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Sample records for carbon regimes results

  1. Changes in Soil Carbon and Enzyme Activity As a Result of Different Long-Term Fertilization Regimes in a Greenhouse Field

    PubMed Central

    Zhang, Lili; Chen, Wei; Burger, Martin; Yang, Lijie; Gong, Ping; Wu, Zhijie

    2015-01-01

    In order to discover the advantages and disadvantages of different fertilization regimes and identify the best management practice of fertilization in greenhouse fields, soil enzyme activities involved in carbon (C) transformations, soil chemical characteristics, and crop yields were monitored after long-term (20-year) fertilization regimes, including no fertilizer (CK), 300 kg N ha-1 and 600 kg N ha-1 as urea (N1 and N2), 75 Mg ha-1 horse manure compost (M), and M with either 300 or 600 kg N ha-1 urea (MN1 and MN2). Compared with CK, fertilization increased crop yields by 31% (N2) to 69% (MN1). However, compared with CK, inorganic fertilization (especially N2) also caused soil acidification and salinization. In the N2 treatment, soil total organic carbon (TOC) decreased from 14.1±0.27 g kg-1 at the beginning of the long-term experiment in 1988 to 12.6±0.11 g kg-1 (P<0.05). Compared to CK, N1 and N2 exhibited higher soil α-galactosidase and β-galactosidase activities, but lower soil α-glucosidase and β-glucosidase activities (P<0.05), indicating that inorganic fertilization had different impacts on these C transformation enzymes. Compared with CK, the M, MN1 and MN2 treatments exhibited higher enzyme activities, soil TOC, total nitrogen, dissolved organic C, and microbial biomass C and N. The fertilization regime of the MN1 treatment was identified as optimal because it produced the highest yields and increased soil quality, ensuring sustainability. The results suggest that inorganic fertilizer alone, especially in high amounts, in greenhouse fields is detrimental to soil quality. PMID:25706998

  2. Changes in soil carbon and enzyme activity as a result of different long-term fertilization regimes in a greenhouse field.

    PubMed

    Zhang, Lili; Chen, Wei; Burger, Martin; Yang, Lijie; Gong, Ping; Wu, Zhijie

    2015-01-01

    In order to discover the advantages and disadvantages of different fertilization regimes and identify the best management practice of fertilization in greenhouse fields, soil enzyme activities involved in carbon (C) transformations, soil chemical characteristics, and crop yields were monitored after long-term (20-year) fertilization regimes, including no fertilizer (CK), 300 kg N ha-1 and 600 kg N ha-1 as urea (N1 and N2), 75 Mg ha-1 horse manure compost (M), and M with either 300 or 600 kg N ha-1 urea (MN1 and MN2). Compared with CK, fertilization increased crop yields by 31% (N2) to 69% (MN1). However, compared with CK, inorganic fertilization (especially N2) also caused soil acidification and salinization. In the N2 treatment, soil total organic carbon (TOC) decreased from 14.1±0.27 g kg-1 at the beginning of the long-term experiment in 1988 to 12.6±0.11 g kg-1 (P<0.05). Compared to CK, N1 and N2 exhibited higher soil α-galactosidase and β-galactosidase activities, but lower soil α-glucosidase and β-glucosidase activities (P<0.05), indicating that inorganic fertilization had different impacts on these C transformation enzymes. Compared with CK, the M, MN1 and MN2 treatments exhibited higher enzyme activities, soil TOC, total nitrogen, dissolved organic C, and microbial biomass C and N. The fertilization regime of the MN1 treatment was identified as optimal because it produced the highest yields and increased soil quality, ensuring sustainability. The results suggest that inorganic fertilizer alone, especially in high amounts, in greenhouse fields is detrimental to soil quality.

  3. Removal of tinidazole from waters by using ozone and activated carbon in dynamic regime.

    PubMed

    Rivera-Utrilla, J; Sánchez-Polo, M; Prados-Joya, G; Ferro-García, M A; Bautista-Toledo, I

    2010-02-15

    The main objective of the present study was to analyze the efficacy of technologies based on ozone and activated carbon in dynamic regime to remove organic micropollutants from waters, using the antibiotic tinidazole (TNZ) as a model compound. Results obtained in static regime show that the presence of activated carbon (GAC) during tinidazole ozonation: (i) increases its removal rate, (ii) reduces oxidation by-product toxicity, and (iii) reduces the concentration of dissolved organic matter. Study of the ozone/activated carbon system in dynamic regime showed that ozonation of tinidazole before the adsorption process considerably improves column performance, increasing the volume of water treated. It was observed that the efficacy of the treatment considerably increased with a shorter contact time between TNZ and O(3) streams before entering the column allowing a much higher volume of TNZ solution to be treated compared with the use of activated carbon alone, and reducing by 75% the amount of activated carbon required per unit of treated water volume. TNZ removal by the O(3)/GAC system is lower in natural waters and especially in wastewaters, than in ultrapure water. The toxicity results obtained during TNZ treatment with O(3)/GAC system showed that toxicity was directly proportional to the concentration of TNZ in the effluent, verifying that oxidation of the organic matter in the natural waters did not increase the toxicity of the system.

  4. Climatic Variability, Fire Regimes and Carbon Dynamics in Dry Forest Ecosystems of the Western US

    NASA Astrophysics Data System (ADS)

    Hessl, A. E.; McKenzie, D.

    2003-12-01

    Historical variability of fire regimes in the western Americas is associated with climatic phenomena such as ENSO. We describe the relationship between fire occurrence and interannual to decadal climatic variability (Palmer Drought Severity Index [PDSI], El Niño/Southern Oscillation [ENSO] and the Pacific Decadal Oscillation [PDO]) and explain how land use changes in the 20th century affected these relationships. Ongoing research uses these past changes to understand the influence of fire regimes on the regional carbon balance. We used 1701 fire-scarred trees collected in five study sites in central and eastern Washington to investigate current year, lagged, and low frequency relationships between composite fire histories and PDSI, PDO, and ENSO (using the Southern Oscillation Index [SOI] as a measure of ENSO variability) using superposed epoch analysis and cross-spectral analysis. Fires tended to occur during dry summers and during the positive phase of the PDO. Cross-spectral analysis indicates that percentage of trees scarred by fire and the PDO are spectrally coherent at 47 years, the approximate cycle of the PDO. Similarly, percentage scarred and ENSO are spectrally coherent at 6 years, the approximate cycle of ENSO. However other results suggest that ENSO was only a weak driver of fire occurrence in the past three centuries. While drought and fire appear to be tightly linked between 1700-1900, the relationship between drought and fire occurrence was disrupted during the 20th century as a result of land use changes. We suggest that long-term fire planning using the PDO may be possible in the PNW, potentially allowing decadal-scale management of fire regimes, prescribed fire and potentially, carbon emissions. Future work will quantify the changes in carbon emissions associated with a return to natural fire regimes and compares them with estimates of carbon emissions associated with current management. To model past, present and future emissions from fire in

  5. Ecosystem carbon storage capacity as affected by disturbance regimes: A general theoretical model

    SciTech Connect

    Weng, Ensheng; Luo, Yiqi; Wang, Weile; Wang, Han; Hayes, Daniel J; McGuire, A. David; Hastings, Alan; Schimel, David

    2012-01-01

    Disturbances have been recognized as a key factor shaping terrestrial ecosystem states and dynamics. A general model that quantitatively describes the relationship between carbon storage and disturbance regime is critical for better understanding large scale terrestrial ecosystem carbon dynamics. We developed a model (REGIME) to quantify ecosystem carbon storage capacities (E[x]) under varying disturbance regimes with an analytical solution E[x] = U {center_dot} {tau}{sub E} {center_dot} {lambda}{lambda} + s {tau} 1, where U is ecosystem carbon influx, {tau}{sub E} is ecosystem carbon residence time, and {tau}{sub 1} is the residence time of the carbon pool affected by disturbances (biomass pool in this study). The disturbance regime is characterized by the mean disturbance interval ({lambda}) and the mean disturbance severity (s). It is a Michaelis-Menten-type equation illustrating the saturation of carbon content with mean disturbance interval. This model analytically integrates the deterministic ecosystem carbon processes with stochastic disturbance events to reveal a general pattern of terrestrial carbon dynamics at large scales. The model allows us to get a sense of the sensitivity of ecosystems to future environmental changes just by a few calculations. According to the REGIME model, for example, approximately 1.8 Pg C will be lost in the high-latitude regions of North America (>45{sup o} N) if fire disturbance intensity increases around 5.7 time the current intensity to the end of the twenty-first century, which will require around 12% increases in net primary productivity (NPP) to maintain stable carbon stocks. If the residence time decreased 10% at the same time additional 12.5% increases in NPP are required to keep current C stocks. The REGIME model also lays the foundation for analytically modeling the interactions between deterministic biogeochemical processes and stochastic disturbance events.

  6. Toward an effective governance regime for geologic carbon storage

    NASA Astrophysics Data System (ADS)

    Mignone, B. K.; Socolow, R. H.

    2007-12-01

    Carbon capture and storage (CCS) technology is currently poised to play a significant role in mitigating CO2 emissions from future fossil fuel combustion, especially from coal-fired power plants, which are expected to rapidly increase in number over the next several decades. At the same time, large-scale deployment of CCS continues to be impeded by concerns about the long-term integrity of geologic storage reservoirs. In this study, we apply established concepts of learning-by-doing to the problem of reservoir leakage. Our results suggest that when learning is present, traditional measures of (initial) reservoir integrity do not sufficiently capture the time- integrated behavior of the system that is most relevant to the global CO2 problem. In one formulation, we find that when learning is explicitly incorporated into a reservoir model, total leakage is always finite and scales approximately quadratically with the learning time constant and inversely with the initial retention time constant. To highlight the policy relevance of this study, we consider the implications of these results for the larger site licensing process. We expect that an upper bound on total allowable leakage will be decided by policymakers. Armed with this number and some informed, expert-driven judgments about the rate at which learning will proceed, a regulator could use our model, or a more sophisticated variant, to calculate an upper bound on the maximum initial leakage rate. This criterion would then be one of several prerequisites to certification. The entire process could be amended over time as new data is made available. We hope that our model will provide a platform for scholars from different fields to engage one another and to work toward an acceptable, compelling and long-lasting management framework for CCS.

  7. Effect of management and soil moisture regimes on wetland soils total carbon and nitrogen in Tanzania

    NASA Astrophysics Data System (ADS)

    Kamiri, Hellen; Kreye, Christine; Becker, Mathias

    2013-04-01

    Wetland soils play an important role as storage compartments for water, carbon and nutrients. These soils implies various conditions, depending on the water regimes that affect several important microbial and physical-chemical processes which in turn influence the transformation of organic and inorganic components of nitrogen, carbon, soil acidity and other nutrients. Particularly, soil carbon and nitrogen play an important role in determining the productivity of a soil whereas management practices could determine the rate and magnitude of nutrient turnover. A study was carried out in a floodplain wetland planted with rice in North-west Tanzania- East Africa to determine the effects of different management practices and soil water regimes on paddy soil organic carbon and nitrogen. Four management treatments were compared: (i) control (non weeded plots); (ii) weeded plots; (iii) N fertilized plots, and (iv) non-cropped (non weeded plots). Two soil moisture regimes included soil under field capacity (rainfed conditions) and continuous water logging compared side-by-side. Soil were sampled at the start and end of the rice cropping seasons from the two fields differentiated by moisture regimes during the wet season 2012. The soils differed in the total organic carbon and nitrogen between the treatments. Soil management including weeding and fertilization is seen to affect soil carbon and nitrogen regardless of the soil moisture conditions. Particularly, the padddy soils were higher in the total organic carbon under continuous water logged field. These findings are preliminary and a more complete understanding of the relationships between management and soil moisture on the temporal changes of soil properties is required before making informed decisions on future wetland soil carbon and nitrogen dynamics. Keywords: Management, nitrogen, paddy soil, total carbon, Tanzania,

  8. Watershed Fire Regime Effects On Particulate Organic Carbon Composition in Oregon and California Coast Range Rivers

    NASA Astrophysics Data System (ADS)

    Hatten, J. A.; Goni, M. A.; Wheatcroft, R. A.; Borgeld, J. C.; Padgett, J. S.; Pasternack, G. B.; Gray, A. B.; Watson, E. B.; Warrick, J. A.

    2010-12-01

    Fire causes major changes to organic carbon, converting biological organic materials to pyrogenic-derived organic carbon (Py-OC), including black carbon. Wildfire also dramatically affects hydrological and erosion processes within watersheds, potentially increasing the erosion and discharge of Py-OC as particulate organic carbon (POC). We hypothesize that the proportion of the POC being discharged as Py-OC will be affected by the watershed’s fire regime, increasing with annual proportion of the watershed burned. During the 2008 and 2009 water years, suspended sediment samples were collected from the Alsea, Umpqua, Eel, Salinas, and Arroyo Seco Rivers draining the Coast Ranges of Oregon and California. Events and discharges of various magnitudes were captured in this sample set. This sample set also included suspended sediment collected from the Arroyo Seco River after a 2008 wildfire burned through a large portion of its watershed. Fine (<63 μm) and coarse (>63 μm) particulate material was analyzed for OC and N. We used cupric oxide oxidation to determine the contribution of Py-OC and unburned organic matter to the POC load of these rivers. The area weighted mean fire return interval decreases from the Douglas fir dominated forests in the Alsea River watershed in the north to the chaparral dominated Arroyo Seco River watershed in the south (Alsea > Umpqua > Eel > Salinas > Arroyo Seco). This translated into an increase in the proportion of each watershed burned from north to south. With the increase in annual proportion of watershed burned we found that the Py-OC content of coarse and fine POC increased from north to south. These results suggest that fire plays an important role in delivering POC to long-term carbon sinks in the coastal and ocean environment.

  9. Carbon rhizodeposition by plants of contrasting strategies for resource acquisition: responses to various nitrogen fertility regimes

    NASA Astrophysics Data System (ADS)

    Baptist, Florence; Aranjuelo, I.; Lopez-Sangil, L.; Rovia, P.; Nogués, S.

    2010-05-01

    Rhizodeposition by plants is one of the most important physiological mechanisms related to carbon and nitrogen cycling which is also believed to vary along the acquisition-conservation continuum. However, owing to methodological difficulties (i.e. narrow zone of soil around roots and rapid assimilation by soil microbes), root exudation and variations between species are one of the most poorly understood belowground process. Although previous approaches such as hydroponic culture based system, permit the chemical analysis of exudates, the fact that this protocol is qualitative, conditions its utility (see review in Phillips et al. 2008). Others techniques based on pulse-labelling approach have been developed to quantify rhizodeposition but are rarely sufficient to uniformly label all plant inputs to soil. Consequently with this typical pulse chase methods, recent assimilates are labeled but the recalcitrant carbon will not be labeled and therefore the contribution of this carbon will not be considered. Hence, traditional pulse labelling is not a quantitative means of tracing carbon due to inhomogeneous labelling and so limits greatly comparative studies of rhizodeposition fluxes at the interspecific level. In this study we developped a new protocole based on a long-term (3 months) steady state 13C labelling in order (1) to quantify rhizodeposition fluxes for six graminoid species caracterized by contrasted nutrient acquisition strategies and (2) to investigate to what extent various level of nitrogen fertility regimes modulate rhizodeposition fluxes. This method will enable to quantify under natural soil conditions both the accumulation of 13C in the soil but also the quantity that has been respired by the microorganisms during a given time and so will give an integrated picture of rhizodeposition fluxes for each species under each nitrogen fertility level. Results are currently being processed and will be presented at the conference. References: Phillips RP, Erlitz

  10. Effects of Successive Rotation Regimes on Carbon Stocks in Eucalyptus Plantations in Subtropical China Measured over a Full Rotation

    PubMed Central

    Li, Xiaoqiong; Ye, Duo; Liang, Hongwen; Zhu, Hongguang; Qin, Lin; Zhu, Yuling; Wen, Yuanguang

    2015-01-01

    Plantations play an important role in carbon sequestration and the global carbon cycle. However, there is a dilemma in that most plantations are managed on short rotations, and the carbon sequestration capacities of these short-rotation plantations remain understudied. Eucalyptus has been widely planted in the tropics and subtropics due to its rapid growth, high adaptability, and large economic return. Eucalyptus plantations are primarily planted in successive rotations with a short rotation length of 6~8 years. In order to estimate the carbon-stock potential of eucalyptus plantations over successive rotations, we chose a first rotation (FR) and a second rotation (SR) stand and monitored the carbon stock dynamics over a full rotation from 1998 to 2005. Our results showed that carbon stock in eucalyptus trees (TC) did not significantly differ between rotations, while understory vegetation (UC) and soil organic matter (SOC) stored less carbon in the SR (1.01 vs. 2.76 Mg.ha-1 and 70.68 vs. 81.08 Mg. ha-1, respectively) and forest floor carbon (FFC) conversely stored more (2.80 vs. 2.34 Mg. ha-1). The lower UC and SOC stocks in the SR stand resulted in 1.13 times lower overall ecosystem carbon stock. Mineral soils and overstory trees were the two dominant carbon pools in eucalyptus plantations, accounting for 73.77%~75.06% and 20.50%~22.39%, respectively, of the ecosystem carbon pool. However, the relative contribution (to the ecosystem pool) of FFC stocks increased 1.38 times and that of UC decreased 2.30 times in the SR versus FR stand. These carbon pool changes over successive rotations were attributed to intensive successive rotation regimes of eucalyptus plantations. Our eight year study suggests that for the sustainable development of short-rotation plantations, a sound silvicultural strategy is required to achieve the best combination of high wood yield and carbon stock potential. PMID:26186367

  11. Effects of Successive Rotation Regimes on Carbon Stocks in Eucalyptus Plantations in Subtropical China Measured over a Full Rotation.

    PubMed

    Li, Xiaoqiong; Ye, Duo; Liang, Hongwen; Zhu, Hongguang; Qin, Lin; Zhu, Yuling; Wen, Yuanguang

    2015-01-01

    Plantations play an important role in carbon sequestration and the global carbon cycle. However, there is a dilemma in that most plantations are managed on short rotations, and the carbon sequestration capacities of these short-rotation plantations remain understudied. Eucalyptus has been widely planted in the tropics and subtropics due to its rapid growth, high adaptability, and large economic return. Eucalyptus plantations are primarily planted in successive rotations with a short rotation length of 6~8 years. In order to estimate the carbon-stock potential of eucalyptus plantations over successive rotations, we chose a first rotation (FR) and a second rotation (SR) stand and monitored the carbon stock dynamics over a full rotation from 1998 to 2005. Our results showed that carbon stock in eucalyptus trees (TC) did not significantly differ between rotations, while understory vegetation (UC) and soil organic matter (SOC) stored less carbon in the SR (1.01 vs. 2.76 Mg.ha(-1) and 70.68 vs. 81.08 Mg. ha(-1), respectively) and forest floor carbon (FFC) conversely stored more (2.80 vs. 2.34 Mg. ha(-1)). The lower UC and SOC stocks in the SR stand resulted in 1.13 times lower overall ecosystem carbon stock. Mineral soils and overstory trees were the two dominant carbon pools in eucalyptus plantations, accounting for 73.77%~75.06% and 20.50%~22.39%, respectively, of the ecosystem carbon pool. However, the relative contribution (to the ecosystem pool) of FFC stocks increased 1.38 times and that of UC decreased 2.30 times in the SR versus FR stand. These carbon pool changes over successive rotations were attributed to intensive successive rotation regimes of eucalyptus plantations. Our eight year study suggests that for the sustainable development of short-rotation plantations, a sound silvicultural strategy is required to achieve the best combination of high wood yield and carbon stock potential.

  12. The influence of hydrodynamic regime on infaunal assemblages inhabiting carbonate sediments on central Pacific seamounts

    NASA Astrophysics Data System (ADS)

    Levin, Lisa A.; Thomas, Cynthia L.

    1989-12-01

    We investigated the following hypotheses for deep seamounts in the central Pacific Ocean: (1) infaunal and microbial abundances are elevated in regions of current intensification, (2) infaunal lifestyles reflect variation in hydrodynamic conditions and (3) bioturbation is more intense in high-energy regimes. Our studies were carried out at three sites: the northwest perimeter of the Horizon Guyot sediment cap (1840 m), which is characterized by strong bottom currents and rippled foraminiferan sands, and the central summits of Horizon Guyot (1480 m) and Magellan Rise (3150 m), whose sediments are unrippled and finer grained. Contrary to our first hypothesis, the high-energy, Horizon perimeter sediments exhibited lower biological activity than the summit sites, as reflected in lower organic nitrogen (0.011% vs. 0.015-0.017%), higher C/N ratios (19 vs 11), lower bacterial counts (1.21 vs 2.03-2.15 × 10 8ml -1) and lower macrofaunal abundances (255 vs 388-829 m -2). Sediment organic carbon values (0.14-0.19%) and meiofaunal abundances (2866-5150 m -2) did not differ significantly among the three sites. Infaunal life habits varied among sites but sediment mixing did not. Macrofauna were found deeper in rippled perimeter sediments than in the cap sediments. Sessility and surface-feeding modes dominated among polychaetes at the higher-energy Horizon perimeter, while motility and subsurface feeding were common in the quieter, finer-grained regimes. Significant sediment mixing takes place on 100-year time scales a all three sites, probably a result of large, infaunal bioturbators at the cap sites and physical sediment instability at the perimeter site. Excess 210Pb exhibited moderately high inventories (38-59 dpm cm -2) and deep penetration (15 cm). Estimated mixing coefficients (D b) ranged from 0.6 to 3.0 cm 2y -1 at the three sites. Our findings indicate that hydrodynamic differences can lead to greater variation in sediment and faunal characteristics on a single

  13. Antecedents of Teachers Fostering Effort within Two Different Management Regimes: An Assessment-Based Accountability Regime and Regime without External Pressure on Results

    ERIC Educational Resources Information Center

    Christophersen, Knut-Andreas; Elstad, Eyvind; Turmo, Are

    2012-01-01

    This article focuses on the comparison of organizational antecedents of teachers' fostering of students' effort in two quite different accountability regimes: one management regime with an external-accountability system and one with no external accountability devices. The methodology involves cross-sectional surveys from two different management…

  14. Salix response to different flow regimes in controlled experiments: first results

    NASA Astrophysics Data System (ADS)

    Gorla, Lorenzo; Signarbieux, Constant; Buttler, Alexandre; Perona, Paolo

    2013-04-01

    Dams and water management for hydropower production, agriculture and other human activities alter the natural flow regime of rivers. The new river hydrograph components depend on the type of impoundment and the policy of regulation but such a different flow regime will likely affect the riparian environment. The main challenge in order to define sustainable flow releases is to quantify hydrological effects in terms of geomorphology and ecosystem response. A considerable lack of knowledge still affects the link hydrology-ecology and inadequate flow rules (e.g., minimal or residual flows) are consequently still widespread: further research in this direction is urgently required. We present an experiment, which aims to investigate the effects of different water stage regimes on riparian vegetation (salix Viminalis cuttings) development in a temperate region (Switzerland). This work describes the installation setup, together with the first results concerning the first of the two scheduled seasons of campaign. Sixty Salix cuttings were planted in non-cohesive sandy-gravel sediment within 1 meter tall plastic pots installed outside in the EPFL campus. After grouping them in three batteries, the water level within them has been varying following three river regimes simulated by adjusting the water level within the pots by means of an automatic hydraulic system. The three water level regimes reproduce a natural flow regime, a minimum residual flow policy, which only conserves peaks during flooding conditions, and an artificial regime conserving only low frequencies (e.g., seasonality) of the natural dynamic. The natural flow regime of the first battery has been applied for two months to the entire system; the three regimes above said started in June 2012. This triggered a plant response transitory regime, which we monitored by measuring plant growth, soil and atmospheric variables. Particularly, measures concern with branches development leaves photosynthesis and

  15. Dynamic regime marginal structural mean models for estimation of optimal dynamic treatment regimes, Part II: proofs of results.

    PubMed

    Orellana, Liliana; Rotnitzky, Andrea; Robins, James M

    2010-03-03

    In this companion article to "Dynamic Regime Marginal Structural Mean Models for Estimation of Optimal Dynamic Treatment Regimes, Part I: Main Content" [Orellana, Rotnitzky and Robins (2010), IJB, Vol. 6, Iss. 2, Art. 7] we present (i) proofs of the claims in that paper, (ii) a proposal for the computation of a confidence set for the optimal index when this lies in a finite set, and (iii) an example to aid the interpretation of the positivity assumption.

  16. Dynamic Regime Marginal Structural Mean Models for Estimation of Optimal Dynamic Treatment Regimes, Part II: Proofs of Results*

    PubMed Central

    Orellana, Liliana; Rotnitzky, Andrea; Robins, James M.

    2010-01-01

    In this companion article to “Dynamic Regime Marginal Structural Mean Models for Estimation of Optimal Dynamic Treatment Regimes, Part I: Main Content” [Orellana, Rotnitzky and Robins (2010), IJB, Vol. 6, Iss. 2, Art. 7] we present (i) proofs of the claims in that paper, (ii) a proposal for the computation of a confidence set for the optimal index when this lies in a finite set, and (iii) an example to aid the interpretation of the positivity assumption. PMID:20405047

  17. Molecular systems under shock compression into the dense plasma regime: carbon dioxide and hydrocarbon polymers

    NASA Astrophysics Data System (ADS)

    Mattsson, Thomas R.; Cochrane, Kyle R.; Root, Seth; Carpenter, John H.

    2013-10-01

    Density Functional Theory (DFT) has proven remarkably accurate in predicting properties of matter under shock compression into the dense plasma regime. Materials where chemistry plays a role are of interest for many applications, including planetary science and inertial confinement fusion (ICF). As examples of systems where chemical reactions are important, and demonstration of the high fidelity possible for these both structurally and chemically complex systems, we will discuss shock- and re-shock of liquid carbon dioxide (CO2) in the range 100 to 800 GPa and shock compression of hydrocarbon polymers, including GDP (glow discharge polymer) which is used as an ablator in laser ICF experiments. Experimental results from Sandia's Z machine validate the DFT simulations at extreme conditions and the combination of experiment and DFT provide reliable data for evaluating existing and constructing future wide-range equations of state models for molecular compounds. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  18. Improved biological phosphorus removal performance driven by the aerobic/extended-idle regime with propionate as the sole carbon source.

    PubMed

    Wang, Dongbo; Li, Xiaoming; Yang, Qi; Zheng, Wei; Wu, Yan; Zeng, Tianjing; Zeng, Guangming

    2012-08-01

    Our previous studies proved that biological phosphorus removal (BPR) could be achieved in an aerobic/extended-idle (AEI) process employing two typical substrates of glucose and acetate as the carbon sources. This paper further evaluated the feasibility of another important substrate, propionate, serving as the carbon source for BPR in the AEI process, and compared the BPR performance between the AEI and anaerobic/oxic (A/O) processes. Two sequencing batch reactors (SBRs) were operated, respectively, as the AEI and A/O regimes for BPR using propionate as the sole substrate. The results showed that the AEI-reactor removed 2.98 ± 0.04-4.06 ± 0.06 mg of phosphorus per g of total suspended solids during the course of the steady operational trial, and the phosphorus content of the dried sludge was reached 8.0 ± 0.4% after 56-day operation, demonstrating the good performance of phosphorus removal. Then, the efficiencies of BPR and the transformations of the intracellular storages were compared between two SBRs. It was observed that the phosphorus removal efficiency was maintained around 95% in the AEI-reactor, and about 83% in the A/O-reactor, although the latter showed much greater transformations of both polyhydroxyalkanoates and glycogen. The facts clearly showed that BPR could be enhanced by the AEI regime using propionate as the carbon source. Finally, the mechanisms for the propionate fed AEI-reactor improving BPR were investigated. It was found that the sludge cultured by the AEI regime had more polyphosphate containing cells than that by the A/O regime. Further investigation revealed that the residual nitrate generated in the last aerobic period was readily deteriorated BPR in the A/O-SBR, but a slight deterioration was observed in the AEI-SBR. Moreover, the lower glycogen transformation measured in the AEI-SBR indicated that the biomass cultured by the AEI regime contained less glycogen accumulating organisms activities than that by the A/O regime.

  19. [Effects of different straw-returning regimes on soil organic carbon and carbon pool management index in Guanzhong Plain, Northwest China].

    PubMed

    Li, Shuo; Li, You-bing; Wang, Shu-juan; Shi, Jiang-lan; Tian, Xiao-hong

    2015-04-01

    A four-year (2008-2012) field experiment was conducted to investigate the effects of different straw-returning regimes on soil total organic carbon (TOC), labile organic carbon (LOC) and the ratio of LOC to TOC (LOC/TOC) as well as TOC stock (SCS) and soil carbon pool management index (CPMI) in a farmland with maize-wheat double cropping system in Guanzhong Plain area, Shaanxi Province, China. The results indicated that soil TOC and LOC contents and SCS were significantly increased when wheat or maize straw was returned to field, and the increasing extent showed the rising order as follows: double straw-returning > single straw-returning > no straw-returning. Compared to no straw returning, a significant increase of TOC and LOC contents and SCS was found in the treatment of wheat straw chopping retention combined with maize straw chopping subsoiling retention (WC-MM), and CPMI of WC-MM was significantly higher than in the other treatments in 0-20 cm soil layer. Compared to no wheat straw returning, soil CPMIs in 0-10 cm and 10-20 cm soil layer increased by 19.1% and 67.9% for the wheat straw chopping returning treatment, and by 22.6% and 32.4% for the maize straw chopping subsoiling treatment, respectively. Correlation analysis showed that soil CPMI was a more effective index reflecting the sequestration of soil organic carbon in 0-30 cm soil layer than the ratio of LOC to TOC. This study thus suggested that WC-MM regime is the best straw-returning regime for soil organic carbon sequestration.

  20. Thermal regime of the deep carbonate reservoir of the Po Plain (Italy)

    NASA Astrophysics Data System (ADS)

    Pasquale, V.; Chiozzi, P.; Verdoya, M.

    2012-04-01

    Italy is one of the most important countries in the world with regard to high-medium enthalpy geothermal resources, a large part of which is already extracted at relatively low cost. High temperatures at shallow to medium depth occur within a wide belt, several hundred kilometre long, west of the Apennines mountain chain. This belt, affected by recent lithosphere extension, includes several geothermal fields, which are largely exploited for electricity generation. Between the Alps and Apennines ranges, the deeper aquifer, occurring in carbonate rocks of the Po Plain, can host medium enthalpy fluids, which are exploited for district heating. Such a general picture of the available geothermal resources has been well established through several geophysical investigations and drillings. Nevertheless, additional studies are necessary to evaluate future developments, especially with reference to the deep carbonate aquifer of the Po Plain. In this paper, we focus on the eastern sector of the plain and try to gain a better understanding of the thermal regime by using synergically geothermal methodologies and geological information. The analysis of the temperatures recorded to about 6 km depth in hydrocarbon wells supplies basic constraints to outline the thermal regime of the sedimentary basin and to investigate the occurrence and importance of hydrothermal processes in the carbonate layer. After correction for drilling disturbance, temperatures were analysed, together with geological information, through an inversion technique based on a laterally constant thermal gradient model. The inferred thermal gradient changes with depth; it is quite low within the carbonate layer, while is larger in the overlying, practically impermeable formations. As the thermal conductivity variation does not justify such a thermal gradient difference, the vertical change can be interpreted as due to convective processes occurring in the carbonate layer, acting as thermal reservoir. The

  1. Classifying organic materials by oxygen-to-carbon elemental ratio to predict the activation regime of cloud condensation nuclei (CCN)

    NASA Astrophysics Data System (ADS)

    Kuwata, M.; Shao, W.; Lebouteiller, R.; Martin, S. T.

    2012-12-01

    The governing highly soluble, slightly soluble, or insoluble activation regime of organic compounds as cloud condensation nuclei (CCN) was examined as a function of oxygen-to-carbon elemental ratio (O : C). New data were collected for adipic, pimelic, suberic, azelaic and pinonic acids. Secondary organic materials (SOMs) produced by α-pinene ozonolysis and isoprene photo-oxidation were also included in the analysis. The saturation concentrations C of the organic compounds in aqueous solutions served as the key parameter for delineating regimes of CCN activation, and the values of C were tightly correlated to the O : C ratios. The highly soluble, slightly soluble, and insoluble regimes of CCN activation were found to correspond to ranges of [O : C] > 0.6, 0.2 < [O : C] < 0.6, and [O : C] < 0.2, respectively. These classifications were evaluated against CCN activation data of isoprene-derived SOM (O : C = 0.69-0.72) and α-pinene-derived SOM (O : C = 0.38-0.48). Isoprene-derived SOM had highly soluble activation behavior, consistent with its high O : C ratio. For α-pinene-derived SOM, although CCN activation can be modeled as a highly soluble mechanism, this behavior was not predicted by the O : C ratio, for which a slightly soluble mechanism was anticipated. Complexity in chemical composition, resulting in continuous water uptake and the absence of a deliquescence transition that can thermodynamically limit CCN activation, might explain the differences of α-pinene-derived SOM compared to the behavior of pure organic compounds. The present results suggest that atmospheric particles dominated by hydrocarbon-like organic components do not activate (i.e. insoluble regime) whereas those dominated by oxygenated organic components activate (i.e. highly soluble regime).

  2. Classifying organic materials by oxygen-to-carbon elemental ratio to predict the activation regime of Cloud Condensation Nuclei (CCN)

    NASA Astrophysics Data System (ADS)

    Kuwata, M.; Shao, W.; Lebouteiller, R.; Martin, S. T.

    2013-05-01

    The governing highly soluble, slightly soluble, or insoluble activation regime of organic compounds as cloud condensation nuclei (CCN) was examined as a function of oxygen-to-carbon elemental ratio (O : C). New data were collected for adipic, pimelic, suberic, azelaic, and pinonic acids. Secondary organic materials (SOMs) produced by α-pinene ozonolysis and isoprene photo-oxidation were also included in the analysis. The saturation concentrations C of the organic compounds in aqueous solutions served as the key parameter for delineating regimes of CCN activation, and the values of C were tightly correlated to the O : C ratios. The highly soluble, slightly soluble, and insoluble regimes of CCN activation were found to correspond to ranges of [O : C] > 0.6, 0.2 < [O : C] < 0.6, and [O : C] < 0.2, respectively. These classifications were evaluated against CCN activation data of isoprene-derived SOM (O : C = 0.69-0.72) and α-pinene-derived SOM (O : C = 0.38-0.48). Isoprene-derived SOM had highly soluble activation behavior, consistent with its high O : C ratio. For α-pinene-derived SOM, although CCN activation can be modeled as a highly soluble mechanism, this behavior was not predicted by the O : C ratio, for which a slightly soluble mechanism was anticipated. Complexity in chemical composition, resulting in continuous water uptake and the absence of a deliquescence transition that can thermodynamically limit CCN activation, might explain the difference in the behavior of α-pinene-derived SOM compared to that of pure organic compounds. The present results suggest that atmospheric particles dominated by hydrocarbon-like organic components do not activate (i.e., insoluble regime) whereas those dominated by oxygenated organic components activate (i.e., highly soluble regime) for typical atmospheric cloud life cycles.

  3. Growth responses of Melastoma malabathricum to elevated carbon dioxide and water regime

    NASA Astrophysics Data System (ADS)

    Nasir, Wan Nur Ain Mat; Ahmad, Wan Juliana Wan; Musa, Nor Lailatul Wahidah

    2016-11-01

    Elevated atmospheric CO2 has significant effects on plant growth depending on the species and the interaction between treatments given. In other words, the impacts vary among species, depending on differences in photosynthetic pathways, intrinsic growth rates and other properties. In this research we studied the effects of increased carbon dioxide concentration and water regimes on a shrub species, Melastoma malabathricum in a shade house at ambient CO2 and open roof greenhouse at elevated CO2. The factor of water stress was also included, in which for each CO2 treatment, the amount of water was given once or twice daily. The treatment of elevated CO2 was at 800 ppm, when the plants were exposed daily from 0900h until 1100h. The plant growth was monitored through their biomass, height and leaf area that were recorded fortnightly for six months. The results showed that the height of M. malabathricum stem in elevated CO2 was significantly higher than those in ambient CO2. Similarly, leaf area in the elevated CO2 showed a big difference with a value of 46.24 cm2 for elevated CO2 with twice watering, but only 17.94 cm2 for ambient CO2 with twice watering. Even for once watering, we can see the values of leaf area were higher with 32.06 cm2 for elevated and 24.35 cm2 in ambient CO2. The above ground and below ground biomass differed significantly between ambient and elevated CO2. Above ground biomass in ambient CO2 was higher than that in elevated CO2 with a percentage of 25.7%. In contrast, the below ground biomass in elevated CO2 was higher than that in ambient CO2 with a percentage of 17.4%. The results suggested that the increment of CO2 concentrations and water regime in the natural environment may influence the growth and ultimately the abundance and distribution of this shrub species in urban forest.

  4. Importance of soil thermal regime in terrestrial ecosystem carbon dynamics in the circumpolar north

    NASA Astrophysics Data System (ADS)

    Jiang, Yueyang; Zhuang, Qianlai; Sitch, Stephen; O'Donnell, Jonathan A.; Kicklighter, David; Sokolov, Andrei; Melillo, Jerry

    2016-07-01

    In the circumpolar north (45-90°N), permafrost plays an important role in vegetation and carbon (C) dynamics. Permafrost thawing has been accelerated by the warming climate and exerts a positive feedback to climate through increasing soil C release to the atmosphere. To evaluate the influence of permafrost on C dynamics, changes in soil temperature profiles should be considered in global C models. This study incorporates a sophisticated soil thermal model (STM) into a dynamic global vegetation model (LPJ-DGVM) to improve simulations of changes in soil temperature profiles from the ground surface to 3 m depth, and its impacts on C pools and fluxes during the 20th and 21st centuries. With cooler simulated soil temperatures during the summer, LPJ-STM estimates ~ 0.4 Pg C yr- 1 lower present-day heterotrophic respiration but ~ 0.5 Pg C yr- 1 higher net primary production than the original LPJ model resulting in an additional 0.8 to 1.0 Pg C yr- 1 being sequestered in circumpolar ecosystems. Under a suite of projected warming scenarios, we show that the increasing active layer thickness results in the mobilization of permafrost C, which contributes to a more rapid increase in heterotrophic respiration in LPJ-STM compared to the stand-alone LPJ model. Except under the extreme warming conditions, increases in plant production due to warming and rising CO2, overwhelm the e nhanced ecosystem respiration so that both boreal forest and arctic tundra ecosystems remain a net C sink over the 21st century. This study highlights the importance of considering changes in the soil thermal regime when quantifying the C budget in the circumpolar north.

  5. Shear-induced lamellar ordering and interfacial sliding in amorphous carbon films: A superlow friction regime

    NASA Astrophysics Data System (ADS)

    Ma, Tian-Bao; Hu, Yuan-Zhong; Xu, Liang; Wang, Lin-Feng; Wang, Hui

    2011-10-01

    A shear-induced phase transition from disorder to lamellar ordering in amorphous carbon films are investigated by molecular dynamics simulations. Formation of well-separated graphene-like interfacial layers is observed with large interlayer distances, diminishing and ultimately vanishing interlayer bonds, which provides a near-frictionless sliding plane. The steady-state velocity accommodation mode after the running-in stage is interfacial sliding between the graphene-like layers, which explains the experimentally observed graphitization and formation of carbon-rich transfer layers. A superlow friction or superlubricity regime with friction coefficient of approximately 0.01 originates from the extremely large repulsive and low shear interactions across the sliding interface.

  6. A Novel Method for Analyzing and Interpreting GCM Results Using Clustered Climate Regimes

    NASA Astrophysics Data System (ADS)

    Hoffman, F. M.; Hargrove, W. W.; Erickson, D. J.; Oglesby, R. J.

    2003-12-01

    A high-performance parallel clustering algorithm has been developed for analyzing and comparing climate model results and long time series climate measurements. Designed to identify biases and detect trends in disparate climate change data sets, this tool combines and simplifies large temporally-varying data sets from atmospheric measurements to multi-century climate model output. Clustering is a statistical procedure which provides an objective method for grouping multivariate conditions into a set of states or regimes within a given level of statistical tolerance. The groups or clusters--statistically defined across space and through time--possess centroids which represent the synoptic conditions of observations or model results contained in each state no matter when or where they occurred. The clustering technique was applied to five business-as-usual (BAU) scenarios from the Parallel Climate Model (PCM). Three fields of significance (surface temperature, precipitation, and soil moisture) were clustered from 2000 through 2098. Our analysis shows an increase in spatial area occupied by the cluster or climate regime which typifies desert regions (i.e., an increase in desertification) and a decrease in the spatial area occupied by the climate regime typifying winter-time high latitude perma-frost regions. The same analysis subsequently applied to the ensemble as a whole demonstrates the consistency and variability of trends from each ensemble member. The patterns of cluster changes can be used to show predicted variability in climate on global and continental scales. Novel three-dimensional phase space representations of these climate regimes show the portion of this phase space occupied by the land surface at all points in space and time. Any single spot on the globe will exist in one of these climate regimes at any single point in time, and by incrementing time, that same spot will trace out a trajectory or orbit among these climate regimes in phase space. When a

  7. Response of vegetation to carbon dioxide - effect of elevated levels of CO{sub 2} on winter wheat under two moisture regimes

    SciTech Connect

    Chaudhuri, U.N.; Burnett, R.B.; Kanemasu, E.T.; Kirkham, M.B.

    1987-12-31

    This report deals with the second-year (1985-86) findings of an on going experiment with winter wheat (Triticum aestivum L.) at different carbon dioxide (CO{sub 2}) levels and under two moisture regimes. The results for the first year are given in the U.S. Department of Energy, Carbon Dioxide Research Division Response of Vegetation to Carbon Dioxide. The purpose of the second year`s experiment was to verify the results of 1984-85. However, based on the performance and the results of 1984-85 experiments, a few modifications were made.

  8. The influence of climate cycles on the water regime and carbonate profile in chernozems of Central European Russia and adjacent territories

    NASA Astrophysics Data System (ADS)

    Bazykina, G. S.; Ovechkin, S. V.

    2016-04-01

    The influence of long-term "dry" and "wet" climatic cycles on the water regime, hydrological parameters, and carbonate profiles of chernozems in Central European Russia and adjacent territories was studied. The hydrological and carbonate profiles were found to change during the wet cycle. However, the upper part of the hydrological profile is basically unchanging, whereas in its lower part, the number of hydrological horizons and contrast in their moistening decrease in the forest-steppe chernozems and increase in the steppe chernozems. The frequency of through wetting of chernozems increases during the wet cycles. The vertical lithological heterogeneity of the parent material affects the soil moisture status. In the wet climatic cycle, the moisture content above the lithological contact increases resulting in the development of the features of soil hydromorphism. In the carbonate profile, the character of pedofeatures is changing: some carbonate neoformations disappear, while the other ones develop. Possible variations of the periodically percolative water regime were revealed in chernozems. The classification of water regime proposed by A.A. Rode may be updated based on the data obtained during the dry climatic cycle. Rode's hypothesis about cyclic variations in the soil water regime is confirmed.

  9. Regimes of Scattering Behavior from Particulate Media: Implcations for Snow containing Black Carbon

    NASA Astrophysics Data System (ADS)

    Jeffery, C. A.; Henderson, B. G.

    2015-12-01

    As is well known from the remote sensing of minerals, absorption features in infrared spectra can change drastically with changes in particle size. These changes are the product of two competing effects: volume scattering where increasing particle size leads to a net increase in absorption, and surface scattering where increasing particle size decreases net absorption. Depending on the relative contribution of volume and surface scattering, absorption features can appear as troughs in reflectivity spectra (volume scattering), sharp peaks (surface scattering), or may disappear out right. Solid ice has a significant absorption feature near 12 microns, that is a candidate for the retrieval of snow morphology from infrared remote sensing. In this presentation, we first overview a new phenomenological theory of the reflectivity of particulate media, with an emphasize on different regimes of scattering behavior. We then investigate the 12 micron feature of pure snow and snow containing black carbon, with an emphasize on how this feature is expected to change with changes in snow grain size, and with varying amounts of black carbon.

  10. Future hydrological regimes of the upper Indus basin: results from the PAPRIKA project.

    NASA Astrophysics Data System (ADS)

    Bocchiola, Daniele; Soncini, Andrea; Confortola, Gabriele; Nana, Ester; Bianchi, Alberto; Rosso, Renzo; Diolaiuti, Guglielmina; Smiraglia, Claudio; von Hardenberg, Jost; Palazzi, Elisa; Provenzale, Antonello; Giorgi, Filippo; Solmon, Fabien; Vuillermoz, Elisa

    2013-04-01

    ) hydrological cycle in the area by feeding the hydrological model with future precipitation and temperature (plus downscaling, whenever necessary) from two climate models, one global (EC-Earth), and one regional (RegCM), the latter specifically set up for SHARE-Paprika project. The projected flow duration curves, some selected flow descriptors, and the significance of modified flow regimes in the Shigar river are then evaluated. We comment upon modified snow cover, ice ablation regime and implications for future water resources and flood regime in the area. The uncertainty of the results is addressed, and future research questions are discussed. Keywords: Upper Indus basin; hydrological models; climate models; future water resources.

