CO2 m-2 s-1 for R0 and 2.5-2.9 versus 2.9-5.6 for Q10); and (3) the intraannual variation in cumulative Rs was controlled by accumulated surface soil temperature. We found that in the summer monsoon-dominated Tibetan alpine grassland, surface soil freezing, bulk soil freezing, and accumulated surface soil temperature are the day-, season-, and year-scale drivers of the non-growing-season Rs, respectively. Our results suggest that warmer winters can trigger carbon loss from this ecosystem because of higher Q10 of thawed than frozen soils.

  18. The dominant erosion processes supplying fine sediment to three major rivers in tropical Australia, the Daly (NT), Mitchell (Qld) and Flinders (Qld) Rivers

    NASA Astrophysics Data System (ADS)

    Caitcheon, Gary G.; Olley, Jon M.; Pantus, Francis; Hancock, Gary; Leslie, Christopher

    2012-05-01

    The tropics of northern Australia have received relatively little attention with regard to the impact of soil erosion on the many large river systems that are an important part of Australia's water resource, especially given the high potential for erosion when long dry seasons are followed by intense wet season rain. Here we use 137Cs concentrations to determine the erosion processes supplying sediment to two major northern Australian Rivers; the Daly River (Northern Territory), and the Mitchell River (Queensland). We also present data from five sediment samples collected from a 100 km reach of the Cloncurry River, a major tributary of the Flinders River (Queensland). Concentrations of 137Cs in the surface soil and subsurface (channel banks and gully) samples were used to derive 'best fit' probability density functions describing their distributions. These modelled distributions are then used to estimate the relative contribution of these two components to the river sediments. Our results are consistent with channel and gully erosion being the dominant source of sediment, with more than 90% of sediment transported along the main stem of these rivers originating from subsoil. We summarize the findings of similar studies on tropical Australian rivers and conclude that the primary source of sediment delivered to these systems is gully and channel bank erosion. Previously, as a result of catchment scale modelling, sheet-wash and rill erosion was considered to be the major sediment source in these rivers. Identifying the relative importance of sediment sources, as shown in this paper, will provide valuable information for land management planning in the region. This study also reinforces the importance of testing model predictions before they are used to target investment in remedial action.

  19. Microbial communities and SOM dynamics along a precipitation gradient

    NASA Astrophysics Data System (ADS)

    Tiemann, Lisa; Billings, Sharon

    2014-05-01

    Many microbial communities are not resistant to changes in their environment, and the subsequently new and structurally distinct communities are not always functionally redundant with their predecessors. As a result, environmental change can lead to long-term changes in microbially-mediated ecosystem processes. More specifically, changes in soil moisture regimes can alter microbial physiology and resource demands, and therefore alter how microbes process soil organic matter (SOM). To better understand how current and future precipitation regimes can influence microbial communities and SOM transformations, we assessed microbial community structure and activity in soils reciprocally transplanted across four sites within a grassland precipitation gradient of 485 to 1003 mm y-1. We show that the soil microbial communities residing at these sites are compositionally distinct from each other, and C mineralization rates and microbial biomass C are highly correlated with contemporary site soil moisture. After sols had been subjected to altered precipitation regimes for1.5 and 2.5 years, microbial community structure shifted. Copiotrophs were more abundant relative to oligotrophs in soils experiencing the largest shifts from their native precipitation regimes, and oligotrophs were more dominant in the soils under the most severe soil moisture stress. In general, microbial community structure, in soils from the driest site, was more resistant to change when subjected to novel precipitation regimes. SOM processing rates were distinct in all transplanted soils from their native controls. These changes were dependent on a significant interaction between the initial microbial community structure and the degree of change in precipitation regime, suggesting the importance of initial microbial community structure as a determinant of future structural trajectories, which can drive SOM transformations. Soils transplanted to drier sites with more variable precipitation exhibited lower

  20. Maximum detection range of low-intensity target edges as a function of variable albedo and precipitation using morphological and segmentation image processing techniques

    NASA Astrophysics Data System (ADS)

    Paiva, Clifford A.

    1995-05-01

    One of the primary inhibitory factors for resolution of automatic target recognition (ATR) performance problems has been the inability to quantitatively characterize low signal-to-noise (SNR) target detection and classification algorithms, especially those which are challenged by high spatial frequency backgrounds. The preceding work addressed obtaining classification statistics and geometric pattern referencing characteristics with the target mean intensity distribution commensurate with the background intensities. The current effort maintains a similar approach; however, the ratio of target-to-background intensity is significantly reduced. This is achieved by increasing the obscurant's ratio of differential scattering cross section-to- total cross section (albedo). The objective is to establish 50 percent of the edgels (target edge pixels) on the target at maximum sensor-to-target range in the presence of high spatial background frequencies, including obscurants. In addition precipitation rate and range, as well as variation in obscurant albedo, are assessed. Since scenario dynamics is sought, no attempt is made to resolve target edgels as a function of a single variable, for example precipitation. All variables are allowed to vary independently. The synthetic smoke generated for these plates incorporates the combat obscuration model for battlefield induced contaminants (COMBIC). The target and background imagery is taken in the LWIR by a Keewenaw Research Center (KRC) TMI FLIR. The final images are morphologically processed, segmented, high SNR scenes. The findings are that the target set need not be of a higher intensity than the surrounding imagery, as required in many matched filter operations; the target need only possess a higher intensity gradient than the background clutter and obscurants. Smoke and obscurant intensities may be significantly reduced, or even removed, by this type of morphological image processing.

  1. Reactive Transport Modeling of Chemical and Isotope Data to Identify Degradation Processes of Chlorinated Ethenes in a Diffusion-Dominated Media

    NASA Astrophysics Data System (ADS)

    Chambon, J. C.; Damgaard, I.; Jeannottat, S.; Hunkeler, D.; Broholm, M. M.; Binning, P. J.; Bjerg, P. L.

    2012-12-01

    , sequential reductive dechlorination, abiotic degradation, isotope fractionation due to degradation and due to diffusion in the clay matrix, as heavier isotopes are expected to diffuse slower than lighter ones. The isotope data are shown to be crucial to distinguish between the tested conceptual models for transport and degradation, and made it possible to select a unique conceptual model for each core profile. This study reveals that biotic and abiotic degradation occurred concurrently in several zones inside the clay matrix, and that abiotic degradation of cis-DCE was the dominant attenuation process in the cores. Furthermore reductive dechlorination of cis-DCE to VC, and further to ethene, was documented in several zones in the low-permeability media. Previous studies have shown that degradation might be limited to high permeability zones in clay tills, thus limiting the applicability of remediation strategies based on enhanced biodegradation. Therefore the occurrence of degradation inside the clay matrix is an important finding, that is further supported by microbial and chemical data. Improved understanding of degradation processes in clay tills is useful for improving the reliability of risk assessment and the design of remediation schemes for chlorinated solvents.

  2. Probing local pH-based precipitation processes in self-assembled silica-carbonate hybrid materials.

    PubMed

    Opel, Julian; Hecht, Mandy; Rurack, Knut; Eiblmeier, Josef; Kunz, Werner; Cölfen, Helmut; Kellermeier, Matthias

    2015-11-01

    Crystallisation of barium carbonate in the presence of silica can lead to the spontaneous assembly of highly complex superstructures, consisting of uniform and largely co-oriented BaCO3 nanocrystals that are interspersed by a matrix of amorphous silica. The formation of these biomimetic architectures (so-called silica biomorphs) is thought to be driven by a dynamic interplay between the components, in which subtle changes of conditions trigger ordered mineralisation at the nanoscale. In particular, it has been proposed that local pH gradients at growing fronts play a crucial role in the process of morphogenesis. In the present work, we have used a special pH-sensitive fluorescent dye to directly trace these presumed local fluctuations by means of confocal laser scanning microscopy. Our data demonstrate the existence of an active region near the growth front, where the pH is locally decreased with respect to the alkaline bulk solution on a length scale of few microns. This observation provides fundamental and, for the first time, direct experimental support for the current picture of the mechanism underlying the formation of these peculiar materials. On the other hand, the absence of any temporal oscillations in the local pH - another key feature of the envisaged mechanism - challenges the notion of autocatalytic phenomena in such systems and raises new questions about the actual role of silica as an additive in the crystallisation process. PMID:26439927

  3. Precipitation Recycling and the Vertical Distribution of Local and Remote Sources of Water for Precipitation

    NASA Technical Reports Server (NTRS)

    Bosilovich, Michael G.; Atlas, Robert (Technical Monitor)

    2002-01-01

    Precipitation recycling is defined as the amount of water that evaporates from a region that precipitates within the same region. This is also interpreted as the local source of water for precipitation. In this study, the local and remote sources of water for precipitation have been diagnosed through the use of passive constituent tracers that represent regional evaporative sources along with their transport and precipitation. We will discuss the differences between this method and the simpler bulk diagnostic approach to precipitation recycling. A summer seasonal simulation has been analyzed for the regional sources of the United States Great Plains precipitation. While the tropical Atlantic Ocean (including the Gulf of Mexico) and the local continental sources of precipitation are most dominant, the vertically integrated column of water contains substantial water content originating from the Northern Pacific Ocean, which is not precipitated. The vertical profiles of regional water sources indicate that local Great Plains source of water dominates the lower troposphere, predominantly in the PBL. However, the Pacific Ocean source is dominant over a large portion of the middle to upper troposphere. The influence of the tropical Atlantic Ocean is reasonably uniform throughout the column. While the results are not unexpected given the formulation of the model's convective parameterization, the analysis provides a quantitative assessment of the impact of local evaporation on the occurrence of convective precipitation in the GCM. Further, these results suggest that local source of water is not well mixed throughout the vertical column.

  4. Probing local pH-based precipitation processes in self-assembled silica-carbonate hybrid materials

    NASA Astrophysics Data System (ADS)

    Opel, Julian; Hecht, Mandy; Rurack, Knut; Eiblmeier, Josef; Kunz, Werner; Cölfen, Helmut; Kellermeier, Matthias

    2015-10-01

    Crystallisation of barium carbonate in the presence of silica can lead to the spontaneous assembly of highly complex superstructures, consisting of uniform and largely co-oriented BaCO3 nanocrystals that are interspersed by a matrix of amorphous silica. The formation of these biomimetic architectures (so-called silica biomorphs) is thought to be driven by a dynamic interplay between the components, in which subtle changes of conditions trigger ordered mineralisation at the nanoscale. In particular, it has been proposed that local pH gradients at growing fronts play a crucial role in the process of morphogenesis. In the present work, we have used a special pH-sensitive fluorescent dye to directly trace these presumed local fluctuations by means of confocal laser scanning microscopy. Our data demonstrate the existence of an active region near the growth front, where the pH is locally decreased with respect to the alkaline bulk solution on a length scale of few microns. This observation provides fundamental and, for the first time, direct experimental support for the current picture of the mechanism underlying the formation of these peculiar materials. On the other hand, the absence of any temporal oscillations in the local pH - another key feature of the envisaged mechanism - challenges the notion of autocatalytic phenomena in such systems and raises new questions about the actual role of silica as an additive in the crystallisation process.Crystallisation of barium carbonate in the presence of silica can lead to the spontaneous assembly of highly complex superstructures, consisting of uniform and largely co-oriented BaCO3 nanocrystals that are interspersed by a matrix of amorphous silica. The formation of these biomimetic architectures (so-called silica biomorphs) is thought to be driven by a dynamic interplay between the components, in which subtle changes of conditions trigger ordered mineralisation at the nanoscale. In particular, it has been proposed that local

  5. Dryland Precipitation Variability and Desertification Processes: An Assessment of Spatial and Temporal Rain Variability within the Grand Canyon, Arizona

    NASA Astrophysics Data System (ADS)

    Caster, J.; Sankey, J. B.; Draut, A.; Fairley, H.; Collins, B. D.; Bedford, D.

    2014-12-01

    In drylands, spatial and temporal rain variability can result from natural climatic cycles, weather patterns, and physiographic factors. In these environments, minor differences in rainfall distribution can invoke significant ecosystem response. The Grand Canyon, Arizona is an iconic dryland environment that receives less than 430 mm of annual rainfall. Recent monitoring of desertification processes at culturally sensitive landscapes in Grand Canyon has examined variability in vegetation, soil crusts, and runoff induced erosion, and identified a lack of knowledge about the nature, drivers and effects of local rainfall variability. We examine rainfall variability using five years of high resolution data collected from 11 weather stations distributed along the Colorado River within Grand Canyon, coupled with 60 years of lower resolution data from National Weather Service Cooperative Observer (NOAA COOP) stations. We characterize spatial and temporal variability in 10-minute rainfall intensity, an important predictor of soil erosion, and daily rainfall depth, an important predictor of biotic cover. We quantify the intensity-daily depth relationship to infer long-term variability in rainfall intensity from the NOAA COOP data that only record rainfall depth. Results confirm findings from previous studies showing a bi-seasonally rainfall pattern with longer duration-lower intensity storms in the cool season and shorter duration-higher intensity storms during the North American Monsoon (NAM).Seasonal differences in rainfall intensity-depth relationships are significant, and suggest NAM storms have greater potential to produce erosion-generating intensities. As NAM rainfall is spatially and inter-annually more variable than cool season rain, yearly rain depths are strongly influenced by NAM fluctuations. These findings will be useful in future efforts to track desertification processes in this and other drylands characterized by complex topography and extreme rainfall

  6. A landscape-scale assessment of plant communities, hydrologic processes, and state-and-transition theory in a western juniper dominated ecosystem

    NASA Astrophysics Data System (ADS)

    Petersen, Steven L.

    Western juniper has rapidly expanded into sagebrush steppe communities in the Intermountain West during the past 120 years. This expansion has occurred across a wide range of soil types and topographic positions. These plant communities, however, are typically treated in current peer-reviewed literature generically. The focus of this research is to investigate watershed level response to Western juniper encroachment at multiple topographic positions. Data collected from plots used to measure vegetation, soil moisture, and infiltration rates show that intercanopy sites within encroached Western juniper communities generally exhibit a significant decrease in intercanopy plant density and cover, decreased infiltration rates, increased water sediment content, and lower soil moisture content. High-resolution remotely sensed imagery and Geographic Information Systems were used with these plot level measurements to characterize and model the landscape-scale response for both biotic and abiotic components of a Western juniper encroached ecosystem. These data and their analyses included an inventory of plant density, plant cover, bare ground, gap distance and cover, a plant community classification of intercanopy patches and juniper canopy cover, soil moisture estimation, solar insulation prediction, slope and aspect. From these data, models were built that accurately predicted shrub density and shrub cover throughout the watershed study area, differentiated by aspect. We propose a new model of process-based plant community dynamics associated with current state-and-transition theory. This model is developed from field measurements and spatially explicit information that characterize the relationship between the matrix mountain big sagebrush plant community and intercanopy plant community patterns occurring within a Western juniper dominated woodland at a landscape scale. Model parameters (states, transitions, and thresholds) are developed based on differences in shrub

  7. Novel electrostatic precipitator using unipolar soft X-ray charger for removing fine particles: Application to a dry de-NOX process.

    PubMed

    Choi, Jeongan; Kim, Hak Joon; Kim, Yong Jin; Kim, Sang Soo; Jung, Jae Hee

    2016-02-13

    The novel electrostatic precipitator (ESP), consisting of a soft X-ray charger and a collection part, was demonstrated and applied to a dry de-NOX process to evaluate its performance in by-product particle removal. NOX gas was oxidized by ozone (O3) and neutralized by ammonia (NH3) sequentially, and finally converted to an ammonium nitrate (NH4NO3) aerosol with ∼ 100-nm peak particle diameter. The unipolar soft X-ray charger was introduced for charging the by-product particles in this dry de-NOX process. For the highest particle collection efficiency, the optimal operating conditions of the soft X-ray charger and collection part were investigated by adjusting the applied voltage of each device. The results showed that ∼ 99% of NOX was removed when the O3/NOX ratio was increased to 2 (i.e., the maximum production conditions of the NH4NO3 by-product particles by the gas-to-particle conversion process). The highest removal efficiency of particle (∼ 90%) was observed with operating conditions of positive polarity and an applied voltage of ∼ 2-3 kV in the charger chamber. The unipolar soft X-ray charger has potential for particle removal systems in industrial settings because of its compact size, ease of operation, and non-interruptive charging mechanism. PMID:26513563

  8. Interannual variability of the atmospheric CO2 growth rate: roles of precipitation and temperature

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Zeng, Ning; Wang, Meirong

    2016-04-01

    The interannual variability (IAV) in atmospheric CO2 growth rate (CGR) is closely connected with the El Niño-Southern Oscillation. However, sensitivities of CGR to temperature and precipitation remain largely uncertain. This paper analyzed the relationship between Mauna Loa CGR and tropical land climatic elements. We find that Mauna Loa CGR lags precipitation by 4 months with a correlation coefficient of -0.63, leads temperature by 1 month (0.77), and correlates with soil moisture (-0.65) with zero lag. Additionally, precipitation and temperature are highly correlated (-0.66), with precipitation leading by 4-5 months. Regression analysis shows that sensitivities of Mauna Loa CGR to temperature and precipitation are 2.92 ± 0.20 PgC yr-1 K-1 and -0.46 ± 0.07 PgC yr-1 100 mm-1, respectively. Unlike some recent suggestions, these empirical relationships favor neither temperature nor precipitation as the dominant factor of CGR IAV. We further analyzed seven terrestrial carbon cycle models, from the TRENDY project, to study the processes underlying CGR IAV. All models capture well the IAV of tropical land-atmosphere carbon flux (CFTA). Sensitivities of the ensemble mean CFTA to temperature and precipitation are 3.18 ± 0.11 PgC yr-1 K-1 and -0.67 ± 0.04 PgC yr-1 100 mm-1, close to Mauna Loa CGR. Importantly, the models consistently show the variability in net primary productivity (NPP) dominates CGR, rather than heterotrophic respiration. Because previous studies have proved that NPP is largely driven by precipitation in tropics, it suggests a key role of precipitation in CGR IAV despite the higher CGR correlation with temperature. Understanding the relative contribution of CO2 sensitivity to precipitation and temperature has important implications for future carbon-climate feedback using such ''emergent constraint''.

  9. Interannual variability of the atmospheric CO2 growth rate: relative contribution from precipitation and temperature

    NASA Astrophysics Data System (ADS)

    Wang, J.; Zeng, N.; Wang, M. R.

    2015-12-01

    The interannual variability (IAV) in atmospheric CO2 growth rate (CGR) is closely connected with the El Niño-Southern Oscillation. However, sensitivities of CGR to temperature and precipitation remain largely uncertain. This paper analyzed the relationship between Mauna Loa CGR and tropical land climatic elements. We find that Mauna Loa CGR lags precipitation by 4 months with a correlation coefficient of -0.63, leads temperature by 1 month (0.77), and correlates with soil moisture (-0.65) with zero lag. Additionally, precipitation and temperature are highly correlated (-0.66), with precipitation leading by 4-5 months. Regression analysis shows that sensitivities of Mauna Loa CGR to temperature and precipitation are 2.92 ± 0.20 Pg C yr-1 K-1 and -0.46 ± 0.07 Pg C yr-1 100 mm-1, respectively. Unlike some recent suggestions, these empirical relationships favor neither temperature nor precipitation as the dominant factor of CGR IAV. We further analyzed seven terrestrial carbon cycle models, from the TRENDY project, to study the processes underlying CGR IAV. All models capture well the IAV of tropical land-atmosphere carbon flux (CFTA). Sensitivities of the ensemble mean CFTA to temperature and precipitation are 3.18 ± 0.11 Pg C yr-1 K-1 and -0.67 ± 0.04 Pg C yr-1 100 mm-1, close to Mauna Loa CGR. Importantly, the models consistently show the variability in net primary productivity (NPP) dominates CGR, rather than soil respiration. Because NPP is largely driven by precipitation, this suggests a key role of precipitation in CGR IAV despite the higher CGR correlation with temperature. Understanding the relative contribution of CO2 sensitivity to precipitation and temperature has important implications for future carbon-climate feedback using such "emergent constraint".

  10. Macroscopic impacts of cloud and precipitation processes on maritime shallow convection as simulated by a large eddy simulation model with bin microphysics

    NASA Astrophysics Data System (ADS)

    Grabowski, W. W.; Wang, L.-P.; Prabha, T. V.

    2015-01-01

    This paper discusses impacts of cloud and precipitation processes on macrophysical properties of shallow convective clouds as simulated by a large eddy model applying warm-rain bin microphysics. Simulations with and without collision-coalescence are considered with cloud condensation nuclei (CCN) concentrations of 30, 60, 120, and 240 mg-1. Simulations with collision-coalescence include either the standard gravitational collision kernel or a novel kernel that includes enhancements due to the small-scale cloud turbulence. Simulations with droplet collisions were discussed in Wyszogrodzki et al. (2013) focusing on the impact of the turbulent collision kernel. The current paper expands that analysis and puts model results in the context of previous studies. Despite a significant increase of the drizzle/rain with the decrease of CCN concentration, enhanced by the effects of the small-scale turbulence, impacts on the macroscopic cloud field characteristics are relatively minor. Model results show a systematic shift in the cloud-top height distributions, with an increasing contribution of deeper clouds for stronger precipitating cases. We show that this is consistent with the explanation suggested in Wyszogrodzki et al. (2013); namely, the increase of drizzle/rain leads to a more efficient condensate offloading in the upper parts of the cloud field. A second effect involves suppression of the cloud droplet evaporation near cloud edges in low-CCN simulations, as documented in previous studies (e.g., Xue and Feingold, 2006). We pose the question whether the effects of cloud turbulence on drizzle/rain formation in shallow cumuli can be corroborated by remote sensing observations, for instance, from space. Although a clear signal is extracted from model results, we argue that the answer is negative due to uncertainties caused by the temporal variability of the shallow convective cloud field, sampling and spatial resolution of the satellite data, and overall accuracy of

  11. Reproducibility of Carbon and Water Cycle by an Ecosystem Process Based Model Using a Weather Generator and Effect of Temporal Concentration of Precipitation on Model Outputs

    NASA Astrophysics Data System (ADS)

    Miyauchi, T.; Machimura, T.

    2014-12-01

    GCM is generally used to produce input weather data for the simulation of carbon and water cycle by ecosystem process based models under climate change however its temporal resolution is sometimes incompatible to requirement. A weather generator (WG) is used for temporal downscaling of input weather data for models, where the effect of WG algorithms on reproducibility of ecosystem model outputs must be assessed. In this study simulated carbon and water cycle by Biome-BGC model using weather data measured and generated by CLIMGEN weather generator were compared. The measured weather data (daily precipitation, maximum, minimum air temperature) at a few sites for 30 years was collected from NNDC Online weather data. The generated weather data was produced by CLIMGEN parameterized using the measured weather data. NPP, heterotrophic respiration (HR), NEE and water outflow were simulated by Biome-BGC using measured and generated weather data. In the case of deciduous broad leaf forest in Lushi, Henan Province, China, 30 years average monthly NPP by WG was 10% larger than that by measured weather in the growing season. HR by WG was larger than that by measured weather in all months by 15% in average. NEE by WG was more negative in winter and was close to that by measured weather in summer. These differences in carbon cycle were because the soil water content by WG was larger than that by measured weather. The difference between monthly water outflow by WG and by measured weather was large and variable, and annual outflow by WG was 50% of that by measured weather. The inconsistency in carbon and water cycle by WG and measured weather was suggested be affected by the difference in temporal concentration of precipitation, which was assessed.

  12. Investigation of the Non-Symmetrical Dependence of Precipitation using Empirical Bivariate Copulas

    NASA Astrophysics Data System (ADS)

    Suroso, Suroso; Bárdossy, András

    2015-04-01

    Precipitation plays important role in hydrological analysis. Some common precipitation models are developed based on the assumption of the symmetrical Gaussian dependence structure. This study tries to examine the asymmetrical spatial dependence of precipitation using empirical bivariate copulas. Empirical bivariate copulas are constructed from all possible pairwise combination of the rain gauge data at different locations located in Singapore and Germany. In addition, concept of regionalized variables in spatial random process is also applied with given separating distance. For any selected time interval, precipitation over the region of interest is assumed to be a realization of spatially stationary random process. In order to take into account temporal characteristics, precipitation with different time scales (hourly, 2-hours, 3-hours, 4-hours, 6-hours, 12-hours, daily, 5-days, 10-days, 15-days, monthly, quarterly) and different seasons are analyzed. The behavior of correlation functions are elaborated considering zero precipitation treated as censored values. Asymmetrical spatial dependence is measured by calculating integration from empirical bivariate copula density in the upper right and the lower left parts for given some thresholds, and then by their comparisons. Similarly, zero precipitation is handled as latent variables, and the thresholds are therefore taken percentiles bigger than probability of zeroes. Gaussian simulation based testing is adopted for counting its degree of uncertainty. Empirical evidences prove that precipitation correlation decrease along with the length of distance interval and increases with the length of time interval. There is an interesting systematic pattern relating to the domination of positive non-symmetrical spatial dependence in comparison to negative and symmetrical dependence in terms of distance and time interval. Number of pairs of rain gauge stations which has positive dependence is clearly seen the biggest for cases

  13. Cross-track sensor precipitation retrievals for the Global Precipitation Measurement mission

    NASA Astrophysics Data System (ADS)

    Kidd, Chris; Randel, David; Stocker, Erich; Kummerow, Christian

    2014-05-01

    The utilization of observations from passive microwave cross-track, or sounders, for global precipitation estimation provides a number of distinct advantages including the potential to retrieve precipitation over cold surface backgrounds and improvements in temporal sampling. As part of the Global Precipitation Measurement (GPM) mission, observations from these cross-track instruments are being incorporated into the overall retrieval framework to enable better temporal and spatial sampling, particularly over regions where surface conditions provide a challenging background against which to observe precipitation. GPM is an international satellite mission and brings together a number of different component satellites and sensors, each contributing observations capable of providing information on precipitation. The joint US-Japan core observatory was launched in early 2014 and carries the GPM Microwave Imager (GMI) and the Dual-frequency Precipitation Radar (DPR). The core observatory serves as a standard against which other sensors in the constellation are calibrated, providing a consistent observational dataset to ensure the highest quality precipitation retrievals to be made. The conically-scanning GMI provides observations from 10.65 GHz through to 166 GHz with dual polarization capabilities, and two 183 GHz channels (+-1 and +-3 GHz) with vertical polarization. The highest frequencies provide resolutions in the order of 4.4x7.3 km. 885 km swath width. The DPR operates at 35.5 GHz and 13.6 GHz with swath widths 120 and 245 km respectively, and a vertical resolution of 250 m. The higher frequency radar will provide a sensitivity down to 12 dBZ, or about 0.2 mmh-1 equivalent rainrate, particularly useful for higher latitudes where light precipitation dominates. Integration of the cross-track sensors into the overall retrieval scheme of the GPM mission is achieved through the GPROF retrieval scheme, utilizing databases based upon observational and modelled data sets

  14. [Acute heart failure: precipitating factors and prevention].