  11. Temperature response functions introduce high uncertainty in modelled carbon stocks in cold temperature regimes

    NASA Astrophysics Data System (ADS)

    Portner, H.; Bugmann, H.; Wolf, A.

    2009-08-01

    Models of carbon cycling in terrestrial ecosystems contain formulations for the dependence of respiration on temperature, but the sensitivity of predicted carbon pools and fluxes to these formulations and their parameterization is not understood. Thus, we made an uncertainty analysis of soil organic matter decomposition with respect to its temperature dependency using the ecosystem model LPJ-GUESS. We used five temperature response functions (Exponential, Arrhenius, Lloyd-Taylor, Gaussian, Van't Hoff). We determined the parameter uncertainty ranges of the functions by nonlinear regression analysis based on eight experimental datasets from northern hemisphere ecosystems. We sampled over the uncertainty bounds of the parameters and run simulations for each pair of temperature response function and calibration site. The uncertainty in both long-term and short-term soil carbon dynamics was analyzed over an elevation gradient in southern Switzerland. The function of Lloyd-Taylor turned out to be adequate for modelling the temperature dependency of soil organic matter decomposition, whereas the other functions either resulted in poor fits (Exponential, Arrhenius) or were not applicable for all datasets (Gaussian, Van't Hoff). There were two main sources of uncertainty for model simulations: (1) the uncertainty in the parameter estimates of the response functions, which increased with increasing temperature and (2) the uncertainty in the simulated size of carbon pools, which increased with elevation, as slower turn-over times lead to higher carbon stocks and higher associated uncertainties. The higher uncertainty in carbon pools with slow turn-over rates has important implications for the uncertainty in the projection of the change of soil carbon stocks driven by climate change, which turned out to be more uncertain for higher elevations and hence higher latitudes, which are of key importance for the global terrestrial carbon budget.

  12. Sedimentary structures formed by upper-regime flows on a Pleistocene carbonate ramp (Favignana Calcarenite, Sicily, Italy)

    NASA Astrophysics Data System (ADS)

    Slootman, Arnoud; Moscariello, Andrea; Cartigny, Matthieu; de Boer, Poppe

    2015-04-01

    flow. Using published experimental Froude numbers for breaking antidune waves, average flow thickness and sediment flux is computed. The ratio of bed volume and sediment flux provides an estimate for the duration of the sediment gravity flows. We show that applying hydraulic equations to upper-regime sedimentary structures in coarse-grained carbonate sandstones reveal that about half of the ramp deposits, that formed over ca. 350 thousand years, were deposited in not more than tens of hours. Our results provide renewed insight into the evolution of the Favignana Calcarenite and other carbonate ramp deposits.

  13. Methane Pyrolysis and Disposing Off Resulting Carbon

    NASA Technical Reports Server (NTRS)

    Sharma, P. K.; Rapp, D.; Rahotgi, N. K.

    1999-01-01

    Sabatier/Electrolysis (S/E) is a leading process for producing methane and oxygen for application to Mars ISPP. One significant problem with this process is that it produces an excess of methane for combustion with the amount of oxygen that is produced. Therefore, one must discard roughly half of the methane to obtain the proper stoichiometric methane/oxygen mixture for ascent from Mars. This is a waste of hydrogen, which must be brought from Earth and is difficult to transport to Mars and store on Mars. To reduce the problem of transporting hydrogen to Mars, the S/E process can be augmented by another process which reduces overall hydrogen requirement. Three conceptual approaches for doing this are (i) recover hydrogen from the excess methane produced by the S/E process, (ii) convert the methane to a higher hydrocarbon or other organic with a lower H/C ratio than methane, and (iii) use a separate process (such as zirconia or reverse water gas shift reaction) to produce additional oxygen, thus utilizing all the methane produced by the Sabatier process. We report our results here on recovering hydrogen from the excess methane using pyrolysis of methane. Pyrolysis has the advantage that it produces almost pure hydrogen, and any unreacted methane can pass through the S/E process reactor. It has the disadvantage that disposing of the carbon produced by pyrolysis presents difficulties. The goals of a research program on recovery of hydrogen from methane are (in descending priority order): 1) Study the kinetics of pyrolysis to arrive at a pyrolysis reactor design that produces high yields in a confined volume at the lowest possible operating temperature; 2) Study the kinetics of carbon burnoff to determine whether high yields can be obtained in a confined volume at acceptable operating temperatures; and 3) Investigate catalytic techniques for depositing carbon as a fine soot which can be physically separated from the reactor. In the JPL program, we have made significant

  14. Methane Pyrolysis and Disposing Off Resulting Carbon

    NASA Technical Reports Server (NTRS)

    Sharma, P. K.; Rapp, D.; Rahotgi, N. K.

    1999-01-01

    Sabatier/Electrolysis (S/E) is a leading process for producing methane and oxygen for application to Mars ISPP. One significant problem with this process is that it produces an excess of methane for combustion with the amount of oxygen that is produced. Therefore, one must discard roughly half of the methane to obtain the proper stoichiometric methane/oxygen mixture for ascent from Mars. This is wasteful of hydrogen, which must be brought from Earth and is difficult to transport to Mars and store on Mars. To reduced the problem of transporting hydrogen to Mars, the S/E process can be augmented by another process which reduces overall hydrogen requirement. Three conceptual approaches for doing this are (1) recover hydrogen from the excess methane produced by the S/E process, (2) convert the methane to a higher hydrocarbon or other organic with a lower H/C ratio than methane, and (3) use a separate process (such as zirconia or reverse water gas shift reaction) to produce additional oxygen, thus utilizing all the methane produced by the Sabatier process. We report our results here on recovering hydrogen from the excess methane using pyrolysis of methane. Pyrolysis has the advantage that it produces almost pure hydrogen, and any unreacted methane can pass through the S/E process reactor. It has the disadvantage that disposing of the carbon produced by pyrolysis presents difficulties. Hydrogen may be obtained from methane by pyrolysis in the temperature range 10000-12000C. The main reaction products are hydrogen and carbon, though very small amounts of higher hydrocarbons, including aromatic hydrocarbons are formed. The conversion efficiency is about 95% at 12000C. One needs to distinguish between thermodynamic equilibrium conversion and conversion limited by kinetics in a finite reactor.

  15. Temperature response functions introduce high uncertainty in modelled carbon stocks in cold temperature regimes

    NASA Astrophysics Data System (ADS)

    Portner, H.; Bugmann, H.; Wolf, A.

    2010-11-01

    Models of carbon cycling in terrestrial ecosystems contain formulations for the dependence of respiration on temperature, but the sensitivity of predicted carbon pools and fluxes to these formulations and their parameterization is not well understood. Thus, we performed an uncertainty analysis of soil organic matter decomposition with respect to its temperature dependency using the ecosystem model LPJ-GUESS. We used five temperature response functions (Exponential, Arrhenius, Lloyd-Taylor, Gaussian, Van't Hoff). We determined the parameter confidence ranges of the formulations by nonlinear regression analysis based on eight experimental datasets from Northern Hemisphere ecosystems. We sampled over the confidence ranges of the parameters and ran simulations for each pair of temperature response function and calibration site. We analyzed both the long-term and the short-term heterotrophic soil carbon dynamics over a virtual elevation gradient in southern Switzerland. The temperature relationship of Lloyd-Taylor fitted the overall data set best as the other functions either resulted in poor fits (Exponential, Arrhenius) or were not applicable for all datasets (Gaussian, Van't Hoff). There were two main sources of uncertainty for model simulations: (1) the lack of confidence in the parameter estimates of the temperature response, which increased with increasing temperature, and (2) the size of the simulated soil carbon pools, which increased with elevation, as slower turn-over times lead to higher carbon stocks and higher associated uncertainties. Our results therefore indicate that such projections are more uncertain for higher elevations and hence also higher latitudes, which are of key importance for the global terrestrial carbon budget.

  16. Evaluation of the feasibility of alcohols serving as external carbon sources for biological phosphorus removal induced by the oxic/extended-idle regime.

    PubMed

    Wang, Dongbo; Zheng, Wei; Li, Xiaoming; Yang, Qi; Liao, Dexiang; Zeng, Guangming

    2013-03-01

    Recently, a novel operational regime (i.e., the oxic/extended-idle [OEI] regime) has been reported to successfully achieve enhanced biological phosphorus removal (EBPR) when employing glucose and volatile fatty acids as the sole substrate. In the OEI regime, polyphosphate accumulating organisms (PAOs) could get a selective advantage over other populations during the extended-idle period where polyphosphate released but polyhydroxyalkanoates and glycogen transformations were negligible/low, thus energy requirements for maintenance purposes in the period could be covered by polyphosphate release. This study further evaluated the feasibility of alcohols as external carbon sources for EBPR induced by the OEI regime, as the available substrate in the raw wastewater is often deficient. First, phosphorus removal in the OEI process was compared, respectively, with methanol and ethanol as the sole substrate. The results showed that the ethanol-reactor achieved 90.8 ± 2.3% of phosphorus removal, which was approximate twofold than the methanol-reactor. Further studies displayed that the cells in the ethanol-reactor contained more PAOs, and had higher activities of exopolyphosphatase and polyphosphate kinase than those in the methanol-reactor. Also, the aerobic transformations of polyhydroxyalkanoates and glycogen in the ethanol-reactor were, respectively, higher and lower than those in the methanol-reactor, which were consistent with the reactors performances. Then, the feasibility of using ethanol as external substrate to enhance EBPR in the OEI process was confirmed for a municipal wastewater. Finally, EBPR performance and metabolic transformation values between the OEI and the anaerobic/oxic (A/O) regimes with ethanol as the sole substrate were compared. The results showed that EBPR in the ethanol-OEI reactor was higher than that in the ethanol-A/O reactor. All the above results proved that ethanol was a favorable external substrate to the OEI regime for EBPR enhancement.

  17. An ecological regime shift resulting from disrupted predator-prey interactions in Holocene Australia.

    PubMed

    Prowse, Thomas A A; Johnson, Christopher N; Bradshaw, Corey J A; Brook, Barry W

    2014-03-01

    The mass extinction events during human prehistory are striking examples of ecological regime shifts, the causes of which are still hotly debated. In Australia, human arrival approximately 50 thousand years ago was associated with the continental-scale extinction of numerous marsupial megafauna species and a permanent change in vegetation structure. An alternative stable state persisted until a second regime shift occurred during the late Holocene, when the largest two remaining marsupial carnivores, the thylacine and devil, disappeared from mainland Australia. These extinctions have been widely attributed to the human-assisted invasion of a competing predator, the dingo. In this unusual case, the simultaneous effects of human "intensification" (population growth and technological advances) and climate change (particularly increased ENSO variability) have been largely overlooked. We developed a dynamic model system capable of simulating the complex interactions between the main predators (humans, thylacines, devils, dingoes) and their marsupial prey (macropods), which we coupled with reconstructions of human population growth and climate change for late-Holocene Australia. Because the strength of important interspecific interactions cannot be estimated directly, we used detailed scenario testing and sensitivity analysis to identify robust model outcomes and investigate competing explanations for the Holocene regime shift. This approach identified human intensification as the most probable cause, while also demonstrating the potential importance of synergies with the effects of climate change. Our models indicate that the prehistoric impact of humans on Australian mammals was not limited to the late Pleistocene (i.e., the megafaunal extinctions) but extended into the late Holocene.

  18. A Comparison of the Role of Episode Nutrient Supply on Pathways of Carbon in Upwelling Regimes

    NASA Technical Reports Server (NTRS)

    Carr, M. E.

    1997-01-01

    Nutrient supply is episode in the ocean even in regions of fairly high and continuous nutrient supply, such as coastal upwelling regimes. The structure of the ecosystem depends on nutrient availability and the different requirements of phytoplankton cells.

  19. Impacts of climate change on fire regimes and carbon stocks of the U.S. Pacific Northwest

    NASA Astrophysics Data System (ADS)

    Rogers, Brendan M.; Neilson, Ronald P.; Drapek, Ray; Lenihan, James M.; Wells, John R.; Bachelet, Dominique; Law, Beverly E.

    2011-09-01

    The diverse vegetation types and carbon pools of the U.S. Pacific Northwest (PNW) are tightly coupled to fire regimes that depend on climate and fire suppression. To realistically assess the effects of twenty-first-century climate change on PNW fire and carbon dynamics, we developed a new fire suppression rule for the MC1 dynamic general vegetation model that we ran under three climate change scenarios. Climate projections from the CSIRO Mk3, MIROC 3.2 medres, and Hadley CM3 general circulation models, forced by the A2 CO2 emissions scenario, were downscaled to a 30 arc-second (˜0.6 km2) grid. Future climates amplify the already strong seasonality of temperature and precipitation across the domain. Simulations displayed large increases in area burned (76%-310%) and burn severities (29%-41%) by the end of the twenty-first century. The relatively dry ecosystems east of the Cascades gain carbon in the future despite projections of more intense wildfires, while the mesic maritime forests lose up to 1.2 Pg C from increased burning. Simulated fire suppression causes overall carbon gains yet leaves ecosystems vulnerable to large future fires. Overall, our simulations suggest the Pacific Northwest has the potential to sequester ˜1 Pg C over the next century unless summer droughts severely intensify fire regimes.

  20. Modeling the transition between upper plane bed regime and sheet flow without an active layer formulation. Preliminary results.

    NASA Astrophysics Data System (ADS)

    Viparelli, E.; Hernandez Moreira, R. R.; Blom, A.

    2015-12-01

    A perusal of the literature on bedload transport revealed that, notwithstanding the large number of studies on bedform morphology performed in the past decades, the upper plane bed regime has not been thoroughly investigated and the distinction between the upper plane bed and sheet flow transport regimes is still poorly defined. Previous experimental work demonstrated that the upper plane bed regime is characterized by long wavelength and small amplitude bedforms that migrate downstream. These bedforms, however, were not observed in experiments on sheet flow transport suggesting that the upper plane bed and the sheet flow are two different regimes. We thus designed and performed experiments in a sediment feed flume in the hydraulic laboratory of the Department of Civil and Environmental Engineering at the University of South Carolina at Columbia to study the transition from upper plane bed to sheet flow regime. Periodic measurements of water surface and bed elevation, bedform geometry and thicknesses of the bedload layer were performed by eyes, and with cameras, movies and a system of six ultrasonic probes that record the variations of bed elevation at a point over time. We used the time series of bed elevations to determine the probability functions of bed elevation. These probability functions are implemented in a continuous model of river morphodynamics, i.e. a model that does not use the active layer approximation to describe the sediment fluxes between the bedload and the deposit and that should thus be able to capture the details of the vertical and streamwise variation of the deposit grain size distribution. This model is validated against the experimental results for the case of uniform material. We then use the validated model in the attempt to study if and how the spatial distribution of grain sizes in the deposit changes from upper plane bed regime to sheet flow and if these results are influenced by the imposed rates of base level rise.

  1. Precipitation and temperature regime over Cyprus as a result of global climate change

    NASA Astrophysics Data System (ADS)

    Giannakopoulos, C.; Hadjinicolaou, P.; Kostopoulou, E.; Varotsos, K. V.; Zerefos, C.

    2010-02-01

    In this study, the impact of global climate change on the temperature and precipitation regime over the island of Cyprus has been investigated. The analysis is based on daily output from a regional climate model (RCM) at a high horizontal resolution (25 km) produced within the framework of the EU-funded ENSEMBLES project. The control run represents the base period 1961-1990 and is used here as reference for comparison with future predictions. Two future periods are studied, 2021-2050 and 2071-2100. For the study area and over the study period, an analysis of the changes associated with the temperature regime and the hydrological cycle, such as mean precipitation and drought duration, is presented. Variations in the mean annual and seasonal rainfall are presented. Changes in the number of hot days/warm nights as well as drought duration are also discussed. These changes should be very important to assess future possible water shortages over the island and to provide a basis for associated impacts on the agricultural sector.

  2. Combining charcoal and elemental black carbon analysis in sedimentary archives: Implications for past fire regimes, the pyrogenic carbon cycle, and the human-climate interactions

    NASA Astrophysics Data System (ADS)

    Thevenon, Florian; Williamson, David; Bard, Edouard; Anselmetti, Flavio S.; Beaufort, Luc; Cachier, Hélène

    2010-07-01

    This paper addresses the quantification of combustion-derived products in oceanic and continental sediments by optical and chemical approaches, and the interest of combining such methods for reconstructing past biomass burning activity and the pyrogenic carbon cycle. In such context, the dark particles > 0.2 µm 2 remaining after the partial digestion of organic matter are optically counted by automated image analysis and defined as charcoal, while the elemental carbon remaining after thermal and chemical oxidative treatments is quantified as black carbon (BC). The obtained pyrogenic carbon records from three sediment core-based case studies, (i) the Late Pleistocene equatorial Pacific Ocean, (ii) the mid-Holocene European Lake Lucerne, and (iii) the Late Holocene African Lake Masoko, are interpreted as proxy records of regional transportation mechanisms and biomass burning activities. The results show that the burial of dark carbon-rich particles in the 360 kyr-long record from the west equatorial Pacific is controlled by the combination of sea-level changes and low-latitude atmospheric circulation patterns (summer monsoon dynamics). However, the three fold increases in charcoal and BC sediment influxes between 53-43 and 12-10 kyr BP suggest that major shifts in fire activity occur synchronously with human colonization in the Indo/Pacific region. The coarse charcoal distribution from a 7.2 kyr record from Lake Lucerne in Switzerland closely matches the regional timing of major technical, land-use, and socio-economic changes during the Neolithic (between ca. 5.7 and 5.2 kyr BP and 4.9-4.5 kyr BP), the Bronze and Iron Ages (at ca. 3.3 and 2.4 kyr BP, respectively), and the industrialization (after AD 1838), pointing to the key impact of human activities on the sources, transportation processes and reservoirs of refractory carbon during the Holocene. In the tropical Masoko maar lake in Tanzania, where charcoal and BC records are highly sensitive to the local climate

  3. Response to multi-generational selection under elevated [CO2] in two temperature regimes suggests enhanced carbon assimilation and increased reproductive output in Brassica napus L.

    PubMed Central

    Frenck, Georg; van der Linden, Leon; Mikkelsen, Teis Nørgaard; Brix, Hans; Jørgensen, Rikke Bagger

    2013-01-01

    Functional plant traits are likely to adapt under the sustained pressure imposed by environmental changes through natural selection. Employing Brassica napus as a model, a multi-generational study was performed to investigate the potential trajectories of selection at elevated [CO2] in two different temperature regimes. To reveal phenotypic divergence at the manipulated [CO2] and temperature conditions, a full-factorial natural selection regime was established in a phytotron environment over the range of four generations. It is demonstrated that a directional response to selection at elevated [CO2] led to higher quantities of reproductive output over the range of investigated generations independent of the applied temperature regime. The increase in seed yield caused an increase in aboveground biomass. This suggests quantitative changes in the functions of carbon sequestration of plants subjected to increased levels of CO2 over the generational range investigated. The results of this study suggest that phenotypic divergence of plants selected under elevated atmospheric CO2 concentration may drive the future functions of plant productivity to be different from projections that do not incorporate selection responses of plants. This study accentuates the importance of phenotypic responses across multiple generations in relation to our understanding of biogeochemical dynamics of future ecosystems. Furthermore, the positive selection response of reproductive output under increased [CO2] may ameliorate depressions in plant reproductive fitness caused by higher temperatures in situations where both factors co-occur. PMID:23762504

  4. Impact of inter-annual climatic variability on ecosystem carbon exchange in two grazed temperate grasslands with contrasting drainage regimes

    NASA Astrophysics Data System (ADS)

    Choncubhair, Órlaith Ní; Humphreys, James; Lanigan, Gary

    2014-05-01

    Temperate grasslands constitute over 30% of the Earth's naturally-occurring biomes and make an important contribution towards the partial mitigation of anthropogenic greenhouse gas emissions by terrestrial ecosystems. Accumulation of carbon (C) in grassland systems predominantly takes place in below-ground repositories, enhanced by the presence of a stable soil environment with low carbon turnover rates, active rhizodeposition and high levels of residue and organic inputs. Predicted future warming is expected to increase productivity in temperate zones, thereby enhancing rates of terrestrial carbon sequestration. However, the susceptibility of many ecosystems, including grasslands, to extreme climatic events and inter-annual variability has been demonstrated previously. Temperature anomalies as well as modifications in the temporal pattern and quantity of precipitation alter the balance between carbon uptake and release processes and a mechanistic understanding of ecosystem response to such changes is still lacking. In the present study, the impact of extreme inter-annual variability in summer rainfall and temperature on carbon dynamics in two rotationally-grazed grasslands in Ireland was examined. The sites experience similar temperate climatic regimes but differ in soil drainage characteristics. Eddy covariance measurements of net ecosystem exchange of carbon were complemented by regular assessment of standing biomass, leaf cover, harvest exports and organic amendment inputs. The summers of 2012 and 2013 showed contrasting climatic conditions, with summer precipitation 93% higher and 25% lower respectively than long-term means. In addition, soil temperatures were 7% lower and 11% higher than expected. Cool, wet conditions in 2012 facilitated net carbon uptake for more than ten months of the year at the poorly-drained site, however the ecosystem switched to a net source of carbon in 2013 during months with significantly reduced rainfall. In contrast, net C

  5. A Numerical Study of the Effect of Periodic Nutrient Supply on Pathways of Carbon in a Coastal Upwelling Regime

    NASA Technical Reports Server (NTRS)

    Carr, Mary-Elena

    1998-01-01

    A size-based ecosystem model was modified to include periodic upwelling events and used to evaluate the effect of episodic nutrient supply on the standing stock, carbon uptake, and carbon flow into mesozooplankton grazing and sinking flux in a coastal upwelling regime. Two ecosystem configurations were compared: a single food chain made up of net phytoplankton and mesozooplankton (one autotroph and one heterotroph, A1H1), and three interconnected food chains plus bacteria (three autotrophs and four heterotrophs, A3H4). The carbon pathways in the A1H1 simulations were under stronger physical control than those of the A3H4 runs, where the small size classes are not affected by frequent upwelling events. In the more complex food web simulations, the microbial pathway determines the total carbon uptake and grazing rates, and regenerated nitrogen accounts for more than half of the total primary production for periods of 20 days or longer between events. By contrast, new production, export of carbon through sinking and mesozooplankton grazing are more important in the A1H1 simulations. In the A3H4 simulations, the turnover time scale of the autotroph biomass increases as the period between upwelling events increases, because of the larger contribution of slow-growing net phytoplankton. The upwelling period was characterized for three upwelling sites from the alongshore wind speed measured by the NASA Scatterometer (NSCAT) and the corresponding model output compared with literature data. This validation exercise for three upwelling sites and a downstream embayment suggests that standing stock, carbon uptake and size fractionation were best supported by the A3H4 simulations, while the simulated sinking fluxes are not distinguishable in the two configurations.

  6. Projected carbon stocks in the conterminous USA with land use and variable fire regimes.

    PubMed

    Bachelet, Dominique; Ferschweiler, Ken; Sheehan, Timothy J; Sleeter, Benjamin M; Zhu, Zhiliang

    2015-12-01

    The dynamic global vegetation model (DGVM) MC2 was run over the conterminous USA at 30 arc sec (~800 m) to simulate the impacts of nine climate futures generated by 3GCMs (CSIRO, MIROC and CGCM3) using 3 emission scenarios (A2, A1B and B1) in the context of the LandCarbon national carbon sequestration assessment. It first simulated potential vegetation dynamics from coast to coast assuming no human impacts and naturally occurring wildfires. A moderate effect of increased atmospheric CO2 on water use efficiency and growth enhanced carbon sequestration but did not greatly influence woody encroachment. The wildfires maintained prairie-forest ecotones in the Great Plains. With simulated fire suppression, the number and impacts of wildfires was reduced as only catastrophic fires were allowed to escape. This greatly increased the expansion of forests and woodlands across the western USA and some of the ecotones disappeared. However, when fires did occur, their impacts (both extent and biomass consumed) were very large. We also evaluated the relative influence of human land use including forest and crop harvest by running the DGVM with land use (and fire suppression) and simple land management rules. From 2041 through 2060, carbon stocks (live biomass, soil and dead biomass) of US terrestrial ecosystems varied between 155 and 162 Pg C across the three emission scenarios when potential natural vegetation was simulated. With land use, periodic harvest of croplands and timberlands as well as the prevention of woody expansion across the West reduced carbon stocks to a range of 122-126 Pg C, while effective fire suppression reduced fire emissions by about 50%. Despite the simplicity of our approach, the differences between the size of the carbon stocks confirm other reports of the importance of land use on the carbon cycle over climate change.

  7. Widely Tunable Single-Photon Source from a Carbon Nanotube in the Purcell Regime

    NASA Astrophysics Data System (ADS)

    Jeantet, A.; Chassagneux, Y.; Raynaud, C.; Roussignol, Ph.; Lauret, J. S.; Besga, B.; Estève, J.; Reichel, J.; Voisin, C.

    2016-06-01

    The narrow emission of a single carbon nanotube at low temperature is coupled to the optical mode of a fiber microcavity using the built-in spatial and spectral matching brought by this flexible geometry. A thorough cw and time-resolved investigation of the very same emitter both in free space and in cavity shows an efficient funneling of the emission into the cavity mode together with a strong emission enhancement corresponding to a Purcell factor of up to 5. At the same time, the emitted photons retain a strong sub-Poissonian statistics. By exploiting the cavity feeding effect on the phonon wings, we locked the emission of the nanotube at the cavity resonance frequency, which allowed us to tune the frequency over a 4 THz band while keeping an almost perfect antibunching. By choosing the nanotube diameter appropriately, this study paves the way to the development of carbon-based tunable single-photon sources in the telecom bands.

  8. The role of hydrologic regimes on dissolved organic carbon composition in an agricultural watershed

    USGS Publications Warehouse

    Hernes, P.J.; Spencer, R.G.M.; Dyda, R.Y.; Pellerin, B.A.; Bachand, P.A.M.; Bergamaschi, B.A.

    2008-01-01

    Willow Slough, a seasonally irrigated agricultural watershed in the Sacramento River valley, California, was sampled weekly in 2006 in order to investigate seasonal concentrations and compositions of dissolved organic carbon (DOC). Average DOC concentrations nearly doubled from winter baseflow (2.75 mg L-1) to summer irrigation (5.14 mg L-1), while a concomitant increase in carbon-normalized vanillyl phenols (0.11 mg 100 mg OC-1 increasing to 0.31 mg 100 mg OC-1, on average) indicates that this additional carbon is likely vascular plant-derived. A strong linear relationship between lignin concentration and total suspended sediments (r2 = 0.79) demonstrates that agricultural management practices that mobilize sediments will likely have a direct and significant impact on DOC composition. The original source of vascular plant-derived DOC to Willow Slough appears to be the same throughout the year as evidenced by similar syringyl to vanillyl and cinnamyl to vanillyl ratios. However, differing diagenetic pathways during winter baseflow as compared to the rest of the year are evident in acid to aldehyde ratios of both vanillyl and syringyl phenols. The chromophoric dissolved organic matter (CDOM) absorption coefficient at 350 nm showed a strong correlation with lignin concentration (r2 = 0.83). Other CDOM measurements related to aromaticity and molecular weight also showed correlations with carbon-normalized yields (e.g. specific UV absorbance at 254 nm (r2 = 0.57) and spectral slope (r2 = 0.54)). Our overall findings suggest that irrigated agricultural watersheds like Willow Slough can potentially have a significant impact on mainstem DOC concentration and composition when scaled to the entire watershed of the main tributary. ?? 2008 Elsevier Ltd.

  9. Gunshot wounds (resulting from execution) of exhumed victims of the communist regime in Poland.

    PubMed

    Szleszkowski, Łukasz; Thannhäuser, Agata; Szwagrzyk, Krzysztof; Kawecki, Jerzy; Jurek, Tomasz

    2014-07-01

    This study presents the results of the analysis of the remains of 23 executed male individuals aged between 21 and 63 years, recovered from Osobowicki Cemetery in Wroclaw (Poland), field 83B, in 2012. In 1948 and 1949, prisoners sentenced to death by firing squad--most of them associated with the post-war anti-communist underground independence movement in Poland--were buried there. The aim of the study was to analyse fatal wounds and the method of execution, and to compare the results to data from archival documents. The results were also compared with studies concerning executions during a later period, i.e. 1949-1954. The research on the method of execution during this period of history carried out during the exhumations in Osobowicki Cemetery was the first conducted on such a scale in Poland. Forensic analysis revealed a wide variety of gunshot wounds inflicted during executions, revealing both gunshots to the head, especially single shots to the back of the head, and cases corresponding to the use of a firing squad, probably equipped with machine guns. The results of the research indicate that capital punishment by shooting was carried out in ways both similar to those the specified in the regulations and completely different.

  10. A Review of Update Clinical Results of Carbon Ion Radiotherapy

    PubMed Central

    Tsujii, Hirohiko; Kamada, Tadashi

    2012-01-01

    Among various types of ion species, carbon ions are considered to have the most balanced, optimal properties in terms of possessing physically and biologically effective dose localization in the body. This is due to the fact that when compared with photon beams, carbon ion beams offer improved dose distribution, leading to the concentration of the sufficient dose within a target volume while minimizing the dose in the surrounding normal tissues. In addition, carbon ions, being heavier than protons, provide a higher biological effectiveness, which increases with depth, reaching the maximum at the end of the beam's range. This is practically an ideal property from the standpoint of cancer radiotherapy. Clinical studies have been carried out in the world to confirm the efficacy of carbon ions against a variety of tumors as well as to develop effective techniques for delivering an efficient dose to the tumor. Through clinical experiences of carbon ion radiotherapy at the National Institute of Radiological Sciences and Gesellschaft für Schwerionenforschung, a significant reduction in the overall treatment time with acceptable toxicities has been obtained in almost all types of tumors. This means that carbon ion radiotherapy has meanwhile achieved for itself a solid place in general practice. This review describes clinical results of carbon ion radiotherapy together with physical, biological and technological aspects of carbon ions. PMID:22798685

  11. GPS results for Macedonia and its importance for the tectonics of the Southern Balkan extensional regime

    NASA Astrophysics Data System (ADS)

    Clark Burchfiel, B.; King, Robert W.; Todosov, Angel; Kotzev, Valentin; Durmurdzanov, Nikola; Serafimovski, Todor; Nurce, Bilbil

    2006-02-01

    GPS results from 25 stations in Macedonia measured in 1996 and 2000 show that Macedonia moves SSE relative to Eurasia essentially as a single crustal piece along with parts of westernmost Bulgaria. Geological studies show active N-S normal faults and two NNW-striking right-lateral faults in western Macedonia, and NW-trending left-lateral faults SE Macedonia, with a region in central Macedonia essentially devoid of active faults. Distribution of seismic activity supports the geological studies. However, the GPS results cannot discriminate the active faulting, except perhaps in the northern part of Macedonia in the Skopje and adjacent areas, where active ~NS extension occurs. Slip-rates on the strike-slip faults must be low, in the range of 0-2 mm/year. There is a progressive increase in GPS velocities southward in northern Greece toward the North Anatolian fault zone, across which the velocities increase and change direction dramatically.

  12. Observations on a Slow Burning Regime for Hydrocarbon Droplets - N-Heptane/Air Results

    NASA Technical Reports Server (NTRS)

    Choi, Mun Y.; Dryer, Frederick L.; Haggard, John B., Jr.

    1991-01-01

    Experiments on n-heptane/airdroplet combustion under reduced gravity have served as a benchmark for much of the existing theoretical efforts on the modeling of sphero-synmmetric droplet burning. New experiments conducted in the NASA-Lewis Research Center 2.2 second droptower (at less than 10 exp -5 g) which emphasize the production of sphero-symmetry and low relative droplet/gas convection produce burning rates in air (for about 1 mm droplets) as much as 40-percent lower than the classical result (0.78 sq mm/s). The burning rate is proportional to the measured droplet/gas relative velocity, and the observed functional dependence is much larger than predicted by published convective correlations. New results clearly indicate that the droplet/laboratory velocity does not correspond to the relative droplet/gas velocity. Thus, the convective effects on droplet combustion is not properly characterized by droplet motion alone. Differences in the burning rates are speculated to result from the effects of the accumulated soot as well as the asymmetry (caused by convection) in the temperature and species distributions surrounding the droplet.

  13. Numerical results on noise-induced dynamics in the subthreshold regime for thermoacoustic systems

    NASA Astrophysics Data System (ADS)

    Gupta, Vikrant; Saurabh, Aditya; Paschereit, Christian Oliver; Kabiraj, Lipika

    2017-03-01

    Thermoacoustic instability is a serious issue in practical combustion systems. Such systems are inherently noisy, and hence the influence of noise on the dynamics of thermoacoustic instability is an aspect of practical importance. The present work is motivated by a recent report on the experimental observation of coherence resonance, or noise-induced coherence with a resonance-like dependence on the noise intensity as the system approaches the stability margin, for a prototypical premixed laminar flame combustor (Kabiraj et al., Phys. Rev. E, 4 (2015)). We numerically investigate representative thermoacoustic models for such noise-induced dynamics. Similar to the experiments, we study variation in system dynamics in response to variations in the noise intensity and in a critical control parameter as the systems approach their stability margins. The qualitative match identified between experimental results and observations in the representative models investigated here confirms that coherence resonance is a feature of thermoacoustic systems. We also extend the experimental results, which were limited to the case of subcritical Hopf bifurcation, to the case of supercritical Hopf bifurcation. We identify that the phenomenon has qualitative differences for the systems undergoing transition via subcritical and supercritical Hopf bifurcations. Two important practical implications are associated with the findings. Firstly, the increase in noise-induced coherence as the system approaches the onset of thermoacoustic instability can be considered as a precursor to the instability. Secondly, the dependence of noise-induced dynamics on the bifurcation type can be utilised to distinguish between subcritical and supercritical bifurcation prior to the onset of the instability.

  14. Shifts in the hydrodynamic regime determine patterns of regional changes of the Arctic Ocean carbon cycle in future climate change projections

    NASA Astrophysics Data System (ADS)

    Ilyina, T.; Heinze, M.; Li, H.; Jungclaus, J. H.; Six, K. D.

    2015-12-01

    In future projections the Arctic Ocean carbon cycle is a hotspot for changes driven by rising CO2 emissions. Concomitantly, the Arctic Ocean hydrodynamic regime undergoes substantial shifts so the net effect on the carbon cycle is not intuitively clear. In the high CO2 scenario RCP8.5 extended until 2300 in projections of the Max Planck Institute's Earth System Model, the averaged Arctic Ocean surface temperature rises by 4°C in 2100 and by 10°C in 2300, respectively. The Arctic becomes free of summer sea ice in the second half of the 21st century, whereas winter sea ice disappears at the beginning of the 23rd century. Owing to increased sea ice melting and runoff, fresh water content increases gradually until the end of the 22nd century and then drops abruptly as a result of an intensification of the saline Atlantic water inflow. Accumulation of Atlantic water collapses the halocline in the central basin of the Arctic Ocean by the first half of the 23rd century. Ongoing warming enhances thermal stratification and the mixed layer shoales. In contrast, halocline erosion and the cooling of the ice free water act in concert to favor formation of convection cells in the central basin. Freshening in the Canada basin and transport of salty water into the Eurasian basin generate a dipole structure in the anomalies of surface salinity. Driven by the rising CO2, the averaged dissolved inorganic carbon (DIC) is growing. Changes in the averaged total alkalinity (TA) go along with the fresh water content evolution and decreasing carbonate ion concentration so that TA drops below preindustrial values. Yet, along with salinity, the Eurasian basin receives waters with higher DIC and TA from the Atlantic. As a result, the distributions of TA and DIC anomalies resemble the dipole pattern projected for salinity. We show that while future changes in the Arctic Ocean carbon cycle proceed at rates determined by atmospheric CO2 levels, the regional patterns are driven by shifts in the

  15. Tc-99 Adsorption on Selected Activated Carbons - Batch Testing Results

    SciTech Connect

    Mattigod, Shas V.; Wellman, Dawn M.; Golovich, Elizabeth C.; Cordova, Elsa A.; Smith, Ronald M.

    2010-12-01

    CH2M HILL Plateau Remediation Company (CHPRC) is currently developing a 200-West Area groundwater pump-and-treat system as the remedial action selected under the Comprehensive Environmental Response, Compensation, and Liability Act Record of Decision for Operable Unit (OU) 200-ZP-1. This report documents the results of treatability tests Pacific Northwest National Laboratory researchers conducted to quantify the ability of selected activated carbon products (or carbons) to adsorb technetium-99 (Tc-99) from 200-West Area groundwater. The Tc-99 adsorption performance of seven activated carbons (J177601 Calgon Fitrasorb 400, J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, J177612 Norit GAC830, J177613 Norit GAC830, and J177617 Nucon LW1230) were evaluated using water from well 299-W19-36. Four of the best performing carbons (J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, and J177613 Norit GAC830) were selected for batch isotherm testing. The batch isotherm tests on four of the selected carbons indicated that under lower nitrate concentration conditions (382 mg/L), Kd values ranged from 6,000 to 20,000 mL/g. In comparison. Under higher nitrate (750 mg/L) conditions, there was a measureable decrease in Tc-99 adsorption with Kd values ranging from 3,000 to 7,000 mL/g. The adsorption data fit both the Langmuir and the Freundlich equations. Supplemental tests were conducted using the two carbons that demonstrated the highest adsorption capacity to resolve the issue of the best fit isotherm. These tests indicated that Langmuir isotherms provided the best fit for Tc-99 adsorption under low nitrate concentration conditions. At the design basis concentration of Tc 0.865 µg/L(14,700 pCi/L), the predicted Kd values from using Langmuir isotherm constants were 5,980 mL/g and 6,870 mL/g for for the two carbons. These Kd values did not meet the target Kd value of 9,000 mL/g. Tests

  16. Order- N electron transport calculations from ballistic to diffusive regimes by a time-dependent wave-packet diffusion method: Application to transport properties of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ishii, Hiroyuki; Kobayashi, Nobuhiko; Hirose, Kenji

    2010-08-01

    We present an order- N [O(N)] calculation method for the quantum electron transport of huge systems up to 80 million atoms. Based on the linear-response Kubo-Greenwood formula, we calculate the conductance through time-dependent diffusion coefficients using the time-dependent wave-packet diffusion approach, which treats the electron wave-packet motion with an O(N) and very high-speed calculation. Combining with molecular-dynamics simulations, we can study the temperature dependence of electron transport properties of materials from atomistic viewpoints from ballistic to diffusive regimes. We apply the present calculation method to transport of the carbon nanotubes (CNTs) with various lengths at various temperatures. In metallic CNTs, the mean-free paths are in good agreements with recent experiments, which reach about 500 nm at room temperature and increase up to several micrometers at low temperature. We find that the resistance increases almost linearly with temperature and takes larger values than expected in the quasiballistic regime. In semiconducting CNTs, the mobilities are affected strongly by the contacts with metallic electrodes through Schottky barriers. The mobilities are maximally 30000cm2/Vs and cut-off frequencies of 300 GHz at room temperature. These calculated results provide useful information to the design of CNT field-effect-transistor devices.

  17. Comparative study of selected Brazilian and Nigerian policies to promote the transfer and development of technology: the role of regime and non-regime factors, and some results from the automobile industry, 1967-80

    SciTech Connect

    Gusau, B.H.

    1985-01-01

    This study is concerned with the policies adopted by Brazil and Nigeria to promote the transfer and development of technology in industry. The objectives are two-fold: (1) to compare and analyze the policies with respect to the automobile industries in the 1967-1980 period; (2) to investigate whether their adoption was solely a function of the different ideological values and issue levels of economic development of the countries, or whether the regimes are solely an expression of the patterns of that development. The study adopted the Comparative Public Policy approach to explore the various hypotheses formulated. The findings showed that Brazil realized more significant results than Nigeria in technology development, while in other areas, such as the curtailment of imports, employment generation, etc., the results are mixed. The study concludes that both regime and industrial development factors influence the variation in the policies, although the regime factor seems to explain more of the variation.

  18. Carbon pools and flows during lab-scale degradation of old landfilled waste under different oxygen and water regimes

    SciTech Connect

    Brandstätter, Christian Laner, David Fellner, Johann

    2015-06-15

    Graphical abstract: Display Omitted - Highlights: • 40 year old waste from an old MSW landfill was incubated in LSR experiments. • Carbon balances for anaerobic and aerobic waste degradation were established. • The transformation of carbon pools during waste degradation was investigated. • Waste aeration resulted in the formation of a new, stable organic carbon pool. • Water addition did not have a significant effect on aerobic waste degradation. - Abstract: Landfill aeration has been proven to accelerate the degradation of organic matter in landfills in comparison to anaerobic decomposition. The present study aims to evaluate pools of organic matter decomposing under aerobic and anaerobic conditions using landfill simulation reactors (LSR) filled with 40 year old waste from a former MSW landfill. The LSR were operated for 27 months, whereby the waste in one pair was kept under anaerobic conditions and the four other LSRs were aerated. Two of the aerated LSR were run with leachate recirculation and water addition and two without. The organic carbon in the solid waste was characterized at the beginning and at the end of the experiments and major carbon flows (e.g. TOC in leachate, gaseous CO{sub 2} and CH{sub 4}) were monitored during operation. After the termination of the experiments, the waste from the anaerobic LSRs exhibited a long-term gas production potential of more than 20 NL kg{sup −1} dry waste, which corresponded to the mineralization of around 12% of the initial TOC (67 g kg{sup −1} dry waste). Compared to that, aeration led to threefold decrease in TOC (32–36% of the initial TOC were mineralized), without apparent differences in carbon discharge between the aerobic set ups with and without water addition. Based on the investigation of the carbon pools it could be demonstrated that a bit more than 10% of the initially present organic carbon was transformed into more recalcitrant forms, presumably due to the formation of humic substances

  19. Long-term trends in carbon, nutrients and stoichiometry in Norwegian coastal waters: Evidence of a regime shift

    NASA Astrophysics Data System (ADS)

    Frigstad, Helene; Andersen, Tom; Hessen, Dag O.; Jeansson, Emil; Skogen, Morten; Naustvoll, Lars-Johan; Miles, Martin W.; Johannessen, Truls; Bellerby, Richard G. J.

    2013-04-01

    A 20-year time series from the Norwegian Coastal Current was explored to examine the effects of advected nutrient supply from the southern North Sea and of large-scale climate variability on hydrography, nutrients and particulate organic matter (seston), focusing on trends in the January to April period in the upper layers (0-30 m). The interannual variability in hydrography, nutrients and seston was correlated with the NAO index, mostly through the inflow of nutrient-rich waters from the southern North Sea. There was a long-term decrease in nutrient concentrations, which according to a water mass analysis followed a reduction in nutrients advected from the German Bight and southern North Sea. The concentrations of carbon and nitrogen in seston, dissolved organic nitrogen and the estimated fraction of non-autotrophic material increased significantly and non-linearly through a sharp transition between 1998 and 2000, and have remained at this level since. Humic coagulation was suggested as the mechanism behind the increase in the non-autotrophic fraction of seston, which could be connected with the reported “darkening” of the coastal Skagerrak and Baltic Sea. Concurrent with the thresholds in suspended material, a decimation of the sugar kelp forest and recruitment failure of key carnivorous fish was reported for the same region, suggesting that a regime shift took place in the early 2000s in the coastal waters of the Norwegian Skagerrak. Our data suggests that the effects of increased freshwater runoff, especially the increased inputs of terrestrial-derived, humic material, could play an important role in the observed, coastal responses.

  20. THERMAL ESCAPE IN THE HYDRODYNAMIC REGIME: RECONSIDERATION OF PARKER's ISENTROPIC THEORY BASED ON RESULTS OF KINETIC SIMULATIONS

    SciTech Connect

    Volkov, Alexey N.; Johnson, Robert E.

    2013-03-10

    The one-dimensional steady-state problem of thermal escape from a single-component atmosphere of mon- and diatomic gases is studied in the hydrodynamic (blow-off) regime using the direct simulation Monte Carlo method for an evaporative-type condition at the lower boundary. The simulations are performed for various depths into an atmosphere, indicated by a Knudsen number, Kn{sub 0}, equal to the ratio of the mean free path of molecules to the radial position of the source surface, ranging from 10 to 10{sup -5}, and for the range of the source Jeans parameter, {lambda}{sub 0}, equal to the ratio of gravitational and thermal energies, specific to blow-off. The results of kinetic simulations are compared with the isentropic model (IM) and the Navier-Stokes model. It is shown that the IM can be simplified if formulated in terms of the local Mach number and Jeans parameter. The simulations predict that at Kn{sub 0} < {approx} 10{sup -3} the flow includes a near-surface non-equilibrium Knudsen layer, a zone where the flow can be well approximated by the IM, and a rarefied far field. The corresponding IM solutions, however, only approach Parker's critical solution as {lambda}{sub 0} approaches the upper limit for blow-off. The IM alone is not capable for predicting the flow and requires boundary conditions at the top of the Knudsen layer. For small Kn{sub 0}, the scaled escape rate and energy loss rate are found to be independent of {lambda}{sub 0}. The simulation results can be scaled to any single-component atmosphere exhibiting blow-off if the external heating above the lower boundary is negligible, in particular, to sublimation-driven atmospheres of Kuiper belt objects.