    PubMed

    Aramburu Bodas, Oscar; Conde Martel, Alicia; Salamanca Bautista, Prado

    2014-03-01

    Acute heart failure episodes, whether onset or decompensation of a chronic form, are most often precipitated by a concurrent process or disease, described as precipitating factors of heart failure. In this article, we review these precipitating factors, their proportions and clinical relevance in general and in subgroups of patients, their relationship with prognosis, and their possible prevention. PMID:24930077

  15. Rivers as archives of paleo-precipitation patterns and extreme precipitation

    NASA Astrophysics Data System (ADS)

    Plink-Bjorklund, Piret

    2016-04-01

    Fluvial systems commonly experience hysteresis and complex signal buffering effects that complicate tracking of allogenic forcing factors and autogenic processes. This paper presents a study of 52 modern and ancient fluvial datasets where river dynamics are dominated by highly seasonal precipitation pattern, such as in monsoonal domain and the bordering subtropical arid to sub-humid climate zones. Rivers that receive significant amounts of their surface water supply from monsoon precipitation characteristically experience seasonal floods, and display seasonally highly variable discharge, controlled by the monsoon trough passage and its related cyclones. The intense summer rainfall causes high-magnitude floods, whereas rivers only transmit a low base flow during the dry winters. Also for many rivers in the sub-humid to arid subtropics, bordering the monsoon domain, the monsoon rain is the main source of surface water recharge. However, such rivers may receive monsoon rain and transmit discharge only during abnormal or strengthened monsoon seasons. This annual discharge variability or range, as compared to the mean annual discharge, distinguishes the monsoonal and subtropical rivers from the rivers in equatorial tropics and temperate perennial precipitation zones, where the annual range is relatively small compared to the annual mean discharge. The positive deviation is clearly demonstrated by comparing the Q90 values to the mean discharge values, indicating flood discharge or magnitude values of >200-400% as compared to the annual mean discharge. Moreover, Q50 values of rivers that receive their surface water supply from monsoon precipitation are less than 10% of the annual mean discharge in some such rivers, and range from 20-50% in most. In comparison, in perennial precipitation zone rivers the Q90 values are within110-160% as compared to the annual mean, and the Q50 values are very close to the annual mean discharge, within 90-98%. Even Q30 values for the

  16. Microbially induced and microbially catalysed precipitation: two different carbonate factories

    NASA Astrophysics Data System (ADS)

    Meister, Patrick

    2016-04-01

    The landmark paper by Schlager (2003) has revealed three types of benthic carbonate production referred to as "carbonate factories", operative at different locations at different times in Earth history. The tropical or T-factory comprises the classical platforms and fringing reefs and is dominated by carbonate precipitation by autotrophic calcifying metazoans ("biotically controlled" precipitation). The cool or C-factory is also biotically controlled but via heterotrophic, calcifying metazoans in cold and deep waters at the continental margins. A further type is the mud-mound or M-factory, where carbonate precipitation is supported by microorganisms but not controlled by a specific enzymatic pathway ("biotically induced" precipitation). How exactly the microbes influence precipitation is still poorly understood. Based on recent experimental and field studies, the microbial influence on modern mud mound and microbialite growth includes two fundamentally different processes: (1) Metabolic activity of microbes may increase the saturation state with respect to a particular mineral phase, thereby indirectly driving the precipitation of the mineral phase: microbially induced precipitation. (2) In a situation, where a solution is already supersaturated but precipitation of the mineral is inhibited by a kinetic barrier, microbes may act as a catalyser, i.e. they lower the kinetic barrier: microbially catalysed precipitation. Such a catalytic effect can occur e.g. via secreted polymeric substances or specific chemical groups on the cell surface, at which the minerals nucleate or which facilitate mechanistically the bonding of new ions to the mineral surface. Based on these latest developments in microbialite formation, I propose to extend the scheme of benthic carbonate factories of Schlager et al. (2003) by introducing an additional branch distinguishing microbially induced from microbially catalysed precipitation. Although both mechanisms could be operative in a M

  17. Co-precipitation of phosphate and carbonate minerals: geological and ecological implications

    NASA Astrophysics Data System (ADS)

    Sanchez-Román, Monica; McKenzie, Judith; Vasconcelos, Crisogono

    2015-04-01

    Microorganisms play an important role in natural environments by controlling the metal cations (e.g., Ca2+, Mg2+, Fe2+) and the anions (CO32-, NH4+, PO43-) that precipitate as biominerals (e.g., carbonates, phosphates). In contrast to phosphate minerals, precipitation of carbonate minerals by bacteria has been widely studied in culture experiments and in natural environments. Moreover, studies of sedimentary phosphate minerals and their geological and ecological implications are rare. Nevertheless, phosphate minerals frequently co-precipitate with carbonates in culture experiments and in natural systems. In the present work, we investigate how microorganisms control the mineralogy and geochemistry of phosphate and carbonate minerals. For this, culture experiments were performed to study the co-precipitation of phosphate and carbonate minerals using aerobic heterotrophic bacteria at sedimentary Earth's surface conditions. Ca-Mg carbonate (dolomite, Mg-calcite) and/or Mg-carbonate (hydromagnesite) precipitated with Mg-phosphate (struvite). In most of the cultures, phosphate was the dominant mineral phase found in the bacterial precipitates and carbonates precipitated after phosphate phases. Notably, in all the cultures, we found a mixture of phosphate and carbonate minerals. This study shines new light into the microbial diagenetic processes involved in the co-precipitation of phosphate and carbonate minerals and links the P and C cycles.

  18. SULFIDE PRECIPITATION OF HEAVY METALS

    EPA Science Inventory

    The research program was initiated with the objective of evaluating a new process, the sulfide precipitation of heavy metals from industrial wastewaters. The process was expected to effect a more complete removal of heavy metals than conventional lime processing because of the mu...

  19. Partitioning of mercury, arsenic, selenium, boron, and chloride in a full-scale coal combustion process equipped with selective catalytic reduction, electrostatic precipitation, and flue gas desulfurization systems

    SciTech Connect

    Chin-Min Cheng; Pauline Hack; Paul Chu; Yung-Nan Chang; Ting-Yu Lin; Chih-Sheng Ko; Po-Han Chiang; Cheng-Chun He; Yuan-Min Lai; Wei-Ping Pan

    2009-09-15

    A full-scale field study was carried out at a 795 MWe coal-fired power plant equipped with selective catalytic reduction (SCR), an electrostatic precipitator (ESP), and wet flue gas desulfurization (FGD) systems to investigate the distribution of selected trace elements (i.e., mercury, arsenic, selenium, boron, and chloride) from coal, FGD reagent slurry, makeup water to flue gas, solid byproduct, and wastewater streams. Flue gases were collected from the SCR outlet, ESP inlet, FGD inlet, and stack. Concurrent with flue gas sampling, coal, bottom ash, economizer ash, and samples from the FGD process were also collected for elemental analysis. By combining plant operation parameters, the overall material balances of selected elements were established. The removal efficiencies of As, Se, Hg, and B by the ESP unit were 88, 56, 17, and 8%, respectively. Only about 2.5% of Cl was condensed and removed from flue gas by fly ash. The FGD process removed over 90% of Cl, 77% of B, 76% of Hg, 30% of Se, and 5% of As. About 90% and 99% of the FGD-removed Hg and Se were associated with gypsum. For B and Cl, over 99% were discharged from the coal combustion process with the wastewater. Mineral trona (trisodium hydrogendicarbonate dehydrate, Na{sub 3}H(CO{sub 3}){sub 2}.2H{sub 2}O) was injected before the ESP unit to control the emission of sulfur trioxide (SO{sub 3}). By comparing the trace elements compositions in the fly ash samples collected from the locations before and after the trona injection, the injection of trona did not show an observable effect on the partitioning behaviors of selenium and arsenic, but it significantly increased the adsorption of mercury onto fly ash. The stack emissions of mercury, boron, selenium, and chloride were for the most part in the gas phase. 47 refs., 3 figs., 11 tabs.

  20. Assessing Bilingual Dominance.

    ERIC Educational Resources Information Center

    Flege, James Emil; Mackay, Ian R. A.; Piske, Thorsten

    2002-01-01

    Used two methods to assess bilingual dominance in four groups of Italian-English bilinguals. Ratios were derived from bilinguals' self-rating of ability to speak and understand Italian compared to English. Dominance in Italian was associated with a relatively high level of performance in Italian (assessed in a translation task) and relatively poor…

  1. Classification of land-sea shifts in tropical precipitation using temperature and moisture change

    NASA Astrophysics Data System (ADS)

    Lambert, Hugo; Ferraro, Angus; Chadwick, Robin

    2016-04-01

    Changes in tropical precipitation under climate change are dominated by shifts in precipitating features. Previous work has shown that meridional change is driven primiarily by the hemispheric contrast of surface temperature change and radiative forcing. What drives zonal changes is less clear, but important to understand because large shifts of precipitation onto and away from land have the potential to cause large changes in water availability. We present a simple compositing scheme based on earlier mean field theory that places climatological precipitation amounts into bins determined by surface temperature and humidity. When temperature and humidity change under climate change, shifts in precipitation are predicted as the location of the warmest and moistest regions changes. The prediction is successful in representing changes in the CMIP5 model mean and large aspects of changes in most of the individual CMIP5 models. Once the shifts are accounted for, we can more easily see how the result of well-known "thermodynamic" and "dynamic" changes in the atmosphere lead to the "rich-get-richer" paradigm wherein the most heavily precipitating bins increase their precipitation the most in a warmer climate. We emphasise that our method is a classification and not a prognostic theory: it shows us the extent to which temperature, moisture and precipitation change are linked. However, it is important not only because it demonstrates that these variables may represent a coupled problem, but also intriguingly, because there is a small group of models for which the method has no skill at all. This suggests that very different processes dominate shifts in precipitation there, giving a focus for future research.

  2. Titanium nitride (TiN) precipitation in a maraging steel during the vacuum arc remelting (VAR) process - Inclusions characterization and modeling

    NASA Astrophysics Data System (ADS)

    Descotes, V.; Bellot, J.-P.; Perrin-Guérin, V.; Witzke, S.; Jardy, A.

    2016-07-01

    Titanium Nitride (TiN) inclusions are commonly observed in a Maraging steel containing Nitrogen and Titanium and remelted in a VAR furnace. They can be easily detected by optical microscopy. A nucleus is observed next to a large number of TiN inclusions. A TEM analysis was carried out on a biphasic nucleus composed of a calcium sulfide (CaS) and a spinel (MgAl2O4), surrounded by a TiN particle. An orientation relationship between these three phases was revealed, which suggests a heterogeneous germination of the TiN particle on the nucleus by epitaxial growth. Based on this observation, on thermodynamic considerations and on previous work, a model has been developed and coupled to a numerical simulation of the VAR process to study the formation and evolution of a TiN distribution in the VAR ingot. Microsegregation is modeled using the lever rule, while the kinetics of precipitation is mainly driven by the supersaturation of the liquid bath. This model highlights the influence of the melt rate on the final size of TiN particles.

  3. Precipitation Processes developed during ARM (1997), TOGA COARE(1992), GATE(1 974), SCSMEX(1998) and KWAJEX(1999): Consistent 2D and 3D Cloud Resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Shie, C.-H.; Simpson, J.; Starr, D.; Johnson, D.; Sud, Y.

    2003-01-01

    Real clouds and clouds systems are inherently three dimensional (3D). Because of the limitations in computer resources, however, most cloud-resolving models (CRMs) today are still two-dimensional (2D). A few 3D CRMs have been used to study the response of clouds to large-scale forcing. In these 3D simulations, the model domain was small, and the integration time was 6 hours. Only recently have 3D experiments been performed for multi-day periods for tropical cloud system with large horizontal domains at the National Center for Atmospheric Research. The results indicate that surface precipitation and latent heating profiles are very similar between the 2D and 3D simulations of these same cases. The reason for the strong similarity between the 2D and 3D CRM simulations is that the observed large-scale advective tendencies of potential temperature, water vapor mixing ratio, and horizontal momentum were used as the main forcing in both the 2D and 3D models. Interestingly, the 2D and 3D versions of the CRM used in CSU and U.K. Met Office showed significant differences in the rainfall and cloud statistics for three ARM cases. The major objectives of this project are to calculate and axamine: (1)the surface energy and water budgets, (2) the precipitation processes in the convective and stratiform regions, (3) the cloud upward and downward mass fluxes in the convective and stratiform regions; (4) cloud characteristics such as size, updraft intensity and lifetime, and (5) the entrainment and detrainment rates associated with clouds and cloud systems that developed in TOGA COARE, GATE, SCSMEX, ARM and KWAJEX. Of special note is that the analyzed (model generated) data sets are all produced by the same current version of the GCE model, i.e. consistent model physics and configurations. Trajectory analyse and inert tracer calculation will be conducted to identify the differences and similarities in the organization of convection between simulated 2D and 3D cloud systems.

  4. Changing Characteristics of Precipitation in China during 1960-2012

    NASA Astrophysics Data System (ADS)

    Wu, S. Y.; Wu, Y.; Wen, J.

    2015-12-01

    In this study, we investigated changes in the precipitation characteristics for China from 1960 to 2012 based on a recent daily precipitation dataset of 666 climate stations and robust non-parametric trend detection techniques. We divided all precipitation events into four non-overlapping categories: light, moderate, heavy and very heavy based on percentile thresholds. We then established the trends for annual total and precipitation of different intensity categories, and examined their regional and seasonal variations. The results show that there was little change in annual total precipitation for entire China, but distinctive regional patterns existed. In general precipitation increased in the west and decreased in east. Precipitation of different intensities in general changed in the same direction as the mean, but heavy and very heavy precipitation events in general had higher rates of change than mean precipitation. The exception was the southeast region, where despite the slight decrease in mean precipitation, heavy and very heavy precipitation still increased significantly. In addition, we used multiple regression models to explore the contribution of changes of frequency and intensity to total precipitation change, and the contributions of changes of precipitation at different intensities to total precipitation change. For western China, total precipitation change was associated more with frequency change, whereas in eastern China intensity contributed more. For precipitation amount, moderate, heavy and very heavy precipitation all contributed to the total change, with little contribution from light precipitation change. For frequency, changes in light and moderate precipitation frequency dominated the total change, with very little contributions from heavy and very heavy precipitation frequency change. In addition, we examined the linkage between summer precipitation in eastern China and the East Asian Summer Monsoon (EASM), found that the northern

  5. Terrestrial water fluxes dominated by transpiration.

    PubMed

    Jasechko, Scott; Sharp, Zachary D; Gibson, John J; Birks, S Jean; Yi, Yi; Fawcett, Peter J

    2013-04-18

    Renewable fresh water over continents has input from precipitation and losses to the atmosphere through evaporation and transpiration. Global-scale estimates of transpiration from climate models are poorly constrained owing to large uncertainties in stomatal conductance and the lack of catchment-scale measurements required for model calibration, resulting in a range of predictions spanning 20 to 65 per cent of total terrestrial evapotranspiration (14,000 to 41,000 km(3) per year) (refs 1, 2, 3, 4, 5). Here we use the distinct isotope effects of transpiration and evaporation to show that transpiration is by far the largest water flux from Earth's continents, representing 80 to 90 per cent of terrestrial evapotranspiration. On the basis of our analysis of a global data set of large lakes and rivers, we conclude that transpiration recycles 62,000 ± 8,000 km(3) of water per year to the atmosphere, using half of all solar energy absorbed by land surfaces in the process. We also calculate CO2 uptake by terrestrial vegetation by connecting transpiration losses to carbon assimilation using water-use efficiency ratios of plants, and show the global gross primary productivity to be 129 ± 32 gigatonnes of carbon per year, which agrees, within the uncertainty, with previous estimates. The dominance of transpiration water fluxes in continental evapotranspiration suggests that, from the point of view of water resource forecasting, climate model development should prioritize improvements in simulations of biological fluxes rather than physical (evaporation) fluxes. PMID:23552893

  6. From precipitation to runoff: Climatic controls on discharge variability

    NASA Astrophysics Data System (ADS)

    Rossi, M. W.; Whipple, K. X.; Vivoni, E. R.

    2012-12-01

    A number of recent studies have stressed the importance of modeling stochastic distributions of flood magnitudes along with thresholds to incision in order to develop more robust predictions of climatic control on fluvial erosion. Some of these studies have used precipitation time-series and others have used discharge time-series to characterize the climate state. While discharge is more directly tied to incision process, precipitation records are generally of longer duration and are more widely available. However, before fluvial incision models can benefit from the wealth of global precipitation data, better understanding of the non-linear transformation from precipitation to runoff is needed. There are a number of possible explanations for this non-linearity that can be broadly characterized into: (1) the statistical structure of precipitation itself (e.g. the autocorrelation of precipitation events); (2) the mediation of rainfall to runoff by the soil water balance (e.g. the role of soil properties and vegetation); and (3) the spatial organization of channel networks. While progress is needed on each of these fronts, we choose to first focus on (1) by examining the statistics of mean daily storm depth, storm frequency, and runoff for the continental U.S. The continental U.S. provides a good setting to explore this issue because it exhibits a wide range of climates (dry to humid; cold to hot; winter-dominated to summer-dominated precipitation) and has a dense observation network for both precipitation and discharge. Specifically, we rely on the United States Historical Climatology Network (USHCN) for meteorological data (1,221 stations) and the Hydro-Climatic Data Network-2009 (HCDN-2009) for hydrological data (704 stations). Stations in these networks have been selected to best reflect the "natural" state by maximizing record length/completeness and minimizing anthropogenic influence. Whereas precipitation is commonly modeled as a Poisson process (i.e. an

  7. C, N and P ratios modulate the dominance of soil N forms, microbial N transformation processes and microbial functional diversity under biological soil crust in a semi-arid grassland.

    NASA Astrophysics Data System (ADS)

    Delgado-Baquerizo, M.; Morillas, L.; Maestre, F.; Gallardo, A.

    2012-04-01

    The biogeochemical cycles of carbon (C), nitrogen (N), and phosphorus (P) modulate the primary production, respiration and decomposition from molecular to global scales on Earth, and constrain organismal responses to global change. Human activities are changing the ratios of those nutrients on soil, but our knowledge about how these cycles modulate key soil processes in drylands is still scarce. In these systems, open spaces between plant canopies are frequently occupied by biological soil crusts (BSCs), which influencesome N cycle processes such as N fixation, nitrification and denitrification, although their effects on the P cycle are poorly known. In this work, we have focused on how different N, C and P ratios may affect the N forms,the dominance of different microbial processes and the microbial functional diversity in dryland soils. We collected soils with and without BSCs from a semi-arid Stipa tenacissima grassland. Soil samples were incubated under 8 different treatments of N,C and P in a full experimental design (Control, N, C, P, N+C, N+P. P+C, C+N+P), and for 4 different periods of incubation (1-to-4 weeks). Changes in soil dissolved organic nitrogen (DON), ammonium, nitrate and total available N, as well as, deploymerization, nitrification and ammonification rates were monitored. Relative dominances were calculated for both N forms and microbial processes. In parallel, microbial functional diversity was estimated for the eight nutrient treatments and for two incubation periods (1 and 3 weeks) by using the Microresp technique. Along the different incubation periods, nitrate was the main dominant N form for the control, N and P treatments; ammonium dominated the C+N treatment, and DON the C and C+P treatments. Relative nitrification rate was the dominant process for the control, N and P treatments throughout the different incubation periods. A mixture of N-forms and processes dominance was found for all other nutrient treatments. Differences between

  8. Dominant flood generating mechanisms across the United States

    NASA Astrophysics Data System (ADS)

    Berghuijs, Wouter R.; Woods, Ross A.; Hutton, Christopher J.; Sivapalan, M.

    2016-05-01

    River flooding can have severe societal, economic, and environmental consequences. However, limited understanding of the regional differences in flood-generating mechanisms results in poorly understood historical flood trends and uncertain predictions of future flood conditions. Through systematic data analyses of 420 catchments we expose the primary drivers of flooding across the contiguous United States. This is achieved by exploring which flood-generating processes control the seasonality and magnitude of maximum annual flows. The regional patterns of seasonality and interannual variabilities of maximum annual flows are, in general, poorly explained by rainfall characteristics alone. For most catchments soil moisture dependent precipitation excess, snowmelt, and rain-on-snow events are found to be much better predictors of the flooding responses. The continental-scale classification of dominant flood-generating processes we generate here emphasizes the disparity in timing and variability between extreme rainfall and flooding and can assist predictions of flooding and flood risk within the continental U.S.

  9. The Impact of Affect on Out-Group Judgments Depends on Dominant Information-Processing Styles: Evidence From Incidental and Integral Affect Paradigms.

    PubMed

    Isbell, Linda M; Lair, Elicia C; Rovenpor, Daniel R

    2016-04-01

    Two studies tested the affect-as-cognitive-feedback model, in which positive and negative affective states are not uniquely associated with particular processing styles, but rather serve as feedback about currently accessible processing styles. The studies extend existing work by investigating (a) both incidental and integral affect, (b) out-group judgments, and (c) downstream consequences. We manipulated processing styles and either incidental (Study 1) or integral (Study 2) affect and measured perceptions of out-group homogeneity. Positive (relative to negative) affect increased out-group homogeneity judgments when global processing was primed, but under local priming, the effect reversed (Studies 1 and 2). A similar interactive effect emerged on attributions, which had downstream consequences for behavioral intentions (Study 2). These results demonstrate that both incidental and integral affect do not directly produce specific processing styles, but rather influence thinking by providing feedback about currently accessible processing styles. PMID:26984013

  10. Vocal Reaction Times of Stuttering Subjects to Tachistoscopically Presented Concrete and Abstract Words: A Closer Look at Cerebral Dominance and Language Processing.

    ERIC Educational Resources Information Center

    Rastatter, Michael P.; Dell, Carl

    1987-01-01

    The study investigated cerebral organization for visual language processing with 14 adult stutterers. Results showed the right hemisphere was superior for analyzing the concrete words while the left hemisphere was responsible for processing the abstract items suggesting some form of linguistic competition between the two hemispheres of this…

  11. Improving the analysis of small precipitates in HSLA steels using a plasma cleaner and ELNES.

    PubMed

    Wilson, J A; Craven, A J

    2003-04-01

    The change from producing high strength low alloy (HSLA) steel sheet by conventional thick slab casting to producing it by direct charged thin slab casting causes a major change in the evolution of the precipitation. A key area of interest is the composition of the sub-10nm precipitates used to produce dispersion hardening. Carbon extraction replicas are frequently used to study precipitates in steels and other metals. When used with annular dark field imaging, this technique gives high contrast images of the precipitates while the thin carbon film adds little background or additional characteristic signals to either electron energy loss spectra or energy dispersive X-ray spectra. The method has the additional major advantage of removing the ferromagnetic matrix when studying HSLA steels. However, when the precipitates contain carbon, the C K-edge is dominated by the contribution from the amorphous carbon film. A plasma cleaner can be used to thin this carbon film to approximately 0.5 nm or less and then the contribution from the carbon in the precipitate can be separated from that in the carbon film using the electron energy loss near edge structure. A similar approach can be taken to separate the oxygen content of the precipitate from that of oxides formed from low-level impurities in the amorphous carbon during the plasma thinning process. In most cases, the precipitate studied here contained little or no oxygen even for the smallest sizes examined (approximately 4 nm). The precipitates contain mainly nitrogen with little carbon. For some compositions, the precipitates are clearly sub-stoichiometric. PMID:12524190

  12. Subseasonal variability of precipitation in China during boreal winter

    NASA Astrophysics Data System (ADS)

    Yao, Y.; Lin, H.; Wu, Q.

    2014-12-01

    Using pentad data of the Northern Hemisphere extended winter from 1979 to 2012 that are derived from the daily rainfall of the National Meteorological Information Center of China, subseasonal variability of precipitation in China is analyzed. The two dominant modes of subseasonal precipitation variability are identified with an empirical orthogonal function (EOF) analysis. The first mode (EOF1) is characterized by a monopole in South China, whereas the second mode (EOF2) has a meridional dipole structure with opposite precipitation anomalies over the Yangtze River Basin and the coastal area of South China. These two modes tend to have a phase shift to each other in both space and time, indicating that part of their variability is related to a common process and represents a southward propagating pattern. The subseasonal variability is decomposed into two components, i.e., that related to the Madden-Julian Oscillation (MJO) and that independent of the MJO. The MJO-related component is obtained using a bivariate linear regression with respect to the MJO index as defined by Wheeler and Hendon. It is found that the MJO contributes to only a small amount (up to 10%) of precipitation variability in South China. EOF1 is associated with the MJO phase 3, corresponding to enhanced equatorial convection in the Indian Ocean and depressed convection in the western Pacific, while EOF2 is related to the MJO phase 5, when the enhanced tropical convection moves to the Maritime continent region. A large part of the subseasonal precipitation variability in China is independent of the MJO. Lagged regression analysis is performed between the leading principal component (PC1) and the MJO-independent component of variability of 500-hPa geopotential height, sea-level pressure and 2-meter air temperature. It is found that the subseasonal precipitation variability in China is related to a wave train from the North Atlantic, development of the Siberian high, and cold air outbreak in East

  13. Plant invasions differentially affected by diversity and dominant species in native- and exotic-dominated grasslands.