  1. Air filtration in the free molecular flow regime: a review of high-efficiency particulate air filters based on carbon nanotubes.

    PubMed

    Li, Peng; Wang, Chunya; Zhang, Yingying; Wei, Fei

    2014-11-01

    Air filtration in the free molecular flow (FMF) regime is important and challenging because a higher filtration efficiency and lower pressure drop are obtained when the fiber diameter is smaller than the gas mean free path in the FMF regime. In previous studies, FMF conditions have been obtained by increasing the gas mean free path through reducing the pressure and increasing the temperature. In the case of carbon nanotubes (CNTs) with nanoscale diameters, it is possible to filtrate in the FMF regime under normal conditions. This paper reviews recent progress in theoretical and experimental studies of air filtration in the FMF regime. Typical structure models of high-efficiency particulate (HEPA) air filters based on CNTs are introduced. The pressure drop in air filters operated in the FMF regime is less than that predicted by the conventional air filtration theory. The thinnest HEPA filters fabricated from single-walled CNT films have an extremely low pressure drop. CNT air filters with a gradient nanostructure are shown to give a much better filtration performance in dynamic filtration. CNT air filters with a hierarchical structure and an agglomerated CNT fluidized bed air filter are also introduced. Finally, the challenges and opportunities for the application of CNTs in air filtration are discussed.

  2. Carbon, nitrogen, and phosphorus stoichiometry of plankton and the nutrient regime in Cabo Frio Bay, SE Brazil.

    PubMed

    Kütter, Vinicius T; Wallner-Kersanach, Monica; Sella, Silvia M; Albuquerque, Ana Luiza S; Knoppers, Bastiaan A; Silva-Filho, Emmanoel V

    2014-01-01

    This long-term study, performed during the years 2003-2005 and 2008-2009, investigated the carbon (C), nitrogen (N), and phosphorus (P) contents of the phyto- and zooplankton communities and the nutrient regime of Cabo Frio Bay, SE Brazil. The information intends to serve as baseline of the plankton C, N, and P stoichiometry for the calibration of biogeochemical and ecological models in support to future findings related to the local and regional phenomena of climatic change. Cabo Frio Bay is a small semienclosed system set adjacent to a region subject to sporadic coastal upwelling. Zooplankton exhibited average annual C, N, and P contents of 11.6 ± 6.9 %, 2.8 ± 1.8 %, and 0.18 ± 0.08 %, and phytoplankton (>20 μm) 6.8 ± 6.0 %, 1.6 ± 1.5 %, and 0.09 ± 0.08 %, respectively. The C/N/P ratios correspond to the lowest already found to date for a marine environment. The low C contents must have been brought about by a predominance of gelatinous zooplankton, like Doliolids/ Salps and also Pteropods. Average annual nutrient concentrations in the water were 0.21 ± 0.1 μM for phosphate, 0.08 ± 0.1 μM for nitrite, 0.74 ± 1.6 μM for nitrate, and 1.27 ± 1.1 μM for ammonium. N/P ratios were around 8:1 during the first study period and 12:1 during the second. The plankton C/N/P and N/P nutrient ratios and elemental concentrations suggest that the system was oligotrophic and nitrogen limited. The sporadic intrusions of upwelling waters during the first study period had no marked effect upon the systems metabolism, likely due to dilution effects and the short residence times of water of the bay.

  3. Carbon Dioxide Sequestration by Direct Mineral Carbonation: Results from Recent Studies and Current Status

    SciTech Connect

    O'Connor, William K.; Dahlin, David C.; Nilsen, David N.; Rush, G.E.; Walters, Richard P.; Turner, Paul C.

    2001-01-01

    Direct mineral carbonation has been investigated as a process to convert gaseous CO2 into a geologically stable, solid final form. The process utilizes a solution of sodium bicarbonate (NaHCO3), sodium chloride (NaCl), and water, mixed with a mineral reactant, such as olivine (Mg2SiO4) or serpentine [Mg3Si2O5(OH)4]. Carbon dioxide is dissolved into this slurry, by diffusion through the surface and gas dispersion within the aqueous phase. The process includes dissolution of the mineral and precipitation of magnesium carbonate (MgCO3) in a single unit operation. Optimum results have been achieved using heat pretreated serpentine feed material, with a surface area of roughly 19 m2 per gram, and high partial pressure of CO2 (PCO2). Specific conditions include: 155?C; PCO2=185 atm; 15% solids. Under these conditions, 78% stoichiometric conversion of the silicate to the carbonate was achieved in 30 minutes. Studies suggest that the mineral dissolution rate is primarily surface controlled, while the carbonate precipitation rate is primarily dependent on the bicarbonate concentration of the slurry. Current studies include further examination of the reaction pathways, and an evaluation of the resource potential for the magnesium silicate reactant, particularly olivine. Additional studies include the examination of various pretreatment options, the development of a continuous flow reactor, and an evaluation of the economic feasibility of the process.

  4. Thermal regime and potential bedrock weathering in alpine rockwalls of Austria: Results from eight years of monitoring (2006-2014)

    NASA Astrophysics Data System (ADS)

    Kellerer-Pirklbauer, Andreas; Wecht, Matthias

    2015-04-01

    Bedrock temperature at sites with a minor winter snow cover gives a good indication for the effects of air temperature anomalies on ground thermal conditions as well as for the intensity of near-surface physical weathering in bedrock. In this study we present results from an ongoing bedrock temperature monitoring program initiated in 2006. Within the framework of this program nine surface boreholes in rockwalls with different slope orientations and two additional boreholes at flat bedrock sites were drilled between August and September 2006 and subsequently instrumented. The altogether eleven rock temperature sites (RTS) are located in the alpine periglacial zone of the Austrian Alps at latitude 46°55' to 47°22' and longitude 12°44' to 14°41'. All RTS have been installed in metamorphic rock (5 x mica schist; 6 x gneiss) at elevations between 1960 and 2725 m asl (mean 2491 m asl.). Three temperature sensors (PT1000) have been inserted at each borehole site at vertical depths of 3, 10 and 30-40 cm. At each RTS the three sensors are connected to a 3-channel miniature temperature datalogger (MTD) manufactured by GeoPrecision, Germany. Our analysis focussed on (a) the variation of mean and extreme daily temperatures at the rock surface and at depth, (b) the variation of the daily temperature range, (c) the number of freeze-thaw-cycles (FTC) and (d) effective freeze-thaw cycles for frost shattering (eFTC), (e) the duration and intensity of freeze-thaw-cycles (DI-FTC), (f) the number of hours and days within the so-called frost-cracking-window (FCW), and effects of (g) aspect and (h) snow cover on the thermal regimes in the bedrock. Results show for instance that the number of FTC and eFTC varied substantially during the observation period at all eleven RTS and at all sensor depths. However, this variation differs from site to site related to snow cover condition, elevation and aspect. For instance, at one lower-elevated (2255 m asl) north exposed RTS the number of

  5. Order-N electron transport calculation from ballistic to diffusive regimes by time-dependent wave-packet diffusion method -Application to carbon nanotubes-

    NASA Astrophysics Data System (ADS)

    Ishii, Hiroyuki; Kobayashi, Nobuhiko; Hirose, Kenji

    2010-03-01

    Using a time-dependent wave-packet diffusion method[1], which treats the quantum electron transport problems of huge systems of up to 80 million atoms, combining with molecular dynamics simulations, we study the electron transport of carbon nanotubes from ballistic to diffusive regimes from an atomistic viewpoint in the unified way. We can simulate the effects of electron- phonon couplings on the transport properties of the nanotubes at various temperatures. We confirm that the obtained mean free path and mobility agree well with recent experimental observations and theoretical calculations, and succeed in evaluating the resistance in entire regime between ballistic and diffusive transport limits. We clarify the resistance is remarkably different from that at the two transport limits, when the length of nanotubes is comparable to the mean free path. [1]H.Ishii, N.Kobayashi, and K.Hirose, Appl.Phys.Express 1(2008) 123002.

  6. Strategies for efficiently selecting PHA producing mixed microbial cultures using complex feedstocks: Feast and famine regime and uncoupled carbon and nitrogen availabilities.

    PubMed

    Oliveira, Catarina S S; Silva, Carlos E; Carvalho, Gilda; Reis, Maria A

    2017-07-25

    Production of polyhydroxyalkanoates (PHAs) by open mixed microbial cultures (MMCs) has been attracting increasing interest as an alternative technology to PHA production by pure cultures, due to the potential for lower costs associated with the use of open systems (eliminating the requirement for sterile conditions) and the utilisation of cheap feedstock (industrial and agricultural wastes). Such technology relies on the efficient selection of an MMC enriched in PHA-accumulating organisms. Fermented cheese whey, a protein-rich complex feedstock, has been used previously to produce PHA using the feast and famine regime for selection of PHA accumulating cultures. While this selection strategy was found efficient when operated at relatively low organic loading rate (OLR, 2g-CODL(-1)d(-1)), great instability and low selection efficiency of PHA accumulating organisms were observed when higher OLR (ca. 6g-CODL(-1)d(-1)) was applied. High organic loading is desirable as a means to enhance PHA productivity. In the present study, a new selection strategy was tested with the aim of improving selection for high OLR. It was based on uncoupling carbon and nitrogen supply and was implemented and compared with the conventional feast and famine strategy. For this, two selection reactors were fed with fermented cheese whey applying an OLR of ca. 8.5g-CODL(-1) (with 3.8g-CODL(-1) resulting from organic acids and ethanol), and operated in parallel under similar conditions, except for the timing of nitrogen supplementation. Whereas in the conventional strategy nitrogen and carbon substrates were added simultaneously at the beginning of the cycle, in the uncoupled substrates strategy, nitrogen addition was delayed to the end of the feast phase (i.e. after exogenous carbon was exhausted). The two different strategies selected different PHA-storing microbial communities, dominated by Corynebacterium and a Xantomonadaceae, respectively with the conventional and the new approaches. The new

  7. Initial second-generation PFB carbonizer pilot plant test results

    SciTech Connect

    Robertson, A.; Van Hook, J. ); Froehlich, R. ); Bonk, D.L. )

    1992-01-01

    Second-generation pressurized fluidized bed combustion (PFBC) plants promise higher efficiency with lower costs of electricity and lower stack emissions. With a l6.55 MPa/538{degree}C/538{degree}C/63.5-mm Hg(2400-psig/1000{degree} F/1000{degree}F/2.5-in.Hg) conventional steam cycle and a 3-percent sulfur Pittsburgh No. 8 coal, a 45-percent efficiency and a cost of electricity {approximately} 20 percent lower than that of a pulverized-coal-fired plant with stack gas scrubbing are being projected. Foster Wheeler Development Corporation has constructed and is operating a second-generation PFB pilot plant at the Foster Wheeler research facility (the John Blizard Research Center) in Livingston, New Jersey. Initial results of the pilot plant carbonizer test program supporting the development of this new type of plant are presented.

  8. Amazon Forest Response to Changes in Rainfall Regime: Results from an Individual-Based Dynamic Vegetation Model

    NASA Astrophysics Data System (ADS)

    Longo, Marcos

    The Amazon is the largest tropical rainforest in the world, and thus plays a major role on global water, energy, and carbon cycles. However, it is still unknown how the Amazon forest will respond to the ongoing changes in climate, especially droughts, which are expected to become more frequent. To help answering this question, in this thesis I developed and improved the representation of biophysical processes and photosynthesis in the Ecosystem Demography model (ED-2.2), an individual-based land ecosystem model. I also evaluated the model biophysics against multiple data sets for multiple forest and savannah sites in tropical South America. Results of this comparison showed that ED-2.2 is able to represent the radiation and water cycles, but exaggerates heterotrophic respiration seasonality. Also, the model generally predicted correct distribution of biomass across different areas, although it overestimated biomass in subtropical savannahs. To evaluate the forest resilience to droughts, I used ED-2.2 to simulate the plant community dynamics at two sites in Eastern Amazonia, and developed scenarios by resampling observed annual rainfall but increasing the probability of selecting dry years. While the model predicted little response at French Guiana, results at the mid-Eastern Amazonia site indicated substantial biomass loss at modest rainfall reductions. Also, the response to drier climate varied within the plant community, with evergreen, early-successional, and larger trees being the most susceptible. The model also suggests that competition for water during prolonged periods of drought caused the largest impact on larger trees, when insufficient wet season rainfall did not recharge deeper soil layers. Finally, results suggested that a decrease in return period of long-lasting droughts could prevent ecosystem recovery. Using different rainfall datasets, I defined vulnerability based on the change in climate needed to reduce the return period of long droughts. The

  9. Carbon dioxide fluxes from Tifway bermudagrass: early results

    NASA Astrophysics Data System (ADS)

    Cotten, David L.; Zhang, G.; Leclerc, M. Y.; Raymer, P.; Steketee, C. J.

    2017-01-01

    This paper reports for the first time preliminary data on carbon uptake of warm-season turfgrass at a well-managed sod farm in south central Georgia. It examines the changes in carbon uptake from one of the most widely used warm-season turfgrass cultivars in the world, Tifway Bermudagrass. It elucidates the role of canopy density and light avalaibility on the net carbon uptake using the eddy-covariance technique. Preliminary evidence suggests that turfgrass is effective at sequestering carbon dioxide during the summer months even when the canopy is being reestablished following a grass harvest.

  10. Collective electronic excitations in the ultra violet regime in 2-D and 1-D carbon nanostructures achieved by the addition of foreign atoms

    NASA Astrophysics Data System (ADS)

    Bangert, U.; Pierce, W.; Boothroyd, C.; Pan, C.-T.; Gwilliam, R.

    2016-06-01

    Plasmons in the visible/UV energy regime have attracted great attention, especially in nano-materials, with regards to applications in opto-electronics and light harvesting; tailored enhancement of such plasmons is of particular interest for prospects in nano-plasmonics. This work demonstrates that it is possible, by adequate doping, to create excitations in the visible/UV regime in nano-carbon materials, i.e., carbon nanotubes and graphene, with choice of suitable ad-atoms and dopants, which are introduced directly into the lattice by low energy ion implantation or added via deposition by evaporation. Investigations as to whether these excitations are of collective nature, i.e., have plasmonic character, are carried out via DFT calculations and experiment-based extraction of the dielectric function. They give evidence of collective excitation behaviour for a number of the introduced impurity species, including K, Ag, B, N, and Pd. It is furthermore demonstrated that such excitations can be concentrated at nano-features, e.g., along nano-holes in graphene through metal atoms adhering to the edges of these holes.

  11. Collective electronic excitations in the ultra violet regime in 2-D and 1-D carbon nanostructures achieved by the addition of foreign atoms

    PubMed Central

    Bangert, U.; Pierce, W.; Boothroyd, C.; Pan, C.-T.; Gwilliam, R.

    2016-01-01

    Plasmons in the visible/UV energy regime have attracted great attention, especially in nano-materials, with regards to applications in opto-electronics and light harvesting; tailored enhancement of such plasmons is of particular interest for prospects in nano-plasmonics. This work demonstrates that it is possible, by adequate doping, to create excitations in the visible/UV regime in nano-carbon materials, i.e., carbon nanotubes and graphene, with choice of suitable ad-atoms and dopants, which are introduced directly into the lattice by low energy ion implantation or added via deposition by evaporation. Investigations as to whether these excitations are of collective nature, i.e., have plasmonic character, are carried out via DFT calculations and experiment-based extraction of the dielectric function. They give evidence of collective excitation behaviour for a number of the introduced impurity species, including K, Ag, B, N, and Pd. It is furthermore demonstrated that such excitations can be concentrated at nano-features, e.g., along nano-holes in graphene through metal atoms adhering to the edges of these holes. PMID:27271352

  12. Collective electronic excitations in the ultra violet regime in 2-D and 1-D carbon nanostructures achieved by the addition of foreign atoms.

    PubMed

    Bangert, U; Pierce, W; Boothroyd, C; Pan, C-T; Gwilliam, R

    2016-06-07

    Plasmons in the visible/UV energy regime have attracted great attention, especially in nano-materials, with regards to applications in opto-electronics and light harvesting; tailored enhancement of such plasmons is of particular interest for prospects in nano-plasmonics. This work demonstrates that it is possible, by adequate doping, to create excitations in the visible/UV regime in nano-carbon materials, i.e., carbon nanotubes and graphene, with choice of suitable ad-atoms and dopants, which are introduced directly into the lattice by low energy ion implantation or added via deposition by evaporation. Investigations as to whether these excitations are of collective nature, i.e., have plasmonic character, are carried out via DFT calculations and experiment-based extraction of the dielectric function. They give evidence of collective excitation behaviour for a number of the introduced impurity species, including K, Ag, B, N, and Pd. It is furthermore demonstrated that such excitations can be concentrated at nano-features, e.g., along nano-holes in graphene through metal atoms adhering to the edges of these holes.

  13. Carbon dynamics of forests in Washington, U.S.A.: 21st century projections based on climate-driven changes in fire regimes.

    PubMed

    Raymond, Crystal L; McKenzie, Donald

    2012-07-01

    During the 21st century, climate-driven changes in fire regimes will be a key agent of change in forests of the U.S. Pacific Northwest (PNW). Understanding the response of forest carbon (C) dynamics to increases in fire will help quantify limits on the contribution of forest C storage to climate change mitigation and prioritize forest types for monitoring C storage and fire management to minimize C loss. In this study, we used projections of 21st century area burned to explore the consequences of changes in fire regimes on C dynamics in forests of Washington State. We used a novel empirical approach that takes advantage of chronosequences of C pools and fluxes and statistical properties of fire regimes to explore the effects of shifting age class distributions on C dynamics. Forests of the western Cascades are projected to be more sensitive to climate-driven increases in fire, and thus projected changes in C dynamics, than forests of the eastern Cascades. In the western Cascades, mean live biomass C is projected to decrease by 24-37%, and coarse woody debris (CWD) biomass C by 15-25% for the 2040s. Loss of live biomass C is projected to be lower for forests of the eastern Cascades and Okanogan Highlands (17-26%), and CWD biomass is projected to increase. Landscape mean net primary productivity is projected to increase in wet low-elevation forests of the western Cascades, but decrease elsewhere. These forests, and moist forests of the Okanogan Highlands, are projected to have the greatest percentage increases in consumption of live biomass. Percentage increases in consumption of CWD biomass are greater than 50% for all regions and up to four times greater than increases in consumption of live biomass. Carbon sequestration in PNW forests will be highly sensitive to increases in fire, suggesting a cautious approach to managing these forests for C sequestration to mitigate anthropogenic CO2 emissions.

  14. Were fossil spring-associated carbonates near Zaca Lake, Santa Barbara, California deposited under an ambient or thermal regime?

    NASA Astrophysics Data System (ADS)

    Ibarra, Yadira; Corsetti, Frank A.; Cheetham, Michael I.; Feakins, Sarah J.

    2014-03-01

    A previously undescribed succession of currently-inactive spring-associated carbonates located near Zaca Lake, Southern California, was investigated in order to determine the nature of deposition (ambient temperature or hydrothermal water, as both are found within the region). The carbonate deposits are up to ~ 1 m thick and formed discontinuously for over 200 m in a narrow valley between two ridges that drain Miocene Monterey Formation bedrock. Depositional facies along the presently dry fluvial path include barrage deposits, narrow fluvial channels, and cascade deposits. The carbonates are mesoscopically banded and contain ubiquitous micro- to macrophyte calcite encrusted fabrics. All of the depositional facies contain alternating bands (~ .05 mm to 5 mm thick) of dark brown and light brown isopachous calcite; the dark brown bands are composed of dense isopachous bladed calcite, whereas the light brown bands are composed of bundles of calcite tubules interpreted as the biosignature of the desmid microalgae Oocardium stratum. Oxygen isotope thermometry utilizing modern water δ18O values from the piped spring reveal depositional water temperature estimates that collectively range from ~ 11 to 16 °C. Stable isotope carbon values exhibit a mean δ13C value of - 9.01 ± 0.62‰ (1σ, n = 27). Our petrographic and geochemical data demonstrate that (1) inactive carbonates were likely sourced from ambient temperature water with a strong soil-zone δ13C signal, (2) the Oocardium calcite biosignature can be used to infer depositional temperature and flow conditions, and (3) the occurrence of extensive carbonates (especially the presence of a perched cascade deposit) indicate the carbonates formed when conditions were much wetter.

  15. Comparing resolved-sideband cooling and measurement-based feedback cooling on an equal footing: Analytical results in the regime of ground-state cooling

    NASA Astrophysics Data System (ADS)

    Jacobs, Kurt; Nurdin, Hendra I.; Strauch, Frederick W.; James, Matthew

    2015-04-01

    We show that in the regime of ground-state cooling, simple expressions can be derived for the performance of resolved-sideband cooling—an example of coherent feedback control—and optimal linear measurement-based feedback cooling for a harmonic oscillator. These results are valid to leading order in the small parameters that define this regime. They provide insight into the origins of the limitations of coherent and measurement-based feedback for linear systems, and the relationship between them. These limitations are not fundamental bounds imposed by quantum mechanics, but are due to the fact that both cooling methods are restricted to use only a linear interaction with the resonator. We compare the performance of the two methods on an equal footing—that is, for the same interaction strength—and confirm that coherent feedback is able to make much better use of the linear interaction than measurement-based feedback. We find that this performance gap is caused not by the back-action noise of the measurement but by the projection noise. We also obtain simple expressions for the maximal cooling that can be obtained by both methods in this regime, optimized over the interaction strength.

  16. Compilation of reinforced carbon-carbon transatlantic abort landing arc jet test results

    NASA Technical Reports Server (NTRS)

    Milhoan, James D.; Pham, Vuong T.; Yuen, Eric H.

    1993-01-01

    This document consists of the entire test database generated to support the Reinforced Carbon-Carbon Transatlantic Abort Landing Study. RCC components used for orbiter nose cap and wing leading edge thermal protection were originally designed to have a multi-mission entry capability of 2800 F. Increased orbiter range capability required a predicted increase in excess of 3300 F. Three test series were conducted. Test series #1 used ENKA-based RCC specimens coated with silicon carbide, treated with tetraethyl orthosilicate, sealed with Type A surface enhancement, and tested at 3000-3400 F with surface pressure of 60-101 psf. Series #2 used ENKA- or AVTEX-based RCC, with and without silicon carbide, Type A or double Type AA surface enhancement, all impregnated with TEOS, and at temperatures from 1440-3350 F with pressures from 100-350 psf. Series #3 tested ENKA-based RCC, with and without silicon carbide coating. No specimens were treated with TEOS or sealed with Type A. Surface temperatures ranged from 2690-3440 F and pressures ranged from 313-400 psf. These combined test results provided the database for establishing RCC material single-mission-limit temperature and developing surface recession correlations used to predict mass loss for abort conditions.

  17. Carbon pools and flows during lab-scale degradation of old landfilled waste under different oxygen and water regimes.

    PubMed

    Brandstätter, Christian; Laner, David; Fellner, Johann

    2015-06-01

    Landfill aeration has been proven to accelerate the degradation of organic matter in landfills in comparison to anaerobic decomposition. The present study aims to evaluate pools of organic matter decomposing under aerobic and anaerobic conditions using landfill simulation reactors (LSR) filled with 40 year old waste from a former MSW landfill. The LSR were operated for 27 months, whereby the waste in one pair was kept under anaerobic conditions and the four other LSRs were aerated. Two of the aerated LSR were run with leachate recirculation and water addition and two without. The organic carbon in the solid waste was characterized at the beginning and at the end of the experiments and major carbon flows (e.g. TOC in leachate, gaseous CO2 and CH4) were monitored during operation. After the termination of the experiments, the waste from the anaerobic LSRs exhibited a long-term gas production potential of more than 20 NL kg(-1) dry waste, which corresponded to the mineralization of around 12% of the initial TOC (67 g kg(-1) dry waste). Compared to that, aeration led to threefold decrease in TOC (32-36% of the initial TOC were mineralized), without apparent differences in carbon discharge between the aerobic set ups with and without water addition. Based on the investigation of the carbon pools it could be demonstrated that a bit more than 10% of the initially present organic carbon was transformed into more recalcitrant forms, presumably due to the formation of humic substances. The source of anaerobic degradation could be identified mainly as cellulose which played a minor role during aerobic degradation in the experiment.

  18. Ireland's deep-water coral carbonate mounds: multidisciplinary research results

    NASA Astrophysics Data System (ADS)

    Kozachenko, M.; Wheeler, A.; Beyer, A.; Blamart, D.; Masson, D.; Olu-Le Roy, K.

    2003-04-01

    Recent international research activity, involving a strong Irish collaboration, has shown that coral reefs are not exclusively associated with warm tropical waters but are also present in the deeper and colder Northeast Atlantic. In the Porcupine Seabight west of Ireland, coral-colonised carbonate mounds (up to 350m high) are present at 600-900m water depth. The corals Lophelia pertusa L. and Madrepora oculata L. contribute to this diverse ecosystem that may also play a significant role in expanding deep-water fisheries. New side-scan sonar, multibeam echosounder, sub-bottom profiler and underwater video imagery supplemented with sedimentological sample material were used to map the seabed in the environs of the Belgica Carbonate Mound province, eastern Porcupine Seabight. The data were integrated in a GIS and provides information on sediment pathways and benthic current patterns within the study area. A facies map of the study area highlights differing sedimentary processes showing evidences for strong northward bottom currents whose interaction has an influence on mounds growth and morphology. This survey revealed mound flanks dominated by sediment waves that give way to coral banks towards the mound summits. A form of coral accumulation was also documented. Detailed analyses of sediment properties from long cores through sediment drifts have generated a high-resolution palaeoclimate record revealing temporal patterns in bottom current strength variations. An accurate assessment of this influence on mound through a comparison with coral growth rates is ongoing.

  19. Brown Carbon: Results From Ground and Airborne Studies

    NASA Astrophysics Data System (ADS)

    Weber, R. J.; Forrister, H.; Liu, J.; Nenes, A.

    2015-12-01

    Brown carbon (BrC) is directly measured with high sensitivity by isolating it from black carbon in aerosol extracts and using long path wave-guide spectrophotometry. Ambient measurements by this approach show that BrC is pervasive and can be found in almost all locations, ranging from urban environments to remote continental sites and upper reaches of the free troposphere. Biomass burning appears to be the major source in many urban and rural locations, but other sources of incomplete combustion, such as vehicle emissions in urban environments also play a role. Secondary aerosols not associated with combustion sources may also contribute, but are likely of lesser importance. Studies of ambient wildfire smoke plumes show that BrC levels decrease as it ages, with a half-life of approximately 10 hours. However, a small fraction of the emitted BrC is stable and may account for much of the BrC observed throughout the atmosphere due to widely dispersed and ubiquitous smoke. A radiative transfer model indicates that this background BrC reduced US continental TOA forcing by 20 percent. Human health studies point to similar chemical components linked to BrC (i.e., HULIS), of this same ubiquitous smoke, as a significant source of adverse cardiorespiratory effects. This talk will summarize findings on BrC sources, transformations and estimates of environmental effects based on bulk measurements.

  20. Primary carbonates and Ca-chloride brines as monitors of a paleo-hydrological regime in the Dead Sea basin

    NASA Astrophysics Data System (ADS)

    Waldmann, Nicolas; Starinsky, Abraham; Stein, Mordechai

    2007-09-01

    Lakes Samra, Lisan and the Dead Sea occupied the Dead Sea basin during the Last Interglacial (˜140-75 ka BP), last glacial (˜70-14 ka BP) and Holocene periods, respectively. The age of Lake Lisan and Samra was determined by U-Th dating of primary aragonites comprising parts of the lacustrine sedimentary sequences. The lakes have periodically deposited sequences of layered calcitic marls (Lake Samra) or laminated primary aragonite (Lake Lisan). The deposition of aragonite as the primary carbonate phase reflects the contribution of the incoming freshwater (loaded with bi-carbonate) and high Mg-, Ca-chloride brine that originated from the subsurface vicinity of the Dead Sea basin. Deposition of calcitic marls suggests a minor effect of the brines. The Ca-chloride subsurface brine has been migrating in and out of the wall rocks of the Dead Sea basin, reflecting the regional hydrological conditions. During most of the last glacial period and during the late Holocene, sufficient precipitation above the Judea Mountains pushed the subsurface Ca-chloride brines into the lakes causing the deposition of aragonite. During the Last Interglacial period the rain that precipitated above the Judea Mountains was insufficient to induce brine flow toward Lake Samra. It appears that sporadic floods provided calcium, bicarbonate and detritus to produce the Samra calcitic marls. Travertines deposited at the Samra-Lisan boundary indicate the early stage in the resumption of groundwater (springs) activity that led to the resurgence of Ca-chloride brine and rise of Lake Lisan. Similar variations in the regional rain precipitation and hydrological activity probably characterized the long-term geochemical evolution of Pleistocene lacustrine water-bodies in the Dead Sea basin, enabling the use of the carbonates as paleo-hydrological monitors.

  1. 75 FR 44766 - Certain Welded Carbon Steel Standard Pipe from Turkey: Final Results of Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-29

    ... International Trade Administration Certain Welded Carbon Steel Standard Pipe from Turkey: Final Results of...) order on certain welded carbon steel standard pipe from Turkey for the January 1, 2008, through December 31, 2008, period of review (POR). See Certain Welded Carbon Steel Standard Pipe From...

  2. 78 FR 21107 - Circular Welded Carbon Steel Pipes and Tubes from Turkey: Preliminary Results of Countervailing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-09

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes from Turkey: Preliminary Results... carbon steel pipes and tubes from Turkey (pipes and tubes from Turkey) for the period of review (POR) of... welded carbon steel pipe and tube with an outside diameter of 0.375 inch or more, but not over 16...

  3. Increase of Carbon Cycle Feedback with Climate Sensitivity: Results from a coupled Climate and Carbon Cycle Model

    SciTech Connect

    Govindasamy, B; Thompson, S; Mirin, A; Wickett, M; Caldeira, K; Delire, C

    2004-04-01

    Coupled climate and carbon cycle modeling studies have shown that the feedback between global warming and the carbon cycle, in particular the terrestrial carbon cycle, could accelerate climate change and result in larger warming. In this paper, we investigate the sensitivity of this feedback for year-2100 global warming in the range of 0 K to 8 K. Differing climate sensitivities to increased CO{sub 2} content are imposed on the carbon cycle models for the same emissions. Emissions from the SRES A2 scenario are used. We use a fully-coupled climate and carbon cycle model, the INtegrated Climate and CArbon model (INCCA) the NCAR/DOE Parallel Coupled Model coupled to the IBIS terrestrial biosphere model and a modified-OCMIP ocean biogeochemistry model. In our model, for scenarios with year-2100 global warming increasing from 0 to 8 K, land uptake decreases from 47% to 29% of total CO{sub 2} emissions. Due to competing effects, ocean uptake (16%) shows almost no change at all. Atmospheric CO{sub 2} concentration increases were 48% higher in the run with 8 K global climate warming than in the case with no warming. Our results indicate that carbon cycle amplification of climate warming will be greater if there is higher climate sensitivity to increased atmospheric CO{sub 2} content; the carbon cycle feedback factor increases from 1.13 to 1.48 when global warming increases from 3.2 to 8 K.

  4. National assessment of geologic carbon dioxide storage resources: results

    USGS Publications Warehouse

    ,

    2013-01-01

    In 2012, the U.S. Geological Survey (USGS) completed an assessment of the technically accessible storage resources (TASR) for carbon dioxide (CO2) in geologic formations underlying the onshore and State waters area of the United States. The formations assessed are at least 3,000 feet (914 meters) below the ground surface. The TASR is an estimate of the CO2 storage resource that may be available for CO2 injection and storage that is based on present-day geologic and hydrologic knowledge of the subsurface and current engineering practices. Individual storage assessment units (SAUs) for 36 basins were defined on the basis of geologic and hydrologic characteristics outlined in the assessment methodology of Brennan and others (2010, USGS Open-File Report 2010–1127) and the subsequent methodology modification and implementation documentation of Blondes, Brennan, and others (2013, USGS Open-File Report 2013–1055). The mean national TASR is approximately 3,000 metric gigatons (Gt). The estimate of the TASR includes buoyant trapping storage resources (BSR), where CO2 can be trapped in structural or stratigraphic closures, and residual trapping storage resources, where CO2 can be held in place by capillary pore pressures in areas outside of buoyant traps. The mean total national BSR is 44 Gt. The residual storage resource consists of three injectivity classes based on reservoir permeability: residual trapping class 1 storage resource (R1SR) represents storage in rocks with permeability greater than 1 darcy (D); residual trapping class 2 storage resource (R2SR) represents storage in rocks with moderate permeability, defined as permeability between 1 millidarcy (mD) and 1 D; and residual trapping class 3 storage resource (R3SR) represents storage in rocks with low permeability, defined as permeability less than 1 mD. The mean national storage resources for rocks in residual trapping classes 1, 2, and 3 are 140 Gt, 2,700 Gt, and 130 Gt, respectively. The known recovery

  5. Carbon-nitrogen interactions regulate climate-carbon cycle feedbacks: results from an atmosphere-ocean general circulation model

    SciTech Connect

    Thornton, Peter E; Doney, Scott C.; Lindsay, Keith; Moore, Jefferson Keith; Mahowald, Natalie; Randerson, James T; Fung, Inez; Lamarque, Jean-Francois H; Feddema, Johan J.

    2009-01-01

    Inclusion of fundamental ecological interactions between carbon and nitrogen cycles in the land component of an atmosphere-ocean general circulation model (AOGCM) leads to decreased carbon uptake associated with CO{sub 2} fertilization, and increased carbon uptake associated with warming of the climate system. The balance of these two opposing effects is to reduce the fraction of anthropogenic CO{sub 2} predicted to be sequestered in land ecosystems. The primary mechanism responsible for increased land carbon storage under radiatively forced climate change is shown to be fertilization of plant growth by increased mineralization of nitrogen directly associated with increased decomposition of soil organic matter under a warming climate, which in this particular model results in a negative gain for the climate-carbon feedback. Estimates for the land and ocean sink fractions of recent anthropogenic emissions are individually within the range of observational estimates, but the combined land plus ocean sink fractions produce an airborne fraction which is too high compared to observations. This bias is likely due in part to an underestimation of the ocean sink fraction. Our results show a significant growth in the airborne fraction of anthropogenic CO{sub 2} emissions over the coming century, attributable in part to a steady decline in the ocean sink fraction. Comparison to experimental studies on the fate of radio-labeled nitrogen tracers in temperate forests indicates that the model representation of competition between plants and microbes for new mineral nitrogen resources is reasonable. Our results suggest a weaker dependence of net land carbon flux on soil moisture changes in tropical regions, and a stronger positive growth response to warming in those regions, than predicted by a similar AOGCM implemented without land carbon-nitrogen interactions. We expect that the between-model uncertainty in predictions of future atmospheric CO{sub 2} concentration and

  6. Carbon savings resulting from the cooling effect of green areas: a case study in Beijing.

    PubMed

    Lin, Wenqi; Wu, Tinghai; Zhang, Chengguo; Yu, Ting

    2011-01-01

    Green areas cool the climate of a city, reduce the energy consumption caused by the urban heat island (UHI) effect, and bring along carbon savings. However, the calculation of carbon savings due to the cooling effect of green areas is still not well understood. We have used a Landsat Enhanced Thematic Mapper Plus (ETM+) image of Beijing, to identify the cooled areas, compute the possible energy used to maintain the temperature differences between cooled areas and their surrounding heated areas, and calculate the carbon savings owing to the avoidance of energy use. Results show that a total amount of 14315.37 tons carbon savings was achieved in the study area and the amount was related to the biomass, the size and the shape of green areas. These results demonstrate the importance of carbon savings resulting from green areas' cooling effect.

  7. 76 FR 67142 - Certain Activated Carbon From the People's Republic of China: Final Results and Partial...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-31

    ...-activation chemical treatment (chemical or water washing, chemical impregnation or other treatment), or... dehydrates molecules in the raw material, and results in the formation of water that is removed from the raw... analysis memoranda. \\13\\ CCT submitted Active Carbon India Private Limited's (``Active Carbon'')...

  8. NON-DESTRUCTIVE IN SITU SOIL CARBON ANALYSIS: PRINCIPLE AND RESULTS.

    SciTech Connect

    WIELOPOLSKI, L.; MITRA, S.; HENDREY, G.; ROGERS, H.; TORBERT, A.; PRIOR, S.

    2003-05-05

    Global warming is promoted by anthropogenic CO{sub 2} emissions into the atmosphere, while at the same time it is partially mitigated by carbon sequestration by terrestrial ecosystems. However, improvement in the understanding and monitoring of below ground carbon processes is essential for evaluating strategies for carbon sequestration including quantification of carbon stores for credits. A system for non-destructive in situ carbon monitoring in soil, based on inelastic neutron scattering (INS), is described. The system can be operated in stationary or scanning mode and measures soil to depth of approximately 30 cm. There is a good agreement between results obtained from INS and standard chemical analysis of soil cores collected from the same study site.

  9. Carbon fluxes resulting from land-use changes in the Tamaulipan thornscrub of northeastern Mexico

    PubMed Central

    Návar-Chaidez, Jose de Jesus

    2008-01-01

    Information on carbon stock and flux resulting from land-use changes in subtropical, semi-arid ecosystems are important to understand global carbon flux, yet little data is available. In the Tamaulipan thornscrub forests of northeastern Mexico, biomass components of standing vegetation were estimated from 56 quadrats (200 m2 each). Regional land-use changes and present forest cover, as well as estimates of soil organic carbon from chronosequences, were used to predict carbon stocks and fluxes in this ecosystem. For the period of 1980–1996, the Tamaulipan thornscrub is presenting an annual deforestation rate of 2.27% indicating that approximately 600 km2 of this plant community are lost every year and that 60% of the original Mexican Tamaulipan thornscrub vegetation has been lost since the 1950's. On the other hand, intensive agriculture, including introduced grasslands increased (4,000 km2) from 32 to 42% of the total studied area, largely at the expense of the Tamaulipan thornscrub forests. Land-use changes from Tamaulipan thornscrub forest to agriculture contribute 2.2 Tg to current annual carbon emissions and standing biomass averages 0.24 ± 0.06 Tg, root biomass averages 0.17 ± 0.03 Tg, and soil organic carbon averages 1.80 ± 0.27 Tg. Land-use changes from 1950 to 2000 accounted for Carbon emissions of the order of 180.1 Tg. Projected land-use changes will likely contribute to an additional carbon flux of 98.0 Tg by the year 2100. Practices to conserve sequester, and transfer carbon stocks in semi-arid ecosystems are discussed as a means to reduce carbon flux from deforestation practices. PMID:18826617

  10. Carbon fluxes resulting from land-use changes in the Tamaulipan thornscrub of northeastern Mexico.

    PubMed

    Návar-Chaidez, Jose de Jesus

    2008-09-30

    Information on carbon stock and flux resulting from land-use changes in subtropical, semi-arid ecosystems are important to understand global carbon flux, yet little data is available. In the Tamaulipan thornscrub forests of northeastern Mexico, biomass components of standing vegetation were estimated from 56 quadrats (200 m2 each). Regional land-use changes and present forest cover, as well as estimates of soil organic carbon from chronosequences, were used to predict carbon stocks and fluxes in this ecosystem.For the period of 1980-1996, the Tamaulipan thornscrub is presenting an annual deforestation rate of 2.27% indicating that approximately 600 km2 of this plant community are lost every year and that 60% of the original Mexican Tamaulipan thornscrub vegetation has been lost since the 1950's. On the other hand, intensive agriculture, including introduced grasslands increased (4,000 km2) from 32 to 42% of the total studied area, largely at the expense of the Tamaulipan thornscrub forests. Land-use changes from Tamaulipan thornscrub forest to agriculture contribute 2.2 Tg to current annual carbon emissions and standing biomass averages 0.24 +/- 0.06 Tg, root biomass averages 0.17 +/- 0.03 Tg, and soil organic carbon averages 1.80 +/- 0.27 Tg. Land-use changes from 1950 to 2000 accounted for Carbon emissions of the order of 180.1 Tg. Projected land-use changes will likely contribute to an additional carbon flux of 98.0 Tg by the year 2100. Practices to conserve sequester, and transfer carbon stocks in semi-arid ecosystems are discussed as a means to reduce carbon flux from deforestation practices.

  11. Targeting carbonic anhydrase to treat diabetic retinopathy: Emerging evidences and encouraging results

    SciTech Connect

    Weiwei, Zhang; Hu, Renming

    2009-12-18

    Diabetic retinopathy (DR) is the leading cause of vision loss among working-age populations in developed countries. Current treatment options are limited to tight glycemic, blood pressure control and destructive laser surgery. Carbonic anhydrases (CAs) are a group of enzymes involving in the rapid conversion of carbon dioxide to bicarbonate and protons. Emerging evidences reveal CA inhibitors hold the promise for the treatment of DR. This article summarizes encouraging results from clinical and animal studies, and reviews the possible mechanisms.

  12. Results of a 1000-hour wear test of 30-cm carbon-carbon ion optics

    NASA Technical Reports Server (NTRS)

    Snyder, John Steven; Brophy, John R.; Anderson, John R.

    2005-01-01

    This paper discusses the results of a 1000-hour wear test intended to determine the erosion resistance and voltage standoff capability of the optics in a relevant environment, i.e. duration testing on an NSTAR-like thruster.

  13. Evaluating Carbon Sequestration and Solar Forcing Feedbacks Resulting from North American Afforestation

    NASA Astrophysics Data System (ADS)

    Mykleby, P.; Snyder, P. K.; Twine, T. E.

    2013-12-01

    The planting of trees and forests has long been accepted as a practical and efficient method to sequester carbon dioxide from the atmosphere. Assertive measures are now needed to ensure that atmospheric levels of carbon dioxide (CO2) do not continue to rise and cause additional planetary warming. However, recent studies have detected inadvertent biophysical feedbacks associated with land cover changes, especially in higher northern latitudes. The changes in surface reflectivity that occur when converting a lighter, more reflective surface, such as a grassland or bare soil, into a darker conifer forest, can result in surface warming due to the forest absorbing more shortwave radiation. This warming counteracts the cooling effect resulting from a reduction in atmospheric CO2 with increased vegetation productivity. This effect is further intensified in the higher northern latitudes where snow cover is prevalent during the long winter; the planting of trees can significantly decrease the reflectivity compared with white snow. The goal of this study is to determine whether the amount of carbon sequestered exceeds the carbon equivalent of the radiative forcing due to the change in surface reflectivity. This study uses the IBIS dynamic vegetation model with modified carbon dynamics for conifer forests validated with numerous Ameriflux and Fluxnet Canada field sites with varying stand ages and species compositions. We present results of model performance based on validation of net ecosystem exchange (NEE) and net radiation observations. Results from this study will be used to assess not only the net effect of conifer forest establishment on the long term carbon storage, but also the duration of time that a given location would remain a carbon sink during the lifetime of the forest. Only then, can policymakers begin to discuss the efficacy of afforestation as a sound climate mitigation strategy.

  14. North American Carbon Balance: Results from the Regional Synthesis Project of the North America Carbon Program (Invited)

    NASA Astrophysics Data System (ADS)

    Post, M.; Huntzinger, D. N.; Davis, K. J.; Raczka, B. M.; Hayes, D. J.; Michalak, A. M.; Wei, Y.; Jacobson, A. R.; Cook, R. B.; Nacp Regional-Interim Synthesis Participants

    2010-12-01

    Past studies have documented continental scale carbon balances for North America but there are large differences among the results. Recent improvements in the amount and quality of available observation-based data, and application of comparative analyses among approach methods, may allow us to reduce disagreement and resolve sources of discrepancies among flux estimates. The North American Carbon Program (NACP) regional interim synthesis project has brought together a large number of spatial data sets, and terrestrial biogeochemistry model (TBM) and atmospheric inversion simulation results to construct a holistic assessment of North America carbon fluxes for the years 2000 to 2005. One of the goals of the interim synthesis project has been to investigate the magnitude and potential causes of the large differences in estimated component and net fluxes over regional scales. Although the results to date have not resolved the disparity in estimates of NA carbon fluxes, they have lead to insights into the ability of various types of data and analysis approaches to understand some of the flux discrepancies among the different estimation approaches. Regional TBM results were compared with inversion and inventory-based estimates, as well as modeled and observed flux estimates from eddy covariance sites. Net ecosystem exchange (NEE) estimates range from -2.9 to 0.68 PgC/yr (inversions) and -1.64 to 0.52 PgC/yr (TBMs) for temperate NA. In boreal NA, TBMs, on average, estimate slightly greater uptake than inversions (-0.12 PgC/yr versus -0.07 PgC/yr), but both methods have similar range in estimates. In Temperate NA, inversions, on average, estimate twice the uptake of TBMs (-0.96 PgC/yr versus -0.41 PgC/yr) and have a greater range in estimates. A comparison of NEE estimates for TBMs with both regional drivers and site-specific data indicates that a component for TBM uncertainty is the quality of reanalysis data used as weather forcing in the regional simulations

  15. 76 FR 63902 - Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-14

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Final Results of... preliminary results of the administrative review of the antidumping duty order on circular welded carbon steel... Welded Carbon Steel Pipes and Tubes From Taiwan, 76 FR 33210 (June 8, 2011) (Preliminary Results)....