    PubMed

    Xu, Xia; Polley, H Wayne; Hofmockel, Kirsten; Daneshgar, Pedram P; Wilsey, Brian J

    2015-12-01

    Plant invasions are an increasingly serious global concern, especially as the climate changes. Here, we explored how plant invasions differed between native- and novel exotic-dominated grasslands with experimental addition of summer precipitation in Texas in 2009. Exotic species greened up earlier than natives by an average of 18 days. This was associated with a lower invasion rate early in the growing season compared to native communities. However, invasion rate did not differ significantly between native and exotic communities across all sampling times. The predictors of invasion rate differed between native and exotic communities, with invasion being negatively influenced by species richness in natives and by dominant species in exotics. Interestingly, plant invasions matched the bimodal pattern of precipitation in Temple, Texas, and did not respond to the pulse of precipitation during the summer. Our results suggest that we will need to take different approaches in understanding of invasion between native and exotic grasslands. Moreover, with anticipated increasing variability in precipitation under global climate change, plant invasions may be constrained in their response if the precipitation pulses fall outside the normal growing period of invaders. PMID:27069615

  14. Temperature-precipitation relationships for Canadian stations

    SciTech Connect

    Isaac, G.A. ); Stuart, R.A. )

    1992-08-01

    The dependence of daily precipitation upon average daily temperature has been examined for all seasons using climatological data from 56 stations across Canada. For east and west coast sites, and the north, more precipitation occurs with warm and cold temperatures during January and July, respectively. In the middle of the country, the temperature dependence tends to increase toward the Arctic, with strong dependencies in the Northwest Territories and weaker dependencies on the Prairies. Southern Ontario and Quebec show almost no dependence of precipitation upon temperature during July, but more precipitation falls during warm weather during the winter. For stations within and immediately downwind of the Rockies, for all seasons, more precipitation occurs when the temperature is colder. These temperature-precipitation relationships can provide information on precipitation formation processes, as well as assistance in weather and climate forecasting.

  15. Global Precipitation Measurement (GPM) implementation

    NASA Astrophysics Data System (ADS)

    Neeck, Steven P.; Kakar, Ramesh K.; Azarbarzin, Ardeshir A.; Hou, Arthur Y.

    2010-10-01

    The Global Precipitation Measurement (GPM) mission will provide enhanced space-based precipitation measurements with sufficient coverage, spatial resolution, temporal sampling, retrieval accuracy, and microphysical information to advance the understanding of Earth's water and energy cycle and to improve predictions of its climate, weather, and hydrometeorological processes. Such improvements will in turn improve decision support systems in broad societal applications (e.g. water resource management, agriculture, transportation, etc). GPM is a partnership between NASA and the Japan Aerospace Exploration Agency (JAXA), building upon their highly successful partnership on the Tropical Rainfall Measuring Mission (TRMM). The GPM architecture consists of NASA satellites operating in partnership with other earth-observing satellites and instruments to produce global precipitation science data. The current generation of multi-satellite global precipitation products based on microwave/infrared sensors from uncoordinated satellite missions has for its anchor the TRMM precipitation radar and the TRMM Microwave Imager measurements over the tropics and subtropics (+/- 35 degrees latitude), with a mean sampling time of approximately 17 hours. The GPM mission will deploy a spaceborne Core Observatory as a reference standard to unify a space constellation of research and operational microwave sensors aimed at providing uniformly calibrated precipitation measurements globally every 2-4 hours. The Core Observatory measurements will provide, for the first time, quantitative information on precipitation particle size distribution needed for improving the accuracy of precipitation estimates by microwave radiometers and radars. In addition, the GPM will also include a second microwave radiometer and a Tracking and Data Relay Satellite (TDRS) communications subsystem for near real time data relay for a future partner-provided constellation satellite. This second GPM Microwave Imager (GMI

  16. Precipitation Climate Data Records

    NASA Astrophysics Data System (ADS)

    Nelson, B. R.; Prat, O.; Vasquez, L.

    2015-12-01

    Five precipitation CDRs are now or soon will be transitioned to NOAA's CDR program. These include the PERSIANN data set, which is a 30-year record of daily adjusted global precipitation based on retrievals from satellite microwave data using artificial neural networks. The AMSU-A/B/Hydrobundle is an 11-year record of precipitable water, cloud water, ice water, and other variables. CMORPH (the NOAA Climate Prediction Center Morphing Technique) is a 17-year record of daily and sub-daily adjusted global precipitation measured from passive microwave and infrared data at high spatial and temporal resolution. GPCP (the Global Precipitation Climatology Project) is an approximately 30-year record of monthly and pentad adjusted global precipitation and a 17-year record of daily adjusted global precipitation. The NEXRAD Reanalysis is a 10-year record of high resolution NEXRAD radar based adjusted CONUS-wide hourly and daily precipitation. This study provides an assessment of the existing and transitioned long term precipitation CDRs and includes the verification of the five precipitation CDRs using various methods including comparison with in-situ data sets and trend analysis. As all of the precipitation related CDRs are transitioned, long term analyses can be performed. Comparisons at varying scales (hourly, daily and longer) of the precipitation CDRs with in-situ data sets are provided as well as a first look at what could be an ensemble long term precipitation data record.

  17. Process dominance shift in solute chemistry as revealed by long-term high-frequency water chemistry observations of groundwater flowing through weathered argillite underlying a steep forested hillslope

    NASA Astrophysics Data System (ADS)

    Kim, Hyojin; Bishop, James K. B.; Dietrich, William E.; Fung, Inez Y.

    2014-09-01

    Significant solute flux from the weathered bedrock zone - which underlies soils and saprolite - has been suggested by many studies. However, controlling processes for the hydrochemistry dynamics in this zone are poorly understood. This work reports the first results from a four-year (2009-2012) high-frequency (1-3 day) monitoring of major solutes (Ca, Mg, Na, K and Si) in the perched, dynamic groundwater in a 4000 m2 zero-order basin located at the Angelo Coast Range Reserve, Northern California. Groundwater samples were autonomously collected at three wells (downslope, mid-slope, and upslope) aligned with the axis of the drainage. Rain and throughfall samples, profiles of well headspace pCO2, vertical profiles and time series of groundwater temperature, and contemporaneous data from an extensive hydrologic and climate sensor network provided the framework for data analysis. All runoff at this soil-mantled site occurs by vertical unsaturated flow through a 5-25 m thick weathered argillite and then by lateral flows to the adjacent channel as groundwater perched over fresher bedrock. Driven by strongly seasonal rainfall, over each of the four years of observations, the hydrochemistry of the groundwater at each well repeats an annual cycle, which can be explained by two end-member processes. The first end-member process, which dominates during the winter high-flow season in mid- and upslope areas, is CO2 enhanced cation exchange reaction in the vadose zone in the more shallow conductive weathered bedrock. This process rapidly increases the cation concentrations of the infiltrated rainwater, which is responsible for the lowest cation concentration of groundwater. The second-end member process occurs in the deeper perched groundwater and either dominates year-round (at the downslope well) or becomes progressively dominant during low flow season at the two upper slope wells. This process is the equilibrium reaction with minerals such as calcite and clay minerals, but not

  18. Autosomal dominant vitreoretinochoroidopathy (ADVIRC).

    PubMed Central

    Blair, N P; Goldberg, M F; Fishman, G A; Salzano, T

    1984-01-01

    We report the second family recognised to have autosomal dominant vitreoretinochoroidopathy. The clinical features were (1) autosomal dominant inheritance; (2) peripheral, coarse pigmentary degeneration of the fundus for 360 degrees, with a relatively discrete posterior border in the equatorial region (this finding may be pathognomonic); (3) superficial punctate yellowish-white opacities in the retina; (4) various vascular abnormalities; (5) breakdown of the blood-retinal barrier; (6) retinal neovascularisation; (7) vitreous abnormalities; and (8) choroidal atrophy. Visual reduction was mainly due to macular oedema or vitreous haemorrhage. Images PMID:6689931

  19. Language after dominant hemispherectomy

    PubMed Central

    Gott, Piggy S.

    1973-01-01

    Linguistic and related cognitive abilities were investigated two years after dominant left hemispherectomy for cerebral malignancy in a 12 year old female. Auditory comprehension of speech was superior to other modes of language abilities with expressive speech being the least developed. Findings suggested an isolation or non-communication between the systems for speaking and for writing and visual perception. It was concluded that language mechanisms in the right hemisphere were not just at a low level of development of the functions found in the dominant hemisphere but were modified as a result of interference by preexistent spatioperceptual systems. Images PMID:4772723

  20. Physiology-based prognostic modeling of the influence of changes in precipitation on a keystone dryland plant species.

    PubMed

    Coe, Kirsten K; Sparks, Jed P

    2014-12-01

    Fluctuations in mean annual precipitation (MAP) will strongly influence the ecology of dryland ecosystems in the future, yet, because individual precipitation events drive growth and resource availability for many dryland organisms, changes in intra-annual precipitation may disproportionately influence future dryland processes. This work examines the hypothesis that intra-annual precipitation changes will drive dryland productivity to a greater extent than changes to MAP. To test this hypothesis, we created a physiology-based model to predict the effects of precipitation change on a widespread biocrust moss that regulates soil structure, water retention, and nutrient cycling in drylands. First, we used the model to examine moss productivity over the next 100 years driven by alterations in MAP by ± 10, 20 and 30%, and changes in intra-annual precipitation (event size and frequency). Productivity increased as a function of MAP, but differed among simulations where intra-annual precipitation was manipulated under constant MAP. Supporting our hypothesis, this demonstrates that, even if MAP does not change, changes in the features of individual precipitation events can strongly influence long-term performance. Second, we used the model to examine 100-year productivity based on projected dryland precipitation from published global and regional models. These simulations predicted 25-63% reductions in productivity and increased moss mortality rates, declines that will likely alter water and nutrient cycling in dryland ecosystems. Intra-annual precipitation in model-based simulations was a stronger predictor of productivity compared to MAP, further supporting our hypothesis, and illustrating that intra-annual precipitation patterns may dominate dryland responses to altered precipitation in a future climate. PMID:25193314

  1. DISSOLUTION OF PLUTONIUM CONTAINING CARRIER PRECIPITATE BY CARBONATE METATHESIS AND SEPARATION OF SULFIDE IMPURITIES THEREFROM BY SULFIDE PRECIPITATION

    DOEpatents

    Duffield, R.B.

    1959-07-14

    A process is described for recovering plutonium from foreign products wherein a carrier precipitate of lanthanum fluoride containing plutonium is obtained and includes the steps of dissolving the carrier precipitate in an alkali metal carbonate solution, adding a soluble sulfide, separating the sulfide precipitate, adding an alkali metal hydroxide, separating the resulting precipitate, washing, and dissolving in a strong acid.

  2. Global climate change and associated precipitation inequality over the Ukraine

    NASA Astrophysics Data System (ADS)

    Voskresenskaya, Elena; Vyshkvarkova, Elena; Polonsky, Alexander

    2013-04-01

    The aim of presentation is the analysis of the climatology of precipitation inequality over the Ukraine and its change and variability associated with global climate processes. Daily precipitation from 19 hydrometeorological stations of Ukraine in XIX-XXI centuries and global Had CRU data sets were analyzed. The method based on Gini index (GI) calculation was used for estimation of precipitation inequality (in this case GI characterizes the contribution of the heavy rainfalls into the total amount of precipitation). Comparison of GI trends with the surface temperature trends permits to analyze the role of regional warming in change of precipitation inequality. In addition, the standard statistical methods were applied to study the variability of this irregularity associated with North Atlantic oscillation (NAO), El-Nino-Southern oscillation (ENSO), Atlantic Multidecadal oscillation (AMO) and Pacific Decadal oscillation (PDO). At first, the typical GIs were estimated for the cold and warm seasons and for the entire year. They vary on the Ukrainian stations from 0.58 at the North-West and North-East to 0.64 at the southern regions. Next, the GI trends in winter (DJF) and summer (JJA) seasons and for entire year were estimated. Their spatial distribution over the Ukraine shows the following features. Yearly GI trends are negative (about -0,0005/100 years) for the most regions of the country, including the Carpathian, forest and forest-steppe zones where intense warming occurs. Positive trends dominate in the steppe regions of Ukraine. They increase southwards and reach 0,0003/100 years in the seaside of the Crimea where warming is mostly insignificant. Principal seasonal differences in the GI trends were found. In summer, over the most territory of Ukraine, except the steppe zone, GI trends are negative, while in winter they are mostly positive. It is shown that contribution of summer heavy precipitation into the total amount of precipitation is 2-3 times more than in

  3. Iron dominated magnets

    SciTech Connect

    Fischer, G.E.

    1985-07-01

    These two lectures on iron dominated magnets are meant for the student of accelerator science and contain general treatments of the subjects design and construction. The material is arranged in the categories: General Concepts and Cost Considerations, Profile Configuration and Harmonics, Magnetic Measurements, a few examples of ''special magnets'' and Materials and Practices. Extensive literature is provided.

  4. Heavy Precipitation Events in Lithuania

    NASA Astrophysics Data System (ADS)

    Bukantis, A.; Rimkus, E.; Kažys, J.