  16. Influence of mesophase activation conditions on the specific capacitance of the resulting carbons

    NASA Astrophysics Data System (ADS)

    Mora, E.; Ruiz, V.; Santamaría, R.; Blanco, C.; Granda, M.; Menéndez, R.; Juarez-Galán, J. M.; Rodríguez-Reinoso, F.

    Mesophase pitch AR24 was directly activated with KOH using different proportions of the activating agent and activation temperatures, to study the effect on the textural characteristics of the resultant activated carbons and how these characteristics influence their behaviour as electrodes in supercapacitors. The textural properties of the activated carbons were studied by gas adsorption and immersion calorimetry. The results indicate that all the carbons produced were mainly microporous, with pore size around 1 nm. The behaviour of these carbons as electrodes in supercapacitors was studied from galvanostatic charge-discharge cycles. The specific capacitance values obtained were very high, reaching 400 and 200 F g -1 at low and high current densities respectively, for the sample activated with (5:1) KOH to mesophase ratio. Nevertheless, the reasons for this high capacitance values cannot be explained only on the basis of the textural characteristics of the activated carbons, as the results indicated that other factors might be also playing a significant role in their electrochemical behaviour.

  17. Monitoring changes in soil carbon resulting from intensive production, a non-traditional agricultural methodology.

    SciTech Connect

    Dwyer, Brian P.

    2013-03-01

    New Mexico State University and a group of New Mexico farmers are evaluating an innovative agricultural technique they call Intensive Production (IP). In contrast to conventional agricultural practice, IP uses intercropping, green fallowing, application of soil amendments and soil microbial inocula to sequester carbon as plant biomass, resulting in improved soil quality. Sandia National Laboratories role was to identify a non-invasive, cost effective technology to monitor soil carbon changes. A technological review indicated that Laser Induced Breakdown Spectroscopy (LIBS) best met the farmers objectives. Sandia partnered with Los Alamos National Laboratory (LANL) to analyze farmers test plots using a portable LIBS developed at LANL. Real-time LIBS field sample analysis was conducted and grab samples were collected for laboratory comparison. The field and laboratory results correlated well implying the strong potential for LIBS as an economical field scale analytical tool for analysis of elements such as carbon, nitrogen, and phosphate.

  18. Carbon Fixation Driven by Molecular Hydrogen Results in Chemolithoautotrophically Enhanced Growth of Helicobacter pylori

    PubMed Central

    Kuhns, Lisa G.; Benoit, Stéphane L.; Bayyareddy, Krishnareddy; Johnson, Darryl; Orlando, Ron; Evans, Alexandra L.; Waldrop, Grover L.

    2016-01-01

    ABSTRACT A molecular hydrogen (H2)-stimulated, chemolithoautotrophic growth mode for the gastric pathogen Helicobacter pylori is reported. In a culture medium containing peptides and amino acids, H2-supplied cells consistently achieved 40 to 60% greater growth yield in 16 h and accumulated 3-fold more carbon from [14C]bicarbonate (on a per cell basis) in a 10-h period than cells without H2. Global proteomic comparisons of cells supplied with different atmospheric conditions revealed that addition of H2 led to increased amounts of hydrogenase and the biotin carboxylase subunit of acetyl coenzyme A (acetyl-CoA) carboxylase (ACC), as well as other proteins involved in various cellular functions, including amino acid metabolism, heme synthesis, or protein degradation. In agreement with this result, H2-supplied cells contained 3-fold more ACC activity than cells without H2. Other possible carbon dioxide (CO2) fixation enzymes were not up-expressed under the H2-containing atmosphere. As the gastric mucus is limited in carbon and energy sources and the bacterium lacks mucinase, this new growth mode may contribute to the persistence of the pathogen in vivo. This is the first time that chemolithoautotrophic growth is described for a pathogen. IMPORTANCE Many pathogens must survive within host areas that are poorly supplied with carbon and energy sources, and the gastric pathogen Helicobacter pylori resides almost exclusively in the nutritionally stringent mucus barrier of its host. Although this bacterium is already known to be highly adaptable to gastric niches, a new aspect of its metabolic flexibility, whereby molecular hydrogen use (energy) is coupled to carbon dioxide fixation (carbon acquisition) via a described carbon fixation enzyme, is shown here. This growth mode, which supplements heterotrophy, is termed chemolithoautotrophy and has not been previously reported for a pathogen. PMID:26929299

  19. 76 FR 62039 - Certain Hot-Rolled Carbon Steel Flat Products From India: Final Results of 2009-2010 Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-06

    ... International Trade Administration Certain Hot-Rolled Carbon Steel Flat Products From India: Final Results of... certain hot-rolled carbon steel flat products from India (``hot-rolled steel'') manufactured by Ispat... Preliminary Results \\2\\ of this review. \\2\\ See Certain Hot-Rolled Carbon Steel Flat Products From...

  20. 75 FR 62366 - Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-08

    ... Welded Carbon Steel Pipes and Tubes From Taiwan: Final Results of Antidumping Duty Administrative Review... administrative review of the antidumping duty order on circular welded carbon steel pipes and tubes from Taiwan. See Preliminary Results of Antidumping Duty Administrative Review: Circular Welded Carbon Steel...

  1. 77 FR 46713 - Circular Welded Carbon Steel Pipes and Tubes From Turkey: Final Results of Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-06

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Turkey: Final Results of...) order on certain welded carbon steel standard pipe from Turkey for the January 1, 2010, through December... Results of Review'' section. \\1\\ See Certain Welded Carbon Steel Standard Pipe From Turkey:...

  2. 75 FR 64696 - Circular Welded Carbon Steel Pipes and Tubes From Thailand: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-20

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Thailand: Final Results of... preliminary results of administrative review of the antidumping duty order on circular ] welded carbon steel... the antidumping duty order on pipes and tubes from Thailand. See Circular Welded Carbon Steel...

  3. 75 FR 4529 - Circular Welded Carbon Steel Pipes and Tubes From Thailand: Final Results of Antidumping Duty New...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-28

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Thailand: Final Results of... circular welded carbon steel pipes and tubes (pipes and tubes) from Thailand. See Circular Welded Carbon Steel Pipes and Tubes from Thailand: Preliminary Results of Antidumping Duty New Shipper Review, 74...

  4. 77 FR 72818 - Circular Welded Carbon Steel Pipes and Tubes From Turkey; Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-06

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Turkey; Final Results of... circular welded carbon steel pipes and tubes from Turkey.\\1\\ This review covers four producers and... section entitled ``Final Results of Review.'' \\1\\ See Circular Welded Carbon Steel Pipes and Tubes...

  5. The effects of a variable temperature regime on the physiology of the reef-building coral Seriatopora hystrix: results from a laboratory-based reciprocal transplant.

    PubMed

    Mayfield, Anderson B; Chan, Pei-Hsun; Putnam, Hollie M; Chen, Chii-Shiarng; Fan, Tung-Yung

    2012-12-01

    To understand the effects of global climate change on reef-building corals, a thorough investigation of their physiological mechanisms of acclimatization is warranted. However, static temperature manipulations may underestimate the thermal complexity of the reefs in which many corals live. For instance, corals of Houbihu, Taiwan, experience changes in temperature of up to 10°C over the course of a day during spring-tide upwelling events. To better understand the phenotypic plasticity of these corals, a laboratory-based experiment was conducted whereby specimens of Seriatopora hystrix from an upwelling reef (Houbihu) and conspecifics from a non-upwelling reef (Houwan) were exposed to both a stable seawater temperature (26°C) regime and a regime characterized by a 6°C fluctuation (23-29°C) over a 12 h period for 7 days. A suite of physiological and molecular parameters was measured in samples of both treatments, as well as in experimental controls, to determine site of origin (SO) and temperature treatment (TT) responses. Only chlorophyll a (chl a) concentration and growth demonstrated the hypothesized trend of higher levels when exposed to a TT that mimicked SO conditions. In contrast, chl a, maximum dark-adapted quantum yield of photosystem II (F(v)/F(m)), and Symbiodinium ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL), photosystem I (psI, subunit III) and phosphoglycolate phosphatase (pgpase) mRNA expression demonstrated significant TT effects. Specifically, levels of these response variables were higher in samples exposed to a variable temperature regime, suggesting that S. hystrix may acclimate to fluctuating temperatures by increasing its capacity for photosynthesis.

  6. Carbon sequestration via reaction with basaltic rocks: geochemical modeling and experimental results

    USGS Publications Warehouse

    Rosenbauer, Robert J.; Thomas, Burt; Bischoff, James L.; Palandri, James

    2012-01-01

    Basaltic rocks are potential repositories for sequestering carbon dioxide (CO2) because of their capacity for trapping CO2 in carbonate minerals. We carried out a series of thermodynamic equilibrium models and high pressure experiments, reacting basalt with CO2-charged fluids over a range of conditions from 50 to 200 °C at 300 bar. Results indicate basalt has a high reactivity to CO2 acidified brine. Carbon dioxide is taken up from solution at all temperatures from 50 to 200 °C, 300 bar, but the maximum extent and rate of reaction occurs at 100 °C, 300 bar. Reaction path simulations utilizing the geochemical modeling program CHILLER predicted an equilibrium carbonate alteration assemblage of calcite, magnesite, and siderite, but the only secondary carbonate identified in the experiments was a ferroan magnesite. The amount of uptake at 100 °C, 300 bar ranged from 8% by weight for a typical tholeite to 26% for a picrite. The actual amount of CO2 uptake and extent of rock alteration coincides directly with the magnesium content of the rock suggesting that overall reaction extent is controlled by bulk basalt Mg content. In terms of sequestering CO2, an average basaltic MgO content of 8% is equivalent to 2.6 × 108 metric ton CO2/km3 basalt.

  7. Carbon sequestration via reaction with basaltic rocks: Geochemical modeling and experimental results

    NASA Astrophysics Data System (ADS)

    Rosenbauer, Robert J.; Thomas, Burt; Bischoff, James L.; Palandri, James

    2012-07-01

    Basaltic rocks are potential repositories for sequestering carbon dioxide (CO2) because of their capacity for trapping CO2 in carbonate minerals. We carried out a series of thermodynamic equilibrium models and high pressure experiments, reacting basalt with CO2-charged fluids over a range of conditions from 50 to 200 °C at 300 bar. Results indicate basalt has a high reactivity to CO2 acidified brine. Carbon dioxide is taken up from solution at all temperatures from 50 to 200 °C, 300 bar, but the maximum extent and rate of reaction occurs at 100 °C, 300 bar. Reaction path simulations utilizing the geochemical modeling program CHILLER predicted an equilibrium carbonate alteration assemblage of calcite, magnesite, and siderite, but the only secondary carbonate identified in the experiments was a ferroan magnesite. The amount of uptake at 100 °C, 300 bar ranged from 8% by weight for a typical tholeite to 26% for a picrite. The actual amount of CO2 uptake and extent of rock alteration coincides directly with the magnesium content of the rock suggesting that overall reaction extent is controlled by bulk basalt Mg content. In terms of sequestering CO2, an average basaltic MgO content of 8% is equivalent to 2.6 × 108 metric ton CO2/km3 basalt.

  8. Organic and elemental carbon filter sets: preparation method and interlaboratory results.

    PubMed

    Chai, Ming; Birch, M Eileen; Deye, Greg

    2012-10-01

    Carbonaceous aerosols play an important role in climate, visibility, air quality, and human health effects, and they have been routinely monitored in workplace and environmental settings. Different thermal analysis methods have been applied to determine the carbon content of carbonaceous aerosols. Good agreement between results for total carbon (TC) generally has been found, but the organic and elemental carbon (OC and EC) fractions determined by different methods often disagree. Measurement uncertainty is mainly due to pyrolysis and charring of OC sample components. Lack of reference materials has impeded progress on method standardization and understanding method biases. A relatively simple method for generating matched filter sets having known OC-EC contents is reported. After generation and analysis of each set to confirm agreement between filters, the filter sets were distributed to six laboratories for an interlaboratory comparison. Analytical results indicate a uniform carbon distribution for the filter sets and good agreement between the participating laboratories. Relative standard deviations (RSDs) for mean TC (OC + EC), OC, and EC results for seven laboratories were <10, 11, and 12% (respectively). Except for one EC result (RSD = 16%), RSDs reported by individual laboratories for TC, OC, and EC were <12%. The method of filter generation is generally applicable and reproducible. Depending on the application, different filter loadings and types of OC materials can be employed. Matched filter sets prepared by the described approach can be used for determining the accuracy of OC-EC methods and thereby contribute to method standardization.

  9. Tree-fall gaps and carbon cycling in the Brazilian Amazon: results from two large forest plots

    NASA Astrophysics Data System (ADS)

    Espirito-Santo, F.; Keller, M.; Linder, E.; De Oliveira, R., Jr.; Pereira, C.; Oliveira, C. G.

    2013-12-01

    The dynamics of gaps play a role in the regimes of tree mortality and production of coarse woody debris (CWD) in forests. Few studies have attempted to map the distribution of gaps in tropical forest and the production of CWD, a large pool of ecosystem carbon. Here we linked gap formation with carbon cycling through analysis of the CWD inside of gaps. We surveyed two large forest inventory plots of 114 and 53 ha of the Tapajós National Forest (TNF) in the Brazilian Amazon during 2008 and 2009, respectively. We mapped all gaps and collected data on light availability, CWD stocks and tree mortality in the field. Gap location, canopy opening (CO) and leaf area index (LAI) estimated in the field were compared with two IKONOS-2 high-resolution satellite images acquired approximately at the time of the field measurements. We provide the first statistics of CWD production based on gap size in the tropical forest literature. In the two large plots (167 ha total area) we found 96 gaps. The gaps represented 1.42% of the total area and gaps < 1 year old accounted for 0.81% of the plot area. In TNF, the production of CWD in recent gaps was 0.76 Mg C ha-1 year-1 and the mean tree mortality was 2.38 stems ha-1 year 1. The area of gaps estimated by using thresholds of light intensity measured by remote sensing optical instruments was twice as large as the gap areas measured on the ground. We found no significant correlation between spectral remote sensing images and CO and LAI, likely because the high faction of shadow in high-resolution satellite images. We conclude that less than 30% of the annual tree mortality and CWD flux was associated with gaps and the detection of gaps with high resolution optical remote sensing remains a challenge because of the high proportion of shadow in the those images. These results highlight the need for permanent plots for long-term carbon studies.

  10. 76 FR 27987 - Circular Welded Carbon Steel Pipes and Tubes From Thailand: Amended Final Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-13

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Thailand: Amended Final... on circular welded carbon steel pipes and tubes from Thailand, which covered Saha Thai Steel Pipe... Welded Carbon Steel Pipes and Tubes from Thailand: Final Results of Antidumping Duty...

  11. 76 FR 42679 - Certain Hot-Rolled Carbon Steel Flat Products From India: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-19

    ... International Trade Administration Certain Hot-Rolled Carbon Steel Flat Products From India: Final Results of... certain hot- rolled carbon steel flat products from India manufactured by Essar Steel Limited (``Essar...\\ of this review. \\2\\ See Certain Hot-Rolled Carbon Steel Flat Products From India: Notice...

  12. 75 FR 43488 - Certain Hot-Rolled Carbon Steel Flat Products From India: Final Results of Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-26

    ... International Trade Administration Certain Hot-Rolled Carbon Steel Flat Products From India: Final Results of... duty (CVD) order on certain hot-rolled carbon steel flat products (hot-rolled carbon steel) from India for the period of review (POR) January 1, 2008, through December 31, 2008. See Certain...

  13. 75 FR 64254 - Certain Hot-Rolled Flat-Rolled Carbon Quality Steel Products From Brazil; Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-19

    ... International Trade Administration Certain Hot-Rolled Flat-Rolled Carbon Quality Steel Products From Brazil... order on certain hot-rolled, flat-rolled carbon quality steel products (hot-rolled steel) from Brazil. See Certain Hot- Rolled Flat-Rolled Carbon Quality Steel Products From Brazil: Preliminary Results...

  14. 78 FR 25701 - Certain Hot-Rolled Carbon Steel Flat Products From India: Notice of Second Amended Final Results...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-02

    ... International Trade Administration Certain Hot-Rolled Carbon Steel Flat Products From India: Notice of Second...) administrative review of certain hot-rolled carbon steel flat products from India for the 2007 review period (the..., 2013 (January 2013 remand results). \\2\\ See Certain Hot-Rolled Carbon Steel Flat Products from...

  15. 78 FR 16247 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea; Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-14

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea... antidumping duty order on corrosion-resistant carbon steel flat products (CORE) from the Republic of Korea... section entitled ``Final Results of Review.'' \\1\\ See Certain Corrosion-Resistant Carbon Steel...

  16. 75 FR 69626 - Certain Welded Carbon Steel Standard Pipes and Tubes From India: Final Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-15

    ... Welded Carbon Steel Standard Pipes and Tubes From India: Final Results of Antidumping Duty Administrative... review of the antidumping duty order on certain welded carbon steel standard pipes and tubes from India... duty order on certain welded carbon steel standard pipes and tubes from India. See Certain...

  17. 78 FR 65272 - Circular Welded Carbon Steel Pipes and Tubes From Thailand: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-31

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Thailand: Final Results of... antidumping duty order on circular welded carbon steel pipes and tubes from Thailand. This review covers two... carbon steel pipes and tubes from Thailand.\\1\\ We invited interested parties to comment on...

  18. 76 FR 64900 - Welded Carbon Steel Pipe and Tube From Turkey: Final Results of Expedited Sunset Review of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-19

    ... International Trade Administration Welded Carbon Steel Pipe and Tube From Turkey: Final Results of Expedited...) initiated a sunset review of the countervailing duty order (CVD) on welded carbon steel pipe and tube from... CVD order on welded carbon steel pipe and tube from Turkey was published in the Federal Register...

  19. 78 FR 71563 - Certain Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Final Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-29

    ... International Trade Administration Certain Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Final... administrative review of the antidumping duty order on certain circular welded carbon steel pipes and tubes from... Carbon Steel Pipes and Tubes From Taiwan: Preliminary Results of Antidumping Duty Administrative...

  20. Assessing Error in Modelled Ocean Carbon Uptake Resulting From Uncertainty in Biogeochemical Parameters

    NASA Astrophysics Data System (ADS)

    Scott, V.; Kettle, H.; Merchant, C. J.; Hankin, R. K.

    2008-12-01

    Estimates of the air-sea CO2 flux produced by ocean biogeochemical models are uncertain due to poorly constrained model parameters. Here, we present the results of an analysis into the biochemical parameters that influence air-sea CO2 flux, and the error that results from uncertainties in these parameters in GCMs. A sensitivity analysis is performed on the Hadley centre Ocean Carbon Cycle (HadOCC) NPZD biogeochemical model used in the HadCM3 GCM. This uses a 1D test bed with forcing from different locations and identifies the parameters that control phytoplankton growth, formation of calcite and the sinking of organic matter to have greatest effect on the calculated air-sea CO2 flux. These parameters are tuned to data at sites with very different biochemical cycles and are then used to explore the resulting error in global ocean carbon fluxes within GCMs.

  1. Physiological changes of the lichen Parmotrema tinctorum as result of carbon nanotubes exposition.

    PubMed

    Viana, Camila de O; Vaz, Raissa P; Cano, Abraham; Santos, Adelina P; Cançado, Luiz G; Ladeira, Luiz O; Junior, Ary Corrêa

    2015-10-01

    Carbon nanotubes (CNT) is one of the more abundant nanomaterial produced in the world. Therefore, it is desirable to access its effects in all environment compartments, in order to mitigate environmental distress. This study aims to verify the potential use of lichens - classical atmospheric pollution indicators - as biomonitors of carbon nanotubes aerosols. To examine cause-effect relationships, preserving environmental microclimatic parameters, the lichen Parmotrema tinctorum (Nyl.) Hale was transplanted to open top chambers where aerosols of CNT were daily added. Physiological parameters such as cell viability, photosynthetic efficiency, cell permeability as well as nanoparticle internalization were assessed. Carbon nanotubes exposure led to reduction on the cell viability of P. tinctorum. The treatment with 100µg/mL of MWCNT-COOH resulted in intracellular ion leakage, probably due to changes in membrane permeability. No alterations on photosynthetic efficiency were detected. Carbon nanotubes entrapment and internalization into the lichen thallus were observed. Short term exposition of CNT produced measurable physiological changes in P. tinctorum lichen. This suggests the possibility of use of lichens as models to assess the environmental impact (air related) of engineered nanomaterials.

  2. Redox freezing and melting in the Earth's deep mantle resulting from carbon-iron redox coupling.

    PubMed

    Rohrbach, Arno; Schmidt, Max W

    2011-04-14

    Very low seismic velocity anomalies in the Earth's mantle may reflect small amounts of melt present in the peridotite matrix, and the onset of melting in the Earth's upper mantle is likely to be triggered by the presence of small amounts of carbonate. Such carbonates stem from subducted oceanic lithosphere in part buried to depths below the 660-kilometre discontinuity and remixed into the mantle. Here we demonstrate that carbonate-induced melting may occur in deeply subducted lithosphere at near-adiabatic temperatures in the Earth's transition zone and lower mantle. We show experimentally that these carbonatite melts are unstable when infiltrating ambient mantle and are reduced to immobile diamond when recycled at depths greater than ∼250 kilometres, where mantle redox conditions are determined by the presence of an (Fe,Ni) metal phase. This 'redox freezing' process leads to diamond-enriched mantle domains in which the Fe(0), resulting from Fe(2+) disproportionation in perovskites and garnet, is consumed but the Fe(3+) preserved. When such carbon-enriched mantle heterogeneities become part of the upwelling mantle, diamond will inevitably react with the Fe(3+) leading to true carbonatite redox melting at ∼660 and ∼250 kilometres depth to form deep-seated melts in the Earth's mantle.

  3. Detecting spatial regimes in ecosystems

    EPA Science Inventory

    Research on early warning indicators has generally focused on assessing temporal transitions with limited application of these methods to detecting spatial regimes. Traditional spatial boundary detection procedures that result in ecoregion maps are typically based on ecological ...

  4. Carbon fiber composites inspection and defect characterization using active infrared thermography: numerical simulations and experimental results.

    PubMed

    Fernandes, Henrique; Zhang, Hai; Figueiredo, Alisson; Ibarra-Castanedo, Clemente; Guimarares, Gilmar; Maldague, Xavier

    2016-12-01

    Composite materials are widely used in the aeronautic industry. One of the reasons is because they have strength and stiffness comparable to metals, with the added advantage of significant weight reduction. Infrared thermography (IT) is a safe nondestructive testing technique that has a fast inspection rate. In active IT, an external heat source is used to stimulate the material being inspected in order to generate a thermal contrast between the feature of interest and the background. In this paper, carbon-fiber-reinforced polymers are inspected using IT. More specifically, carbon/PEEK (polyether ether ketone) laminates with square Kapton inserts of different sizes and at different depths are tested with three different IT techniques: pulsed thermography, vibrothermography, and line scan thermography. The finite element method is used to simulate the pulsed thermography experiment. Numerical results displayed a very good agreement with experimental results.

  5. Airborne Carbon Dioxide Laser Absorption Spectrometer for IPDA Measurements of Tropospheric CO2: Recent Results

    NASA Technical Reports Server (NTRS)

    Spiers, Gary D.; Menzies, Robert T.

    2008-01-01

    The National Research Council's decadal survey on Earth Science and Applications from Space[1] recommended the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission for launch in 2013-2016 as a logical follow-on to the Orbiting Carbon Observatory (OCO) which is scheduled for launch in late 2008 [2]. The use of a laser absorption measurement technique provides the required ability to make day and night measurements of CO2 over all latitudes and seasons. As a demonstrator for an approach to meeting the instrument needs for the ASCENDS mission we have developed the airborne Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) which uses the Integrated Path Differential Absorption (IPDA) Spectrometer [3] technique operating in the 2 micron wavelength region.. During 2006 a short engineering checkout flight of the CO2LAS was conducted and the results presented previously [4]. Several short flight campaigns were conducted during 2007 and we report results from these campaigns.

  6. Basal insulin regime change from Lantus to Toujeo resulted in fewer hypoglycaemic episodes in a 28-year-old man with diabetes mellitus.

    PubMed

    Shields, Alexandra; Sankaranarayanan, Sailesh

    2016-06-15

    An active 28-year-old man with type 1 diabetes mellitus reported a reduced number of hypoglycaemic episodes following change in basal regime insulin glargine from U100 Lantus to U300 Toujeo. Consequently, an improved quality of life was also reported. Flash-based glucose monitoring was utilised to record 24-hour continuous glucose levels throughout two comparable 60-day periods before and after the change in regimen. Low blood glucose was most likely between 03:00 and 08:00. Nocturnal hypoglycaemic episodes (≤3.9 mmol/L) reduced by an average of 2.5 episodes per week. Severe hypoglycaemic episodes (≤2.9 mmol/L) reduced to an average of 0.4 per week, down from 1.5 per week. Nocturnal hypoglycaemic episodes reduced in frequency and severity. Furthermore, nocturnal hypoglycaemia episodes occurred in a more predictable time window. This was especially important in the reported reduction of impact on the patient's quality of life, as the episodes tended to be associated with anxiety and low mood. Patient education needed to facilitate this change was minimal, and benefits to the patient were great, including decreased sleep disturbances and reduced risk of associated anxiety symptoms.

  7. Purification and sidewall functionalization of multiwalled carbon nanotubes and resulting bioactivity in two macrophage models

    PubMed Central

    Hamilton, Raymond F.; Xiang, Chengcheng; Li, Ming; Ka, Ibrahima; Yang, Feng; Ma, Dongling; Porter, Dale W.; Wu, Nianqiang; Holian, Andrij

    2014-01-01

    This study examined the consequences of surface carboxylation of multiwalled carbon nanotubes (MWCNT) on bioactivity. Since commercial raw MWCNT contain impurities that may affect their bioactivity, HCl refluxing was exploited to purify raw “as-received” MWCNT by removing the amorphous carbon layer on the MWCNT surface and reducing the metal impurities (e.g. Ni). The removal of amorphous carbon layer was confirmed by Raman spectroscopy and thermogravimetric analysis. Furthermore, the HCl-purified MWCNT provided more available reaction sites, leading to enhanced sidewall functionalization. The sidewall of HCl-purified MWCNT was further functionalized with the −COOH moiety by HNO3 oxidation. This process resulted in four distinct MWCNT: raw, purified, −COOH-terminated raw MWCNT, and −COOH-terminated purified MWCNT. Freshly isolated alveolar macrophages from C57Bl/6 mice were exposed to these nanomaterials to determine the effects of the surface chemistry on the bioactivity in terms of cell viability and inflammasome activation. Inflammasome activation was confirmed using inhibitors of cathepsin B and Caspase-1. Purification reduced the cell toxicity and inflammasome activation slightly compared to raw MWCNT. In contrast, functionalization of MWCNT with the −COOH group dramatically reduced the cytotoxicity and inflammasome activation. Similar results were seen using THP-1 cells supporting their potential use for high-throughput screening. This study demonstrated that the toxicity and bioactivity of MWCNT were diminished by removal of the Ni contamination and/or addition of −COOH groups to the sidewalls. PMID:23480196

  8. Scattering of sulfur ions by carbon: Classical-trajectory Monte Carlo results

    SciTech Connect

    Slabkowska, Katarzyna; Polasik, Marek; Janowicz, Maciej

    2003-01-01

    We analyze classically the scattering of sulfur ions by carbon using the classical-trajectory Monte Carlo method. It is assumed that the scatterer and scattered nuclei are coupled to each other as well as to all electrons, but there is no coupling between electrons themselves. To initialize the state of both atoms, quasiexact energies are used that are obtained from the Dirac-Fock method. Effective charges are used to partially take into account the intra-atomic interactions between electrons. We concentrate on the cross sections for production of vacancies in the K and L shells and capture of electrons to K, L, and M shells of the sulfur ions. The dependence of these cross sections on the energy of the projectile sulfur ions and on the initial charge states of these ions is analyzed. Our results will be helpful in the interpretation of x-ray spectra from highly ionized fast sulfur projectiles passing through a carbon foil.

  9. Organic breakdown products resulting from hydrothermal carbonization of brewer's spent grain.

    PubMed

    Poerschmann, J; Weiner, B; Koehler, R; Kopinke, F-D

    2015-07-01

    Hydrothermal carbonization of brewer's spent grain resulted in a solid hydrochar and an aqueous phase rich in macromolecular dissolved organic matter. Both phases were analyzed with regard to low molecular weight organic compounds (MW<500 Da) in lyophilized form by exhaustive solvent extraction followed by pre-chromatographic derivatization and GC/MS-analysis. Low molecular weight acids, O-functionalized phenols, cyclopentenone derivatives, and benzenediols accounted for the majority of organic analytes in both hydrothermal carbonization product streams while being absent in solvent extracts of the pristine biomass. The pattern of short chain functionalized acids in the pristine biomass and in the hydrothermally produced matrices turned out very different. Acylglycerines as the most abundant lipids in pristine brewer's spent grain were quantitatively hydrolyzed under hydrothermal conditions. The recovery of total fatty acids present in the pristine biomass amounted to 19%. The major fraction of hydrophobic breakdown products including fatty acids, fatty alcohols, and sterols was sorbed onto the hydrochar.

  10. 75 FR 32911 - Preliminary Results of Antidumping Duty Administrative Review: Circular Welded Carbon Steel Pipes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-10

    ... Welded Carbon Steel Pipes and Tubes From Taiwan AGENCY: Import Administration, International Trade... administrative review of the antidumping duty order on circular welded carbon steel pipes and tubes from Taiwan... circular welded carbon steel pipes and tubes from Taiwan. See Certain Circular Welded Carbon Steel...

  11. 76 FR 33210 - Preliminary Results of Antidumping Duty Administrative Review: Circular Welded Carbon Steel Pipes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-08

    ... Welded Carbon Steel Pipes and Tubes From Taiwan AGENCY: Import Administration, International Trade... administrative review of the antidumping duty order on circular welded carbon steel pipes and tubes from Taiwan... circular welded carbon steel pipes and tubes from Taiwan. See Certain Circular Welded Carbon Steel...

  12. Ecosystem Model Performance at Wetlands: Results from the North American Carbon Program Site Synthesis

    NASA Astrophysics Data System (ADS)

    Sulman, B. N.; Desai, A. R.; Schroeder, N. M.; NACP Site Synthesis Participants

    2011-12-01

    Northern peatlands contain a significant fraction of the global carbon pool, and their responses to hydrological change are likely to be important factors in future carbon cycle-climate feedbacks. Global-scale carbon cycle modeling studies typically use general ecosystem models with coarse spatial resolution, often without peatland-specific processes. Here, seven ecosystem models were used to simulate CO2 fluxes at three field sites in Canada and the northern United States, including two nutrient-rich fens and one nutrient-poor, sphagnum-dominated bog, from 2002-2006. Flux residuals (simulated - observed) were positively correlated with measured water table for both gross ecosystem productivity (GEP) and ecosystem respiration (ER) at the two fen sites for all models, and were positively correlated with water table at the bog site for the majority of models. Modeled diurnal cycles at fen sites agreed well with eddy covariance measurements overall. Eddy covariance GEP and ER were higher during dry periods than during wet periods, while model results predicted either the opposite relationship or no significant difference. At the bog site, eddy covariance GEP had no significant dependence on water table, while models predicted higher GEP during wet periods. All models significantly over-estimated GEP at the bog site, and all but one over-estimated ER at the bog site. Carbon cycle models in peatland-rich regions could be improved by incorporating better models or measurements of hydrology and by inhibiting GEP and ER rates under saturated conditions. Bogs and fens likely require distinct treatments in ecosystem models due to differences in nutrients, peat properties, and plant communities.

  13. 78 FR 28190 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-14

    ... International Trade Administration Carbon and Certain Alloy Steel Wire Rod From Mexico: Final Results of... carbon and certain alloy steel wire rod (wire rod) from Mexico. The period of review (POR) is October 1... Federal Register the Preliminary Results of the antidumping duty administrative review of wire rod...

  14. 77 FR 73616 - Certain Cut-to-Length Carbon Steel Plate From the People's Republic of China: Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-11

    ... the review are as follows: Bao/Baoshan International Trade Corp./Bao Steel Metals Trading Corp... Cut-to-Length Carbon Steel Plate From the People's Republic of China: Final Results of Antidumping... preliminary results of the administrative review (``AR'') of certain cut-to-length carbon steel plate...

  15. 77 FR 61738 - Circular Welded Carbon Steel Pipes and Tubes From Thailand: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-11

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Thailand: Final Results of... preliminary results of administrative review of the antidumping duty order on circular welded carbon steel... (Pacific Pipe) and Saha Thai Steel Pipe (Public) Company, Ltd. (Saha Thai). Based on our analysis of...

  16. 78 FR 79665 - Welded Carbon Steel Standard Pipe and Tube Products From Turkey: Final Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-31

    ... Carbon Steel Standard Pipe and Tube Products From Turkey: Final Results of Antidumping Duty... order on welded carbon steel standard pipe and tube products (welded pipe and tube) from Turkey.\\1\\ The... Tube Products from Turkey: Preliminary Results of Antidumping Duty Administrative Review; 2011-2012,...

  17. Advancements for Active Remote Sensing of Carbon Dioxide from Space using the ASCENDS CarbonHawk Experiment Simulator: First Results

    NASA Astrophysics Data System (ADS)

    Obland, M. D.; Nehrir, A. R.; Lin, B.; Harrison, F. W.; Kooi, S. A.; Choi, Y.; Plant, J.; Yang, M. M.; Antill, C.; Campbell, J. F.; Ismail, S.; Browell, E. V.; Meadows, B.; Dobler, J. T.; Zaccheo, T. S.; Moore, B., III; Crowell, S.

    2014-12-01

    The ASCENDS CarbonHawk Experiment Simulator (ACES) is an Intensity-Modulated Continuous-Wave lidar system recently developed at NASA Langley Research Center that seeks to advance technologies and techniques critical to measuring atmospheric column carbon dioxide (CO2) mixing ratios in support of the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. These advancements include: (1) increasing the power-aperture product to approach ASCENDS mission requirements by implementing multi-aperture telescopes and multiple co-aligned laser transmitters; (2) incorporating high-efficiency, high-power Erbium-Doped Fiber Amplifiers (EDFAs); (3) developing and incorporating a high-bandwidth, low-noise HgCdTe detector and transimpedence amplifier (TIA) subsystem capable of long-duration operation on Global Hawk aircraft, and (4) advancing algorithms for cloud and aerosol discrimination. The ACES instrument architecture is being developed for operation on high-altitude aircraft and will be directly scalable to meet the ASCENDS mission requirements. ACES simultaneously transmits five laser beams: three from commercial EDFAs operating near 1571 nm, and two from the Exelis oxygen (O2) Raman fiber laser amplifier system operating near 1260 nm. The Integrated-Path Differential Absorption (IPDA) lidar approach is used at both wavelengths to independently measure the CO2 and O2 column number densities and retrieve the average column CO2 mixing ratio. The outgoing laser beams are aligned to the field of view of ACES' three fiber-coupled 17.8-cm diameter athermal telescopes. The backscattered light collected by the three telescopes is sent to the detector/TIA subsystem, which has a bandwidth of 4.7 MHz and operates service-free using a tactical dewar and cryocooler. Two key laser modulation approaches are being tested to significantly mitigate the effects of thin clouds on the retrieved CO2 column amounts. Full instrument development concluded in the

  18. Preliminary results of carbon cycling in southwestern ecosystems: Implications for climate change

    SciTech Connect

    Klopatek, C.C. |; Murphy, K.L.; Klopatek, J.M.

    1995-12-31

    By determining the C pool sizes, cycling and relative sequestering rates, the authors intend to estimate the effects of a vegetation change caused by a temperature increase and available moisture decrease. A predominant source of C for the soil compartment is the plant litter and its subsequent decomposition. The resulting effect of temperature and moisture on decomposition will vary according to the biome and litter quality of that biome. Litter quality, referring to the carbon and other nutrient fractions, strongly influences the potential rate of decomposition. The preliminary findings indicate that litter quality and moisture, not temperature, are the major controlling variables in decomposition.

  19. Carbon dioxide removal system for closed loop atmosphere revitalization, candidate sorbents screening and test results

    NASA Astrophysics Data System (ADS)

    Mattox, E. M.; Knox, J. C.; Bardot, D. M.

    2013-05-01

    Due to the difficulty and expense it costs to resupply manned-spacecraft habitats, a goal is to create a closed loop atmosphere revitalization system, in which precious commodities such as oxygen, carbon dioxide, and water are continuously recycled. Our aim is to test other sorbents for their capacity for future spacecraft missions, such as on the Orion spacecraft, or possibly lunar or Mars mission habitats to see if they would be better than the zeolite sorbents on the 4-bed molecular sieve. Some of the materials being tested are currently used for other industry applications. Studying these sorbents for their specific spacecraft application is different from that for applications on earth because in space, there are certain power, mass, and volume limitations that are not as critical on Earth. In manned-spaceflight missions, the sorbents are exposed to a much lower volume fraction of CO2 (0.6% volume CO2) than on Earth. LiLSX was tested for its CO2 capacity in an atmosphere like that of the ISS. Breakthrough tests were run to establish the capacities of these materials at a partial pressure of CO2 that is seen on the ISS. This paper discusses experimental results from benchmark materials, such as results previously obtained from tests on Grade 522, and the forementioned candidate materials for the Carbon Dioxide Removal Assembly (CDRA) system.

  20. Multi-century Changes to Global Climate and Carbon Cycle: Results from a Coupled Climate and Carbon Cycle Model

    SciTech Connect

    Bala, G; Caldeira, K; Mirin, A; Wickett, M; Delire, C

    2005-02-17

    In this paper, we use a coupled climate and carbon cycle model to investigate the global climate and carbon cycle changes out to year 2300 that would occur if CO{sub 2} emissions from all the currently estimated fossil fuel resources were released to the atmosphere. By year 2300, the global climate warms by about 8 K and atmospheric CO{sub 2} reaches 1423 ppmv. The warming is higher than anticipated because the sensitivity to radiative forcing increases as the simulation progresses. In our simulation, the rate of emissions peak at over 30 PgC yr{sup -1} early in the 22nd century. Even at year 2300, nearly 50% of cumulative emissions remain in the atmosphere. In our simulations both soils and living biomass are net carbon sinks throughout the simulation. Despite having relatively low climate sensitivity and strong carbon uptake by the land biosphere, our model projections suggest severe long-term consequences for global climate if all the fossil-fuel carbon is ultimately released to the atmosphere.

  1. 77 FR 20782 - Circular Welded Carbon Steel Pipes and Tubes From Thailand: Preliminary Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-06

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Thailand: Preliminary... administrative review of the antidumping duty order on circular welded carbon steel pipes and tubes from Thailand... circular welded carbon steel pipes and tubes have been made below normal value (NV) during the March...

  2. 78 FR 26748 - Certain Activated Carbon From the People's Republic of China: Preliminary Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-08

    ... International Trade Administration Certain Activated Carbon From the People's Republic of China: Preliminary... duty order on certain activated carbon from the People's Republic of China (``PRC'') for the period of... The merchandise subject to the order is certain activated carbon.\\1\\ The products are...

  3. 77 FR 66954 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Preliminary Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-08

    ... International Trade Administration Carbon and Certain Alloy Steel Wire Rod From Mexico: Preliminary Results of... on carbon and certain alloy steel wire rod (wire rod) from Mexico. The period of review is October 1... certain alloy steel wire rod. The product is currently classified under the Harmonized Tariff Schedule...

  4. 77 FR 69790 - Certain Hot-Rolled Carbon Steel Flat Products From the People's Republic of China: Final Results...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-21

    ... International Trade Administration Certain Hot-Rolled Carbon Steel Flat Products From the People's Republic of... Results of the 2010-2011 administrative review of the antidumping duty order on certain hot- rolled carbon steel flat products (``hot-rolled steel'') from the People's Republic of China (``PRC''). The period...

  5. 78 FR 19210 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-29

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea...) has completed its administrative review of the countervailing duty (CVD) order on corrosion-resistant...\\ See Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Preliminary Results...

  6. 78 FR 64916 - Circular Welded Carbon Steel Pipes and Tubes From Turkey: Final Results of Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-30

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Turkey: Final Results of... administrative review of the countervailing duty (CVD) order on circular welded carbon steel pipes and tubes (steel pipes and tubes) from Turkey for the January 1, 2011, through December 31, 2011, period of...

  7. 78 FR 286 - Circular Welded Carbon Steel Pipes and Tubes From Turkey; Amended Final Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-03

    ... Welded Carbon Steel Pipes and Tubes From Turkey; Amended Final Results of Antidumping Duty Administrative... and tubes from Turkey for the period of review (POR) May 1, 2010, through April 30, 2011.\\1\\ We are..., as amended (the Act). \\1\\ See Circular Welded Carbon Steel Pipes and Tubes from Turkey; Final...

  8. Granular Activated Carbon Treatment May Result in Higher Predicted Genotoxicity in the Presence of Bromide.

    PubMed

    Krasner, Stuart W; Lee, Tiffany Chih Fen; Westerhoff, Paul; Fischer, Natalia; Hanigan, David; Karanfil, Tanju; Beita-Sandí, Wilson; Taylor-Edmonds, Liz; Andrews, Robert C

    2016-09-06

    Certain unregulated disinfection byproducts (DBPs) are more of a health concern than regulated DBPs. Brominated species are typically more cytotoxic and genotoxic than their chlorinated analogs. The impact of granular activated carbon (GAC) on controlling the formation of regulated and selected unregulated DBPs following chlorine disinfection was evaluated. The predicted cyto- and genotoxicity of DBPs was calculated using published potencies based on the comet assay for Chinese hamster ovary cells (assesses the level of DNA strand breaks). Additionally, genotoxicity was measured using the SOS-Chromotest (detects DNA-damaging agents). The class sum concentrations of trihalomethanes, haloacetic acids, and unregulated DBPs, and the SOS genotoxicity followed the breakthrough of dissolved organic carbon (DOC), however the formation of brominated species did not. The bromide/DOC ratio was higher than the influent through much of the breakthrough curve (GAC does not remove bromide), which resulted in elevated brominated DBP concentrations in the effluent. Based on the potency of the haloacetonitriles and halonitromethanes, these nitrogen-containing DBPs were the driving agents of the predicted genotoxicity. GAC treatment of drinking or reclaimed waters with appreciable levels of bromide and dissolved organic nitrogen may not control the formation of unregulated DBPs with higher genotoxicity potencies.

  9. [Tribological properties of carbon fiber-reinforced plastic. Experimental and clinical results].

    PubMed

    Früh, H J; Ascherl, R; Hipp, E

    1997-02-01

    Wear of the articulating components (especially PE-UHMW) of total hip endoprostheses is the most important technical factor limiting the functional lifetime. To minimize wear debris, ceramic heads, according to ISO 6474 (Al2O3), have been used, from 1969 paired with Al2O3 and since 1975 paired with PE-UHMW. Al2O3 balls articulating with cups made from CFRP have been in clinical use since 1988. Laboratory experiments and in-vivo testing showed minimized wear debris and mild biological response to wear products using CFRP (carbon fiber reinforced plastic) instead of PE-UHMW as the cup material. The articulating surfaces of retrieved ceramic heads (Al2O3-Biolox) and cementless CFRP cups (carbon fiber reinforced plastic, Caproman) were compared using sphericity measurement techniques, scanning electron microscopy (SEM) and roughness measurements (including advanced roughness parameters Rvk or Rpk according to ISO 4287). Altogether, the first results of the clinical study showed that the combination Al2O3-ball/CFRP-cup came up to the expected lower wear rates compared with the conventional combinations. The wear rates are comparable with the combination Al2O3/Al2O3 without the material-related problems of ceramic components in all ceramic combinations.

  10. Results and Discussion on Physical Property Calculation from Pore Microstructures of Carbonate Rocks

    NASA Astrophysics Data System (ADS)

    Lee, M.; Keehm, Y.

    2014-12-01

    In this paper, we report results and discussion on the physical properties estimation of carbonate rocks using pore microstructures. We obtained high-resolution 3D microstructures with different porosity-types (inter-particle, vuggy/moldic, and fracture) from the X-ray microtomography technique. We calculated permeability, electrical conductivity, and P-wave velocity using the Lattice-Boltzmann method and finite element methods. We also applied the pore-scale simulation techniques to different sub-blocks from the original 3D pore geometry (2,0003 voxels) to determine the heterogeneity of pore geometry. For the inter-particle porosity-type, the calculated transport properties (permeability and electrical conductivity) show very similar trends to clastic sediments. These relations can be modeled by common empirical relations such as Kozeny-Carman relation for porosity-permeability or Archie's equation for porosity-formation factor. For the vuggy or fracture porosity-type, it is difficult to determine any consistent relations; therefore we tried to build conceptual models with cracks or vugs to establish quantitative relations. On the other hand, P-wave velocity showed very little dependence on the porosity-types, due to high frame stiffness of carbonate rocks. Acknowledgements: This research was supported by the Basic Research Project of the Korea Institute of Geoscience and Mineral Resources (KIGAM) funded by the Ministry of Trade, Industry and Energy of Korea (GP2012-029).

  11. Radiative Forcing associated with Particulate Carbon Emissions resulting from the Use of Mercury Control Technology

    NASA Astrophysics Data System (ADS)

    Clack, H.; Penner, J. E.; Lin, G.

    2013-12-01

    Mercury is a persistent, toxic metal that bio-accumulates within the food web and causes neurological damage and fetal defects in humans. The U.S. was the first country to regulate the leading anthropogenic source of mercury into the atmosphere: coal combustion for electric power generation. The U.S. EPA's 2005 Clean Air Mercury Rule (CAMR) was replaced and further tightened in 2012 by the Mercury and Air Toxics Standard (MATS), which required existing coal-fired utilities to reduce their mercury emissions by approximately 90% by 2015. Outside the U.S., the Governing Council of the United Nations Environment Programme (UNEP) has passed the legally binding Minamata global mercury treaty that compels its signatory countries to prevent and reduce the emission and release of mercury. The most mature technology for controlling mercury emissions from coal combustion is the injection into the flue gas of powdered activated carbon (PAC) adsorbents having chemically treated surfaces designed to rapidly oxidize and adsorb mercury. However, such PAC is known to have electrical properties that make it difficult to remove from flue gas via electrostatic precipitation, by far the most common particulate control technology used in countries such as the U.S., India, and China which rely heavily on coal for power generation. As a result, PAC used to control mercury emissions can be emitted into the atmosphere, the sub-micron fraction of which may result in unintended radiative forcing similar to black carbon (BC). Here, we estimate the potential increases in secondary BC emissions, those not produced from combustion but arising instead from the use of injected PAC for mercury emission reduction. We also calculate the radiative forcing associated with these secondary BC emissions by using a global atmospheric chemical transport model coupled with a radiative transfer model.

  12. A Terrestrial Ecosystem Full Verified Carbon Accounting for Russian Land: Results and Uncertainty

    NASA Astrophysics Data System (ADS)

    Shvidenko, A.; Schepaschenko, D.; Maksyutov, S.

    2010-12-01

    We present a terrestrial full carbon account (FCA) for Russian land in a spatially explicit form for 2009 and aggregated country-wide annual estimates for 2004-2008. The integrated methodology of the FCA takes into account the fuzzy character of the studied systems. IIASA’s landscape-ecosystem approach (LEA) is used for designing the account boundaries and assessment of major pools and fluxes. An Integrated Land Information System (ILIS) serves as the information background of the FCA. The ILIS is based on a system integration of all available ground data and multi-sensor remote sensing applications. The ILIS includes a georeferenced hybrid land cover (~500 land classes, resolution 1 x 1 km), corresponding attributive datasets and sets of empirical and semi-empirical ecosystem and landscape models. The latter are based on long-period measurements of ecological parameters with corrections - if necessary - due to weather specifics of individual growth seasons. On average, terrestrial ecosystems of Russia served as a sink of roughly 0.6 Pg C yr-1 during the last five years which exceeds the technosphere’s emissions of the country by about one third. Two major fluxes (net primary production and heterotrophic respiration) for all productive lands of the country are estimated at 323 and 204 g C yr-1 m-2, respectively. Disturbance and consumption of plant products comprise from 15 to 20% of the net primary production. Forests serve as a major component of the sink (~85% of the country’s total). Disturbed forests and peatlands, as well as cultivated agricultural lands, are a relatively small carbon source. The interannual variability of the net ecosystem carbon balance are mostly driven by climatic conditions and natural disturbance (fire, insects) of the growth periods and is in limits of 10-15% for the country as a whole, but could exceed 25-30% for large regions with weather anomalies of the vegetation periods. Uncertainty within the LEA was assessed for all

  13. Woody plant encroachment effect on soil organic carbon dynamics: results from a latitudinal gradient in Italy

    NASA Astrophysics Data System (ADS)

    Pellis, Guido; Chiti, Tommaso; Moscatelli, Maria Cristina; Marinari, Sara; Papale, Dario

    2016-04-01

    Woody plant encroachment into pastures and grasslands represents a significant land cover change phenomenon, with a considerable impact on carbon dynamics at an ecosystem level. It was estimated that 7.64% of the Southern Europe land was subject to that process between 1950 to 2010. As a result of woody encroachment, changes in vegetation composition can produce substantial changes to the soil organic carbon (SOC) cycle. Despite the numerous papers published on land-use change, an evaluation of the IPCC terrestrial carbon pools changes occurring during woody encroachment on abandoned pastures and grasslands is still lacking, particularly for the Italian territory. Therefore, the aim of this study was to investigate the role of woody encroachment on carbon sequestration over abandoned pastures and grasslands in Alpine and Apennine ecosystems, with a particular focus on the SOC. We applied a chronosequence approach to seven selected sites located along a latitudinal gradient in Italy. Each chronosequence consisted of a pasture currently managed, three sites abandoned at different times in the past and, finally, a mature forest stand representing the last phase of the succession. The European Commission sampling protocols to certify SOC changes was adopted to estimate the variations following woody encroachment. Soil samples were collected at different depths in the topsoil (0-30 cm) and subsoil (30-70 cm), despite the original protocol formulation being limited to the topsoil only. In addition, aboveground living biomass (AGB), dead wood and litter were also measured following international protocols. Considering all C pools together, woody plant encroachment leads to a progressive C stock accumulation in all the chronosequences. The total C stock of mature forest stands ranges from 1.78±0.11 times (Eastern Alps) to 2.48±0.31 times (central Apennine) the initial value on pastures. Unsurprisingly, the C stocks of AGB, dead wood and litter all increase during the

  14. 78 FR 21105 - Circular Welded Carbon Steel Pipes and Tubes From Thailand: Preliminary Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-09

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Thailand: Preliminary... tubes from Thailand. This review covers two producers/exporters of the subject merchandise, Saha Thai... The products covered by the antidumping order are certain circular welded carbon steel pipes and...

  15. 78 FR 34335 - Certain Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-07

    ... International Trade Administration Certain Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Preliminary... pipes and tubes from Taiwan. The period of review (POR) is May 1, 2011, through April 30, 2012, and the... is certain circular welded carbon steel pipes and tubes from Taiwan. The product is...

  16. Effects of free air carbon dioxide enrichment and drought stress on the feed value of maize silage fed to sheep at different thermal regimes.

    PubMed

    Lohölter, Malte; Meyer, Ulrich; Manderscheid, Remy; Weigel, Hans-Joachim; Erbs, Martin; Flachowsky, Gerhard; Dänicke, Sven

    2012-08-01

    Information about the effects of rising atmospheric CO2 concentration and drought on the feed value of maize silage and interactions with the thermal environment during feeding is limited. A free air carbon dioxide enrichment facility was operated in a maize field to generate an elevated CO2 concentration of 550 ppm. Drought was induced by the exclusion of precipitation in one half of all experimental plots. Plants were harvested, chopped and ensiled. In a balance experiment on sheep, the nutrient digestibility was determined for three climatic treatments (temperate, temperature humidity index (THI) 57-63; mild heat, THI 68-71; severe heat, THI 75-80). The CO2 concentration and drought did not alter the crude nutrient content of silage dry matter (DM) or nutrient and organic matter (OM) digestibility. Drought increased the concentration of deoxynivalenol (DON, p < 0.001). The drought-associated increase of DON was reduced by CO2 enrichment (p = 0.003). The lowest digestibility of acid detergent fibre (p = 0.024) and neutral detergent fibre (p = 0.005) was observed during the coldest climate. OM digestibility increased during mild heat (p = 0.023). This study did not indicate considerable alterations of the feed value of maize silage due to increased atmospheric CO2 and drought. Enriched CO2 may decrease DON contaminations during drought. The thermal environment during the balance experiment did not interact with feeding maize silage grown under elevated CO2, but may affect cell wall and OM digestibility.

  17. An intercomparison of carbon monoxide, nitric oxide, and hydroxyl measurement techniques - Overview of results

    NASA Technical Reports Server (NTRS)

    Hoell, J. M.; Gregory, G. L.; Carroll, M. A.; Mcfarland, M.; Ridley, B. A.; Davis, D. D.; Bradshaw, J.; Rodgers, M. O.; Torres, A. L.; Condon, E. P.

    1984-01-01

    Results from an intercomparison of methods to measure carbon monoxide (CO), nitric oxide (NO), and the hydroxyl radical (OH) are discussed. The intercomparison was conducted at Wallops Island, Virginia, in July 1983 and included a laser differential absorption and three grab sample/gas chromatograph methods for CO, a laser-induced fluorescence (LIF) and two chemiluminescence methods for NO, and two LIF methods and a radiocarbon tracer method for OH. The intercomparison was conducted as a field measurement program involving ambient measurements of CO (150-300 ppbv) and NO (10-180 pptv) from a common manifold with controlled injection of CO in incremental steps from 20 to 500 ppbv and NO in steps from 10 to 220 pptv. Only ambient measurements of OH were made. The agreement between the techniques was on the order of 14 percent for CO and 17 percent for NO. Hardware difficulties during the OH tests resulted in a data base with insufficient data and uncertanties too large to permit a meaningful intercomposition.

  18. Organic compounds in olive mill wastewater and in solutions resulting from hydrothermal carbonization of the wastewater.

    PubMed

    Poerschmann, J; Weiner, B; Baskyr, I

    2013-09-01

    Organic components in olive mill wastewater (OMW) were analyzed by exhaustive solvent extraction of the lyophilisate followed by pre-chromatographic derivatization techniques and GC/MS-analysis of the extracts. Simple biophenols including tyrosol (Tyr), hydroxytyrosol (OH-Tyr) and homovanillic alcohol as well as complex biophenols including decarbomethoxy ligostride aglycon and decarbomethoxy oleuropein aglycon proved most abundant analytes. Hydroxylated benzoic and cinnamic acids are less abundant, which may indicate a humification process to have occurred. The pattern of organic components obtained from native OMW was compared with that obtained from hydrothermal carbonization (HTC) of the waste product. Former results provided strong evidence that HTC of OMW at 220°C for 14h results in an almost complete hydrolysis of complex aglycons. However, simple biophenols were not decomposed on hydrothermal treatment any further. Phenol and benzenediols as well as low molecular weight organic acids proved most abundant analytes which were generated due to HTC. Similarly to aglycons, lipids including most abundant acylglycerines and less abundant wax esters were subjected almost quantitatively to hydrolysis under hydrothermal conditions. Fatty acids (FAs) released from lipids were further decomposed. The pathways of volatile analytes in both native OMW and aqueous HTC solutions were studied by solventless headspace-Solid Phase Micro Extraction. Basically, a wide array low molecular alcohols and ketones occurring in native OMW survived the HTC process.

  19. From carbon numbers to ecosystem services: usable results comparing natural versus managed lands

    NASA Astrophysics Data System (ADS)

    Bachelet, D. M.; Ferschweiler, K.; Sheehan, T.; Sleeter, B. M.; Zhu, Z.

    2015-12-01

    We ran the MC2 dynamic vegetation model for the conterminous US at 30 arc sec with and without land use and fire suppression for several climate change scenarios. We translated model results into key ecosystem services (ES) such as climate regulation through carbon uptake and sequestration (global climate) or through transpiration (regional climate) as well as water provision through runoff and throughflow. We also projected timber production and gauged the risk of production lost to fire and/or drought by simulating fuel loads and forest vigor annually through the 21st century. We calculated the rising irrigation demand for agricultural land which, coupled with available information on groundwater resources, could help plan for future cropping systems. By combining these results we can evaluate land cover value across the country in terms of quantity and quality of services rendered. By comparing projections with and without landuse and fire suppression we can illustrate differences in regulating and provisioning services between managed and natural lands.

  20. Low CO2 results in a rearrangement of carbon metabolism to support C4 photosynthetic carbon assimilation in Thalassiosira pseudonana.

    PubMed

    Kustka, Adam B; Milligan, Allen J; Zheng, Haiyan; New, Ashley M; Gates, Colin; Bidle, Kay D; Reinfelder, John R

    2014-11-01

    The mechanisms of carbon concentration in marine diatoms are controversial. At low CO2 , decreases in O2 evolution after inhibition of phosphoenolpyruvate carboxylases (PEPCs), and increases in PEPC transcript abundances, have been interpreted as evidence for a C4 mechanism in Thalassiosira pseudonana, but the ascertainment of which proteins are responsible for the subsequent decarboxylation and PEP regeneration steps has been elusive. We evaluated the responses of T. pseudonana to steady-state differences in CO2 availability, as well as to transient shifts to low CO2 , by integrated measurements of photosynthetic parameters, transcript abundances and quantitative proteomics. On shifts to low CO2 , two PEPC transcript abundances increased and then declined on timescales consistent with recoveries of Fv /Fm , non-photochemical quenching (NPQ) and maximum chlorophyll a-specific carbon fixation (Pmax ), but transcripts for archetypical decarboxylation enzymes phosphoenolpyruvate carboxykinase (PEPCK) and malic enzyme (ME) did not change. Of 3688 protein abundances measured, 39 were up-regulated under low CO2 , including both PEPCs and pyruvate carboxylase (PYC), whereas ME abundance did not change and PEPCK abundance declined. We propose a closed-loop biochemical model, whereby T. pseudonana produces and subsequently decarboxylates a C4 acid via PEPC2 and PYC, respectively, regenerates phosphoenolpyruvate (PEP) from pyruvate in a pyruvate phosphate dikinase-independent (but glycine decarboxylase (GDC)-dependent) manner, and recuperates photorespiratory CO2 as oxaloacetate (OAA).

  1. SO{sub 2} removal and CO{sub 2} capture by limestone resulting from calcination/sulfation/carbonation cycles

    SciTech Connect

    Yan Li; Steve Buchi; John R. Grace; C. Jim Lim

    2005-10-01

    Experiments were conducted in a dual-environment thermogravimetric reactor to investigate the interaction between calcination, sulfation, and carbonation for a limestone that had previously been shown to sulfate primarily in an unreacted core manner. The results indicate that carbon dioxide (CO{sub 2}) can reactivate partially sulfated sorbent particles, contributing to an increase in overall calcium utilization efficiency. The ability of sorbents to recapture CO{sub 2} decreases when cycles of calcination and carbonation are performed, following a pattern similar to sulfation/hydration cycling. 16 refs., 10 figs., 3 tabs.

  2. Incorporation of inorganic carbon by Antarctic cryptoendolithic fungi

    NASA Technical Reports Server (NTRS)

    Palmer, R. J. Jr; Friedmann, E. I.

    1988-01-01

    Fungi isolated from the cryptoendolithic community of the Ross Desert are capable of fixing inorganic carbon. Results suggest that lichen mycobionts and parasymbionts are adapted to different water regimes in the cryptoendolithic environment.

  3. Incorporation of inorganic carbon by Antarctic cryptoendolithic fungi.

    PubMed

    Palmer, R J; Friedmann, E I

    1988-01-01

    Fungi isolated from the cryptoendolithic community of the Ross Desert are capable of fixing inorganic carbon. Results suggest that lichen mycobionts and parasymbionts are adapted to different water regimes in the cryptoendolithic environment.

  4. Does Iron Fertilization Lead to Enhanced Carbon Sequestration? A Synthesis of Polar Star Results.

    SciTech Connect

    Buesseler, K.O.

    2002-12-01

    This research synthesized activities related to work conducted as part of the Southern Ocean Iron Experiment (SOFeX) which investigated the effects of iron fertilization on enhanced carbon sequestration. The primary interest was in the fate of sinking particles which carry carbon to the deep ocean, where it can be sequestered from the atmosphere for >100-1000 year time scales. This was accomplished through direct measurements of thorium-234, a naturally occurring particle reactive radionuclide that traces shallow particle export; SF6 measurements to track the position of the Fe fertilized region; and the collection of ancillary data and samples to augment the study of major C, nutrient and elemental budgets as well as appropriate samples for biological study. Results of this work show a small, but progressively increasing flux of particulate organic C to depth as a consequence of Fe fertilization. This is the first data set to show any effect of Fe fertilization on C sequestration in the Southern Ocean. The changes in particle export during SOFeX are significant, but only possible to detect given what is arguably the largest 234Th data set ever collected as part of an oceanographic experiment. Most prior 234Th studies, simply use a steady-state approximation and ignore advective and diffusive fluxes in the calculation of 234Th fluxes. High resolution time-series of average 0-50m 234Th activities in and out of the Southern patch find a clear steady decrease in 234Th flux that is slightly larger in vs. out of the Fe fertilized patch. This decrease must be included in the full 234Th flux calculation and the deliberate tagging of this water mass with SF6 combined with time-series sampling allowed for a careful evaluation of this non-steady state (NSS) term. Likewise, the addition of SF6 allows for the evaluation of vertical exchange (via the gradient of SF6 below the patch) and dilution effects (after correction for atmospheric losses). In most set tings these physical

  5. A dense Black Carbon network in the region of Paris, France: Implementation, objectives, and first results

    NASA Astrophysics Data System (ADS)

    Sciare, Jean; Petit, Jean-Eudes; Sarda-Esteve, Roland; Bonnaire, Nicolas; Gros, Valérie; Pernot, Pierre; Ghersi, Véronique; Ampe, Christophe; Songeur, Charlotte; Brugge, Benjamin; Debert, Christophe; Favez, Olivier; Le Priol, Tiphaine; Mocnik, Grisa

    2013-04-01

    Motivations. Road traffic and domestic wood burning emissions are two major contributors of particulate pollution in our cities. These two sources emit ultra-fine, soot containing, particles in the atmosphere, affecting health adversely, increasing morbidity and mortality from cardiovascular and respiratory conditions and casing lung cancer. A better characterization of soot containing aerosol sources in our major cities provides useful information for policy makers for assessment, implementation and monitoring of strategies to tackle air pollution issues affecting human health with additional benefits for climate change. Objectives. This study on local sources of primary Particulate Matter (PM) in the megacity of Paris is a follow-up of several programs (incl. EU-FP7-MEGAPOLI) that have shown that fine PM - in the Paris background atmosphere - is mostly secondary and imported. A network of 14 stations of Black Carbon has been implemented in the larger region of Paris to provide highly spatially resolved long term survey of local combustion aerosols. To our best knowledge, this is the first time that such densely BC network is operating over a large urban area, providing novel information on the spatial/temporal distribution of combustion aerosols within a post-industrialized megacity. Experimental. As part of the PRIMEQUAL "PREQUALIF" project, a dense Black Carbon network (of 14 stations) has been installed over the city of Paris beginning of 2012 in order to produce spatially resolved Equivalent Black Carbon (EBC) concentration maps with high time resolution through modeling and data assimilation. This network is composed of various real-time instruments (Multi-Angle Absorption Photometer, MAAP by THERMO; Multi-wavelength Aethalometers by MAGEE Scientific) implemented in contrasted sites (rural background, urban background, traffic) complementing the regulated measurements (PM, NOx) in the local air quality network AIRPARIF (http

  6. DISSOLVED ORGANIC CARBON TRENDS RESULTING FROM CHANGES IN ATMOSPHERIC DEPOSITION CHEMISTRY

    EPA Science Inventory

    Several hypotheses have been proposed to explain recent, widespread increases in concentrations of dissolved organic carbon (DOC) in the surface waters of glaciated landscapes across eastern North America and northern and central Europe. Some invoke anthropogenic forcing through ...

  7. Analysis of results of biomass forest inventory in northeastern Amazon for development of REDD+ carbon project.

    PubMed

    Mello, Leonel N C; Sales, Marcio H R; Rosa, Luiz P

    2016-03-01

    In Brazil, a significant reduction in deforestation rates occurred during the last decade. In spite of that fact, the average annual rates are still too high, approximately 400.000 ha/year (INPE/Prodes). The projects of emissions reduction through avoided deforestation (REED+) are an important tool to reduce deforestation rates in Brazil. Understanding the amazon forest structure, in terms of biomass stock is key to design avoided deforestation strategies. In this work, we analyze data results from aboveground biomass of 1,019.346,27 hectares in the state of Pará. It was collected data from 16,722 trees in 83 random independent plots. It was tested 4 allometric equations, for DBH > 10cm: Brown et al. (1989), Brown and Lugo (1999), Chambers et al. (2000), Higuchi et al. (1998). It revealed that the biggest carbon stock of above ground biomass is stocked on the interval at DBH between 30cm and 80cm. This biomass compartment stocks 75.70% of total biomass in Higuchi et al. (1998) equation, 75.56% of total biomass in Brown et al. (1989) equation, 78.83% of total biomass in Chambers et al. (2000) equation, and 73.22% in Brown and Lugo (1999) equation.

  8. Testing and Results of Vacuum Swing Adsorption Units for Spacesuit Carbon Dioxide and Humidity Control

    NASA Technical Reports Server (NTRS)

    McMillin, Summer; Broerman, Craig; Swickrath, Mike; Anderson, Molly

    2010-01-01

    A principal concern for extravehicular activity (EVA) space suits is the capability to control carbon dioxide (CO2) and humidity (H2O) for the crewmember. The release of CO2 in a confined or unventilated area is dangerous for human health and leads to asphyxiation; therefore, CO2 and H2O become leading factors in the design and development of the spacesuit. An amine-based CO2 and H2O vapor sorbent for use in pressure-swing re-generable beds has been developed by Hamilton Sundstrand. The application of solid-amine materials with vacuum swing adsorption technology has shown the capacity to concurrently manage CO2 and H2O levels through a fully regenerative cycle eliminating mission constraints imposed with non-regenerative technologies. Two prototype solid amine-based systems, known as rapid cycle amine (RCA), were designed to continuously remove CO2 and H2O vapor from a flowing ventilation stream through the use of a two-bed amine based, vacuum-swing adsorption system. The Engineering and Science Contract Group (ESCG) RCA is the first RCA unit implementing radial flow paths, whereas the Hamilton Sundstrand RCA was designed with linear flow paths. Testing was performed in a sea-level pressure environment and a reduced-pressure environment with simulated human metabolic loads in a closed-loop configuration. This paper presents the experimental results of laboratory testing for a full-size and a sub-scale test article. The testing described here characterized and evaluated the performance of each RCA unit at the required Portable Life Support Subsystem (PLSS) operating conditions. The test points simulated a range of crewmember metabolic rates. The experimental results demonstrate the ability of each RCA unit to sufficiently remove CO2 and H2O from a closed loop ambient or subambient atmosphere.

  9. Differences in chemical composition of soil organic carbon resulting from long-term fertilization strategies.

    PubMed

    Li, Zengqiang; Zhao, Bingzi; Wang, Qingyun; Cao, Xiaoyan; Zhang, Jiabao

    2015-01-01

    Chemical composition of soil organic carbon (SOC) is central to soil fertility. We hypothesize that change in SOC content resulting from various long-term fertilization strategies accompanies the shift in SOC chemical structure. This study examined the effect of fertilization strategies along with the time of fertilizer application on the SOC composition by 13C nuclear magnetic resonance (NMR) spectroscopy. The soils (Aquic Inceptisol) subjected to seven fertilizer treatments were collected in 1989, 1999 and 2009, representing 0, 10 and 20 years of fertilization, respectively. The seven fertilizer treatments were (1-3) balanced fertilization with application of nitrogen (N), phosphorus (P) and potassium (K) including organic compost (OM), half organic compost plus half chemical fertilizer (1/2OM), and pure chemical NPK fertilizer (NPK); (4-6) unbalanced chemical fertilization without application of one of the major elements including NP fertilizer (NP), PK fertilizer (PK), and NK fertilizer (NK); and (7) an unamended control (CK). The SOC content in the balanced fertilization treatments were 2.3-52.6% and 9.4-64.6% higher than in the unbalanced fertilization/CK treatments in 1999 and 2009, respectively, indicating significant differences in SOC content with time of fertilizer application between the two treatment groups. There was a significantly greater proportion of O-alkyl C and a lower proportion of aromatic C in the balanced fertilization than in unbalanced fertilization/CK treatments in 1999, but not in 2009, because their proportions in the former treatments approached the latter in 2009. Principal component analysis further showed that the C functional groups from various fertilization strategies tended to become compositionally similar with time. The results suggest that a shift in SOC chemical composition may be firstly dominated by fertilization strategies, followed by fertilization duration.

  10. Testing and Results of Vacuum Swing Adsorption Units for Spacesuit Carbon Dioxide and Humidity Control

    NASA Technical Reports Server (NTRS)

    McMillin, Summer D.; Broerman, Craig D.; Swickrath, Michael; Anderson, Molly

    2011-01-01

    A principal concern for extravehicular activity (EVA) spacesuits is the capability to control carbon dioxide (CO2) and humidity (H2O) for the crewmember. The release of CO2 in a confined or unventilated area is dangerous for human health and leads to asphyxiation; therefore, CO2 and H2O control become leading factors in the design and development of the spacesuit. An amine-based CO2 and H2O vapor sorbent for use in pressure-swing regenerable beds has been developed by Hamilton Sundstrand. The application of solidamine materials with vacuum swing adsorption technology has shown the capacity to concurrently manage CO2 and H2O levels through a fully regenerative cycle eliminating mission constraints imposed with nonregenerative technologies. Two prototype solid amine-based systems, known as rapid cycle amine (RCA), were designed to continuously remove CO2 and H2O vapor from a flowing ventilation stream through the use of a two-bed amine based, vacuum-swing adsorption system. The Engineering and Science Contract Group (ESCG) RCA implements radial flow paths, whereas the Hamilton Sundstrand RCA was designed with linear flow paths. Testing was performed in a sea-level pressure environment and a reduced-pressure environment with simulated human metabolic loads in a closed-loop configuration. This paper presents the experimental results of laboratory testing for a full-size and a sub-scale test article. The testing described here characterized and evaluated the performance of each RCA unit at the required Portable Life Support Subsystem (PLSS) operating conditions. The test points simulated a range of crewmember metabolic rates. The experimental results demonstrated the ability of each RCA unit to sufficiently remove CO2 and H2O from a closed loop ambient or sub-ambient atmosphere.

  11. Integrated Assessment Modeling of Carbon Sequestration and Land Use Emissions Using Detailed Model Results and Observations

    SciTech Connect

    Dr. Atul Jain

    2005-04-17

    This report outlines the progress on the development and application of Integrated Assessment Modeling of Carbon Sequestrations and Land Use Emissions supported by the DOE Office of Biological and Environmental Research (OBER), U.S. Department of Energy, Grant No. DOE-DE-FG02-01ER63069. The overall objective of this collaborative project between the University of Illinois at Urbana-Champaign (UIUC), Oak Ridge National Laboratory (ORNL), Lawrence Livermore National Laboratory (LLNL), and Pacific Northwest National Laboratory (PNNL) was to unite the latest advances in carbon cycle research with scientifically based models and policy-related integrated assessment tools that incorporate computationally efficient representations of the latest knowledge concerning science and emission trajectories, and their policy implications. As part of this research we accomplished the following tasks that we originally proposed: (1) In coordination with LLNL and ORNL, we enhanced the Integrated Science Assessment Model's (ISAM) parametric representation of the ocean and terrestrial carbon cycles that better represent spatial and seasonal variations, which are important to study the mechanisms that influence carbon sequestration in the ocean and terrestrial ecosystems; (2) Using the MiniCAM modeling capability, we revised the SRES (IPCC Special Report on Emission Scenarios; IPCC, 2000) land use emission scenarios; and (3) On the application front, the enhanced version of ISAM modeling capability is applied to understand how short- and long-term natural carbon fluxes, carbon sequestration, and human emissions contribute to the net global emissions (concentrations) trajectories required to reach various concentration (emission) targets. Under this grant, 21 research publications were produced. In addition, this grant supported a number of graduate and undergraduate students whose fundamental research was to learn a disciplinary field in climate change (e.g., ecological dynamics and

  12. Interactions Between Mineral Surfaces, Substrates, Enzymes, and Microbes Result in Hysteretic Temperature Sensitivities and Microbial Carbon Use Efficiencies and Weaker Predicted Carbon-Climate Feedbacks

    NASA Astrophysics Data System (ADS)

    Riley, W. J.; Tang, J.

    2014-12-01

    We hypothesize that the large observed variability in decomposition temperature sensitivity and carbon use efficiency arises from interactions between temperature, microbial biogeochemistry, and mineral surface sorptive reactions. To test this hypothesis, we developed a numerical model that integrates the Dynamic Energy Budget concept for microbial physiology, microbial trait-based community structure and competition, process-specific thermodynamically ­­based temperature sensitivity, a non-linear mineral sorption isotherm, and enzyme dynamics. We show, because mineral surfaces interact with substrates, enzymes, and microbes, both temperature sensitivity and microbial carbon use efficiency are hysteretic and highly variable. Further, by mimicking the traditional approach to interpreting soil incubation observations, we demonstrate that the conventional labile and recalcitrant substrate characterization for temperature sensitivity is flawed. In a 4 K temperature perturbation experiment, our fully dynamic model predicted more variable but weaker carbon-climate feedbacks than did the static temperature sensitivity and carbon use efficiency model when forced with yearly, daily, and hourly variable temperatures. These results imply that current earth system models likely over-estimate the response of soil carbon stocks to global warming.

  13. Stable Isotopic Variability in the Carbon Cycle: Reconciling Ocean Model Results with Atmospheric Observations

    NASA Astrophysics Data System (ADS)

    Alden, C. B.; White, J. W.; Miller, J. B.

    2009-12-01

    In the face of rising sea levels, species extinction, unpredictable precipitation changes, and other potential impacts of anthropogenic climate change, there is a push for the scientific community to expand our current understanding of the major sources and sinks of global warming’s most implicated culprit, CO2. Knowing the mechanisms controlling CO2 sinks and sources will be vital for policy-makers to make informed decisions regarding its mitigation. The stable carbon isotope, 13C, can be used to partition CO2 fluxes into land and ocean components. The major fluxes of this gas (fossil fuel, ocean and land) impose distinctive and predictable fractionation patterns upon the stable isotope ratio, making it an ideal tool for distinguishing between them. One drawback to this method is that photosynthesis and respiration are not contemporaneous, and because the 13C of atmospheric CO2 is being continuously depleted through the burning of 12C-rich fossil fuels (the Suess effect), there is an isotopic “disequilibrium flux” between CO2 moving into and out of the ocean and land reservoirs. In this study, we take a new approach and seek to reconcile independent estimates of time histories of ocean fluxes with atmospheric observations. We use a combination of atmospheric CO2 and 13CO2 data, fossil fuel emission estimates, and recent ocean model results (from two different approaches) for the ocean CO2 flux, within a box-inverse model as well as a 2D transport model. We calculate time series of land flux, disequilibrium flux and photosynthetic fractionation from 1991 through 2008. Our findings reveal that if ocean variability is as small as is suggested by the ocean model, and the isotopic variability is forced into the disequilibrium flux, then the resulting disequilibrium flux has very large interannual variability (~35 PgC‰/yr). While large interannual variability in DIS seems incompatible with the Suess effect alone, it could be explained by interannual variations

  14. Thermostructural Analysis of Carbon Cloth Phenolics "Ply Lifting" and Correlation to LHMEL Test Results

    NASA Technical Reports Server (NTRS)

    Clayton, Louie

    2004-01-01

    This paper provides a discussion of the history of Carbon Cloth Phenolic (CCP) ply lifting in the Redesigned Solid Rocket Motor (RSRM) Program, a brief presentation of theoretical methods used for analytical evaluation, and results of parametric analyses of CCP material subject to test conditions of the Laser Hardened Material Evaluation Laboratory. CCP ply lift can occur in regions of the RSRM nozzle where ply angle to flame surface is generally less than about 20 degrees. There is a heat rate dependence on likelihood and severity of the condition with the higher heating rates generally producing more ply lift. The event occurs in-depth, near the heated surface, where the load necessary to mechanically separate the CCP plies is produced by the initial stages of pyrolysis gas generation due to the thermal decomposition of the phenolic resin matrix. Due to the shallow lay-up angle of the composite, normal components of the indepth mechanical load, due to "pore pressure", are imparted primarily as a cross-ply tensile force on the interlaminar ply boundaries. Tensile capability in the cross-ply (out of plane) direction is solely determined by the matrix material capability. The elevated temperature matrix material capabilities are overcome by pressure induced mechanical normal stress and ply-lift occurs. A theoretical model used for CCP in-depth temperature, pressure, and normal stress prediction, based on first principles, is briefly discussed followed by a parametric evaluation of response variables subject to boundary conditions typical of on-going test programs at the LHMEL facility. Model response demonstrates general trends observed in test and provides insight into the interactivity of material properties and constitutive relationships.

  15. Jellyfish blooms result in a major microbial respiratory sink of carbon in marine systems.

    PubMed

    Condon, Robert H; Steinberg, Deborah K; del Giorgio, Paul A; Bouvier, Thierry C; Bronk, Deborah A; Graham, William M; Ducklow, Hugh W

    2011-06-21

    Jellyfish blooms occur in many estuarine and coastal regions and may be increasing in their magnitude and extent worldwide. Voracious jellyfish predation impacts food webs by converting large quantities of carbon (C), fixed by primary producers and consumed by secondary producers, into gelatinous biomass, which restricts C transfer to higher trophic levels because jellyfish are not readily consumed by other predators. In addition, jellyfish release colloidal and dissolved organic matter (jelly-DOM), and could further influence the functioning of coastal systems by altering microbial nutrient and DOM pathways, yet the links between jellyfish and bacterioplankton metabolism and community structure are unknown. Here we report that jellyfish released substantial quantities of extremely labile C-rich DOM, relative to nitrogen (25.6 ± 31.6 C:1N), which was quickly metabolized by bacterioplankton at uptake rates two to six times that of bulk DOM pools. When jelly-DOM was consumed it was shunted toward bacterial respiration rather than production, significantly reducing bacterial growth efficiencies by 10% to 15%. Jelly-DOM also favored the rapid growth and dominance of specific bacterial phylogenetic groups (primarily γ-proteobacteria) that were rare in ambient waters, implying that jelly-DOM was channeled through a small component of the in situ microbial assemblage and thus induced large changes in community composition. Our findings suggest major shifts in microbial structure and function associated with jellyfish blooms, and a large detour of C toward bacterial CO(2) production and away from higher trophic levels. These results further suggest fundamental transformations in the biogeochemical functioning and biological structure of food webs associated with jellyfish blooms.

  16. Carbon-monoxide poisoning resulting from exposure to ski-boat exhaust--Georgia, June 2002.

    PubMed

    2002-09-20

    Carbon monoxide (CO) is an odorless, colorless gas produced from the incomplete combustion of carbon-based fuels such as gasoline or wood. In the United States, CO poisoning causes approximately 500 unintentional deaths each year. Although CO poisonings often have been reported to occur in enclosed and semi-enclosed environments, they can also occur in open-air environments. This report describes two related cases of CO poisoning that occurred in children who were participating in recreational activities on a ski boat. Recreational boaters should be aware of the dangers of open-air CO poisoning, and engineering solutions are needed to reduce the amount of CO in boat exhaust.

  17. Arctic circulation regimes.

    PubMed

    Proshutinsky, Andrey; Dukhovskoy, Dmitry; Timmermans, Mary-Louise; Krishfield, Richard; Bamber, Jonathan L

    2015-10-13

    Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability.

  18. Arctic circulation regimes

    PubMed Central

    Proshutinsky, Andrey; Dukhovskoy, Dmitry; Timmermans, Mary-Louise; Krishfield, Richard; Bamber, Jonathan L.

    2015-01-01

    Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability. PMID:26347536

  19. Fire regime zonation under current and future climate over eastern Canada.

    PubMed

    Boulanger, Yan; Gauthier, Sylvie; Gray, David R; Le Goff, Héloïse; Lefort, Patrick; Morissette, Jacques

    2013-06-01

    Fire is a major disturbance in Canadian forests. Along with fuel and ignition characteristics, climatic conditions are seen as one of the main drivers of fire regimes. Projected changes in climate are expected to significantly influence fire regimes in Canada. As fire regime greatly shapes large-scale patterns in biodiversity, carbon, and vegetation, as well as forest and fire management strategies, it becomes necessary to define regions where current and future fire regimes are homogeneous. Random Forests (RF) modeling was used to relate fire regime attributes prevailing between 1961 and 1990 in eastern Canada with climatic/fire-weather and environmental variables. Using climatic normals outputs from the Canadian Regional Climate Model (CRCM), we delineated current (1961-1990) and future (2011-2040, 2040-2070, 2071 2100) homogeneous fire regime (HFR) zones. Heterogeneous response of fire regime to climate changes is projected for eastern Canada with some areas (e.g., western Quebec) experiencing very small alterations while others (e.g., southeastern Ontario) are facing great shifts. Overall, models predicted a 2.2- and 2.4-fold increase in the number of fires and the annual area burned respectively mostly as a result of an increase in extreme fire-weather normals and mean drought code. As extreme fire danger would occur later in the fire season on average, the fire season would shift slightly later (5-20 days) in the summer for much of the study area while remaining relatively stable elsewhere. Although fire regime values would change significantly over time, most zone boundaries would remain relatively stable. The information resulting from HFR zonations is clearly of interest for forest and fire management agencies as it reveals zones with peculiar fire regimes that would have been hidden otherwise using predefined administrative or ecological stratifications.

  20. How does carbon dioxide permeate cell membranes? A discussion of concepts, results and methods

    PubMed Central

    Endeward, Volker; Al-Samir, Samer; Itel, Fabian; Gros, Gerolf

    2013-01-01

    We review briefly how the thinking about the permeation of gases, especially CO2, across cell and artificial lipid membranes has evolved during the last 100 years. We then describe how the recent finding of a drastic effect of cholesterol on CO2 permeability of both biological and artificial membranes fundamentally alters the long-standing idea that CO2—as well as other gases—permeates all membranes with great ease. This requires revision of the widely accepted paradigm that membranes never offer a serious diffusion resistance to CO2 or other gases. Earlier observations of “CO2-impermeable membranes” can now be explained by the high cholesterol content of some membranes. Thus, cholesterol is a membrane component that nature can use to adapt membrane CO2 permeability to the functional needs of the cell. Since cholesterol serves many other cellular functions, it cannot be reduced indefinitely. We show, however, that cells that possess a high metabolic rate and/or a high rate of O2 and CO2 exchange, do require very high CO2 permeabilities that may not be achievable merely by reduction of membrane cholesterol. The article then discusses the alternative possibility of raising the CO2 permeability of a membrane by incorporating protein CO2 channels. The highly controversial issue of gas and CO2 channels is systematically and critically reviewed. It is concluded that a majority of the results considered to be reliable, is in favor of the concept of existence and functional relevance of protein gas channels. The effect of intracellular carbonic anhydrase, which has recently been proposed as an alternative mechanism to a membrane CO2 channel, is analysed quantitatively and the idea considered untenable. After a brief review of the knowledge on permeation of O2 and NO through membranes, we present a summary of the 18O method used to measure the CO2 permeability of membranes and discuss quantitatively critical questions that may be addressed to this method. PMID

  1. Net Carbon Emissions from Deforestation in Bolivia during 1990-2000 and 2000-2010: Results from a Carbon Bookkeeping Model.

    PubMed

    Andersen, Lykke E; Doyle, Anna Sophia; del Granado, Susana; Ledezma, Juan Carlos; Medinaceli, Agnes; Valdivia, Montserrat; Weinhold, Diana

    2016-01-01

    Accurate estimates of global carbon emissions are critical for understanding global warming. This paper estimates net carbon emissions from land use change in Bolivia during the periods 1990-2000 and 2000-2010 using a model that takes into account deforestation, forest degradation, forest regrowth, gradual carbon decomposition and accumulation, as well as heterogeneity in both above ground and below ground carbon contents at the 10 by 10 km grid level. The approach permits detailed maps of net emissions by region and type of land cover. We estimate that net CO2 emissions from land use change in Bolivia increased from about 65 million tons per year during 1990-2000 to about 93 million tons per year during 2000-2010, while CO2 emissions per capita and per unit of GDP have remained fairly stable over the sample period. If we allow for estimated biomass increases in mature forests, net CO2 emissions drop to close to zero. Finally, we find these results are robust to alternative methods of calculating emissions.

  2. Net Carbon Emissions from Deforestation in Bolivia during 1990-2000 and 2000-2010: Results from a Carbon Bookkeeping Model

    PubMed Central

    Andersen, Lykke E.; Doyle, Anna Sophia; del Granado, Susana; Ledezma, Juan Carlos; Medinaceli, Agnes; Valdivia, Montserrat; Weinhold, Diana

    2016-01-01

    Accurate estimates of global carbon emissions are critical for understanding global warming. This paper estimates net carbon emissions from land use change in Bolivia during the periods 1990–2000 and 2000–2010 using a model that takes into account deforestation, forest degradation, forest regrowth, gradual carbon decomposition and accumulation, as well as heterogeneity in both above ground and below ground carbon contents at the 10 by 10 km grid level. The approach permits detailed maps of net emissions by region and type of land cover. We estimate that net CO2 emissions from land use change in Bolivia increased from about 65 million tons per year during 1990–2000 to about 93 million tons per year during 2000–2010, while CO2 emissions per capita and per unit of GDP have remained fairly stable over the sample period. If we allow for estimated biomass increases in mature forests, net CO2 emissions drop to close to zero. Finally, we find these results are robust to alternative methods of calculating emissions. PMID:26990865

  3. Regime Shifts in the Anthropocene: Drivers, Risks, and Resilience

    PubMed Central

    Rocha, Juan Carlos; Peterson, Garry D.; Biggs, Reinette

    2015-01-01

    Many ecosystems can experience regime shifts: surprising, large and persistent changes in the function and structure of ecosystems. Assessing whether continued global change will lead to further regime shifts, or has the potential to trigger cascading regime shifts has been a central question in global change policy. Addressing this issue has, however, been hampered by the focus of regime shift research on specific cases and types of regime shifts. To systematically assess the global risk of regime shifts we conducted a comparative analysis of 25 generic types of regime shifts across marine, terrestrial and polar systems; identifying their drivers, and impacts on ecosystem services. Our results show that the drivers of regime shifts are diverse and co-occur strongly, which suggests that continued global change can be expected to synchronously increase the risk of multiple regime shifts. Furthermore, many regime shift drivers are related to climate change and food production, whose links to the continued expansion of human activities makes them difficult to limit. Because many regime shifts can amplify the drivers of other regime shifts, continued global change can also be expected to increase the risk of cascading regime shifts. Nevertheless, the variety of scales at which regime shift drivers operate provides opportunities for reducing the risk of many types of regime shifts by addressing local or regional drivers, even in the absence of rapid reduction of global drivers. PMID:26267896

  4. Regime shifts in the anthropocene: drivers, risks, and resilience.

    PubMed

    Rocha, Juan Carlos; Peterson, Garry D; Biggs, Reinette

    2015-01-01

    Many ecosystems can experience regime shifts: surprising, large and persistent changes in the function and structure of ecosystems. Assessing whether continued global change will lead to further regime shifts, or has the potential to trigger cascading regime shifts has been a central question in global change policy. Addressing this issue has, however, been hampered by the focus of regime shift research on specific cases and types of regime shifts. To systematically assess the global risk of regime shifts we conducted a comparative analysis of 25 generic types of regime shifts across marine, terrestrial and polar systems; identifying their drivers, and impacts on ecosystem services. Our results show that the drivers of regime shifts are diverse and co-occur strongly, which suggests that continued global change can be expected to synchronously increase the risk of multiple regime shifts. Furthermore, many regime shift drivers are related to climate change and food production, whose links to the continued expansion of human activities makes them difficult to limit. Because many regime shifts can amplify the drivers of other regime shifts, continued global change can also be expected to increase the risk of cascading regime shifts. Nevertheless, the variety of scales at which regime shift drivers operate provides opportunities for reducing the risk of many types of regime shifts by addressing local or regional drivers, even in the absence of rapid reduction of global drivers.

  5. Carbon isotope analysis of conodont organic material--Procedure and preliminary results

    SciTech Connect

    Over, D.J. . Dept. of Geological Sciences); Grossman, E.L. )

    1992-01-01

    Conodonts, the phosphatic microfossil remains of an extinct pelagic animal, are well suited for isotopic studies of Paleozoic marine organic carbon. The author report here what they believe are the first delta C-13 data for the organic matrix of conodont elements. Conodont delta C-13 values (PDB) for Upper Devonian Palmatolepis platform elements from a single interval of the Chappel Limestones in Texas range from [minus]24.5 to [minus]25.6 [per thousand] (n = 5). Lower Carboniferous Siphonodella platform elements from the same interval in the Chappel Limestone range from [minus]26.3 to [minus]27.3 [per thousand] (n = 2). Upper Carboniferous Streptognathodus elegantulus platform elements from four intervals in a 3.9 m section of the Necessity Shale in Texas range from [minus]23.0 to [minus]24.0 [per thousand] (n = 4). delta C-13 values also differ significantly between the three sample groups. Average values were [minus]4.7, [minus]7.1, and [minus]8.3 [per thousand] respectively, however, the relevance of these values is unclear. The conodont organic carbon isotopic values are within the range of delta C-13 values in sedimentary organic matter of late Paleozoic age. Although the data are limited, they show that significant isotopic differences occur between genera and between stratigraphically separate units. These isotopic differences in delta C-13 may be related to local changes in source of organic carbon, global changes in the carbon budget, or to dietary differences among conodont animals. Future study is directed toward evaluating the importance of each of these factors.

  6. JPL Carbon Dioxide Laser Absorption Spectrometer Data Processing Results for the 2010 Flight Campaign

    NASA Technical Reports Server (NTRS)

    Jacob, Joseph C.; Spiers, Gary D.; Menzie, Robert T.; Christensen, Lance E.