    2010-09-01

    Analysis of heavy precipitation events in Lithuania is presented in this work. Research was divided into two parts. Spatial distribution and dynamic of heavy precipitation events in Lithuania during observation period (1961-2008) is presented in the first part and climate predictions for XXI century according to outputs of CCLM model are in the second. Daily data from 17 meteorological stations were used for the analysis of heavy precipitation events in Lithuania. Research covers period from 1961 to 2008. Annual and seasonal heavy precipitation values and the recurrence of extreme daily and 3-day precipitation events were analyzed. Spatial distribution of heavy precipitation events in Lithuania was determined; the trends of such precipitation recurrence were identified. Also, daily and 3-day annual maxima probabilities were calculated using the Generalized Extreme Value (GEV) distribution. 10, 30 and 100 years return period was analyzed. Finally, atmospheric circulation processes during heavy precipitation events were described using the adapted Hess & Brezowski macrocirculation form classification Predictions of changes of heavy precipitation recurrence in Lithuania are also presented in this study. Output data of the regional climate model CCLM (COSMO - Climate Limited-area Model) for the period 1971-2100 were used. Predictions were based on A1B and B1 emission scenarios. Despite of relatively small area and quite negligible differences in altitude there are significant unevenness in spatial distribution of heavy precipitation events in Lithuania. The mean annual number of cases when daily precipitation amount exceeded 10 mm fluctuates from 12.4 to 21.9 and from 5.3 to 10.5 when 3-day precipitation exceeded 20 mm. The probability of maximum precipitation amount for 10 year return period appears very familiar to spatial distribution of heavy precipitation recurrence: the highest values can be expected in the western part (55-60 mm daily and 75-85 mm in 3-days

  5. Development and demonstration of process and components for the control of aluminum-air-battery electrolyte composition through the precipitation of aluminum trihydroxide. Final report

    SciTech Connect

    Swansiger, T. G.; Misra, C.

    1982-05-11

    Physical property data on density, viscosity, and electrical conductivity were developed and reduced to correlation form for synthetic electrolytes containing nominally 7 g/L Sn and 0.20 g/L Ga in 3,4,5,6 M NaOH. Concentrations of Al(OH)/sub 4/ were selected at six levels for each NaOH concentration and ranged from 0 to as high as 4 M Al(OH)/sub 4/ at 6 M NaOH. Measurements of each property were made at 25, 40, 60, and 80 C. The effect of the Sn and Ga impurities was to increase density by a relatively small percentage, increase viscosity by a significant percentage, and decrease electrical conductance by a significant percentage. Isothermal, batch precipitation experiments at 40, 60, and 80 C were utilized to develop data from which kinetic and solubility correlations were derived as functions of electrolyte and system parameters. Precipitation rate was negatively affected by tin in solution, with a 40% reduction in the rate constant being attributed to 0.06 M Sn. Both Sn and Ga co-precipitated with the Al(OH)/sub 3/ to an extent strongly dependent on temperature. Very high precipitation rates resulted in Na levels in product exceeding the target level of 0.24% Na on the hydrate basis. The incorporation of Na in product was also a strong function of temperature. A total of 108 computer simulations were performed and documented to delineate the region of feasible operation with respect to meeting the aluminate production specification. A full-scale precipitator was operated in a continuous mode to assess production rate, population changes with time, and hardware aspects. A digester was used to perform the function of an Al-Air battery, that is to drive Al(OH)/sub 4//sup -/ into solution. Results are presented in detail. (WHK)

  6. METHOD FOR REMOVING CONTAMINATION FROM PRECIPITATES

    DOEpatents

    Stahl, G.W.

    1959-01-01

    An improvement in the bismuth phosphate carrier precipitation process is presented for the recovery and purification of plutonium. When plutonium, in the tetravalent state, is carried on a bismuth phosphate precipitate, amounts of centain of the fission products are carried along with the plutonium. The improvement consists in washing such fission product contaminated preeipitates with an aqueous solution of ammonium hydrogen fluoride. since this solution has been found to be uniquely effective in washing fission production contamination from the bismuth phosphate precipitate.

  7. Distinct Escape Pathway by Hepatitis C Virus Genotype 1a from a Dominant CD8+ T Cell Response by Selection of Altered Epitope Processing

    PubMed Central

    Walker, Andreas; Skibbe, Kathrin; Steinmann, Eike; Pfaender, Stephanie; Kuntzen, Thomas; Megger, Dominik A.; Groten, Svenja; Sitek, Barbara; Lauer, Georg M.; Kim, Arthur Y.; Pietschmann, Thomas; Allen, Todd M.

    2015-01-01

    ABSTRACT Antiviral CD8+ T cells are a key component of the adaptive immune response against HCV, but their impact on viral control is influenced by preexisting viral variants in important target epitopes and the development of viral escape mutations. Immunodominant epitopes highly conserved across genotypes therefore are attractive for T cell based prophylactic vaccines. Here, we characterized the CD8+ T cell response against the highly conserved HLA-B*51-restricted epitope IPFYGKAI1373–1380 located in the helicase domain of NS3 in people who inject drugs (PWID) exposed predominantly to HCV genotypes 1a and 3a. Despite this epitope being conserved in both genotypes, the corresponding CD8+ T cell response was detected only in PWID infected with genotype 3a and HCV-RNA negative PWID, but not in PWID infected with genotype 1a. In genotype 3a, the detection of strong CD8+ T cell responses was associated with epitope variants in the autologous virus consistent with immune escape. Analysis of viral sequences from multiple cohorts confirmed HLA-B*51-associated escape mutations inside the epitope in genotype 3a, but not in genotype 1a. Here, a distinct substitution in the N-terminal flanking region located 5 residues upstream of the epitope (S1368P; P = 0.00002) was selected in HLA-B*51-positive individuals. Functional assays revealed that the S1368P substitution impaired recognition of target cells presenting the endogenously processed epitope. The results highlight that, despite an epitope being highly conserved between two genotypes, there are major differences in the selected viral escape pathways and the corresponding T cell responses. IMPORTANCE HCV is able to evolutionary adapt to CD8+ T cell immune pressure in multiple ways. Beyond selection of mutations inside targeted epitopes, this study demonstrates that HCV inhibits epitope processing by modification of the epitope flanking region under T cell immune pressure. Selection of a substitution five amino acids

  8. From nature-dominated to human-dominated environmental changes

    NASA Astrophysics Data System (ADS)

    Messerli, Bruno; Grosjean, Martin; Hofer, Thomas; Núñez, Lautaro; Pfister, Christian

    2000-01-01

    To what extent is it realistic and useful to view human history as a sequence of changes from highly vulnerable societies of hunters and gatherers through periods with less vulnerable, well buffered and highly productive agrarian-urban societies to a world with regions of extreme overpopulation and overuse of life support systems, so that vulnerability to climatic-environmental changes and extreme events is again increasing? This question cannot be fully answered in our present state of knowledge, but at least we can try to illustrate, with three case studies from different continents, time periods and ecosystems, some fundamental changes in the relationship between natural processes and human activities that occur, as we pass from a nature-dominated to a human dominated environment. 1. Early-mid Holocene: Nature dominated environment — human adaptation, mitigation, and migration. In the central Andes, the Holocene climate changed from humid (10,800-8000 BP) to extreme arid (8000-3600 BP) conditions. Over the same period, prehistoric hunting communities adopted a more sedentary pattern of resource use by settling close to the few perennial water bodies, where they began the process of domesticating camelids around 5000 BP and irrigation from about 3100 BP. 2. Historical period: An agrarian society in transition from an "enduring" to an innovative human response. Detailed documentary evidence from Western Europe may be used to reconstruct quite precisely the impacts of climatic variations on agrarian societies. The period considered spans a major transition from an apparently passive response to the vagaries of the environment during the 16th century to an active and innovative attitude from the onset of the agrarian revolution in the late 18th century through to the present day. The associated changes in technology and in agricultural practices helped to create a society better able to survive the impact of climatic extremes. 3. The present day: A human dominated

  9. Precipitation estimates from MSG SEVIRI daytime, night-time and twilight data with random forests

    NASA Astrophysics Data System (ADS)

    Kühnlein, Meike; Appelhans, Tim; Thies, Boris; Nauss, Thomas

    2014-05-01

    We introduce a new rainfall retrieval technique based on MSG SEVIRI data which aims to retrieve rainfall rates in a continuous manner (day, twilight and night) at high temporal resolution. Due to the deficiencies of existing optical rainfall retrievals, the focus of this technique is on assigning rainfall rates to precipitating cloud areas in connection with extra-tropical cyclones in mid-latitudes including both convective and advective-stratiform precipitating cloud areas. The technique is realized in three steps: (i) Precipitating cloud areas are identified. (ii) The precipitating cloud areas are separated into convective and advective-stratiform precipitating areas. (iii) Rainfall rates are assigned to the convective and advective-stratiform precipitating areas, respectively. Therefore, considering the dominant precipitation processes of convective and advective-stratiform precipitation areas within extra-tropical cyclones, satellite-based information on the cloud top height, cloud top temperature, cloud phase and cloud water path are used to retrieve information about precipitation. The approach uses the ensemble classification and regression technique random forests to develop the prediction algorithms. Random forest models contain a combination of characteristics that make them well suited for its application in precipitation remote sensing. One of the key advantages is the ability to capture non-linear association of patterns between predictors and response which becomes important when dealing with complex non-linear events like precipitation. Using a machine learning approach differentiates the proposed technique from most state-of-the-art satellite-based rainfall retrievals which generally use conventional parametric approaches. To train and validate the model, the radar-based RADOLAN RW product from the German Weather Service (DWD) is used which provides area-wide gauge-adjusted hourly precipitation information. Beside the overall performance of the

  10. Solar wind drivers of energetic electron precipitation

    NASA Astrophysics Data System (ADS)

    Asikainen, T.; Ruopsa, M.

    2016-03-01

    Disturbances of near-Earth space are predominantly driven by coronal mass ejections (CMEs) mostly originating from sunspots and high-speed solar wind streams (HSSs) emanating from coronal holes. Here we study the relative importance of CMEs and HSSs as well as slow solar wind in producing energetic electron precipitation. We use the recently corrected energetic electron measurements from the Medium Energy Proton Electron Detector instrument on board low-altitude NOAA/Polar Orbiting Environmental Satellites from 1979 to 2013. Using solar wind observations categorized into three different flow types, we study the contributions of these flows to annual electron precipitation and their efficiencies in producing precipitation. We find that HSS contribution nearly always dominates over the other flows and peaks strongly in the declining solar cycle phase. CME contribution mostly follows the sunspot cycle but is enhanced also in the declining phase. The efficiency of both HSS and CME peaks in the declining phase. We also study the dependence of electron precipitation on solar wind southward magnetic field component, speed, and density and find that the solar wind speed is the dominant factor affecting the precipitation. Since HSSs enhance the average solar wind speed in the declining phase, they also enhance the efficiency of CMEs during these times and thus have a double effect in enhancing energetic electron precipitation.

  11. Advanced Microwave Precipitation Radiometer (AMPR) for remote observation of precipitation

    NASA Technical Reports Server (NTRS)

    Galliano, J. A.; Platt, R. H.

    1990-01-01

    The design, development, and tests of the Advanced Microwave Precipitation Radiometer (AMPR) operating in the 10 to 85 GHz range specifically for precipitation retrieval and mesoscale storm system studies from a high altitude aircraft platform (i.e., ER-2) are described. The primary goals of AMPR are the exploitation of the scattering signal of precipitation at frequencies near 10, 19, 37, and 85 GHz together to unambiguously retrieve precipitation and storm structure and intensity information in support of proposed and planned space sensors in geostationary and low earth orbit, as well as storm-related field experiments. The development of AMPR will have an important impact on the interpretation of microwave radiances for rain retrievals over both land and ocean for the following reasons: (1) A scanning instrument, such as AMPR, will allow the unambiguous detection and analysis of features in two dimensional space, allowing an improved interpretation of signals in terms of cloud features, and microphysical and radiative processes; (2) AMPR will offer more accurate comparisons with ground-based radar data by feature matching since the navigation of the ER-2 platform can be expected to drift 3 to 4 km per hour of flight time; and (3) AMPR will allow underflights of the SSM/I satellite instrument with enough spatial coverage at the same frequencies to make meaningful comparisons of the data for precipitation studies.

  12. In silico Proteome-wide Amino aCid and Elemental Composition (PACE) Analysis of Expression Proteomics Data Provides A Fingerprint of Dominant Metabolic Processes

    PubMed Central

    Good, David M.; Mamdoh, Anwer; Budamgunta, Harshavardhan; Zubarev, Roman A.