    2011-01-01

    As a precursor to and validation of the core technology necessary for NASA's Active Sensing of CO2 Emissions over Nights, Days,and Seasons (ASCENDS) mission, we flew JPL's Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) in a campaign of five flights onboard NASA's DC-8 Airborne Laboratory in July 2010. This is the latest in a series of annual flight campaigns that began in 2006, and our first on the DC-8 aircraft.

  7. Solid and Gas-Phase Spectroscopy of Cosmic Carbon Analogs: Results and Perspectives

    NASA Technical Reports Server (NTRS)

    Salama, Farid; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    The laboratory studies of interstellar carbon materials analogs (PAHs, Fullerenes, chains) will be discussed with their advantages and limitations from the point of view of the application to astrophysical processes. The discussion will focus on the newest generation of laboratory experiments that has been developed in order to provide a closer simulation of space environments and a better support to space missions. The astrophysical implications and future perspectives will be stressed.

  8. Field Test Results of Corrosion-Resistant Coatings for Carbon-Steel Steam Condensate Return Lines

    DTIC Science & Technology

    1994-04-01

    20 and 40 ppm. Note that addition of sodium sulfite promotes a higher level of total dissolved solids, which increases the boiler blowdown rate. 2O...some form of external treatment process, including- 1. Demineralization 2. Hot lime softening 3. Split-stream, sodium hydrogen, ion exchange 4. Chloride...water due to system leakage occuring in carbon-steel condensate return lines within buildings. The makeup water is taken from the Potomac River, sodium

  9. Hall effect in hopping regime

    NASA Astrophysics Data System (ADS)

    Avdonin, A.; Skupiński, P.; Grasza, K.

    2016-02-01

    A simple description of the Hall effect in the hopping regime of conductivity in semiconductors is presented. Expressions for the Hall coefficient and Hall mobility are derived by considering averaged equilibrium electron transport in a single triangle of localization sites in a magnetic field. Dependence of the Hall coefficient is analyzed in a wide range of temperature and magnetic field values. Our theoretical result is applied to our experimental data on temperature dependence of Hall effect and Hall mobility in ZnO.

  10. Radiative forcing associated with particulate carbon emissions resulting from the use of mercury control technology.

    PubMed

    Lin, Guangxing; Penner, Joyce E; Clack, Herek L

    2014-09-02

    Injection of powdered activated carbon (PAC) adsorbents into the flue gas of coal fired power plants with electrostatic precipitators (ESPs) is the most mature technology to control mercury emissions for coal combustion. However, the PAC itself can penetrate ESPs to emit into the atmosphere. These emitted PACs have similar size and optical properties to submicron black carbon (BC) and thus could increase BC radiative forcing unintentionally. The present paper estimates, for the first time, the potential emission of PAC together with their climate forcing. The global average maximum potential emissions of PAC is 98.4 Gg/yr for the year 2030, arising from the assumed adoption of the maximum potential PAC injection technology, the minimum collection efficiency, and the maximum PAC injection rate. These emissions cause a global warming of 2.10 mW m(-2) at the top of atmosphere and a cooling of -2.96 mW m(-2) at the surface. This warming represents about 2% of the warming that is caused by BC from direct fossil fuel burning and 0.86% of the warming associated with CO2 emissions from coal burning in power plants. Its warming is 8 times more efficient than the emitted CO2 as measured by the 20-year-integrated radiative forcing per unit of carbon input (the 20-year Global Warming Potential).

  11. CO2 release due to impact devolatilization of carbonate: Results of shock experiments

    NASA Astrophysics Data System (ADS)

    Bell, Mary Sue

    2016-04-01

    A study of pure, single crystal calcite shocked to pressures from 9.0 to 60.8 GPa was conducted to address contradictory data for carbonate shock behavior. The recovered materials were analyzed optically and by transmission electron microscopy (TEM), as well as by thermogravimetry (TGA), X-ray diffraction (XRD), and Raman-spectroscopy. In thin section, progressive comminution of calcite is observed although grains remain birefringent to at least 60.8 GPa. TGA analysis reveals a positive correlation between percent of mass loss due to shock and increasing shock pressure (R = 0.77) and suggests that shock loading leads to the modest removal of structural volatiles in this pressure range. XRD patterns of shocked Iceland spar samples produce peaks that are qualitatively and quantitatively less intense, more diffuse, and shift to lower o2θ. However, the regularity observed in these shocked powder patterns suggests that structures with very uniform unit cell separations persist to shock pressures as high as 60.8 GPa. Raman spectral analyses indicate no band asymmetry and no systematic peak shifting or broadening. TEM micrographs display progressively diminishing crystallite domain sizes. Selected area electron diffraction (SAED) patterns reveal no signatures of amorphous material. These data show that essentially intact calcite is recovered at shock pressures up to 60.8 GPa with only slight mass loss (~7%). This work suggests that the amount of CO2 gas derived from shock devolatilization of carbonate by large meteorite impacts into carbonate targets has been (substantially) overestimated.

  12. CarboxyHemoglobin Formation Due to Transient Exposure to High Level Carbon Monoxide: Experimental Results and an Explanatory Model

    DTIC Science & Technology

    1994-09-30

    W. B. Saunders, 1986. Hauk, H . and Neuberger, M. Carbon monoxide uptake and the resulting carboxyhe- moglobin in man. Eur. J. Apo2l. Physiol. 53: 186...190, 1984. Jones, R. H ., Ellicott, M. F., Cadigan, J. B. and Gaensler, E. A. The relationship between alveolar and blood carbon monoxide...1987a. Tikuisis, P., Madill, H . D., Gill, B. J., Lewis, W. F., Cox, K. M. and Kane, D. M. A critical an_:ys:, of the use of the CFK equation in

  13. Fracture trace map and single-well aquifer test results in a carbonate aquifer in Berkeley County, West Virginia

    USGS Publications Warehouse

    McCoy, Kurt J.; Podwysocki, Melvin H.; Crider, E. Allen; Weary, David J.

    2005-01-01

    These data contain information on the results of single-well aquifer tests, lineament analysis, and a bedrock geologic map compilation for the low-lying carbonate and shale areas of eastern Berkeley County, West Virginia. Efforts have been initiated by management agencies of Berkeley County in cooperation with the U.S. Geological Survey to further the understanding of the spatial distribution of fractures in the carbonate regions and their correlation with aquifer properties. This report presents transmissivity values from about 200 single-well aquifer tests and a map of fracture-traces determined from aerial photos and field investigations. Transmissivity values were compared to geologic factors possibly affecting its magnitude.

  14. 78 FR 60850 - Carbon and Certain Alloy Steel Wire Rod From Brazil: Final Results of the Expedited Second Sunset...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-02

    ... International Trade Administration Carbon and Certain Alloy Steel Wire Rod From Brazil: Final Results of the... certain alloy steel wire rod (wire rod) from Brazil would be likely to lead to continuation or recurrence... Department initiated the second sunset review of the CVD order \\1\\ on wire rod from Brazil pursuant...

  15. 75 FR 1495 - Certain Hot-Rolled Carbon Steel Flat Products From India: Preliminary Results of Countervailing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-11

    ...The Department of Commerce (the Department) is conducting an administrative review of the countervailing duty (CVD) order on certain hot-rolled carbon steel flat products from India for the period of review (POR) January 1, 2008, through December 31, 2008. These preliminary results cover one company Tata Steel Limited (Tata). For the information on the net subsidy rate for the reviewed......

  16. Detecting spatial regimes in ecosystems

    USGS Publications Warehouse

    Sundstrom, Shana M.; Eason, Tarsha; Nelson, R. John; Angeler, David G.; Barichievy, Chris; Garmestani, Ahjond S.; Graham, Nicholas A.J.; Granholm, Dean; Gunderson, Lance; Knutson, Melinda; Nash, Kirsty L.; Spanbauer, Trisha; Stow, Craig A.; Allen, Craig R.

    2017-01-01

    Research on early warning indicators has generally focused on assessing temporal transitions with limited application of these methods to detecting spatial regimes. Traditional spatial boundary detection procedures that result in ecoregion maps are typically based on ecological potential (i.e. potential vegetation), and often fail to account for ongoing changes due to stressors such as land use change and climate change and their effects on plant and animal communities. We use Fisher information, an information theory-based method, on both terrestrial and aquatic animal data (U.S. Breeding Bird Survey and marine zooplankton) to identify ecological boundaries, and compare our results to traditional early warning indicators, conventional ecoregion maps and multivariate analyses such as nMDS and cluster analysis. We successfully detected spatial regimes and transitions in both terrestrial and aquatic systems using Fisher information. Furthermore, Fisher information provided explicit spatial information about community change that is absent from other multivariate approaches. Our results suggest that defining spatial regimes based on animal communities may better reflect ecological reality than do traditional ecoregion maps, especially in our current era of rapid and unpredictable ecological change.

  17. Carbon, oxygen and biological productivity in the Southern Ocean in and out the Kerguelen plume: CARIOCA drifter results

    NASA Astrophysics Data System (ADS)

    Merlivat, L.; Boutin, J.; d'Ovidio, F.

    2015-06-01

    The Kerguelen Plateau region in the Indian sector of the Southern Ocean supports annually a large-scale phytoplankton bloom which is naturally fertilized with iron. As part of the second Kerguelen Ocean and Plateau compared Study expedition (KEOPS2) in austral spring (October-November 2011), one CARbon Interface OCean Atmosphere (CARIOCA) buoy was deployed east of the Kerguelen Plateau. It drifted eastward downstream along the Kerguelen plume. Hourly surface measurements of pCO2, O2 and ancillary observations were collected between 1 November 2011 and 12 February 2012 with the aim of characterizing the spatial and temporal variability of the biological net community production, NCP, downstream the Kerguelen Plateau, assessing the impact of iron-induced productivity on the biological inorganic carbon consumption and consequently on the CO2 flux exchanged at the air-sea interface. The trajectory of the buoy up to mid-December was within the longitude range 72-83° E, close to the polar front and then in the polar frontal zone, PFZ, up to 97° E. From 17 November to 16 December, the buoy drifted within the Kerguelen plume following a filament carrying dissolved iron, DFe, for a total distance of 700 km. In the first part of the trajectory of the buoy, within the iron plume, the ocean surface waters were always a sink for CO2 and a source for O2, with fluxes of respective mean values equal to -8 mmol CO2 and +38 mmol O2 m-2 d-1. To the east, as the buoy escaped the iron-enriched filament, the fluxes were in the opposite direction, with respective mean values of +5 mmol CO2 and -48 mmol O2 m-2 d-1. These numbers clearly indicate the strong impact of biological processes on the biogeochemistry in the surface waters within the Kerguelen plume in November-mid-December, while it is undetectable to the east in the PFZ from mid- December to mid-February. While the buoy follows the Fe-enriched filament, simultaneous observations of dissolved inorganic carbon (DIC) and

  18. Three regimes of relativistic beam - plasma interaction

    SciTech Connect

    Muggli, P.; Allen, B.; Fang, Y.; Yakimenko, V.; Babzien, M.; Kusche, K.; Fedurin, M.; Vieira, J.; Martins, J.; Silva, L.

    2012-12-21

    Three regimes of relativistic beam - plasma interaction can in principle be reached at the ATF depending on the relative transverse and longitudinal size of the electron bunch when compared to the cold plasma collisionless skin depth c?{omega}{sub pe}: the plasma wakefield accelerator (PWFA), the self-modulation instability (SMI), and the current filamentation instability (CFI) regime. In addition, by choosing the bunch density, the linear, quasi-nonlinear and non linear regime of the PWFA can be reached. In the case of the two instabilities, the bunch density determines the growth rate and therefore the occurrence or not of the instability. We briefly describe these three regimes and outline results demonstrating that all these regime have or will be reached experimentally. We also outline planned and possible follow-on experiments.

  19. Regimes of DNA confined in a nanochannel

    NASA Astrophysics Data System (ADS)

    Dai, Liang; Doyle, Patrick

    2014-03-01

    Scaling regimes for polymers confined to tubular channels are well established when the channel cross-sectional dimension is either very small (Odjik regime) or large (classic de Gennes regime) relative to the polymer Kuhn length. In the literature, there is no clear consensus regarding the intermediate region and if subregimes even exist to connect these two classic bounding regimes. The confluence of emerging single DNA mapping technologies and a resurged interest in the fundamental properties of confined polymers has led to extensive research in this area using DNA as a model system. Due to the DNA molecule's properties and limitations of nanofabrication, most experiments are performed in this intermediate regime with channel dimensions of a few Kuhn lengths. Here we use simulations and theory to reconcile conflicting theories and show that there are indeed extended de Gennes, partial alignment and hairpin regimes located between the two classic regimes. Simulations results for both chain extension and free energy support the existence of these regimes. This research was supported by the National Research Foundation Singapore through the Singapore MIT Alliance for Research and Technology's research program in BioSystems and Micromechanics, the National Science Foundation (CBET-1335938).

  20. Results.

    ERIC Educational Resources Information Center

    Zemsky, Robert; Shaman, Susan; Shapiro, Daniel B.

    2001-01-01

    Describes the Collegiate Results Instrument (CRI), which measures a range of collegiate outcomes for alumni 6 years after graduation. The CRI was designed to target alumni from institutions across market segments and assess their values, abilities, work skills, occupations, and pursuit of lifelong learning. (EV)

  1. Changes in mineralogical and leaching properties of converter steel slag resulting from accelerated carbonation at low CO2 pressure.

    PubMed

    van Zomeren, André; van der Laan, Sieger R; Kobesen, Hans B A; Huijgen, Wouter J J; Comans, Rob N J

    2011-11-01

    Steel slag can be applied as substitute for natural aggregates in construction applications. The material imposes a high pH (typically 12.5) and low redox potential (Eh), which may lead to environmental problems in specific application scenarios. The aim of this study is to investigate the potential of accelerated steel slag carbonation, at relatively low pCO2 pressure (0.2 bar), to improve the environmental pH and the leaching properties of steel slag, with specific focus on the leaching of vanadium. Carbonation experiments are performed in laboratory columns with steel slag under water-saturated and -unsaturated conditions and temperatures between 5 and 90 °C. Two types of steel slag are tested; free lime containing (K3) slag and K1 slag with a very low free lime content. The fresh and carbonated slag samples are investigated using a combination of leaching experiments, geochemical modelling of leaching mechanisms and microscopic/mineralogical analysis, in order to identify the major processes that control the slag pH and resulting V leaching. The major changes in the amount of sequestered CO2 and the resulting pH reduction occurred within 24h, the free lime containing slag (K3-slag) being more prone to carbonation than the slag with lower free lime content (K1-slag). While carbonation at these conditions was found to occur predominantly at the surface of the slag grains, the formation of cracks was observed in carbonated K3 slag, suggesting that free lime in the interior of slag grains had also reacted. The pH of the K3 slag (originally pH±12.5) was reduced by about 1.5 units, while the K1 slag showed a smaller decrease in pH from about 11.7 to 11.1. However, the pH reduction after carbonation of the K3 slag was observed to lead to an increased V-leaching. Vanadium leaching from the K1 slag resulted in levels above the limit values of the Dutch Soil Quality Decree, for both the untreated and carbonated slag. V-leaching from the carbonated K3 slag remained

  2. Health effects of carbon-containing particulate matter: focus on sources and recent research program results.

    PubMed

    Rohr, Annette; McDonald, Jacob

    2016-02-01

    Air pollution is a complex mixture of gas-, vapor-, and particulate-phase materials comprised of inorganic and organic species. Many of these components have been associated with adverse health effects in epidemiological and toxicological studies, including a broad spectrum of carbonaceous atmospheric components. This paper reviews recent literature on the health impacts of organic aerosols, with a focus on specific sources of organic material; it is not intended to be a comprehensive review of all the available literature. Specific emission sources reviewed include engine emissions, wood/biomass combustion emissions, biogenic emissions and secondary organic aerosol (SOA), resuspended road dust, tire and brake wear, and cooking emissions. In addition, recent findings from large toxicological and epidemiological research programs are reviewed in the context of organic PM, including SPHERES, NPACT, NERC, ACES, and TERESA. A review of the extant literature suggests that there are clear health impacts from emissions containing carbon-containing PM, but difficulty remains in apportioning responses to certain groupings of carbonaceous materials, such as organic and elemental carbon, condensed and gas phases, and primary and secondary material. More focused epidemiological and toxicological studies, including increased characterization of organic materials, would increase understanding of this issue.

  3. Diagenesis of bank margin carbonates monitors glacio-eustacy: modeling and core study results

    SciTech Connect

    Matthews, R.K.; Al-Saqri, K.; Frohlich, C.

    1985-01-01

    Subsiding bank margin carbonates provide a monitoring system for high frequency sea level fluctuations. When sea level rises, new reefs and skeletal sands accumulate to near high-stand sea level. When sea level falls, subaerial exposure and related meteoric and mixed water diagenesis rapidly impart their mineralogic, isotopic, chemical, and petrographic signature on the strata. The authors model the interaction of fluctuating sea level (Milankovitch frequencies) and subsiding bank margin carbonates. Characteristic diagenetic lithologies occur seemingly randomly interbedded and unrelatable to specific subaerial exposure surfaces. This is similar to the pattern observed in Eocene bank margin skeletal sands of Kirkuk Field, Iraq. Meteoric diagenesis dominates the upper 35 meters of the authors core. The next 85 meters contain randomly alternating beds of meteoric limestone, mixed water dolomite, and limestone with well-preserved skeletal grains. This sequence is consistent with rapid glacio-eustatic fluctuations of Late Eocene sea level followed by a 35 to 50 meter glacio-eustatic lowering of average sea level at or near Eocene/Oligocene boundary.

  4. Results of a European interlaboratory comparison on CO2 sorption on activated carbon and coals

    NASA Astrophysics Data System (ADS)

    Gensterblum, Yves; Busch, Andreas; Krooss, Bernhard; de Weireld, Guy; Billemont, Pierre; van Hemert, Patrick; Wolf, Karl-Heinz

    2013-04-01

    For the assessment of CO2 storage in coal seams or enhanced coalbed methane production (ECBM), the sorption properties of natural coals are important parameters. Since more and more laboratories worldwide are concerned with measurements of gas sorption on coal it is indispensable to establish quality standards for such experiments. The first two interlaboratory studies on CO2 sorption on coal (Goodman et al. 2004, 2007) revealed a poor agreement of sorption isotherms among the participating laboratories, particularly in the high-pressure range. During the MOVECBM (http://www.movecbm.eu/) project funded by the European Commission (6th framework), an interlaboratory comparison of CO2 sorption on selected coals and activated carbon was initiated. Measurements were performed on dry samples at 45° C using the manometric and the gravimetric method. up to a final pressure of 15 MPa. The first set of high-pressure sorption measurements was performed on a Filtrasorb 400 activated carbon sample in order to minimise heterogeneity effects and to optimize the experimental procedures for the individual (manometric or gravimetric) methods (Gensterblum et al. 2009). Since comparability for the activated carbon was excellent, the measurements were continued using natural coals of various rank (anthracite, bituminous coal and lignite) to study the influence of heterogeneities and varying starting conditions on the CO2 sorption properties (Gensterblum et al. 2010). Compared to the poor reproducibility observed in previous interlaboratory studies (Goodman et al., 2004, 2007) this European study showed excellent agreement (<5 % deviation) among the participating laboratories with good repeatability. The sorption data and technical information on the different experimental setups have been used to investigate errors and potential pitfalls in the assessment of high-pressure CO2 sorption isotherms. References Gensterblum Y., P. van Hemert, P. Billemont, A. Busch, B.M. Krooss, G. de

  5. Preliminary Results from the NASA Orbiting Carbon Observatory-2 (OCO-2)

    NASA Astrophysics Data System (ADS)

    Crisp, D.; Eldering, A.; Gunson, M. R.

    2014-12-01

    The NASA Orbiting Carbon Observatory - 2 (OCO-2) was successfully launched from Vandenberg Air Force Base at 9:56:44 UTC on July 2, 2014. After a series of spacecraft checkout activities and orbit raising maneuvers, OCO-2 was inserted at the front of the 705-km Afternoon constellation (A-Train) on August 3rd. This presentation will summarize the science objectives, review the measurement approach, and introduce some preliminary data from the first few months of operation. OCO-2 was designed to return estimates of the column-averaged atmospheric carbon dioxide (CO2) dry air mole fraction (XCO2) with the precision, resolution, and coverage needed to quantify CO2 surface fluxes on regional scales. To meet these goals, it carries and points a 3-channel grating spectrometer that collects high resolution, co-bore-sighted spectra of reflected sunlight in the 765 nm O2 A-band and in the CO2 bands centered near 1610 and 2060 nm. Each channel records 24 spectra per second along a narrow (< 0.8-degree) track, returning about one million soundings each day. At least 10% of these soundings are expected to be sufficiently cloud free to yield full-column estimates of XCO2with single-sounding accuracies of 0.25 % on regional scales at monthly intervals. The instrument is calibrated using on-board sources and targets, the Moon, well-characterized surface sites (Pollock et al. this session), and comparisons with nearly-coincident observations from the Japanese Greenhouse gases Observing SATellite (GOSAT; Kuze et al. this session). Cloudy soundings are identified and screened out (Taylor et al. this session) and the remaining soundings are analyzed to yield spatially-resolved estimates of XCO2 and other geophysical products (c.f. Frankenberg et al. this session). OCO-2 XCO2 estimates are then validated against those from the Total Carbon Column Observing Network (TCCON) to assess their accuracy and precision (Wennberg et al. this session). Preliminary products from each step of this

  6. Climate change impacts on the vegetation carbon cycle of the Iberian Peninsula—Intercomparison of CMIP5 results

    NASA Astrophysics Data System (ADS)

    Aparício, Sara; Carvalhais, Nuno; Seixas, Júlia

    2015-04-01

    The vulnerability of a water-limited region like the Iberian Peninsula (IP) to climate changes drives a great concern and interest in understanding its impacts on the carbon cycle, namely, in terms of biomass production. This study assesses the effects of climate change and rising CO2 on forest growth, carbon sequestration, and water-use efficiency on the IP by late 21st century using 12 models from the CMIP5 project (Coupled Model Intercomparison Project Phase 5). We find a strong agreement among the models under representative concentration pathway 4.5 (RCP4.5) scenario, mostly regarding projected forest growth and increased primary production (13, 9% of gross primary production (GPP) increase projected by the models ensemble). Under RCP8.5 scenario, the results are less conclusive, as seven models project both GPP and net primary production to increase (up to 83% and 69%, respectively), while the remaining four models project the IP as a potential carbon source by late century. Divergences in carbon mass in wood predictions could be attributed to model structures, such as the N cycle, land model component, land cover data and parameterization, and distinct clusters of Earth System Models (ESMs). ESMs divergences in carbon feedbacks are likely being highly impacted by parameterization divergences and susceptibility to climate change and CO2 fertilization effect. Despite projected rainfall reductions, we observe a strong agreement between models regarding the increase of water-use efficiency (by 21% and 34%) under RCP4.5 and RCP8.5, respectively. Results suggest that rising CO2 has the potential to partially alleviate the adverse effects of drought.

  7. First results on stable isotopes in fluid inclusions in cryogenic carbonates from Ural Mountains (Russia)

    NASA Astrophysics Data System (ADS)

    Dublyansky, Yuri; Luetscher, Mark; Spötl, Christoph; Töchterle, Paul; Kadebskaya, Olga

    2015-04-01

    Cryogenic cave carbonates (CCC) were found in a number of caves in the Ural. In contrast to the CCC previously reported from Central Europe, the Uralian CCC have larger sizes (up to 4-5 cm), which allows for more detailed petrographic and geochemical studies. CCCs from Uralian caves commonly show spherulitic shapes due to crystal splitting, supporting the model of calcite precipitating in a freezing water pond. δ18O values of studied CCCs are lower by 1 to 14 o compared to noncryogenic speleothems of Pleistocene and Holocene age from the same caves. δ18O and δ13C values are inversely correlated and typically show a fractionation between the core and the rim of individual samples. These trends are similar to those reported for CCCs from European caves (Žák et al., 2004). Petrographic observations performed on doubly polished, 100-150 micron-thick sections revealed abundant fluid inclusions, trapped between fibres of the spherulites. Petrographic relationships suggest that these inclusions are primary. The isotopic composition of water trapped in fluid inclusions in CCCs from two caves was analyzed following mechanical crushing at 120 °C, cryo-trapping of released water, pyrolysis on glassy carbon at 1400 °C (TC/EA device; Thermo), and analysis of the evolved gases on an isotope ratio mass spectrometer (Delta V Advantage; Thermo Fisher). The lack of peaks on the m/z 2 trace during the heating of the loaded crushing cell attests for a good sealing of the fluid inclusions. The measured δD values range between -136 o and -145 o VSMOW. The values measured in CCCs are more negative than the typical values of fluid inclusion water measured in the Holocene stalagmites from central Ural (-99 to -108 ). This shift toward more negative values is attributed to the isotopic fractionation between ice and water during the freezing. Reference: Žák et al., 2004, Chemical Geology, 2006, 119-136.

  8. Cryogenic cave carbonates as an archive of Late Pleistocene permafrost in the Ural Mountains: preliminary results

    NASA Astrophysics Data System (ADS)

    Dublyansky, Yuri; Kadebskaya, Olga; Cheng, Hai; Luetscher, Mark; Spötl, Christoph

    2015-04-01

    A specific type of cave deposits, cryogenic cave carbonates (CCCs), was discovered in the late 1980s in several caves of Central Europe. Unlike 'common' speleothems that form primarily due to degassing of CO2 from Ca2+ and HCO3- -rich waters, CCCs form by freezing-induced segregation (Žák et al., 2004). The formation of CCCs, hence, requires the presence of both liquid water and freezing temperatures. The latter combination may occur in caves in two situations: (1) freezing-thawing cycles in cave entrance zones; and (2) degrading permafrost conditions, when the active layer reaches the cave ceiling, whilst the deeper parts of the cave remain frozen. The latter situation is associated with a particular type of CCCs, which can be used as a marker for permafrost conditions. Because cave carbonates can be accurately dated using the U/Th method, CCCs may be used to identify events of (degrading) palaeo-permafrost conditions. In this study, CCCs were identified and sampled in four caves, located along a 1000 km-long transect from the northern to the southern Ural Associating the CCCs to permafrost conditions was possible on the basis of field observations (locations deep inside the cave, far from entrance zones) and stable isotope properties (strongly depleted δ18O values, inverse correlation between δ18O and δ13C). Chaikovskiy et al. (2014) reported five U/Th analyses of CCC from three caves: 16.7 ka and 104.8 ka (Divja Cave, northern Ural); and 13.4 ka, 86.5 ka and 125.3 ka (Rossijskaya and Usvinskaya Caves, central Ural). In this study we report 25 additional U/Th ages from northern and central Ural, as well as the first CCC age from southern Ural (Shulgan-Tash Cave). Most of the younger ages (

  9. Gas flaring and resultant air pollution: A review focusing on black carbon.

    PubMed

    Fawole, Olusegun G; Cai, X-M; MacKenzie, A R

    2016-09-01

    Gas flaring is a prominent source of VOCs, CO, CO2, SO2, PAH, NOX and soot (black carbon), all of which are important pollutants which interact, directly and indirectly, in the Earth's climatic processes. Globally, over 130 billion cubic metres of gas are flared annually. We review the contribution of gas flaring to air pollution on local, regional and global scales, with special emphasis on black carbon (BC, "soot"). The temporal and spatial characteristics of gas flaring distinguishes it from mobile combustion sources (transport), while the open-flame nature of gas flaring distinguishes it from industrial point-sources; the high temperature, flame control, and spatial compactness distinguishes gas flaring from both biomass burning and domestic fuel-use. All of these distinguishing factors influence the quantity and characteristics of BC production from gas flaring, so that it is important to consider this source separately in emissions inventories and environmental field studies. Estimate of the yield of pollutants from gas flaring have, to date, paid little or no attention to the emission of BC with the assumption often being made that flaring produces a smokeless flame. In gas flares, soot yield is known to depend on a number of factors, and there is a need to develop emission estimates and modelling frameworks that take these factors into consideration. Hence, emission inventories, especially of the soot yield from gas flaring should give adequate consideration to the variation of fuel gas composition, and to combustion characteristics, which are strong determinants of the nature and quantity of pollutants emitted. The buoyant nature of gas flaring plume, often at temperatures in the range of 2000 K, coupled with the height of the stack enables some of the pollutants to escape further into the free troposphere aiding their long-range transport, which is often not well-captured by model studies.

  10. Carbon, oxygen and biological productivity in the Southern Ocean in and out the Kerguelen plume: CARIOCA drifter results

    NASA Astrophysics Data System (ADS)

    Merlivat, L.; Boutin, J.; d'Ovidio, F.

    2014-12-01

    The Kerguelen Plateau region in the Indian sector of the Southern Ocean supports annually a large-scale phytoplankton bloom which is naturally fertilized with iron. As part of the second Kerguelen Ocean and Plateau compared Study expedition (KEOPS2) in austral spring (October-November 2011), one Carioca buoy was deployed east of the Kerguelen plateau. It drifted eastward downstream in the Kerguelen plume. Hourly surface measurements of pCO2, O2 and ancillary observations were collected between 1 November 2011 to 12 February 2012 with the aim of characterizing the spatial and temporal variability of the biological Net Community Production (NCP) downstream the Kerguelen plateau, assess the impact of iron-induced productivity on the biological carbon consumption and consequently on the CO2 flux exchanged at the air-sea interface. The trajectory of the buoy until mid-December was within the longitude range, 72-83° E, close to the polar front and then in the polar frontal zone, PFZ, until 97° E. From 17 November to 16 December, the buoy drifted within the Kerguelen plume following a filament carrying dissolved iron, DFe, for a total distance of 700 km. In the first part of the trajectory, the ocean surface waters are a sink for CO2 and a source for CO2, with fluxes of respective mean values equal to -8 and +38 mmol CO2 m-2 d-1. Eastward, as the buoy escapes the iron enriched filament, the fluxes are in opposite direction, with respective mean values of +5 and -48 mmol O2 m-2 d-1. These numbers clearly indicate the strong impact of biological processes on the biogeochemistry in the surface waters within the Kerguelen plume in November-mid-December, while it is undetectable eastward in the PFZ from mid-December to mid-February. While the buoy follows the Fe enriched filament, simultaneous observations of dissolved inorganic carbon, DIC, and dissolved oxygen, O2, highlight biological events lasting from 2 to 4 days. Stoichiometric ratios, O2/C, between 1.1 and 1.4 are

  11. Carbon emissions as a result of land use change and accelerated soil erosion: perspectives in time & space.

    NASA Astrophysics Data System (ADS)

    Van Oost, K.; Verstraeten, G.; Notebaert, B.; Broothaerts, N.; Doetterl, S.; Wiaux, F.

    2012-04-01

    Carbon emissions as a result of anthropogenic land use have drastically altered the global C cycle. Analyses reported that land use change has released 156 Pg C from vegetation and soils to the atmosphere in the period 1850-2000, equivalent to c. 50% of fossil fuel emissions. More recently, longer-term analysis of human-induced land cover change have highlighted the importance of past land use changes, with estimates of pre-industrial Holocene carbon emissions ranging between 50 and 357 Pg C. Current global vegetation models represent well the net terrestrial C exchange from both vegetation and soils accompanying land use change. In contrast, C exchange associated with accelerated soil erosion following the conversion of land to agricultural use is not accounted for. Large amounts of C have been exposed to mineralization and burial as a result of agricultural erosion and deposition but its significance for both current and past fluxes of carbon due to changes in land use remains poorly quantified. Here, we present an overview of the key controls on soil erosion-induced changes in C exchange between the soil and the atmosphere. We provide evidence of how erosion processes increase the stabilization potential of soils by advecting mineral surfaces through the soil column. Accelerated erosion provides fresh mineral surfaces to the biologically active soil layer where it can stabilize organic matter inputs from plants at sites of erosion. In combination with the deep burial of allochthonous and autochtonous carbon and the inhibited decomposition upon burial, this acts as a sink mechanism. The conditions under which accelerated erosion leads to the chemical and physical breakdown of soil and a biomass reduction following soil degradation, resulting in a net source are also identified. We also present the integrated biotic flux of carbon for the Holocene as a result of both anthropogenic land use change and accelerated erosion for a large coupled upland

  12. The relationship between void waves and flow regime transition

    SciTech Connect

    Lahey, R.T. Jr.; Drew, D.A.; Kalkach-Navarro, S.; Park, J.W.

    1992-12-31

    The results of an extensive experimental and analytical study on the relationship between void waves and flow regime transition are presented, in particular, the bubbly/slug flow regime transition. It is shown that void wave instability signals a flow regime transition.

  13. Plant interspecific differences in arbuscular mycorrhizal colonization as a result of soil carbon addition.

    PubMed

    Eschen, René; Müller-Schärer, Heinz; Schaffner, Urs

    2013-01-01

    Soil nutrient availability and colonization by arbuscular mycorrhizal fungi are important and potentially interacting factors shaping vegetation composition and succession. We investigated the effect of carbon (C) addition, aimed at reducing soil nutrient availability, on arbuscular mycorrhizal colonization. Seedlings of 27 plant species with different sets of life-history traits (functional group affiliation, life history strategy and nitrophilic status) were grown in pots filled with soil from a nutrient-rich set-aside field and amended with different amounts of C. Mycorrhizal colonization was progressively reduced along the gradient of increasing C addition in 17 out of 27 species, but not in the remaining species. Grasses had lower colonization levels than forbs and legumes and the decline in AM fungal colonization was more pronounced in legumes than in other forbs and grasses. Mycorrhizal colonization did not differ between annual and perennial species, but decreased more rapidly along the gradient of increasing C addition in plants with high Ellenberg N values than in plants with low Ellenberg N values. Soil C addition not only limits plant growth through a reduction in available nutrients, but also reduces mycorrhizal colonization of plant roots. The effect of C addition on mycorrhizal colonization varies among plant functional groups, with legumes experiencing an overproportional reduction in AM fungal colonization along the gradient of increasing C addition. We therefore propose that for a better understanding of vegetation succession on set-aside fields one may consider the interrelationship between plant growth, soil nutrient availability and mycorrhizal colonization of plant roots.

  14. Experimental Results in Support of Simulating Progressive Crush in Carbon-Fiber Textile Composites

    SciTech Connect

    DeTeresa, S J; Allison, L M; Cunningham, B J; Freeman, DC; Saculla, M D; Sanchez, R J; Winchester, S W

    2001-04-02

    This report summarizes the findings of an experimental program conducted to support the modeling of the crush behavior of triaxial braid carbon fiber composites. The matrix material as well as braided panels and tubes were characterized in order to determine material properties, to assess failure modes, and to provide a test bed for new analytical and numerical tools developed specifically for braided composites. The matrix material selected by the ACC was an epoxy vinyl ester (Ashland Hetron 922). Tensile tests were used to compare two formulations-one used by the ACC and one recommended by the resin supplier. The latter was a faster reacting system and gelled in one-third the time of the ACC formulation. Both formulations had an average elongation at failure that was only half of the resin supplier's reported value. Only one specimen of each type came close to the reported elongation value and it was shown that failure invariably initiated at both surface and internal defects. Overall, the tensile properties of the two formulations were nearly identical, but those of the ACC system were more consistent. The properties of the ACC matrix formulation were measured in tension, shear, and compression and the average properties obtained in these tests are summarized.

  15. Seasonal Dynamics of Water, Carbon, and Energy Flux in Mesquite Forest: Project Overview and Preliminary Results

    NASA Astrophysics Data System (ADS)

    Williams, D. G.; Scott, R.; Lin, G.; Martens, D.; Watts, C.; Goodrich, D.; Garatuza, J.; Rodriguez, J.; Edwards, E.; Hultine, K.; Yepez, E.; Ellsworth, P.; Cable, W.; vanHaren, J.; Pierce, D.

    2001-12-01

    Mesquite is the dominant woody plant in floodplain environments of warm deserts in the southwestern US and thus plays a central role in biogeochemical cycling and energy exchange at landscape and potentially regional scales. Our project investigates the biotic and abiotic controls over seasonal dynamics of energy exchange, CO2 uptake and release, and evapotranspiration within a mature mesquite forest on the San Pedro River floodplain in southeastern Arizona. The growing season in the upper San Pedro River basin is punctuated by a very hot, dry period in early summer followed by monsoon rains that stimulate prolific growth of under story C4 grasses. Our general objectives are to determine the impact of summer rains on net ecosystem CO2 exchange (NEE), evapotranspiration (ET), energy fluxes and soil nutrient cycling, and to understand and model component fluxes in these two-layered canopies. We are continuously monitoring NEE and ET using an eddy covariance system mounted on a 14-m tall tower at the site. Three intensive field campaigns (pre-, mid-, and post-monsoon) included measurements of eddy fluxes beneath the mesquite canopy, mesquite sap flow, mesquite leaf area index, mesquite and grass water sources and stomatal conductance, soil moisture distribution, soil respiration, soil carbon and nitrogen pools, and isotopic composition of CO2 and water vapor within and above the canopy boundary layer. This talk will highlight some of the important findings from the first year of this project. >http://www.tucson.ars.ag.gov/~russell/mesquitehome.htm

  16. Preliminary results on the effects of afforestation of maize soils with Populus alba L., on carbon metabolism

    NASA Astrophysics Data System (ADS)

    García-Campos, Elena; Zorita, Félix; Gil-Sotres, Fernando; Leirós, Mā Carmen; Trasar-Cepeda, Carmen

    2010-05-01

    Transformation of a natural soil to agricultural land is generally assumed to be accompanied by increased mineralization of the organic matter and increased CO2emissions; in contrast, afforestation of agricultural soil is thought to lead to sequestration of carbon and incorporation of atmospheric CO2 into the organic matter. In other words the type of management and land use determine whether soils act as carbon sinks or sources, so that transformation of agricultural land to forest land is generally considered to be accompanied by an increase in edaphic carbon, although it is not clear whether this effect is always produced or if it depends on the agricultural history of the land being afforested. In light of the recognised importance of forest land in sequestering C, and therefore in regulating climate change, in 1992 the EU established Regulation 2080 to promote the afforestation of marginal agricultural land. This had strong repercussions in regions such as Galicia (NW Spain) as the afforestation was mainly applied to good quality agricultural land rather than to marginal land. Although, as a result, large areas of agricultural land have been afforested in Galicia, the associated effects on edaphic carbon have not been widely investigated. The present study involves analysis of large number of afforested soils, planted with different trees and located in different areas throughout Galicia (NW Spain), with the aim of investigating the effects on carbon metabolism in agricultural soils transformed for forestry use. Here we report the preliminary results concerning the observed effects on carbon metabolism in six soils afforested with poplar, Populus alba L., of age between 4 and 8 years. In addition to the six soils planted with poplars, adjacent agricultural soils (x6) were analyzed. In each case the adjacent soil was the same as the original soil prior to afforestation, and all were maize soils. Samples of the soils were collected in autumn, after harvesting

  17. Modelling the role of fires in the terrestrial carbon balance by incorporating SPITFIRE into the global vegetation model ORCHIDEE - Part 1: simulating historical global burned area and fire regimes

    NASA Astrophysics Data System (ADS)

    Yue, C.; Ciais, P.; Cadule, P.; Thonicke, K.; Archibald, S.; Poulter, B.; Hao, W. M.; Hantson, S.; Mouillot, F.; Friedlingstein, P.; Maignan, F.; Viovy, N.

    2014-11-01

    Fire is an important global ecological process that influences the distribution of biomes, with consequences for carbon, water, and energy budgets. Therefore it is impossible to appropriately model the history and future of the terrestrial ecosystems and the climate system without including fire. This study incorporates the process-based prognostic fire module SPITFIRE into the global vegetation model ORCHIDEE, which was then used to simulate burned area over the 20th century. Special attention was paid to the evaluation of other fire regime indicators such as seasonality, fire size and fire length, next to burned area. For 2001-2006, the simulated global spatial extent of fire agrees well with that given by satellite-derived burned area data sets (L3JRC, GLOBCARBON, GFED3.1), and 76-92% of the global burned area is simulated as collocated between the model and observation, depending on which data set is used for comparison. The simulated global mean annual burned area is 346 Mha yr-1, which falls within the range of 287-384 Mha yr-1 as given by the three observation data sets; and is close to the 344 Mha yr-1 by the GFED3.1 data when crop fires are excluded. The simulated long-term trend and variation of burned area agree best with the observation data in regions where fire is mainly driven by climate variation, such as boreal Russia (1930-2009), along with Canada and US Alaska (1950-2009). At the global scale, the simulated decadal fire variation over the 20th century is only in moderate agreement with the historical reconstruction, possibly because of the uncertainties of past estimates, and because land-use change fires and fire suppression are not explicitly included in the model. Over the globe, the size of large fires (the 95th quantile fire size) is underestimated by the model for the regions of high fire frequency, compared with fire patch data as reconstructed from MODIS 500 m burned area data. Two case studies of fire size distribution in Canada and US

  18. Effect of Carbon Ion Radiotherapy for Sacral Chordoma: Results of Phase I-II and Phase II Clinical Trials

    SciTech Connect

    Imai, Reiko; Kamada, Tadashi; Tsuji, Hiroshi; Sugawara, Shinji; Serizawa, Itsuko; Tsujii, Hirohiko; Tatezaki, Shin-ichiro

    2010-08-01

    Purpose: To summarize the results of treatment for sacral chordoma in Phase I-II and Phase II carbon ion radiotherapy trials for bone and soft-tissue sarcomas. Patients and Methods: We performed a retrospective analysis of 38 patients with medically unresectable sacral chordomas treated with the Heavy Ion Medical Accelerator in Chiba, Japan between 1996 and 2003. Of the 38 patients, 30 had not received previous treatment and 8 had locally recurrent tumor after previous resection. The applied carbon ion dose was 52.8-73.6 Gray equivalents (median, 70.4) in a total of 16 fixed fractions within 4 weeks. Results: The median patient age was 66 years. The cranial tumor extension was S2 or greater in 31 patients. The median clinical target volume was 523 cm{sup 3}. The median follow-up period was 80 months. The 5-year overall survival rate was 86%, and the 5-year local control rate was 89%. After treatment, 27 of 30 patients with primary tumor remained ambulatory with or without supportive devices. Two patients experienced severe skin or soft-tissue complications requiring skin grafts. Conclusion: Carbon ion radiotherapy appears effective and safe in the treatment of patients with sacral chordoma and offers a promising alternative to surgery.

  19. 78 FR 34340 - Welded Carbon Steel Standard Pipe and Tube Products From Turkey: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-07

    ... did not. The preliminary results are listed below in the section titled ``Preliminary Results of... produced by Borusan and Erbosan for which these companies did not know that the merchandise was...

  20. Global net land carbon sink: Results from the Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP)

    NASA Astrophysics Data System (ADS)

    Huntzinger, D. N.; Schwalm, C. R.; Michalak, A. M.; Cook, R. B.; Jacobson, A. R.; Schaefer, K. M.; Dasgupta, A.; Poco, J.

    2013-12-01

    The Multi-scale Synthesis and Model Intercomparison Project (MsTMIP) is a formal model intercomparison effort focused on improving the diagnosis and attribution of carbon exchange at regional and global scales. Here we present results from the terrestrial biospheric models participating in the MsTMIP effort, focusing on global and regional model estimates of the net land carbon sink. When compared to estimates of the residual net land sink inferred from atmospheric CO2 observations (i.e., fossil fuel emission + land use land cover change - atmospheric increase - ocean uptake), MsTMIP models predict, on average, a weaker global net land uptake of carbon. There is a large spread in MsTMIP estimates of the net land sink (e.g., -2.5 to 5.0 Pg C/yr in 2010, where a negative flux represents a net release to the atmosphere). Some models consistently show the land surface as a net source of carbon to the atmosphere, which is inconsistent with the atmospheric record. In addition, we examine how model estimates of the cumulative global net sink diverge over the period 1900 to 2010, and the degree to which model sensitivity to forcing factors and fundamental differences in model formulation contribute to this divergence. We link differences in estimates of the cumulative land sink back to each model's sensitivity to key forcing factors including climate variability, CO2 fertilization, nitrogen limitation, and land cover / land-use change. For example, the strength of carbon uptake in most models appears to be strongly coupled with atmospheric CO2 concentrations (CO2 fertilization effect). The strength of this relationship, however, varies across models with some models exhibiting a very strong CO2 fertilization effect (e.g., ORCHIDEE), while others not so (e.g., CLM). To inform the comparison across models, structural differences (i.e., which processes are included and how those processes are parameterized) among the participating models are evaluated using hierarchical

  1. Sources of Respired Carbon in a Northern Minnesota Ombrotrophic Spruce Bog: Preliminary 14C Results from the SPRUCE Site.

    NASA Astrophysics Data System (ADS)

    Guilderson, T. P.; McNicol, G.; Machin, A.; Hanson, P. J.; McFarlane, K. J.; Osuna, J. L.; Pett-Ridge, J.; Singleton, M. J.

    2014-12-01

    A significant uncertainty in future land-surface carbon budgets is the response of wetlands to climate change. A corollary and related question is the future net climate (radiative) forcing impact from wetlands. Active wetlands emit both CO2 and CH4 to the atmosphere. CH4 is, over a few decades, a much more potent greenhouse gas than CO2. CO2 has a longer atmospheric lifetime and a longer 'tail' to its radiative influence. Whether wetlands are a net source or sink of atmospheric carbon under future climate change will depend on ecosystem response to rising temperatures and elevated CO2. The largest uncertainty in future wetland C-budgets, and their climate forcing is the stability of the large below-ground carbon stocks, often in the form of peat, and the partitioning of CO2 and CH4 released via ecosystem respiration. In advance of a long-term experimental warming and elevated CO2 manipulation at the DOE Spruce and Peatland Responses Under Climatic and Environmental Change (SPRUCE) site in the Marcell Experimental Forest, we have characterized the source of respired carbon used for both the production of CO2 and CH4. Samples were collected in early June, late July, and will be collected in early September from three large (~1.1 m2, ~0.5m3) chambers from the control plot, and two of the experimental plots selected for heating (+9°C, +4.5°C). Early June fluxes from the three chambers were ~5500 mgC-m-2-d-1 and ~16 mgC-m-2-d-1 for CO2 and CH4 respectively. Radiocarbon analysis of CO2 and CH4 indicate that the source for the respired carbon is for the most part recent, with most 14C values between 30 and 40‰ - i.e., carbon that was photosynthetically fixed in the last few years. In concert with rising air and ground temperatures fluxes in late July increased to ~6500 mgC-m-2-d-1 and ~86 mgC-m-2-d-1. Although deep-heating was initiated in mid to late June we hypothesize that the July respiration signal is dominated by the regular seasonal cycle of natural warming

  2. Drought effects on litterfall, wood production and belowground carbon cycling in an Amazon forest: results of a throughfall reduction experiment.

    PubMed

    Brando, Paulo M; Nepstad, Daniel C; Davidson, Eric A; Trumbore, Susan E; Ray, David; Camargo, Plínio

    2008-05-27

    The Amazon Basin experiences severe droughts that may become more common in the future. Little is known of the effects of such droughts on Amazon forest productivity and carbon allocation. We tested the prediction that severe drought decreases litterfall and wood production but potentially has multiple cancelling effects on belowground production within a 7-year partial throughfall exclusion experiment. We simulated an approximately 35-41% reduction in effective rainfall from 2000 through 2004 in a 1ha plot and compared forest response with a similar control plot. Wood production was the most sensitive component of above-ground net primary productivity (ANPP) to drought, declining by 13% the first year and up to 62% thereafter. Litterfall declined only in the third year of drought, with a maximum difference of 23% below the control plot. Soil CO2 efflux and its 14C signature showed no significant treatment response, suggesting similar amounts and sources of belowground production. ANPP was similar between plots in 2000 and declined to a low of 41% below the control plot during the subsequent treatment years, rebounding to only a 10% difference during the first post-treatment year. Live aboveground carbon declined by 32.5Mgha-1 through the effects of drought on ANPP and tree mortality. Results of this unreplicated, long-term, large-scale ecosystem manipulation experiment demonstrate that multi-year severe drought can substantially reduce Amazon forest carbon stocks.

  3. Flow regimes during immiscible displacement

    DOE PAGES

    Armstrong, Ryan T.; Mcclure, James; Berrill, Mark A.; ...

    2017-02-01

    Fractional ow of immiscible phases occurs at the pore scale where grain surfaces and phases interfaces obstruct phase mobility. However, the larger scale behavior is described by a saturation-dependent phenomenological relationship called relative permeability. As a consequence, pore-scale parameters, such as phase topology and/ or geometry, and details of the flow regime cannot be directly related to Darcy-scale flow parameters. It is well understood that relative permeability is not a unique relationship of wetting-phase saturation and rather depends on the experimental conditions at which it is measured. Herein we use fast X-ray microcomputed tomography to image pore-scale phase arrangements duringmore » fractional flow and then forward simulate the flow regimes using the lattice-Boltzmann method to better understand the underlying pore-scale flow regimes and their influence on Darcy-scale parameters. We find that relative permeability is highly dependent on capillary number and that the Corey model fits the observed trends. At the pore scale, while phase topologies are continuously changing on the scale of individual pores, the Euler characteristic of the nonwetting phase (NWP) averaged over a sufficiently large field of view can describe the bulk topological characteristics; the Euler characteristic decreases with increasing capillary number resulting in an increase in relative permeability. Lastly, we quantify the fraction of NWP that flows through disconnected ganglion dynamics and demonstrate that this can be a significant fraction of the NWP flux for intermediate wetting-phase saturation. Furthermore, rate dependencies occur in our homogenous sample (without capillary end effect) and the underlying cause is attributed to ganglion flow that can significantly influence phase topology during the fractional flow of immiscible phases.« less

  4. Acid rain and weathering damage to carbonate building stone: Results of material loss measurements

    SciTech Connect

    Reddy, M.M.; Youngdahl, C.A.

    1986-11-01

    Marble and limestone specimens were exposed to atmospheric conditions at four eastern US sites. A number of methods were employed for damage assessment; this paper describes the results of chemical and physical measurements of material loss. Good agreement was observed among results obtained with different methods. A rate of surface recession near 15 ..mu..m/y was observed for skyward surfaces of marble tested in North Carolina, and comparable results were obtained at the other test sites. Response of the porous limestone was assessed with greater difficulty; a rate of loss similar to that of marble was inferred. Initial correlations of material loss with environmental factors are briefly discussed.

  5. Acid rain and weathering damage to carbonate building stone: Results of material loss measurements

    SciTech Connect

    Reddy, M.; Youngdahl, C.A.

    1987-01-01

    Marble and limestone specimens were exposed to atmospheric conditions at four eastern U.S. sites. A number of methods were employed for damage assessment; this paper describes the results of chemical and physical measurements of material loss. Good agreement was observed among results obtained with different methods. A rate of surface recession near 15 ..mu..m/y was observed for skyward surfaces of marble tested in North Carolina, and comparable results were obtained at the other test sites. Response of the porous limestone was assessed with greater difficulty; a rate of loss similar to that of marble was inferred. Initial correlations of material loss with environmental factors are briefly discussed.

  6. 75 FR 18788 - Circular Welded Carbon Steel Pipes and Tubes from Thailand: Preliminary Results and Rescission...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-13

    ..., 2010) (SSSS from Mexico); see also Stainless Steel Plate in Coils From Belgium: Final Results of... cost changes and sales prices during the POR. See Preliminary Cost Calculation Memo. See, e.g.,...

  7. New constraints on the formation history of carbonates in the CI chondrite Ivuna from the Mn-53-Cr-53 chronometer: Preliminary results

    NASA Astrophysics Data System (ADS)

    Endress, M.; Zinner, E.; Weber, D.; Bischoff, A.

    1994-07-01

    Carbonates and sulfates are common in CI chondrites and are believed to have resulted from aqueous alteration processes on the CI parent body. The carbonates occur mostly either as single grains or as polycrystalline chunks and are dominated by dolomites with varying Fe, Mg, and Mn contents. Calcites and breunnerites are less abundant. Since dolomites have MnO contents of up to 15 wt% and generally low Cr2O3 contents, we carried our exploratory SIMS analyses on dolomites in order to determine, whether a Mn-53-Cr-53 chronometer could provide constraints on the formation times of carbonates in CIs. We focused on carbonate fragments in Ivuna, since they can be easily recognized in thin sections, but also measured one carbonate from Orgueil. Our data indicate that aqueous alteration must have occurred soon after formation of the Ivuna parent body, perhaps even before accretion and accumulation was completed. Our results are similar to, but more stringent than, those obtained from Sr isotope data on carbonates in Orgueil, which imply that Ca-Mg carbonate precipitation was completed within 50 m.y. after formation of the Orgueil parent body. Further Mn-Cr studies, now underway, are disigned to determine whether or not carbonate fragments and carbonate grains in distinct lithic units of Ivuna, and different carbonate phases like dolomites and breunnerites precipitated at the same time.

  8. QuickStats: Number of Deaths Resulting from Unintentional Carbon Monoxide Poisoning,* by Month and Year - National Vital Statistics System, United States, 2010-2015.

    PubMed

    2017-03-03

    During 2010-2015, a total of 2,244 deaths resulted from unintentional carbon monoxide poisoning, with the highest numbers of deaths each year occurring in winter months. In 2015, a total of 393 deaths resulting from unintentional carbon monoxide poisoning occurred, with 36% of the deaths occurring in December, January, or February.

  9. Second Generation International Space Station (ISS) Total Organic Carbon Analyzer (TOCA) Verification Testing and On-Orbit Performance Results

    NASA Technical Reports Server (NTRS)

    Bentley, Nicole L.; Thomas, Evan A.; VanWie, Michael; Morrison, Chad; Stinson, Richard G.

    2010-01-01

    The Total Organic Carbon Analyzer (TOGA) is designed to autonomously determine recovered water quality as a function of TOC. The current TOGA has been on the International Space Station since November 2008. Functional checkout and operations revealed complex operating considerations. Specifically, failure of the hydrogen catalyst resulted in the development of an innovative oxidation analysis method. This method reduces the activation time and limits the hydrogen produced during analysis, while retaining the ability to indicate TOC concentrations within 25% accuracy. Subsequent testing and comparison to archived samples returned from the Station and tested on the ground yield high confidence in this method, and in the quality of the recovered water.

  10. Preliminary Results of the Permafrost Carbon Study in the Lower Kolyma Lowland (Eastern Siberia) Based on Drilling Record

    NASA Astrophysics Data System (ADS)

    Spektor, V. V.; Kholodov, A. L.; Bulygina, E. B.; Andreeva, V.; Broderick, D.; Spawn, S.; Natali, S.; Davydova, A.

    2012-12-01

    In 2012, the Polaris Project (thepolarisproject.org, Director R.M. Holmes) has conducted the permafrost drilling on the Kolyma Lowland for a complex study of permafrost carbon as a potential source for microbial decomposition. In July 2012, the first two boreholes, 15.1 and 13.4 m in depth, were drilled. The first borehole (BH 12/1) was drilled in the stratum of ice complex (yedoma) on the local watershed near the Schuch'e lake in the vicinity of the town Chersky (N68°44.7' E161°23'). The depth of active layer is 45 cm. The permafrost to the depth of 15.1 m represents grey and brown silts with predominant homogeneous structure. Silts contain numerous thread-like roots, scarce plant macrofossils, and in places are colored with unclear spots of ferrugination. Cryostructure is mainly pore ice or thin lense-like ice layers. Wedge ice is observed in the interval 12.5-12.9 m. The moisture volumetric percentage of silts varies along the stratum, mainly, between 40-50%. The organic content, defined in every 20 cm of the core as a loss on ignition, varies between 2-4%. The second borehole (BH 12/2), located in the Pleistocene Park (N68°30.8' E161°30') was drilled through modern floodplain sediments (0-0.6 m) of the Kolyma River with polygonal network at the surface, underlain by peat (0.6-1.3 m), silt deposits of thermokarst lake (1.3-12.0 m), and river grey sands (12.0-13.4 m). The active layer thickness is 65 cm. The cryostructure is predominantly lattice-like. Silts contain modern wedge ice at the depth of 2.5-2.7 m. Mollusk shells and large amount of plant macrofossils are observed in the interval 5.7-8.0 m. The organic content in the thermokarst deposits varies in average within 2-3 %, but is about 1% in the underlying river sands. To investigate permafrost carbon, samples for microbial and enzyme activities, as well as samples of trapped gases were collected from different horizons of frozen cores. Samples for palynological, diatom, and lithological analyses, as

  11. Option pricing with regime switching by trinomial tree method

    NASA Astrophysics Data System (ADS)

    Yuen, Fei Lung; Yang, Hailiang

    2010-02-01

    We present a fast and simple tree model to price simple and exotic options in Markov Regime Switching Model (MRSM) with multi-regime. We modify the trinomial tree model of Boyle (1986) [12] by controlling the risk neutral probability measure in different regime states to ensure that the tree model can accommodate the data of all different regimes at the same time preserving its combining tree structure. In MRSM, the market might not be complete, therefore we provide some ideas and discussions on managing the regime switching risk in support of our results.

  12. Biological and physical forcing of carbonate chemistry in an upwelling filament off northwest Africa: Results from a Lagrangian study

    NASA Astrophysics Data System (ADS)

    Loucaides, Socratis; Tyrrell, Toby; Achterberg, Eric P.; Torres, Ricardo; Nightingale, Philip D.; Kitidis, Vassilis; Serret, Pablo; Woodward, Malcolm; Robinson, Carol

    2012-09-01

    The Mauritanian upwelling system is one of the most biologically productive regions of the world's oceans. Coastal upwelling transfers nutrients to the sun-lit surface ocean, thereby stimulating phytoplankton growth. Upwelling of deep waters also supplies dissolved inorganic carbon (DIC), high levels of which lead to low calcium carbonate saturation states in surface waters, with potentially adverse effects on marine calcifiers. In this study an upwelled filament off the coast of northwest Africa was followed using drifting buoys and sulphur hexafluoride to determine how the carbonate chemistry changed over time as a result of biological, physical and chemical processes. The initial pHtot in the mixed layer of the upwelled plume was 7.94 and the saturation states of calcite and aragonite were 3.4 and 2.2, respectively. As the plume moved offshore over a period of 9 days, biological uptake of DIC (37 μmol kg-1) reduced pCO2 concentrations from 540 to 410 μatm, thereby increasing pHtot to 8.05 and calcite and aragonite saturation states to 4.0 and 2.7 respectively. The increase (25 μmol kg-1) in total alkalinity over the 9 day study period can be accounted for solely by the combined effects of nitrate uptake and processes that alter salinity (i.e., evaporation and mixing with other water masses). We found no evidence of significant alkalinity accumulation as a result of exudation of organic bases by primary producers. The ongoing expansion of oxygen minimum zones through global warming will likely further reduce the CaCO3 saturation of upwelled waters, amplifying any adverse consequences of ocean acidification on the ecosystem of the Mauritanian upwelling system.

  13. Hydrothermal replacement of biogenic and abiogenic aragonite by Mg-carbonates - Relation between textural control on effective element fluxes and resulting carbonate phase

    NASA Astrophysics Data System (ADS)

    Jonas, Laura; Müller, Thomas; Dohmen, Ralf; Immenhauser, Adrian; Putlitz, Benita

    2017-01-01

    Dolomitization, i.e., the secondary replacement of calcite or aragonite (CaCO3) by dolomite (CaMg[CO3]2), is one of the most volumetrically important carbonate diagenetic processes. It occurs under near surface and shallow burial conditions and can significantly modify rock properties through changes in porosity and permeability. Dolomitization fronts are directly coupled to fluid pathways, which may be related to the initial porosity/permeability of the precursor limestone, an existing fault network or secondary porosity/permeability created through the replacement reaction. In this study, the textural control on the replacement of biogenic and abiogenic aragonite by Mg-carbonates, that are typical precursor phases in the dolomitization process, was experimentally studied under hydrothermal conditions. Aragonite samples with different textural and microstructural properties exhibiting a compact (inorganic aragonite single crystal), an intermediate (bivalve shell of Arctica islandica) and open porous structure (skeleton of coral Porites sp.) were reacted with a solution of 0.9 M MgCl2 and 0.015 M SrCl2 at 200 °C. The replacement of aragonite by a Ca-bearing magnesite and a Mg-Ca carbonate of non-stoichiometric dolomitic composition takes place via a dissolution-precipitation process and leads to the formation of a porous reaction front that progressively replaces the aragonite precursor. The reaction leads to the development of porosity within the reaction front and distinctive microstructures such as gaps and cavities at the reaction interface. The newly formed reaction rim consists of chemically distinct phases separated by sharp boundaries. It was found that the number of phases and their chemical variation decreases with increasing initial porosity and reactive surface area. This observation is explained by variations in effective element fluxes that result in differential chemical gradients in the fluid within the pore space of the reaction rim. Observed

  14. Calcification of the planktonic foraminifera Globigerina bulloides and carbonate ion concentration: Results from the Santa Barbara Basin

    NASA Astrophysics Data System (ADS)

    Osborne, Emily B.; Thunell, Robert C.; Marshall, Brittney J.; Holm, Jessica A.; Tappa, Eric J.; Benitez-Nelson, Claudia; Cai, Wei-Jun; Chen, Baoshan

    2016-08-01

    Planktonic foraminiferal calcification intensity, reflected by shell wall thickness, has been hypothesized to covary with the carbonate chemistry of seawater. Here we use both sediment trap and box core samples from the Santa Barbara Basin to evaluate the relationship between the calcification intensity of the planktonic foraminifera species Globigerina bulloides, measured by area density (µg/µm2), and the carbonate ion concentration of seawater ([CO32-]). We also evaluate the influence of both temperature and nutrient concentration ([PO43-]) on foraminiferal calcification and growth. The presence of two G. bulloides morphospecies with systematically different calcification properties and offset stable isotopic compositions was identified within sampling populations using distinguishing morphometric characteristics. The calcification temperature and by extension calcification depth of the more abundant "normal" G. bulloides morphospecies was determined using δ18O temperature estimates. Calcification depths vary seasonally with upwelling and were used to select the appropriate [CO32-], temperature, and [PO43-] depth measurements for comparison with area density. Seasonal upwelling in the study region also results in collinearity between independent variables complicating a straightforward statistical analysis. To address this issue, we use additional statistical diagnostics and a down core record to disentangle the respective roles of each parameter on G. bulloides calcification. Our results indicate that [CO32-] is the primary variable controlling calcification intensity while temperature influences shell size. We report a modern calibration for the normal G. bulloides morphospecies that can be used in down core studies of well-preserved sediments to estimate past [CO32-].

  15. Results from Carbon Dioxide Washout Testing Using a Suited Manikin Test Apparatus with a Space Suit Ventilation Test Loop

    NASA Technical Reports Server (NTRS)

    Chullen, Cinda; Conger, Bruce; Kanne, Bryan; McMillin, Summer; Vonau, Walt; Swickrath, Mike

    2016-01-01

    NASA is developing an advanced portable life support system (PLSS) to meet the needs of a new NASA advanced space suit. The PLSS is one of the most critical aspects of the space suit providing the necessary oxygen, ventilation, and thermal protection for an astronaut performing a spacewalk. The ventilation subsystem in the PLSS must provide sufficient carbon dioxide (CO2) removal and ensure that the CO2 is washed away from the oronasal region of the astronaut. CO2 washout is a term used to describe the mechanism by which CO2 levels are controlled within the helmet to limit the concentration of CO2 inhaled by the astronaut. Accumulation of CO2 in the helmet or throughout the ventilation loop could cause the suited astronaut to experience hypercapnia (excessive carbon dioxide in the blood). A suited manikin test apparatus (SMTA) integrated with a space suit ventilation test loop was designed, developed, and assembled at NASA in order to experimentally validate adequate CO2 removal throughout the PLSS ventilation subsystem and to quantify CO2 washout performance under various conditions. The test results from this integrated system will be used to validate analytical models and augment human testing. This paper presents the system integration of the PLSS ventilation test loop with the SMTA including the newly developed regenerative Rapid Cycle Amine component used for CO2 removal and tidal breathing capability to emulate the human. The testing and analytical results of the integrated system are presented along with future work.

  16. Effect of carbon taxes and subsidies on optimal forest rotation age and supply of carbon services

    SciTech Connect

    Kooten, G.C. van; Binkley, C.S.; Delcourt, G.

    1995-05-01

    Carbon taxes and subsidies will affect the optimal forest rotation and, consequently, the carbon stored in forests. Unlike the Hartman rotation, where externality benefits are a function of the volume of timber growing on a site at any time, carbon benefits are a function of the change in biomass. Theoretical and empirical results (for coastal British Columbia and northern Alberta) indicate that, under some tax regimes, it may be socially optimal never to harvest the trees. In general, inclusion of the external benefits from carbon uptake results in rotation ages only a bit longer than the financial (Faustmann) rotation age. 27 refs., 2 figs., 2 tabs.

  17. 75 FR 4779 - Certain Cut-to-Length Carbon-Quality Steel Plate Products From Italy: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-29

    ... International Trade Administration Certain Cut-to-Length Carbon-Quality Steel Plate Products From Italy... duty order on certain cut-to-length carbon- quality steel plate products from Italy. This review covers... antidumping duty order on certain cut-to-length carbon- quality steel plate products (steel plate) from...

  18. 75 FR 27297 - Certain Hot-Rolled Carbon Steel Flat Products from India: Notice of Final Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-14

    ... International Trade Administration Certain Hot-Rolled Carbon Steel Flat Products from India: Notice of Final... antidumping duty administrative review for certain hot-rolled carbon steel flat products from India (``Indian Hot-Rolled''). See Certain Hot-Rolled Carbon Steel Flat Products from India: Notice of...

  19. 76 FR 65497 - Certain Hot-Rolled Carbon Steel Flat Products From India: Amended Final Results of Countervailing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-21

    ... International Trade Administration Certain Hot-Rolled Carbon Steel Flat Products From India: Amended Final... of the countervailing duty order on certain hot-rolled carbon steel flat products (HRCS) from India..., to reflect the CIT's decision in Essar. See Certain Hot-Rolled Carbon Steel Flat Products from...

  20. 76 FR 22868 - Certain Hot-Rolled Flat-Rolled Carbon-Quality Steel Products From Brazil: Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-25

    ... International Trade Administration Certain Hot-Rolled Flat-Rolled Carbon-Quality Steel Products From Brazil... certain hot-rolled flat-rolled carbon- quality steel products (HRS) from Brazil for the period January 1...: Background Since the issuance of Certain Hot-Rolled Flat-Rolled Carbon-Quality Steel Products From...

  1. 77 FR 13093 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-05

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea... administrative review of the countervailing duty (``CVD'') order on corrosion-resistant carbon steel flat... Review'' below. \\1\\ See Corrosion-Resistant Carbon Steel Flat Products from the Republic of...

  2. The Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) FTS: Results From the 2012/13 Alaska Campaigns

    NASA Astrophysics Data System (ADS)

    Kurosu, Thomas P.; Miller, Charles E.; Dinardo, Stephen J.

    2014-05-01

    The Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) is an aircraft-based Earth Venture 1 mission to study the carbon balance of the Alaskan Arctic ecosystem, with a particular focus on carbon release from melting permafrost. Operating from its base in Fairbanks, AK, the CARVE aircraft covers a range of principle flight paths in the Alaskan interior, the Yukon River valley, and the northern Alaska coast around Barrow and Dead Horse. Flight paths are chosen to maximize ecosystem variability and cover burn-recovery/regrowth sequences. CARVE observations cover the Arctic Spring/Summer/Fall seasons, with multiple flights per season and principle flight path. Science operations started in May 2012 and are currently envisaged to continue until 2015. The CARVE suite of instruments includes flask measurements, in situ gas analyzers for CO2, CH4 and CO observations, and a three-band polarizing Fourier Transform Spectrometer (FTS) for column measurements of CO2, CH4, CO, their interfering species (e.g., H2O), and O2. The FTS covers the spectral regions of 4,200-4,900 cm-1, 5,800-6,400 cm-1, and 12,900-13,200 cm-1, with a spectral resolution of 0.2 cm-1. Aircraft-based FTS science observations in Alaska have been performed since 23-05-2012. First-version data products from all CARVE instruments derived from observations during the 2012 campaign were publicly released earlier in 2013. The FTS has performed well during flight conditions, particularly with respect to vibration damping. Outstanding challenges include the need for improved spectral and radiometric calibration, as well as compensating for low signal-to-noise spectra acquired under Alaskan flight conditions. We present results from FTS column observations of CO2, CH4, and CO, observed during the 2012 and 2013 campaigns, including preliminary comparisons of CARVE FTS measurements with satellite observations of CO2 from TANSO/GOSAT and CO from MOPITT.

  3. Identifying natural flow regimes using fish communities

    NASA Astrophysics Data System (ADS)

    Chang, Fi-John; Tsai, Wen-Ping; Wu, Tzu-Ching; Chen, Hung-kwai; Herricks, Edwin E.

    2011-10-01

    SummaryModern water resources management has adopted natural flow regimes as reasonable targets for river restoration and conservation. The characterization of a natural flow regime begins with the development of hydrologic statistics from flow records. However, little guidance exists for defining the period of record needed for regime determination. In Taiwan, the Taiwan Eco-hydrological Indicator System (TEIS), a group of hydrologic statistics selected for fisheries relevance, is being used to evaluate ecological flows. The TEIS consists of a group of hydrologic statistics selected to characterize the relationships between flow and the life history of indigenous species. Using the TEIS and biosurvey data for Taiwan, this paper identifies the length of hydrologic record sufficient for natural flow regime characterization. To define the ecological hydrology of fish communities, this study connected hydrologic statistics to fish communities by using methods to define antecedent conditions that influence existing community composition. A moving average method was applied to TEIS statistics to reflect the effects of antecedent flow condition and a point-biserial correlation method was used to relate fisheries collections with TEIS statistics. The resulting fish species-TEIS (FISH-TEIS) hydrologic statistics matrix takes full advantage of historical flows and fisheries data. The analysis indicates that, in the watersheds analyzed, averaging TEIS statistics for the present year and 3 years prior to the sampling date, termed MA(4), is sufficient to develop a natural flow regime. This result suggests that flow regimes based on hydrologic statistics for the period of record can be replaced by regimes developed for sampled fish communities.

  4. An Assessment of Fire Regime Changes in the Northern Rocky Mountain Region Using Simulated Historical Fire Maps and Remotely Sensed Current Fires

    NASA Astrophysics Data System (ADS)

    Zhao, F.; Zhu, Z.; Huang, C.

    2011-12-01

    Wildland fire is a primary ecosystem process that shapes the landscape of Western United States. Changes in fire regime can therefore have profound impact on ecosystem functions and services, including carbon cycling, habitat conditions, and biodiversity. This poster presents a study on current fire regime and changes in the Northern Rocky Mountain region assessed using contemporary and historical fire regimes. Contemporary fire records from 1984 to 2008 were obtained from the Monitoring Trends in Burn Severity (MTBS) project. Historical (pre-EuroAmerican settlement) fire regimes and fire regime condition class (FRCC), produced by the LANDFIRE project, were simulated using a Landscape Succession Model (LANDSUM). We extracted historical fire frequency (Mean Fire Interval) and fire severity (percentage of severe fire) data from LANDFIRE, and calculated current fire frequency and severity using MTBS data by following the FRCC definition, to evaluate changes in fire regimes in Northern Rocky Mountain area. Preliminary results reveal that the current fire regime in Northern Rocky Mountains may exhibit a general pattern of longer return intervals and more severe fires. Biophysical Setting (BpS) map units from LANDFIRE are used as study units to describe environmental gradients and will be used to further examine whether the observed fire regime changes are controlled by land cover or biophysical settings. The findings of this study will help reveal contemporary fire dynamics in this region and serve for future fire studies and other forest management applications.

  5. An analytical study of nitrogen oxides and carbon monoxide emissions in hydrocarbon combustion with added nitrogen - Preliminary results

    NASA Technical Reports Server (NTRS)

    Bittker, D. A.

    1980-01-01

    The influence of ground-based gas turbine combustor operating conditions and fuel-bound nitrogen (FBN) found in coal-derived liquid fuels on the formation of nitrogen oxides and carbon monoxide is investigated. Analytical predictions of NOx and CO concentrations are obtained for a two-stage, adiabatic, perfectly-stirred reactor operating on a propane-air mixture, with primary equivalence ratios from 0.5 to 1.7, secondary equivalence ratios of 0.5 or 0.7, primary stage residence times from 12 to 20 msec, secondary stage residence times of 1, 2 and 3 msec and fuel nitrogen contents of 0.5, 1.0 and 2.0 wt %. Minimum nitrogen oxide but maximum carbon monoxide formation is obtained at primary zone equivalence ratios between 1.4 and 1.5, with percentage conversion of FBN to NOx decreasing with increased fuel nitrogen content. Additional secondary dilution is observed to reduce final pollutant concentrations, with NOx concentration independent of secondary residence time and CO decreasing with secondary residence time; primary zone residence time is not observed to affect final NOx and CO concentrations significantly. Finally, comparison of computed results with experimental values shows a good semiquantitative agreement.

  6. Diffusivity of carbon in iron and steels at high temperatures

    NASA Astrophysics Data System (ADS)

    Tibbetts, Gary G.

    1980-09-01

    Although the literature contains many measurements of the diffusivity of carbon in Fe and steels, recent progress in plasma carburizing has made this regime around 1050 °C and over 1% carbon concentration of great interest. We have measured the diffusivity of carbon in steel from 975 to 1075 °C up to 1.3% carbon concentration by the steady-state method. Our results are in agreement with previous measurements of Smith and Wells, Batz, and Mehl in the regime of low temperatures and carbon concentrations. Using activation energies determined over a wider temperature range by the latter authors, we derive as an empirical expression for D throughout the range of temperatures and concentrations investigated, D=0.47 exp (-1.6 C) ×exp[-(37 000-6600 C)/RT] cm2/sec. Here, C is expressed in weight percent carbon and the energies are in cal/mole.

  7. Fire regime in Mediterranean ecosystem

    NASA Astrophysics Data System (ADS)

    Biondi, Guido; Casula, Paolo; D'Andrea, Mirko; Fiorucci, Paolo

    2010-05-01

    The analysis of burnt areas time series in Mediterranean regions suggests that ecosystems characterising this area consist primarily of species highly vulnerable to the fire but highly resilient, as characterized by a significant regenerative capacity after the fire spreading. In a few years the area burnt may once again be covered by the same vegetation present before the fire. Similarly, Mediterranean conifer forests, which often refers to plantations made in order to reforest the areas most severely degraded with high erosion risk, regenerate from seed after the fire resulting in high resilience to the fire as well. Only rarely, and usually with negligible damages, fire affects the areas covered by climax species in relation with altitude and soil types (i.e, quercus, fagus, abies). On the basis of these results, this paper shows how the simple Drossel-Schwabl forest fire model is able to reproduce the forest fire regime in terms of number of fires and burned area, describing whit good accuracy the actual fire perimeters. The original Drossel-Schwabl model has been slightly modified in this work by introducing two parameters (probability of propagation and regrowth) specific for each different class of vegetation cover. Using model selection methods based on AIC, the model with the optimal number of classes with different fire behaviour was selected. Two different case studies are presented in this work: Regione Liguria and Regione Sardegna (Italy). Both regions are situated in the center of the Mediterranean and are characterized by a high number of fires and burned area. However, the two regions have very different fire regimes. Sardinia is affected by the fire phenomenon only in summer whilst Liguria is affected by fires also in winter, with higher number of fires and larger burned area. In addition, the two region are very different in vegetation cover. The presence of Mediterranean conifers, (Pinus Pinaster, Pinus Nigra, Pinus halepensis) is quite spread in

  8. Gradual regime shifts in fairy circles

    PubMed Central

    Zelnik, Yuval R.; Meron, Ehud; Bel, Golan

    2015-01-01

    Large responses of ecosystems to small changes in the conditions—regime shifts—are of great interest and importance. In spatially extended ecosystems, these shifts may be local or global. Using empirical data and mathematical modeling, we investigated the dynamics of the Namibian fairy circle ecosystem as a case study of regime shifts in a pattern-forming ecosystem. Our results provide new support, based on the dynamics of the ecosystem, for the view of fairy circles as a self-organization phenomenon driven by water–vegetation interactions. The study further suggests that fairy circle birth and death processes correspond to spatially confined transitions between alternative stable states. Cascades of such transitions, possible in various pattern-forming systems, result in gradual rather than abrupt regime shifts. PMID:26362787

  9. Gradual regime shifts in fairy circles.

    PubMed

    Zelnik, Yuval R; Meron, Ehud; Bel, Golan

    2015-10-06

    Large responses of ecosystems to small changes in the conditions--regime shifts--are of great interest and importance. In spatially extended ecosystems, these shifts may be local or global. Using empirical data and mathematical modeling, we investigated the dynamics of the Namibian fairy circle ecosystem as a case study of regime shifts in a pattern-forming ecosystem. Our results provide new support, based on the dynamics of the ecosystem, for the view of fairy circles as a self-organization phenomenon driven by water-vegetation interactions. The study further suggests that fairy circle birth and death processes correspond to spatially confined transitions between alternative stable states. Cascades of such transitions, possible in various pattern-forming systems, result in gradual rather than abrupt regime shifts.

  10. The Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) FTS: Results From the 2012/13 Alaska Campaigns

    NASA Astrophysics Data System (ADS)

    kurosu, T. P.; Miller, C. E.; Dinardo, S.

    2013-12-01

    The Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) is an aircraft-based Earth Venture 1 mission to study the carbon balance of the Alaskan Arctic ecosystem, with a particular focus on carbon release from melting permafrost. Operating from its base in Fairbanks, AK, the CARVE aircraft covers a range of principle flight paths in the Alaskan interior, the Yukon River valley, and northern Alaska coast around Barrow and Dead Horse. Flight paths are chosen to maximize ecosystem variability and and cover burn-recovery/regrowth sequences. CARVE observations cover the Arctic Spring/Summer/Fall seasons, with multiple flights per season and principle flight paths. Science operations started in 05/2012 and are currently envisaged to continue until 2015. The CARVE suite of instruments includes flask measurements and in situ gas analyzers for CO2, CH4 and CO observations, an active/passive L-band radar for surface conditions (freeze/thaw state), and a three-band polarizing Fourier Transform Spectrometer (FTS) for column measurements of CO2, CH4, CO, and interfering species (e.g., H2O). The FTS covers the spectral regions of 4,200-4,900 cm-1 (CH4, CO), 5,800-6,400 cm-1 (CO2), and 12,900-13,200 cm-1 (O2), with a spectral resolution of 0.2 cm-1. Aircraft-based FTS science observations in Alaska have been performed since 23-05-2012. First-version data products from all CARVE instruments derived from observations during the 2012 campaign were publicly released earlier in 2013. The FTS has performed well during flight conditions, particularly with respect to vibration damping. Outstanding challenges include the need for improved spectral and radiometric calibration, as well as compensating for low signal-to-noise spectra acquired under Alaskan flight conditions. We present results from FTS column observations of CO2, CH4, and CO, observed during the 2012 and 2013 campaigns, including preliminary comparisons of CARVE FTS measurements with satellite observations of CO2

  11. Carbon sink activity is stronger under grazing than under mowing: results from a paired eddy flux towers experiment

    NASA Astrophysics Data System (ADS)

    Pintér, Krisztina; Balogh, János; Koncz, Péter; Hidy, Dóra; Cserhalmi, Dóra; Papp, Marianna; Fóti, Szilvia; Nagy, Zoltán

    2014-05-01

    Effect of grazing vs. mowing on carbon balance of a grassland was investigated by a paired eddy towers (one of them measuring the grazed, the another the mowed treatment) experiment at the Bugacpuszta sandy grassland site (HU-Bug, 46.69° N, 19.6° E, 114m asl, 10.4 ° C annual mean temperature, 562 mm annual precipitation sum) located in the Hungarian Plain. Eddy covariance measurements started in July, 2002. The area of the mowed treatment is 1 ha, it is located within the grazed treatment (500 ha). Electric fence was set up around the selected area in spring of 2011. Study years include 2011, 2012 and 2013. The pasture is managed extensively (average grazing pressure of 0.5 cattle per hectare), the cattle herd regularly took several kilometres during a grazing day. Annual net ecosystem exchange (NEE) of the grassland is strongly limited by precipitation, there were 2 source years within the 11 years (2003-2013) of measurements, during which the average annual balance was -109 gCm-2year-1 with standard deviation of 106 gCm-2year-1. Carbon sink activity of the grassland was stronger in the grazed treatment than in the mowed treatment during the three year study period (paired t-test, P=0.058). In the grazed treatment the average sink strength was -142.8 ±40 gCm-2year-1, while in the mowed treatment the average sink strength was -61.5 ±46.5 gCm-2year-1. Differences of carbon balances between the treatments were positively correlated to the annual sum of evapotranspiration (ET), while ETs of the treatments were almost identical (differences within a 10mm year-1 range) in each study year. Water use efficiency in the mowed treatment was 44% of that in the grazed treatment (P=0.045) as a result of the differences in sink capacity. The higher sensitivity to drought by the mowed treatment manifested in decreased sink capacity during summer and in decreased regeneration capacity during autumn rains as shown by the cumulative NEE in the different years. Minor but

  12. An analytical study of nitrogen oxides and carbon monoxide emissions in hydrocarbon combustion with added nitrogen, preliminary results

    NASA Technical Reports Server (NTRS)

    Bittker, D. A.

    1979-01-01

    The effect of combustor operating conditions on the conversion of fuel-bound nitrogen (FBN) to nitrogen oxides NO sub x was analytically determined. The effect of FBN and of operating conditions on carbon monoxide (CO) formation was also studied. For these computations, the combustor was assumed to be a two stage, adiabatic, perfectly-stirred reactor. Propane-air was used as the combustible mixture and fuel-bound nitrogen was simulated by adding nitrogen atoms to the mixture. The oxidation of propane and formation of NO sub x and CO were modeled by a fifty-seven reaction chemical mechanism. The results for NO sub x and CO formation are given as functions of primary and secondary stage equivalence ratios and residence times.

  13. Optical and Thermo-optical Properties of Polyimide-Single-Walled Carbon Nanotube Films: Experimental Results and Empirical Equations

    NASA Technical Reports Server (NTRS)

    Smith, Joseph G., Jr.; Connell, John W.; Watson, Kent A.; Danehy, Paul M.

    2005-01-01

    The incorporation of single-walled carbon nanotubes (SWNTs) into the bulk of space environmentally durable polymers at loading levels greater than or equal to 0.05 wt % has afforded thin films with surface and volume resistivities sufficient for electrostatic charge mitigation. However, the optical transparency at 500 nm decreased and the thermo-optical properties (solar absorptivity and thermal emissivity) increased with increaed SWNT loading. These properties were also dependent on film thickness. The absorbance characteristics of the films as a function of SWNT loading and film thickness were measured and determined to follow the classical Beer-Lambert law. Based on these results, an empirical relationship was derived and molar absorptivities determined for both the SWNTs and polymer matrix to provide a predictive approximation of these properties. The molar absorptivity determined for SWNTs dispersed in the polymer was comparable to reported solution determined values for HiPco SWNTs.

  14. Microbial biogeochemistry of coastal upwelling regimes in a changing ocean

    NASA Astrophysics Data System (ADS)

    Capone, Douglas G.; Hutchins, David A.

    2013-09-01

    Coastal upwelling regimes associated with eastern boundary currents are the most biologically productive ecosystems in the ocean. As a result, they play a disproportionately important role in the microbially mediated cycling of marine nutrients. These systems are characterized by strong natural variations in carbon dioxide concentrations, pH, nutrient levels and sea surface temperatures on both seasonal and interannual timescales. Despite this natural variability, changes resulting from human activities are starting to emerge. Carbon dioxide derived from fossil fuel combustion is adding to the acidity of upwelled low-pH waters. Low-oxygen waters associated with coastal upwelling systems are growing in their extent and intensity as a result of a rise in upper ocean temperatures and productivity. And nutrient inputs to the coastal ocean continue to grow. Coastal upwelling systems may prove more resilient to changes resulting from human activities than other ocean ecosystems because of their ability to function under extremely variable conditions. Nevertheless, shifts in primary production, fish yields, nitrogen gain and loss, and the flux of climate-relevant gases could result from the perturbation of these highly productive and dynamic ecosystems.

  15. Dynamic treatment regimes: technical challenges and applications

    PubMed Central

    Lizotte, Daniel J.; Qian, Min; Pelham, William E.; Murphy, Susan A.

    2014-01-01

    Dynamic treatment regimes are of growing interest across the clinical sciences because these regimes provide one way to operationalize and thus inform sequential personalized clinical decision making. Formally, a dynamic treatment regime is a sequence of decision rules, one per stage of clinical intervention. Each decision rule maps up-to-date patient information to a recommended treatment. We briefly review a variety of approaches for using data to construct the decision rules. We then review a critical inferential challenge that results from nonregularity, which often arises in this area. In particular, nonregularity arises in inference for parameters in the optimal dynamic treatment regime; the asymptotic, limiting, distribution of estimators are sensitive to local perturbations. We propose and evaluate a locally consistent Adaptive Confidence Interval (ACI) for the parameters of the optimal dynamic treatment regime. We use data from the Adaptive Pharmacological and Behavioral Treatments for Children with ADHD Trial as an illustrative example. We conclude by highlighting and discussing emerging theoretical problems in this area. PMID:25356091

  16. Carbon dioxide production in surface sediments of temporarily anoxic basins (Baltic Sea) and resulting sediment-water interface fluxes

    NASA Astrophysics Data System (ADS)

    Böttcher, M. E.; Al-Raei, A. M.; Winde, V.; Lenz, C.; Dellwig, O.; Leipe, T.; Segl, M.; Struck, U.

    2009-04-01

    Organic matter is mineralized in marine sediments by microbial activity using predominantly oxygen, sulfate, and metal oxides as electron acceptors. Modern euxinic basins as found in the Baltic Sea or the Black Sea are of particular importance because they may serve as type systems for anoxia in Earth's history. We present here results from biogeochemical investigations carried out in the Baltic deeps (Gotland Basin, Landsort Deep) during the first scientific cruise of RV M.S. MERIAN in 2006, additionally during RV Prof. Penck cruises in 2006 and 2007. Short sediment cores were obtained with a multi-corer and analyzed for particulate and dissolved main, minor and trace elements, pH, DIC, methane alkalinity, besides the stable carbon isotopes of dissolved inorganic carbon (DIC). Microsensors were applied to analyze steep gradients of oxygen, sulphide and sulphate. Pore water profiles are evaluated in terms of process rates and associated element fluxes using the PROFILE software (Berg et al., 1998, L&O). Gross and net anaerobic mineralization rates were additionally obtained from core incubations with 35S. Steep gradients in DIC are associated with a strong enrichment of the light stable isotope resulting in the Gotland basin from oxidized OM. Element fluxes across the sediment-water interface are compared with literature data and show for the Baltic Sea a dependence from bottom water redox conditions, and sediment compositions and formation conditions (e.g., accumulation rates). DIC in the anoxic part of the water column in the Landsort Deep and the Gotland Deep show relatively similar isotope values, close to the bottom water value, but steep gradients towards heavier values above the pelagic redoxcline. Acknowledgements: The research was supported by Leibniz IO Warnemünde, DFG (Cruise RV MSM MERIAN 01), and MPG. Thanks to B. Schneider and F. Pollehne stimulating discussions, and S. Lage and A. Schipper for technical support.

  17. Magnetostratigraphy of Mesozoic shallow-water carbonates: Preliminary results from the Middle Jurassic of the Paris basin

    SciTech Connect

    Aissaoui, D.M.; Kirschvink, J.L. )

    1991-03-01

    The use of sedimentary paleomagnetism has enhanced greatly our understanding of the timing of deposition and diagenesis of Cenozoic platform and reefal carbonates. Its application to similar but older deposits will have direct implications for economic exploration and development. The authors report here preliminary paleomagnetic results from the Middle Jurassic limestones of the Paris basin (France). The samples consist mainly of bioclastic and oolitic limestones deposited in ancient counterpart of the shallow-water environments of the Bahama platform. The Jurassic samples are stable to progressive, incremental demagnetization and exhibit magnetization patterns identical to Cenozoic rocks from the Bahama platform or Mururoa Atoll. The natural remanent magnetization of these limestones is weak and comprised between 7.7 x 10{sup {minus}9} to 1.8 x 10{sup {minus}8} AM{sup 2}/kg. Magnetic components of both normal and reversed polarity are observed. Paired isothermal remanent magnetization (IRM) and alternating field demagnetization experiments show that most of the remanence is lost between 20 and 45 mT, which is typical of single-domain biogenic magnetite or maghemite. The ratio of IRM at H{sub RG} to the saturation IRM ranges from 35 to 42% indicating a moderate to low interparticle interaction. This is confirmed by the anhysteretic remanent magnetization as compared with intact, freeze-dried cells of magnetotactic bacteria and chiton teeth. Magnetic minerals extracted from the Jurassic samples are examined to further confirm the occurrence of SD magnetite within the Middle Jurassic limestones of the Paris basin. The preliminary results suggest that the strata should be good for the paleomagnetic investigation of Mesozoic shallow-water carbonates.

  18. Carbonized asphaltene-based carbon-carbon fiber composites

    DOEpatents

    Bohnert, George; Lula, James; Bowen, III, Daniel E.

    2016-12-27

    A method of making a carbon binder-reinforced carbon fiber composite is provided using carbonized asphaltenes as the carbon binder. Combinations of carbon fiber and asphaltenes are also provided, along with the resulting composites and articles of manufacture.

  19. Thermophoretic force on nanocylinders in the free molecule regime

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Luo, Shuang; Xia, Guodong

    2017-03-01

    We theoretically investigate the thermophoresis of nanocylinders in the free molecule regime, wherein the nonrigid-body effect is taken into account. The analytical formulas of the thermophoretic forces on cylinders suspended in both simple gases and binary gas mixtures are derived for the two limiting collision models, i.e., specular and diffuse scatterings, based on the gas kinetic theory. In the limit of the rigid-body collision, the expressions can be reduced to the theoretical results of Garcia-Ybarra and Rosner [AIChE J. 35, 139 (1989), 10.1002/aic.690350115]. The thermophoretic velocities of the nanocylinders (including carbon nanotubes and long-chain n -alkanes) have been evaluated and it is found that the influence of the nonrigid-body effect on thermophoresis is significant for the case of small cylinder radius and low temperatures.