    2013-01-01

    Proteome-wide Amino aCid and Elemental composition (PACE) analysis is a novel and informative way of interrogating the proteome. The PACE approach consists of in silico decomposition of proteins detected and quantified in a proteomics experiment into 20 amino acids and five elements (C, H, N, O and S), with protein abundances converted to relative abundances of amino acids and elements. The method is robust and very sensitive; it provides statistically reliable differentiation between very similar proteomes. In addition, PACE provides novel insights into proteome-wide metabolic processes, occurring, e.g., during cell starvation. For instance, both Escherichia coli and Synechocystis down-regulate sulfur-rich proteins upon sulfur deprivation, but E. coli preferentially down-regulates cysteine-rich proteins while Synechocystis mainly down-regulates methionine-rich proteins. Due to its relative simplicity, flexibility, generality and wide applicability, PACE analysis has the potential of becoming a standard analytical tool in proteomics. PMID:23917074

  13. Bedform genesis in bedrock substrates: Insights into formative processes from a new experimental approach and the importance of suspension-dominated abrasion

    NASA Astrophysics Data System (ADS)

    Yin, Daowei; Peakall, Jeff; Parsons, Dan; Chen, Zhongyuan; Averill, Heather Macdonald; Wignall, Paul; Best, Jim

    2016-02-01

    Bedrock channels are common in the natural environment, and bedrock channel erosion sets the pace of denudation in many river catchments. However, in comparison to the large number of studies concerning the formation of alluvial bedforms, relatively few investigations have concerned bedrock bedform genesis. Field-based analysis of sculptured forms within bedrock channels has been restricted notably by the slow rate of bedform development in such environments. Furthermore, only a limited number of flume-scale experiments have been conducted that attempt to simulate the genesis of sculpted bedforms in bedrock channels. This study demonstrates that optimisation of clay beds through analysis of clay strength enables the development of features analogous to bedrock river channel bedforms - even at a scale that is orders of magnitude smaller than some natural examples. Three sets of suspended sediment-laden experiments were carried out using hard, medium, and soft clay bed substrates. A suite of erosive bedforms (including potholes, flutes, and furrows) developed on all experimental beds. All observed erosional features have clear equivalents to those observed in natural bedrock rivers. Bed shear strength was found to be a significant factor for the genesis of different types of simulated bedrock bedforms in our experiments with other factors, such as flow velocity, bed slope, and flow depth held approximately constant. Importantly, in a subset of experiments performed with an absence of suspended sediment, fluid flow did not result in the erosion and development of bedforms in the clay bed. Hence, this work illustrates that abrasion by suspended sediments is the key process required for the formation of these simulated bedrock bedforms in our experiments, in the absence of bedload abrasion; other processes such as plucking, cavitation, and dissolution will have been negligible.

  14. [Dominant, motivation and behavior].

    PubMed

    Batuev, A S

    1982-01-01

    It was shown in experiments on cats with elaborated conditioned running to the left (with fresh food) and right (with salted food) feeding troughs that conditioned signals may change the current behaviour in spite of real unconditioned stimuli. The fresh food signal produces a conditioned "freshening" of the salt meat, which may be regarded as a successful physiological model of gustatory illusions. With a free choice of different salinity of food from different cups of each feeding though, behaviour is corrected by unconditioned factors, i.e. real salinity of food. As a result the thresholds of eating salt food from both feeding troughs are equalized. The facts are discussed in the light of the dominant principle, i.e. that central program which is built on the basis of the dominant motivation, of previous experience and current analysis of surroundings. PMID:7164569

  15. Gamma prime precipitation mechanisms and solute partitioning in Ni-base alloys

    NASA Astrophysics Data System (ADS)

    Rojhirunsakool, Tanaporn

    Nickel-base superalloys have been emerged as materials for gas turbines used for jet propulsion and electricity generation. The strength of the superalloys depends mainly from an ordered precipitates of L12 structure, so called gamma prime (gamma') dispersed within the disorder gamma matrix. The Ni-base alloys investigated in this dissertation comprise both model alloy systems based on Ni-Al-Cr and Ni-Al-Co as well as the commercial alloy Rene N5. Classical nucleation and growth mechanism dominates the gamma' precipitation process in slowed-cooled Ni-Al-Cr alloys. The effect of Al and Cr additions on gamma' precipitate size distribution as well as morphological and compositional development of gamma' precipitates were characterized by coupling transmission electron microscopy (TEM) and 3D atom probe (3DAP) techniques. Rapid quenching Ni-Al-Cr alloy experiences a non-classical precipitation mechanism. Structural evolution of the gamma' precipitates formed and subsequent isothermal annealing at 600 °C were investigated by coupling TEM and synchrotron-based high-energy xray diffraction (XRD). Compositional evolution of the non-classically formed gamma' precipitates was determined by 3DAP and Langer, Bar-on and Miller (LBM) method. Besides homogeneous nucleation, the mechanism of heterogeneous gamma' precipitation involving a discontinuous precipitation mechanism, as a function of temperature, was the primary focus of study in case of the Ni-Al-Co alloy. This investigation coupled SEM, SEM-EBSD, TEM and 3DAP techniques. Lastly, solute partitioning and enrichment of minor refractory elements across/at the gamma/ gamma' interfaces in the commercially used single crystal Rene N5 superalloy was investigated by using an advantage of nano-scale composition investigation of 3DAP technique.

  16. Dominance in vertebrate broods and litters.

    PubMed

    Drummond, Hugh

    2006-03-01

    Drawing on the concepts and theory of dominance in adult vertebrates, this article categorizes the relationships of dominance between infant siblings, identifies the behavioral mechanisms that give rise to those relationships, and proposes a model to explain their evolution. Dominance relationships in avian broods can be classified according to the agonistic roles of dominants and subordinates as "aggression-submission," "aggression-resistance," "aggression-aggression," "aggression-avoidance," "rotating dominance," and "flock dominance." These relationships differ mainly in the submissiveness/pugnacity of subordinates, which is pivotal, and in the specificity/generality of the learning processes that underlie them. As in the dominance hierarchies of adult vertebrates, agonistic roles are engendered and maintained by several mechanisms, including differential fighting ability, assessment, trained winning and losing (especially in altricial species), learned individual relationships (especially in precocial species), site-specific learning, and probably group-level effects. An evolutionary framework in which the species-typical dominance relationship is determined by feeding mode, confinement, cost of subordination, and capacity for individual recognition, can be extended to mammalian litters and account for the aggression-submission and aggression-resistance observed in distinct populations of spotted hyenas and the "site-specific dominance" (teat ownership) of some pigs, felids, and hyraxes. Little is known about agonism in the litters of other mammals or broods of poikilotherms, but some species of fish and crocodilians have the potential for dominance among broodmates. PMID:16602272

  17. Extraction and characterization of lignin from oil palm biomass via ionic liquid dissolution and non-toxic aluminium potassium sulfate dodecahydrate precipitation processes.

    PubMed

    Mohtar, S S; Tengku Malim Busu, T N Z; Md Noor, A M; Shaari, N; Yusoff, N A; Bustam Khalil, M A; Abdul Mutalib, M I; Mat, H B

    2015-09-01

    The objective of this study is to extract and characterize lignin from oil palm biomass (OPB) by dissolution in 1-butyl-3-methylimidazolium chloride ([bmim][Cl]), followed by the lignin extraction through the CO2 gas purging prior to addition of aluminum potassium sulfate dodecahydrate (AlK(SO4)2 · 12H2O). The lignin yield, Y(L) (%wt.) was found to be dependent of the types of OPB observed for all precipitation methods used. The lignin recovery, RL (%wt.) obtained from CO2-AlK(SO4)2 · 12H2O precipitation was, however dependent on the types of OPB, which contradicted to that of the acidified H2SO4 and HCl solutions of pH 0.7 and 2 precipitations. Only about 54% of lignin was recovered from the OPB. The FTIR results indicate that the monodispersed lignin was successfully extracted from the OPT, OPF and OPEFB having a molecular weight (MW) of 1331, 1263 and 1473 g/mol, and degradation temperature of 215, 207.5 and 272 °C, respectively. PMID:26038325

  18. Waste and Simulant Precipitation Issues

    SciTech Connect

    Steele, W.V.

    2000-11-29

    As Savannah River Site (SRS) personnel have studied methods of preparing high-level waste for vitrification in the Defense Waste Processing Facility (DWPF), questions have arisen with regard to the formation of insoluble waste precipitates at inopportune times. One option for decontamination of the SRS waste streams employs the use of an engineered form of crystalline silicotitanate (CST). Testing of the process during FY 1999 identified problems associated with the formation of precipitates during cesium sorption tests using CST. These precipitates may, under some circumstances, obstruct the pores of the CST particles and, hence, interfere with the sorption process. In addition, earlier results from the DWPF recycle stream compatibility testing have shown that leaching occurs from the CST when it is stored at 80 C in a high-pH environment. Evidence was established that some level of components of the CST, such as silica, was leached from the CST. This report describes the results of equilibrium modeling and precipitation studies associated with the overall stability of the waste streams, CST component leaching, and the presence of minor components in the waste streams.

  19. Precipitation during irradiation: an experimental example

    SciTech Connect

    Gelles, D.S.

    1981-01-01

    Neutron damage can significantly alter the process of precipitation from supersaturated solid solution. This is demonstrated by a series of experiments using a precipitation strengthened superalloy, Nimonic PE16 irradiated with fast neutrons over the temperature 400 to 650/sup 0/C. In disagreement with earlier predictions, precipitate development is found to be controlled by the competing processes of Ostwald coarsening and solute segregation due to drag by point defects to point defect sinks. Analysis of the kinetics of Ostwald coarsening reveals significant enhancement of diffusion rates due to irradiation in agreement with predictions and involving an activation energy on the order of one quarter that of thermal diffusion. Unusual precipitate morphologies were observed such as void shells, linear precipitate arrays and Archimedes' screw configurations. However, predicted temperature dependencies for solute segregation are not obeyed. An explanation is presented involving the coupling of the Ostwald coarsening mechanism with the solute segregation process.

  20. The Precipitation Characteristics of ISCCP Tropical Weather States

    NASA Technical Reports Server (NTRS)

    Lee, Dongmin; Oreopoulos, Lazaros; Huffman, George J.; Rossow, William B.; Kang, In-Sik

    2011-01-01

    We examine the daytime precipitation characteristics of the International Satellite Cloud Climatology Project (ISCCP) weather states in the extended tropics (35 deg S to 35 deg N) for a 10-year period. Our main precipitation data set is the TRMM Multisatellite Precipitation Analysis 3B42 data set, but Global Precipitation Climatology Project daily data are also used for comparison. We find that the most convective weather state (WS1), despite an occurrence frequency below 10%, is the most dominant state with regard to surface precipitation, producing both the largest mean precipitation rates when present and the largest percent contribution to the total precipitation of the tropical zone of our study; yet, even this weather state appears to not precipitate about half the time. WS1 exhibits a modest annual cycle of domain-average precipitation rate, but notable seasonal shifts in its geographic distribution. The precipitation rates of the other weather states tend to be stronger when occurring before or after WS1. The relative contribution of the various weather states to total precipitation is different between ocean and land, with WS1 producing more intense precipitation on average over ocean than land. The results of this study, in addition to advancing our understanding of the current state of tropical precipitation, can serve as a higher order diagnostic test on whether it is distributed realistically among different weather states in atmospheric models.

  1. Enhanced interannual precipitation variability increases plant functional diversity that in turn ameliorates negative impact on productivity.

    PubMed

    Gherardi, Laureano A; Sala, Osvaldo E

    2015-12-01

    Although precipitation interannual variability is projected to increase due to climate change, effects of changes in precipitation variance have received considerable less attention than effects of changes in the mean state of climate. Interannual precipitation variability effects on functional diversity and its consequences for ecosystem functioning are assessed here using a 6-year rainfall manipulation experiment. Five precipitation treatments were switched annually resulting in increased levels of precipitation variability while maintaining average precipitation constant. Functional diversity showed a positive response to increased variability due to increased evenness. Dominant grasses decreased and rare plant functional types increased in abundance because grasses showed a hump-shaped response to precipitation with a maximum around modal precipitation, whereas rare species peaked at high precipitation values. Increased functional diversity ameliorated negative effects of precipitation variability on primary production. Rare species buffered the effect of precipitation variability on the variability in total productivity because their variance decreases with increasing precipitation variance. PMID:26437913

  2. Influence of precipitation pulses on long-term Prosopis ferox dynamics in the Argentinean intermontane subtropics.

    PubMed

    Morales, Mariano S; Villalba, Ricardo

    2012-02-01

    Biological processes in arid communities are associated with episodic precipitation pulses. We postulate that annual to decadal-scale precipitation pulses modulate the dynamics of the intermontane Prepuna woodlands. To study this hypothesis, we have assessed the influence of precipitation pulses on the rates of growth and survival of Prosopis ferox in the Prepuna woodlands during the past century. Tree ages from several P. ferox stands were used to reconstruct the establishment patterns at each sampling site. Ring-width chronologies provided the basis to assess the influence of annual versus multiannual precipitation pulses on radial growth and establishment over time. Both the radial growth and the stand dynamics of P. ferox at the regional scale were found to be largely modulated by climate, with precipitation the dominant factor influencing interannual variations in P. ferox ring-widths. Our analysis of dendrochronological dating data on 885 individuals of P. ferox revealed a period of abundant establishment from the mid-1970s to beginning of 1990 s, which is coincident with an interval of remarkable above-average precipitation. However, tree-growth and establishment patterns at the local scale in the Prepuna also reflected land-use changes, particularly long-term variations in livestock intensity. The P. ferox dynamics documented here substantiates the hierarchical concept of "resource-pulse" in dry ecosystems, with precipitation pulses of different lengths modulating distinct dynamic processes in the P. ferox woodlands. Interannual variations in precipitation influence year-to-year patterns of P. ferox radial growth, whereas multiannual oscillations in rainfall influence episodic events of tree establishment. The long-term interval considered in this study enabled us to disentangle the roles of natural versus human controls on P. ferox dynamics in the region. PMID:21805299

  3. Stable isotopes composition of precipitation fallen over Cluj-Napoca, Romania, between 2009-2012

    SciTech Connect

    Puscas, R.; Feurdean, V.; Simon, V.

    2013-11-13

    The paper presents the deuterium and oxygen 18 content from All precipitations events, which have occured over Cluj-Napoca, Romania from 2009 until 2012. Time series for δ{sup 2}H and δ{sup 18}O values point out both the seasonal variation that has increased amplitude reflecting the continental character of the local climate as well as dramatic variations of isotopic content of successive precipitation events, emphasizing the anomalous values. These fluctuations are the footprint of the variations and trends in climate events. Local Meteoric Water Line (LMWL), reflecting the δ{sup 2}H - δ{sup 18}O correlation, has the slop and the intercept slightly deviated from the GMWL, indicating that the dominant process affecting local precipitations are close to the equilibrium condition. LMWL has a slope smaller then that of the GMWL in the warm season due to lower humidity and a slope closest to the slop of GMWL in cold season with high humidity. The δ{sup 2}H and δ{sup 18}O values both for the precipitation events and monthly mean values are positively correlated with the temperature values with a very good correlation factor. The values of δ{sup 2}H and δ{sup 18}O are not correlated with amount of precipitation, the 'amount effect' of isotopic composition of precipitation is not observed for this site.

  4. Impact of interannual variations in aerosol particle sources on orographic precipitation over California's Central Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Creamean, J. M.; Ault, A. P.; White, A. B.; Neiman, P. J.; Ralph, F. M.; Minnis, P.; Prather, K. A.

    2015-01-01

    Aerosols that serve as cloud condensation nuclei (CCN) and ice nuclei (IN) have the potential to profoundly influence precipitation processes. Furthermore, changes in orographic precipitation have broad implications for reservoir storage and flood risks. As part of the CalWater field campaign (2009-2011), the variability and associated impacts of different aerosol sources on precipitation were investigated in the California Sierra Nevada using an aerosol time-of-flight mass spectrometer for precipitation chemistry, S-band profiling radar for precipitation classification, remote sensing measurements of cloud properties, and surface meteorological measurements. The composition of insoluble residues in precipitation samples collected at a surface site contained mostly local biomass burning and long-range transported dust and biological particles (2009), local sources of biomass burning and pollution (2010), and long-range transport from distant sources (2011). Although differences in the sources were observed from year-to-year, the most consistent source of dust and biological residues were associated with storms consisting of deep convective cloud systems with significant quantities of precipitation initiated in the ice phase. Further, biological residues were dominant (up to 40%) during storms with relatively warm cloud temperatures (up to -15 °C), supporting the important role bioparticles can play as ice nucleating particles. On the other hand, lower percentages of residues from local biomass burning and pollution were observed over the three winter seasons (on average 31 and 9%, respectively). When precipitation quantities were relatively low, these residues most likely served as CCN, forming smaller more numerous cloud droplets at the base of shallow cloud systems, and resulting in less efficient riming processes. The correlation between the source of aerosols within clouds and precipitation type and quantity will be further probed in models to understand the

  5. Thermophoretically Dominated Aerosol Coagulation

    NASA Astrophysics Data System (ADS)

    Rosner, Daniel E.; Arias-Zugasti, Manuel

    2011-01-01

    A theory of aerosol coagulation due to size-dependent thermophoresis is presented. This previously overlooked effect is important when local temperature gradients are large, the sol population is composed of particles of much greater thermal conductivity than the carrier gas, with mean diameters much greater than the prevailing gas mean free path, and an adequate “spread” in sizes (as in metallurgical mists or fumes). We illustrate this via a population-balance analysis of the evolution of an initially log-normal distribution when this mechanism dominates ordinary Brownian diffusion.

  6. Evidence of Mineral Dust Altering Cloud Microphysics and Precipitation

    NASA Technical Reports Server (NTRS)

    Min, Qilong; Li, Rui; Lin, Bing; Joseph, Everette; Wang, Shuyu; Hu, Yongxiang; Morris, Vernon; Chang, F.

    2008-01-01

    Multi-platform and multi-sensor observations are employed to investigate the impact of mineral dust on cloud microphysical and precipitation processes in mesoscale convective systems. It is clearly evident that for a given convection strength,small hydrometeors were more prevalent in the stratiform rain regions with dust than in those regions that were dust free. Evidence of abundant cloud ice particles in the dust sector, particularly at altitudes where heterogeneous nucleation process of mineral dust prevails, further supports the observed changes of precipitation. The consequences of the microphysical effects of the dust aerosols were to shift the precipitation size spectrum from heavy precipitation to light precipitation and ultimately suppressing precipitation.

  7. Absolute nutrient concentration measurements in cell culture media: (1)H q-NMR spectra and data to compare the efficiency of pH-controlled protein precipitation versus CPMG or post-processing filtering approaches.

    PubMed

    Goldoni, Luca; Beringhelli, Tiziana; Rocchia, Walter; Realini, Natalia; Piomelli, Daniele

    2016-09-01

    The NMR spectra and data reported in this article refer to the research article titled "A simple and accurate protocol for absolute polar metabolite quantification in cell cultures using q-NMR" [1]. We provide the (1)H q-NMR spectra of cell culture media (DMEM) after removal of serum proteins, which show the different efficiency of various precipitating solvents, the solvent/DMEM ratios, and pH of the solution. We compare the data of the absolute nutrient concentrations, measured by PULCON external standard method, before and after precipitation of serum proteins and those obtained using CPMG (Carr-Purcell-Meiboom-Gill) sequence or applying post-processing filtering algorithms to remove, from the (1)H q-NMR spectra, the proteins signal contribution. For each of these approaches, the percent error in the absolute value of every measurement for all the nutrients is also plotted as accuracy assessment. PMID:27331118

  8. The Global Precipitation Measurement Mission

    NASA Astrophysics Data System (ADS)

    Jackson, Gail

    2014-05-01

    The Global Precipitation Measurement (GPM) mission's Core satellite, scheduled for launch at the end of February 2014, is well designed estimate precipitation from 0.2 to 110 mm/hr and to detect falling snow. Knowing where and how much rain and snow falls globally is vital to understanding how weather and climate impact both our environment and Earth's water and energy cycles, including effects on agriculture, fresh water availability, and responses to natural disasters. The design of the GPM Core Observatory is an advancement of the Tropical Rainfall Measuring Mission (TRMM)'s highly successful rain-sensing package [3]. The cornerstone of the GPM mission is the deployment of a Core Observatory in a unique 65o non-Sun-synchronous orbit to serve as a physics observatory and a calibration reference to improve precipitation measurements by a constellation of 8 or more dedicated and operational, U.S. and international passive microwave sensors. The Core Observatory will carry a Ku/Ka-band Dual-frequency Precipitation Radar (DPR) and a multi-channel (10-183 GHz) GPM Microwave Radiometer (GMI). The DPR will provide measurements of 3-D precipitation structures and microphysical properties, which are key to achieving a better understanding of precipitation processes and improving retrieval algorithms for passive microwave radiometers. The combined use of DPR and GMI measurements will place greater constraints on possible solutions to radiometer retrievals to improve the accuracy and consistency of precipitation retrievals from all constellation radiometers. Furthermore, since light rain and falling snow account for a significant fraction of precipitation occurrence in middle and high latitudes, the GPM instruments extend the capabilities of the TRMM sensors to detect falling snow, measure light rain, and provide, for the first time, quantitative estimates of microphysical properties of precipitation particles. The GPM Core Observatory was developed and tested at NASA

  9. A Process-Modeling Study of Aerosol-Cloud-Precipitation Interactions in Response to Controlled Seawater Spray in Marine Boundary Layer (Invited)

    NASA Astrophysics Data System (ADS)

    Wang, H.; Rasch, P. J.; Feingold, G.

    2010-12-01

    Vast areas of the oceanic surface are covered by stratocumulus (Sc) clouds. They significantly enhance the reflection of incoming solar radiation back to space, leading to a considerable cooling of the Earth-atmosphere system. It has been argued that a 4% increase in the areal coverage or a 0.06 increase in cloud albedo of Sc clouds can offset the warming by atmospheric CO2 doubling (Randall et al. 1984; Latham et al. 2008). Acting as cloud condensation nuclei (CCN), aerosol particles can modify cloud albedo, cloud longevity and precipitation efficiency. Recent observational and modeling studies have suggested that aerosol, through its effect on precipitation, can alter cloud cellular structures in marine Sc region, representing a powerful modification of clouds by aerosol. The possibility of mitigating global warming by spraying sea-salt particles into marine boundary layer to brighten Sc clouds was raised by Latham (1990). The idea has been evaluated by several global climate model studies but their inability to represent cloud-scale dynamics and microphysics raises questions about the validity of the results. Using a high-resolution version of the Weather Research and Forecasting (WRF) model, we investigate the impact of seawater spray on the formation and evolution of marine Sc through aerosol-cloud-precipitation interactions and dynamical feedback. We will demonstrate how injected aerosol particles are transported from the ocean surface into clouds and affect cloud microphysics and macrophysics under various meteorological conditions. We will also use simulation results to explore whether the influx of sea-salt aerosols always enhances cloud albedo and how the performance depends on the distribution of sprayers.

  10. Global Precipitation Measurement

    NASA Technical Reports Server (NTRS)

    Hou, Arthur Y.; Skofronick-Jackson, Gail; Kummerow, Christian D.; Shepherd, James Marshall

    2008-01-01

    This chapter begins with a brief history and background of microwave precipitation sensors, with a discussion of the sensitivity of both passive and active instruments, to trace the evolution of satellite-based rainfall techniques from an era of inference to an era of physical measurement. Next, the highly successful Tropical Rainfall Measuring Mission will be described, followed by the goals and plans for the Global Precipitation Measurement (GPM) Mission and the status of precipitation retrieval algorithm development. The chapter concludes with a summary of the need for space-based precipitation measurement, current technological capabilities, near-term algorithm advancements and anticipated new sciences and societal benefits in the GPM era.

  11. Ability of NCAR RegCM2 in reproducing the dominant physical processes during the anomalous rainfall episodes in the summer of 1991 over the Yangtze-Huaihe valley

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Zhao, Y. C.; Ding, Y. H.

    2002-03-01

    The excessively torrential rainfall over the Yangtze-Huaihe valley during the summer of 1991 is simulated with an updated version of the second generation NCAR regional climate model (RegCM2) as a case study to evaluate the model's performance in reproducing the daily precipitation and the associated physical factors contributing to the generation of the anomalous rainfall. This simulation is driven by large-scale atmospheric lateral boundary conditions derived from the European Center for Medium Range Weather Forecast (ECMWF) analysis. The simulation period is May to August 1991. The model domain covers East Asia and its adjacent oceanic regions, The model resolution is 60 km x 60 km in the horizontal and 23 layers in the vertical. The model can reasonably reproduce the daily precipitation events over East Asia for the summer of 1991, especially in the Yangtze-Huaihe valley where the anomalous rainfall occurred. The spatial and temporal structure of some important physical variables and processes related to the generation of the anomalous rainfall are analyzed, The time evolution of simulated upward vertical motion and horizontal convergence agrees with the five rainfall episodes over this subregion. The water vapor feeding the rainfall is mostly transported by the horizontal atmospheric motions from outside of the region rather than from local sources. The subtropical high over the western Pacific Ocean controls the progress and retreat of the summer monsoon over East Asia, and the RegCM2 can simulate the northward migration and southward retreat of subtropical high over the western Pacific Ocean. Furthermore, the model can represent the daily variation of the low level jet, which is crucial in the water vapor transport to the Yangtze-Huaihe valley.

  12. Are hourly precipitation extremes increasing faster than daily precipitation extremes?

    NASA Astrophysics Data System (ADS)

    Barbero, Renaud; Fowler, Hayley; Blenkinsop, Stephen; Lenderink, Geert

    2016-04-01

    Extreme precipitation events appear to be increasing with climate change in many regions of the world, including the United States. These extreme events have large societal impacts, as seen during the recent Texas-Oklahoma flooding in May 2015 which caused several billion in damages and left 47 deaths in its path. Better understanding of past changes in the characteristics of extreme rainfall events is thus critical for reliable projections of future changes. Although it has been documented in several studies that daily precipitation extremes are increasing across parts of the contiguous United States, very few studies have looked at hourly extremes. However, this is of primary importance as recent studies on the temperature scaling of extreme precipitation have shown that increases above the Clausius-Clapeyron (~ 7% °C‑1) are possible for hourly precipitation. In this study, we used hourly precipitation data (HPD) from the National Climatic Data Center and extracted more than 1,000 stations across the US with more than 40 years of data spanning the period 1950-2010. As hourly measurements are often associated with a range of issues, the data underwent multiple quality control processes to exclude erroneous data. While no significant changes were found in annual maximum precipitation using both hourly and daily resolution datasets, significant increasing trends in terms of frequency of episodes exceeding present-day 95th percentiles of wet hourly/daily precipitation were observed across a sign