  20. On the regimes of charge reversal.

    PubMed

    Jiménez-Angeles, Felipe; Lozada-Cassou, Marcelo

    2008-05-07

    Charge reversal of the planar electrical double layer is studied by means of a well known integral equation theory. By a numerical analysis, a diagram is constructed with the onset points of charge reversal in the space of the fundamental variables of the system. Within this diagram, two regimes of charge reversal are identified, which are referred to as oscillatory and nonoscillatory. We found that these two regimes can be distinguished through a simple formula. Furthermore, a symmetry between electrostatic and size correlations in charge reversal is exhibited. Agreement of our results with other theories and molecular simulations data is discussed.

  1. Convective Regimes in Crystallizing Basaltic Magma Chambers

    NASA Astrophysics Data System (ADS)

    Gilbert, A. J.; Neufeld, J. A.; Holness, M. B.

    2015-12-01

    Cooling through the chamber walls drives crystallisation in crustal magma chambers, resulting in a cumulate pile on the floor and mushy regions at the walls and roof. The liquid in many magma chambers, either the bulk magma or the interstitial liquid in the mushy regions, may convect, driven either thermally, due to cooling, or compositionally, due to fractional crystallization. We have constructed a regime diagram of the possible convective modes in a system containing a basal mushy layer. These modes depend on the large-scale buoyancy forcing characterised by a global Rayleigh number and the proportion of the chamber height constituting the basal mushy region. We have tested this regime diagram using an analogue experimental system composed of a fluid layer overlying a pile of almost neutrally buoyant inert particles. Convection in this system is driven thermally, simulating magma convection above and within a porous cumulate pile. We observe a range of possible convective regimes, enabling us to produce a regime diagram. In addition to modes characterised by convection of the bulk and interstitial fluid, we also observe a series of regimes where the crystal pile is mobilised by fluid motions. These regimes feature saltation and scouring of the crystal pile by convection in the bulk fluid at moderate Rayleigh numbers, and large crystal-rich fountains at high Rayleigh numbers. For even larger Rayleigh numbers the entire crystal pile is mobilised in what we call the snowglobe regime. The observed mobilisation regimes may be applicable to basaltic magma chambers. Plagioclase in basal cumulates crystallised from a dense magma may be a result of crystal mobilisation from a plagioclase-rich roof mush. Compositional convection within such a mush could result in disaggregation, enabling the buoyant plagioclase to be entrained in relatively dense descending liquid plumes and brought to the floor. The phenocryst load in porphyritic lavas is often interpreted as a

  2. Markovian quantum master equation beyond adiabatic regime.

    PubMed

    Yamaguchi, Makoto; Yuge, Tatsuro; Ogawa, Tetsuo

    2017-01-01

    By introducing a temporal change time scale τ_{A}(t) for the time-dependent system Hamiltonian, a general formulation of the Markovian quantum master equation is given to go well beyond the adiabatic regime. In appropriate situations, the framework is well justified even if τ_{A}(t) is faster than the decay time scale of the bath correlation function. An application to the dissipative Landau-Zener model demonstrates this general result. The findings are applicable to a wide range of fields, providing a basis for quantum control beyond the adiabatic regime.

  3. Markovian quantum master equation beyond adiabatic regime

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Makoto; Yuge, Tatsuro; Ogawa, Tetsuo

    2017-01-01

    By introducing a temporal change time scale τA(t ) for the time-dependent system Hamiltonian, a general formulation of the Markovian quantum master equation is given to go well beyond the adiabatic regime. In appropriate situations, the framework is well justified even if τA(t ) is faster than the decay time scale of the bath correlation function. An application to the dissipative Landau-Zener model demonstrates this general result. The findings are applicable to a wide range of fields, providing a basis for quantum control beyond the adiabatic regime.

  4. Barium in Twilight Zone suspended matter as a potential proxy for particulate organic carbon remineralization: Results for the North Pacific

    SciTech Connect

    Dehairs, F.; Jacquet, S.; Savoye, N.; Van Mooy, B.A.S.; Buesseler, K.; Bishop, J.K.B.; Lamborg, C.H.; Elskens, M.; Baeyens, W.; Boyd, P.W.; Casciotti, K.L.; Monnin, C.

    2008-04-10

    This study focuses on the fate of exported organic carbon in the twilight zone at two contrasting environments in the North Pacific: the oligotrophic ALOHA site (22 degrees 45 minutes N 158 degrees W; Hawaii; studied during June-July 2004) and the mesotrophic Subarctic Pacific K2 site (47 degrees N, 161 degrees W; studied during July-August 2005). Earlier work has shown that non-lithogenic, excess particulate Ba (Ba{sub xs}) in the mesopelagic water column is a potential proxy of organic carbon remineralization. In general Ba{sub xs} contents were significantly larger at K2 than at ALOHA. At ALOHA the Ba{sub xs} profiles from repeated sampling (5 casts) showed remarkable consistency over a period of three weeks, suggesting that the system was close to being at steady state. In contrast, more variability was observed at K2 (6 casts sampled) reflecting the more dynamic physical and biological conditions prevailing in this environment. While for both sites Ba{sub xs} concentrations increased with depth, at K2 a clear maximum was present between the base of the mixed layer at around 50m and 500m, reflecting production and release of Ba{sub xs}. Larger mesopelagic Ba{sub xs} contents and larger bacterial production in the twilight zone at the K2 site indicate that more material was exported from the upper mixed layer for bacterial degradation deeper, compared to the ALOHA site. Furthermore, application of a published transfer function (Dehairs et al., 1997) relating oxygen consumption to the observed Ba{sub xs} data indicated that the latter were in good agreement with bacterial respiration, calculated from bacterial production. These results corroborate earlier findings highlighting the potential of Ba{sub xs} as a proxy for organic carbon remineralization. The range of POC remineralization rates calculated from twilight zone excess particulate Ba contents did also compare well with the depth dependent POC flux decrease as recorded by neutrally buoyant sediment traps

  5. The influence of temperature calibration on the OC–EC results from a dual-optics thermal carbon analyzer

    EPA Science Inventory

    The Sunset Laboratory Dual-Optical Carbonaceous Analyzer that simultaneously measures transmission and reflectance signals is widely used in thermal-optical analysis of particulate matter samples. Most often this instrument is used to measure total carbon (TC), organic carbon (O...

  6. Changes in constituent equilibrium leaching and pore water characteristics of a Portland cement mortar as a result of carbonation.

    PubMed

    Garrabrants, A C; Sanchez, F; Kosson, D S

    2004-01-01

    Two equilibrium-based characterization protocols were applied to ground samples of a cement-based material containing metal oxide powders in both noncarbonated and carbonated states. The effects of carbonation were shown through comparison of (i) material buffering capacity, (ii) constituent equilibrium as a function of leachate pH, and (iii) constituent solubility and release as a function of liquid-to-solid (LS) ratio. As expected, the material alkalinity was significantly neutralized during carbonation. In addition, carbonation of the cement material led to the formation of calcium carbonate and a corresponding increase in arsenic release across the entire pH range. The solubility as a function of pH for lead and copper was lower in the alkaline pH range (pH>9) for carbonated samples compared with the parent material. When solubility and release as a function of LS ratio was compared, carbonation was observed to decrease calcium solubility, sodium and potassium release, and ionic strength. In response to carbonate solid formation, chloride and sulfate release as a function of LS ratio was observed to increase. Trends in constituent concentration as a function of LS ratio were extrapolated to estimate pore water composition at a 0.06 mL/g LS ratio. Significant differences were observed upon comparison of estimated pore water composition to leachate concentrations extracted at LS ratio of 5 mL/g. These differences show that practical laboratory extractions cannot be assumed directly representative of pore water concentrations.

  7. 78 FR 67334 - Suspension Agreement on Certain Cut-to-Length Carbon Steel Plate From Ukraine; Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-12

    ... International Trade Administration Suspension Agreement on Certain Cut-to-Length Carbon Steel Plate From Ukraine... administrative review of the suspension agreement on certain cut-to-length carbon steel plate from Ukraine... (Azovstal) and Ilyich Iron and Steel Works (Ilyich). See Suspension Agreement on Certain...

  8. 76 FR 65179 - Certain Welded Carbon Steel Standard Pipe From Turkey: Extension of Time for Preliminary Results...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-20

    ... International Trade Administration Certain Welded Carbon Steel Standard Pipe From Turkey: Extension of Time for... countervailing duty order on certain welded carbon steel standard pipe from Turkey covering the period of review... ve Ticaret A.S., and the Government of the Republic of Turkey. There are 14 programs under review...

  9. 75 FR 19369 - Certain Hot-Rolled Flat-Rolled Carbon Quality Steel Products from Brazil: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-14

    ... International Trade Administration Certain Hot-Rolled Flat-Rolled Carbon Quality Steel Products from Brazil... conducting an administrative review of the antidumping duty order on certain hot-rolled flat-rolled carbon quality steel products (hot-rolled steel) from Brazil. The review covers Usinas Siderurgicas de...

  10. 75 FR 43931 - Certain Hot-Rolled Flat-Rolled Carbon-Quality Steel Products from Brazil: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-27

    ... International Trade Administration Certain Hot-Rolled Flat-Rolled Carbon-Quality Steel Products from Brazil... a sunset review of the countervailing duty (``CVD'') order on certain hot-rolled flat-rolled carbon... Department initiated the second sunset review of the countervailing duty order on hot-rolled...

  11. 75 FR 80455 - Certain Hot-Rolled Carbon Steel Flat Products From India: Amended Final Results of Countervailing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-22

    ... International Trade Administration Certain Hot-Rolled Carbon Steel Flat Products From India: Amended Final... administrative review of the countervailing duty order on certain hot-rolled carbon steel flat products (HRCS... review of HRCS from India covering the POR of January 1, 2006, through December 31, 2006. See Certain...

  12. 76 FR 77775 - Certain Hot-Rolled Carbon Steel Flat Products From India: Amended Final Results of Countervailing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-14

    ... International Trade Administration Certain Hot-Rolled Carbon Steel Flat Products From India: Amended Final... administrative review of the countervailing duty order on certain ] hot-rolled carbon steel flat products (HRCS... of HRCS from India covering the POR of January 1, 2008, through December 31, 2008. See Certain...

  13. 77 FR 27438 - Certain Corrosion-Resistant Carbon Steel Flat Products From Korea: Final Results of Expedited...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-10

    ... International Trade Administration Certain Corrosion-Resistant Carbon Steel Flat Products From Korea: Final... third five-year sunset review of the countervailing duty order on certain corrosion-resistant carbon..., plated, or coated with corrosion-resistant metals such as zinc, aluminum, or zinc-, aluminum-, nickel-...

  14. Results of rainfall simulation to estimate sediment-bound carbon and nitrogen loss from an Atlantic Coastal Plain (USDA) ultisol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The impact of erosion on soil and carbon loss and redistribution within landscapes is an important component for developing estimates of carbon sequestration potential, management plans to maintain soil quality, and transport of sediment bound agrochemicals. Soils of the Southeastern U.S. Coastal Pl...

  15. 75 FR 63439 - Certain Welded Carbon Steel Standard Pipes and Tubes From India: Extension of the Final Results...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-15

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Certain Welded Carbon Steel Standard Pipes and Tubes From India: Extension of... and tubes from India. See Certain Welded Carbon Steel Standard Pipes and Tubes from India:...

  16. 75 FR 73033 - Circular Welded Carbon Steel Pipes and Tubes from Thailand: Amended Final Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-29

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes from Thailand: Amended Final... steel pipes and tubes (pipes and tubes) from Thailand, covering the period March 1, 2008 through... published in the Federal Register on October 20, 2010. See Circular Welded Carbon Steel Pipes and Tubes...

  17. Understanding the fate of black (pyrogenic) carbon in soil: Preliminary results from a long term field trial

    NASA Astrophysics Data System (ADS)

    Meredith, Will; Ascough, Philippa; Bird, Michael; Large, David; Shen, Licheng; Snape, Colin

    2014-05-01

    Black carbon (BC, also known as pyrogenic carbon) is an 'inert' form of carbon and has been proposed as a means of long-term carbon sequestration, particularly by amending soils and sediments with BC known as biochar. While there is abundant anecdotal evidence of biochar stability over extended timescales it is essential to gain a greater understanding of the degree and mechanisms of biochar degradation in the environment. This study aims to quantitatively assess the stability of biochar by investigating samples from field degradation trials first buried during 2009 in a tropical soil, and recovered after 12 and 36 month intervals. Catalytic hydropyrolysis (HyPy) is a novel analytical tool for the isolation of BC [1] in which high hydrogen pressure (150 bar) and a sulphided Mo catalyst reductively remove the non-BC fraction of the chars, and so isolate the most stable portion of the biochar, defined as BC(HyPy). This method also allows for the non-BC(HyPy) fraction of a sample, which from charcoal is known to include small ring PAHs (<7 rings) of pyrogenic origin to be recovered for molecular characterisation by GC-MS [2]. Biochars made from algae, sugarcane bagasse, and beech wood at 305, 414 and 512°C were emplaced under a variety of conditions allowing variables such as leaf cover, soil depth and pH to be investigated. Char stability (as measured by BC(HyPy) content) is dependent on both the feedstock and temperature of formation. HyPy is known to discriminate (in terms of BC isolation) against low temperature chars, composed of relatively small aromatic clusters [1], resulting in the low BC(HyPy) contents reported for the 305°C chars. Fresh charcoals, and those not subject to environmental degradation have display a similar distribution of aromatic clusters in the non-BC(HyPy) fraction, with 2 to 7 ring PAHs abundant [2]. However, environmentally degraded charcoals such as that from a Chinese river sediment, and an Australian river estuary [3] show a more

  18. Impact of land use change on the land atmosphere carbon flux of South and South East Asia: A Synthesis of Dynamic Vegetation Model Results

    NASA Astrophysics Data System (ADS)

    Cervarich, M.; Shu, S.; Jain, A. K.; Poulter, B.; Stocker, B.; Arneth, A.; Viovy, N.; Kato, E.; Wiltshire, A.; Koven, C.; Sitch, S.; Zeng, N.; Friedlingstein, P.

    2015-12-01

    Understanding our present day carbon cycle and possible solutions to recent increases in atmospheric carbon dioxide is dependent upon quantifying the terrestrial carbon budget. Currently, global land cover and land use change is estimated to emit 0.9 PgC yr-1 compared to emissions due to fossil fuel combustion and cement production of 8.4 PgC yr-1. South and Southeast Asia (India, Nepal, Bhutan, Bangladesh, Burma, Thailand, Laos, Vietnam, Cambodia, Malaysia, Philippines, Indonesia, Pakistan, Myanmar, and Singapore) is a region of rapid land cover and land use change due to the continuous development of agriculture, deforestation, reforestation, afforestation, and the increased demand of land for people to live. In this study, we synthesize outputs of nine models participated in Global Carbon Budget Project to identify the carbon budget of South and southeast Asia, diagnose the contribution of land cover and land use change to carbon emissions and assess areas of uncertainty in the suite of models. Uncertainty is determined using the standard deviation and the coefficient of variation of net ecosystem exchange and its component parts. Results show the region's terrestrial biosphere was a source of carbon emissions from the 1980 to the early 1990s. During the same time period, land cover and land use change increasingly contributed to carbon emission. In the most recent two decades, the region became a carbon sink since emission due to land cover land use changes. Spatially, the greatest total emissions occurred in the tropical forest of Southeast Asia. Additionally, this is the subregion with the greatest uncertainty and greatest biomass. Model uncertainty is shown to be proportional to total biomass. The atmospheric impacts of ENSO are shown to suppress the net biosphere productivity in South and Southeast Asia leading to years of increased carbon emissions.

  19. Technology Advancement for Active Remote Sensing of Carbon Dioxide from Space Using the ASCENDS CarbonHawk Experiment Simulator: First Results

    NASA Technical Reports Server (NTRS)

    Obland, Michael D.; Nehrir, Amin R.; Lin, Bing; Harrison, F. Wallace; Kooi, Susan; Choi, Yonghoon; Plant, James; Yang, Melissa; Antill, Charles; Campbell, Joel; Ismail, Syed; Browell, Edward V.; Meadows, Byron; Dobler, Jeremy; Zaccheo, T. Scott; Moore, Berrien; Crowell, Sean

    2015-01-01

    The ASCENDS CarbonHawk Experiment Simulator (ACES) is a newly developed lidar developed at NASA Langley Research Center and funded by NASA's Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP) that seeks to advance technologies critical to measuring atmospheric column carbon dioxide (CO2) mixing ratios in support of the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. The technology advancements targeted include: (1) increasing the power-aperture product to approach ASCENDS mission requirements by implementing multi-aperture telescopes and multiple co-aligned laser transmitters; (2) incorporating high-efficiency, high-power Erbium-Doped Fiber Amplifiers (EDFAs); (3) developing and incorporating a high-bandwidth, low-noise HgCdTe detector and transimpedence amplifier (TIA) subsystem capable of long-duration autonomous operation on Global Hawk aircraft, and (4) advancing algorithms for cloud and aerosol discrimination. The ACES instrument architecture is being developed for operation on high-altitude aircraft and will be directly scalable to meet the ASCENDS mission requirements. These technologies are critical towards developing not only spaceborne instruments but also their airborne simulators, with lower platform requirements for size, mass, and power, and with improved instrument performance for the ASCENDS mission. ACES transmits five laser beams: three from commercial EDFAs operating near 1.57 microns, and two from the Exelis oxygen (O2) Raman fiber laser amplifier system operating near 1.26 microns. The three EDFAs are capable of transmitting up to 10 watts average optical output power each and are seeded by compact, low noise, stable, narrow-linewidth laser sources stabilized with respect to a CO2 absorption line using a multi-pass gas absorption cell. The Integrated-Path Differential Absorption (IPDA) lidar approach is used at both wavelengths to independently measure the CO2 and O2 column number

  20. Adsorption of lactate dehydrogenase enzyme on carbon nanotubes: how to get accurate results for the cytotoxicity of these nanomaterials.

    PubMed

    Forest, Valérie; Figarol, Agathe; Boudard, Delphine; Cottier, Michèle; Grosseau, Philippe; Pourchez, Jérémie

    2015-03-31

    Carbon nanotube (CNT) cytotoxicity is frequently investigated using in vitro classical toxicology assays. However, these cellular tests, usually based on the use of colorimetric or fluorimetric dyes, were designed for chemicals and may not be suitable for nanosized materials. Indeed, because of their unique physicochemical properties CNT can interfere with the assays and bias the results. To get accurate data and draw reliable conclusions, these artifacts should be carefully taken into account. The aim of this study was to evaluate qualitatively and quantitatively the interferences occurring between CNT and the commonly used lactate dehydrogenase (LDH) assay. Experiments under cell-free conditions were performed, and it was clearly demonstrated that artifacts occurred. They were due to the intrinsic absorbance of CNT on one hand and the adsorption of LDH at the CNT surface on the other hand. The adsorption of LDH on CNT was modeled and was found to fit the Langmuir model. The K(ads) and n(eq) constants were defined, allowing the correction of results obtained from cellular experiments to get more accurate data and lead to proper conclusions on the cytotoxicity of CNT.

  1. Carbon doped GaN buffer layer using propane for high electron mobility transistor applications: Growth and device results

    SciTech Connect

    Li, X.; Nilsson, D.; Danielsson, Ö.; Pedersen, H.; Janzén, E.; Forsberg, U.; Bergsten, J.; Rorsman, N.

    2015-12-28

    The creation of a semi insulating (SI) buffer layer in AlGaN/GaN High Electron Mobility Transistor (HEMT) devices is crucial for preventing a current path beneath the two-dimensional electron gas (2DEG). In this investigation, we evaluate the use of a gaseous carbon gas precursor, propane, for creating a SI GaN buffer layer in a HEMT structure. The carbon doped profile, using propane gas, is a two stepped profile with a high carbon doping (1.5 × 10{sup 18 }cm{sup −3}) epitaxial layer closest to the substrate and a lower doped layer (3 × 10{sup 16 }cm{sup −3}) closest to the 2DEG channel. Secondary Ion Mass Spectrometry measurement shows a uniform incorporation versus depth, and no memory effect from carbon doping can be seen. The high carbon doping (1.5 × 10{sup 18 }cm{sup −3}) does not influence the surface morphology, and a roughness root-mean-square value of 0.43 nm is obtained from Atomic Force Microscopy. High resolution X-ray diffraction measurements show very sharp peaks and no structural degradation can be seen related to the heavy carbon doped layer. HEMTs are fabricated and show an extremely low drain induced barrier lowering value of 0.1 mV/V, demonstrating an excellent buffer isolation. The carbon doped GaN buffer layer using propane gas is compared to samples using carbon from the trimethylgallium molecule, showing equally low leakage currents, demonstrating the capability of growing highly resistive buffer layers using a gaseous carbon source.

  2. Carbon doped GaN buffer layer using propane for high electron mobility transistor applications: Growth and device results

    NASA Astrophysics Data System (ADS)

    Li, X.; Bergsten, J.; Nilsson, D.; Danielsson, Ö.; Pedersen, H.; Rorsman, N.; Janzén, E.; Forsberg, U.

    2015-12-01

    The creation of a semi insulating (SI) buffer layer in AlGaN/GaN High Electron Mobility Transistor (HEMT) devices is crucial for preventing a current path beneath the two-dimensional electron gas (2DEG). In this investigation, we evaluate the use of a gaseous carbon gas precursor, propane, for creating a SI GaN buffer layer in a HEMT structure. The carbon doped profile, using propane gas, is a two stepped profile with a high carbon doping (1.5 × 1018 cm-3) epitaxial layer closest to the substrate and a lower doped layer (3 × 1016 cm-3) closest to the 2DEG channel. Secondary Ion Mass Spectrometry measurement shows a uniform incorporation versus depth, and no memory effect from carbon doping can be seen. The high carbon doping (1.5 × 1018 cm-3) does not influence the surface morphology, and a roughness root-mean-square value of 0.43 nm is obtained from Atomic Force Microscopy. High resolution X-ray diffraction measurements show very sharp peaks and no structural degradation can be seen related to the heavy carbon doped layer. HEMTs are fabricated and show an extremely low drain induced barrier lowering value of 0.1 mV/V, demonstrating an excellent buffer isolation. The carbon doped GaN buffer layer using propane gas is compared to samples using carbon from the trimethylgallium molecule, showing equally low leakage currents, demonstrating the capability of growing highly resistive buffer layers using a gaseous carbon source.

  3. Film thickness for different regimes of fluid-film lubrication

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.

    1980-01-01

    Film thickness equations are provided for four fluid-film lubrication regimes found in elliptical contacts. These regimes are isoviscous-rigid; viscous-rigid; elastohydrodynamic lubrication of low-elastic-modulus materials (soft EHL), or isoviscous-elastic; and elastohydrodynamic lubrication of high-elastic-modulus materials (hard EHL), or viscous-elastic. The influence or lack of influence of elastic and viscous effects is the factor that distinguishes these regimes. The results are presented as a map of the lubrication regimes, with film thickness contours on a log-log grid of the viscosity and elasticity for three values of the ellipticity parameter.

  4. Delinating Thermohaline Double-Diffusive Rayleigh Regimes

    NASA Astrophysics Data System (ADS)

    Graf, T.; Walther, M.; Kolditz, O.; Liedl, R.

    2013-12-01

    In natural systems, convective flow induced from density differences may occur in near-coastal aquifers, atmospheric boundary layers, oceanic streams or within the earth crust. Whether an initially stable, diffusive regime evolves into a convective (stable or chaotic) regime, or vice versa, depends on the system's framing boundary conditions. A conventional parameter to express the relation between diffusive and convective forces of such a density-driven regime is Rayleigh number (Ra). While most systems are mainly dominated by only a single significant driving force (i.e. only temperature or salinity), some systems need to consider two boundary processes (e.g. deep, thus warm, haline flow in porous media). In that case, a two-dimensional, 'double-diffusive' Rayleigh system can be defined. Nield (1998) postulated a boundary between diffusive and convective regime at RaT + RaC = 4pi^2 in the first quadrant (Q1), with Rayleigh numbers for temperature and concentration respectively. The boundary in the forth quadrant (Q4) could not exactly be determined, yet the approximate position estimated. Simulations with HydroGeoSphere (Therrien, 2010) using a vertical, quadratic, homogeneous, isotropic setup confirmed the existence of the 4pi^2-boundary and revealed additional regimes (diffusive, single-roll, double-roll, chaotic) in Q1. Also, non-chaotic, oscillating patterns could be identified in Q4. More detailed investigations with OpenGeoSys (Kolditz, 2012) confirmed the preceding HGS results, and, using a 1:10-scaled domain (height:length), uncovered even more distinctive regimes (diffusive, minimum ten roles, supposely up to 25 roles, and chaotic?) in Q1, while again, oscillating patterns were found in the transition zone between diffusive and chaotic regimes in Q4. Output of numerical simulations from Q1 and Q4 show the mentioned regimes (diffusive, stable-convective, stable-oscillatory, chaotic) while results are displayed in context of a possible delination between

  5. Dissolved organic carbon concentration controls benthic primary production: results from in situ chambers in north-temperate lakes

    USGS Publications Warehouse

    Godwin, Sean C.; Jones, Stuart E.; Weidel, Brian C.; Solomon, Christopher T.

    2014-01-01

    We evaluated several potential drivers of primary production by benthic algae (periphyton) in north-temperate lakes. We used continuous dissolved oxygen measurements from in situ benthic chambers to quantify primary production by periphyton at multiple depths across 11 lakes encompassing a broad range of dissolved organic carbon (DOC) and total phosphorous (TP) concentrations. Light-use efficiency (primary production per unit incident light) was inversely related to average light availability (% of surface light) in 7 of the 11 study lakes, indicating that benthic algal assemblages exhibit photoadaptation, likely through physiological or compositional changes. DOC alone explained 86% of the variability in log-transformed whole-lake benthic production rates. TP was not an important driver of benthic production via its effects on nutrient and light availability. This result is contrary to studies in other systems, but may be common in relatively pristine north-temperate lakes. Our simple empirical model may allow for the prediction of whole-lake benthic primary production from easily obtained measurements of DOC concentration.

  6. Long-Term Efficacy and Safety Profile of Lanthanum Carbonate: Results for up to 6 Years of Treatment

    PubMed Central

    Hutchison, Alastair J.; Barnett, M. Edwina; Krause, Rolfdieter; Kwan, Jonathan T.C.; Siami, Ghodrat A.

    2008-01-01

    Background/Aims Lanthanum carbonate (LC, FOSRENOL®) is an effective phosphate binder for which tolerability and a safety profile have been reported in haemodialysis patients. Patients from previous studies entered a 2-year extension, enabling assessment of efficacy and safety for up to 6 years of LC monotherapy. Methods Patients from four previous trials entered this study. Results Ninety-three patients started the extension, with 22 entering a sixth year of LC treatment. Two-thirds of all patients received LC doses of 2,250 or 3,000 mg/day. Reductions in serum phosphate and calcium × phosphate product were maintained for up to 6 years. There were no new or unexpected adverse events (AEs), and no increase in the incidence of events with increasing treatment exposure. Over the complete duration of therapy, treatment-related AEs occurred in 25.8% of patients and were primarily gastrointestinal in nature. No clinically relevant changes in liver function tests were observed and there was no evidence of adverse effects on the liver, bone or the central nervous system. Conclusions LC monotherapy was effective and well tolerated for up to 6 years with no evidence of safety concerns or increased frequency of AEs. PMID:18667837

  7. Cost-effective choices of marine fuels in a carbon-constrained world: results from a global energy model.

    PubMed

    Taljegard, Maria; Brynolf, Selma; Grahn, Maria; Andersson, Karin; Johnson, Hannes

    2014-11-04

    The regionalized Global Energy Transition model has been modified to include a more detailed shipping sector in order to assess what marine fuels and propulsion technologies might be cost-effective by 2050 when achieving an atmospheric CO2 concentration of 400 or 500 ppm by the year 2100. The robustness of the results was examined in a Monte Carlo analysis, varying uncertain parameters and technology options, including the amount of primary energy resources, the availability of carbon capture and storage (CCS) technologies, and costs of different technologies and fuels. The four main findings are (i) it is cost-effective to start the phase out of fuel oil from the shipping sector in the next decade; (ii) natural gas-based fuels (liquefied natural gas and methanol) are the most probable substitutes during the study period; (iii) availability of CCS, the CO2 target, the liquefied natural gas tank cost and potential oil resources affect marine fuel choices significantly; and (iv) biofuels rarely play a major role in the shipping sector, due to limited supply and competition for bioenergy from other energy sectors.

  8. Epidemiological study of the incidence of cancers eligible for proton or carbon ions therapy: methodology and results of recruitment estimation.

    PubMed

    Patin, Stéphanie; Pommier, Pascal; Yi, Hu; Baron, Marie Hélène; Balosso, Jacques

    2013-01-01

    Context. Hadrontherapy is an innovative form of radiotherapy using beams of protons or carbon ions able to destroy some radio-resistant tumours. Because these tumours are highly specific amongst all cancerous tumours, it is impossible to determine the incidence of these diseases from surveillance registries. Goal. To assess, within the Rhône-Alpes region, the incidence of cancers being hadrontherapy indications. Method. Prospective, multicentre continuous data collection during 1 year, by practitioners participating to multidisciplinary tumor board. Tumours are inoperable, radio resistant, at primary stage of development, or locally recurrent, with low metastatic potential. Results. Study involved 27 healthcare centres, 52 groups of specialist practitioners. The estimated incidence of cancers eligible for hadrontherapy in the Rhône-Alpes region in 2010, that is, for 34 locations in all, is of 8.5/100 000 inhabitants. Appraisal of the low potential of metastatic progression is impeded, because these are rare diseases, whose outcome is unfamiliar to investigators. Conclusion. Future epidemiological studies will need to focus on prognosis and on the metastatic progression rate of these diseases. Indeed, there are few information available on this subject in the literature that could be used to improve preventive measures, medical care, and the surveillance of these rare cancers.

  9. Epidemiological Study of the Incidence of Cancers Eligible for Proton or Carbon Ions Therapy: Methodology and Results of Recruitment Estimation

    PubMed Central

    Patin, Stéphanie; Pommier, Pascal; Yi, Hu; Baron, Marie Hélène; Balosso, Jacques

    2013-01-01

    Context. Hadrontherapy is an innovative form of radiotherapy using beams of protons or carbon ions able to destroy some radio-resistant tumours. Because these tumours are highly specific amongst all cancerous tumours, it is impossible to determine the incidence of these diseases from surveillance registries. Goal. To assess, within the Rhône-Alpes region, the incidence of cancers being hadrontherapy indications. Method. Prospective, multicentre continuous data collection during 1 year, by practitioners participating to multidisciplinary tumor board. Tumours are inoperable, radio resistant, at primary stage of development, or locally recurrent, with low metastatic potential. Results. Study involved 27 healthcare centres, 52 groups of specialist practitioners. The estimated incidence of cancers eligible for hadrontherapy in the Rhône-Alpes region in 2010, that is, for 34 locations in all, is of 8.5/100 000 inhabitants. Appraisal of the low potential of metastatic progression is impeded, because these are rare diseases, whose outcome is unfamiliar to investigators. Conclusion. Future epidemiological studies will need to focus on prognosis and on the metastatic progression rate of these diseases. Indeed, there are few information available on this subject in the literature that could be used to improve preventive measures, medical care, and the surveillance of these rare cancers. PMID:23864858

  10. Increased iron availability resulting from increased CO2 enhances carbon and nitrogen metabolism in the economical marine red macroalga Pyropia haitanensis (Rhodophyta).

    PubMed

    Chen, Binbin; Zou, Dinghui; Yang, Yufeng

    2017-04-01

    Ocean acidification caused by rising CO2 is predicted to increase the concentrations of dissolved species of Fe(II) and Fe(III), leading to the enhanced photosynthetic carbon sequestration in some algal species. In this study, the carbon and nitrogen metabolism in responses to increased iron availability under two CO2 levels (390 μL L(-1) and 1000 μL L(-1)), were investigated in the maricultivated macroalga Pyropia haitanensis (Rhodophyta). The results showed that, elevated CO2 increased soluble carbonhydrate (SC) contents, resulting from enhanced photosynthesis and photosynthetic pigment synthesis in this algae, but declined its soluble protein (SP) contents, resulting in increased ratio of SC/SP. This enhanced photosynthesis performance and carbon accumulation was more significant under iron enrichment condition in seawater, with higher iron uptake rate at high CO2 level. As a key essential biogenic element for algae, Fe-replete functionally contributed to P. haitanensis photosynthesis. Increased SC fundamentally provided carbon skeletons for nitrogen assimilation. The significant increase of carbon and nitrogen assimilation finally contributed to enhanced growth in this alga. This was also intuitively reflected by respiration that provided energy for cellular metabolism and algal growth. We propose that, in the predicted scenario of rising atmospheric CO2, P. haitanensis is capable to adjust its physiology by increasing its carbon and nitrogen metabolism to acclimate the acidified seawater, at the background of global climate change and simultaneously increased iron concentration due to decreased pH levels.

  11. Comparison of Global Model Results from the Carbon-Land Model Intercomparison Project (C-LAMP) with Free-Air Carbon Dioxide Enrichment (FACE) Manipulation Experiments

    SciTech Connect

    Hoffman, Forrest M; Randerson, Jim; Fung, Inez; Thornton, Peter E; Covey, Curtis; Bonan, Gordon; Running, Steven; Norby, Richard J

    2008-01-01

    Free-Air CO{sub 2} Enrichment (FACE) manipulation experiments have been carried out at a handful of sites to gauge the response of the biosphere to significant increases in atmospheric [CO{sub 2}]. Early synthesis results from four temperate forest sites suggest that the response of net primary productivity (NPP) is conserved across a broad range of productivity with a stimulation at the median of 23 {+-} 2% when the surrounding air [CO{sub 2}] was raised to 550{approx}ppm. As a part of the Carbon-Land Model Intercomparison Project (C-LAMP), a community-based model-data comparison activity, the authors have performed a global FACE modeling experiment using two terrestrial biogeochemistry modules, CLM3-CASA and CLM3-CN, coupled to the National Center for Atmospheric Research (NCAR) Community Climate System Model (CCSM). The two models were forced with an improved NCEP/NCAR reanalysis data set and reconstructed atmospheric [CO{sub 2}] and N deposition data through 1997. At the beginning of 1997 in the transient simulations, global atmospheric [CO{sub 2}] was abruptly raised to 550{approx}ppm, the target value used at the FACE sites. In the control runs, [CO{sub 2}] continued to rise following observations until 2004, after which it was held constant out to year 2100. In both simulations, the last 25 years of reanalysis forcing and a constant N deposition were applied after year 2004. Across all forest biomes, the NPP responses from both models are weaker than those reported for the four FACE sites. Moreover, model responses vary widely geographically with a decreasing trend of NPP increases from 40{sup o}N to 70{sup o}N. For CLM3-CASA, the largest responses occur in arid regions of western North America and central Asia, suggesting that responses are most strongly influenced by increased water use efficiency for this model. CLM3-CN exhibits consistently weaker responses than CLM3-CASA' with the strongest responses in central Asia, but significantly constrained by N

  12. Comparison of two thermal-optical methods for the determination of organic carbon and elemental carbon: Results from the southeastern United States

    NASA Astrophysics Data System (ADS)

    Cheng, Yuan; Zheng, Mei; He, Ke-bin; Chen, Yingjun; Yan, Bo; Russell, Armistead G.; Shi, Wenyan; Jiao, Zheng; Sheng, Guoying; Fu, Jiamo; Edgerton, Eric S.

    2011-02-01

    A total of 333 PM 2.5 samples were collected at four sites in the southeastern Aerosol Research and Characterization Study (SEARCH) network during four seasons from 2003 to 2005 and were simultaneously analyzed by two common thermal-optical methods, the National Institute of Occupational Safety and Health (NIOSH) method and the Interagency Monitoring of Protected Visual Environments (IMPROVE) method. The concentrations of total carbon measured by the two methods were comparable, whereas the split of organic carbon (OC) and elemental carbon (EC) was significantly different. The NIOSH-defined EC was lower (up to 80%) than that defined by IMPROVE since the NIOSH method applied the transmittance charring correction and a much higher peak inert mode temperature. The discrepancy between NIOSH- and IMPROVE-defined EC showed distinct seasonal and spatial variations. Potential factors contributing to this discrepancy besides the analytical method were investigated. The discrepancy between NIOSH- and IMPROVE-defined EC was larger in the spring compared to winter due to the influence of biomass burning, which is known to emit significant amount of brown carbon that would complicate the split of OC and EC. The NIOSH-defined EC to IMPROVE-defined EC ratio reached its minimum (0.2-0.5) in the summer, when the largest discrepancy was observed. This was most likely to be attributed to the influence of secondary organic aerosol (SOA). Moreover, the discrepancy between NIOSH- and IMPROVE-defined EC was larger in the coastal and the rural sites where the presence of abundant SOA was found based on previous studies in this region, providing supporting evidence that SOA could contribute to the observed discrepancy in summer.

  13. Estimation of metabolic heat production and methane emission in Sahiwal and Karan Fries heifers under different feeding regimes

    PubMed Central

    Kumar, Sunil; Singh, S. V.; Pandey, Priyanka; Kumar, Narendra; Hooda, O. K.

    2016-01-01

    Aim: The objective of this study was designed to estimate the metabolic heat production and methane emission in Sahiwal and Karan Fries (Holstein-Friesian X Tharparkar) heifers under two different feeding regimes, i.e., feeding regime-1 as per the National Research Council (NRC) (2001) and feeding regime-2 having 15% higher energy (supplementation of molasses) than NRC (2001). Materials and Methods: Six (n = 6) healthy heifers of Sahiwal and Karan Fries with 18-24 months of age were selected from Indian Council of Agricultural Research-National Dairy Research Institute, Karnal. An initial 15 days was maintained under feeding regime-1 and feeding regime-2 as adaptation period; actual experiment was conducted from 16th day onward for next 15 days. At the end of feeding regimes (on day 15th and 16th), expired air and volume were collected in Douglas bag for two consecutive days (morning [6:00 am] and evening [4:00 pm]). The fraction of methane and expired air volume were measured by methane analyzer and wet test meter, respectively. The oxygen consumption and carbon dioxide production were measured by iWorx LabScribe2. Results: The heat production (kcal/day) was significantly (p<0.05) higher in feeding regime-2 as compared to feeding regimen-1 in both breeds. The heat production per unit metabolic body weight was numerically higher in feeding regime-1 than feeding regime-2; however, the values were found statistically non-significant (p>0.05). The energy loss as methane (%) from total heat production was significantly (p<0.05) higher in feeding regime-1. The body weight (kg), metabolic body weight (W0.75), and basal metabolic rate (kcal/kg0.75) were significantly (p<0.05) higher in feeding regime-2 in both breeds. Conclusions: This study indicates that higher energy diet by supplementing molasses may reduce energy loss as methane and enhance the growth of Sahiwal and Karan Fries heifers. PMID:27284226

  14. Regime Dependant Microphysical Variability in Darwin, Australia

    NASA Astrophysics Data System (ADS)

    Dolan, B.; Rutledge, S. A.; Lang, T. J.

    2010-12-01

    Of utmost importance for global precipitation estimates from satellites such as TRMM and the upcoming Global Precipitation Measurement (GPM) is to understand processes that lead to variability in precipitation on sub-seasonal, seasonal, and climatological scales. Many studies have linked differences in rainfall characteristics such as mean diameter (D0) to sub-seasonal regime variability forced by large scale wind shifts, topography, and continental and maritime convection, across various regions of the globe. Several analyses have tied differences between regimes to differing microphysical processes that drive changes in the drop-size distributions occurring in convective rainfall. For example, decreased ice mass aloft and smaller mean diameters are indicative of warm rain processes, while vigorous ice formation leads to large, melting ice to create large drops. If the microphysical variability in different regimes is characterized and understood, the results could be used to improve satellite precipitation algorithms. The polarimetric, Doppler C-band radar, CPOL, located near Darwin, Australia provides a unique platform to study differences in microphysics between land and ocean, as well as variability between monsoon and break periods. The focus of this study is to examine the microphysical processes occurring in four distinct regimes around Darwin (monsoon-land, monsoon-ocean, break-land, break-ocean), using polarimetric data from CPOL. Analyses such as contoured frequency by altitude (CFADs) diagrams, cumulative distribution functions, and mean profiles of precipitation water mass, precipitation ice mass, reflectivity, differential reflectivity and specific differential phase will aide in understanding the physics of precipitation in these regimes. The formation of precipitation ice aloft, warm rain processes, and the contributions of warm rain and cold cloud processes including melting of ice into large drops, will be linked to differences in D0, rain

  15. Modeling the spatiotemporal variability in subsurface thermal regimes across a low-relief polygonal tundra landscape

    NASA Astrophysics Data System (ADS)

    Kumar, Jitendra; Collier, Nathan; Bisht, Gautam; Mills, Richard T.; Thornton, Peter E.; Iversen, Colleen M.; Romanovsky, Vladimir

    2016-09-01

    Vast carbon stocks stored in permafrost soils of Arctic tundra are under risk of release to the atmosphere under warming climate scenarios. Ice-wedge polygons in the low-gradient polygonal tundra create a complex mosaic of microtopographic features. This microtopography plays a critical role in regulating the fine-scale variability in thermal and hydrological regimes in the polygonal tundra landscape underlain by continuous permafrost. Modeling of thermal regimes of this sensitive ecosystem is essential for understanding the landscape behavior under the current as well as changing climate. We present here an end-to-end effort for high-resolution numerical modeling of thermal hydrology at real-world field sites, utilizing the best available data to characterize and parameterize the models. We develop approaches to model the thermal hydrology of polygonal tundra and apply them at four study sites near Barrow, Alaska, spanning across low to transitional to high-centered polygons, representing a broad polygonal tundra landscape. A multiphase subsurface thermal hydrology model (PFLOTRAN) was developed and applied to study the thermal regimes at four sites. Using a high-resolution lidar digital elevation model (DEM), microtopographic features of the landscape were characterized and represented in the high-resolution model mesh. The best available soil data from field observations and literature were utilized to represent the complex heterogeneous subsurface in the numerical model. Simulation results demonstrate the ability of the developed modeling approach to capture - without recourse to model calibration - several aspects of the complex thermal regimes across the sites, and provide insights into the critical role of polygonal tundra microtopography in regulating the thermal dynamics of the carbon-rich permafrost soils. Areas of significant disagreement between model results and observations highlight the importance of field-based observations of soil thermal and

  16. Results of the TTF-TCNQ and the calcium carbonate crystallization on the Long Duration Exposure Facility

    NASA Technical Reports Server (NTRS)

    Nielsen, Kjeld Flemming; Lind, M. David

    1992-01-01

    Experiment A0139A on the Long Duration Exposure Facility (LDEF) carried four large containers into orbit five years with crystal growth solutions for lead sulfide, calcium carbonate, and TTF-TCNQ. Although temperature data was lost, the experimental program had been working since the valves in all containers had been opened. All four experiments produced crystals of varying quality. The calcium carbonate crystals had the best appearance. The TTF-TCNQ crystals were packed together near the valve openings of the container. When taken apart, the single crystals showed some unusual morphological properties. X ray investigations as well as conductivity measurements on long duration space grown TTF-TCNQ crystals will be presented. Comparisons will be made with our previous space solution growth experiments. The TTF-TCNQ crystals are no longer of the highest interest, so this activity has been terminated in favor of calcium carbonate and calcium phosphate crystallizations.

  17. Attitudes about Carbon Monoxide Safety in the United States: Results from the 2005 and 2006 HealthStyles Survey

    PubMed Central

    King, Michael E; Damon, Scott A

    2011-01-01

    Objectives. We sought to identify attitudes and behaviors related to carbon monoxide (CO) safety that can be targeted with public health prevention strategies in the U.S. Methods. The Centers for Disease Control and Prevention added questions about (1) proper placement of gas-powered generators, (2) maintenance of fuel-burning appliances, and (3) use of CO detectors to the 2005 and 2006 HealthStyles national health marketing surveys. Results. In 2005, 63.3% of HealthStyles respondents agreed with or were uncertain about the incorrect statement, “It is safe to run a generator in a garage as long as the door is open,” while 43.1% agreed with or were uncertain about the incorrect statement, “It is safe to run a generator in the basement.” Most of the 2006 respondents (63.5%) agreed that it is important to have their furnace inspected annually. However, fewer than half of the 2006 respondents (42.0%)—most of whom were homeowners—reported owning a CO detector. Conclusions. A large proportion of adults in the U.S. reported attitudes and behaviors that may place them at increased risk for unintentional, non-fire-related CO poisoning, suggesting that current safety messages may not be reaching much of the public. Prevention messages should continue to promote proper generator placement, maintenance of fuel-burning appliances, and use of CO detectors. Development of a comprehensive national strategy for CO surveillance and communication may help identify populations at increased risk and prevent future poisonings. PMID:21563717

  18. Cloud regimes as phase transitions

    NASA Astrophysics Data System (ADS)

    Stechmann, Samuel N.; Hottovy, Scott

    2016-06-01

    Clouds are repeatedly identified as a leading source of uncertainty in future climate predictions. Of particular importance are stratocumulus clouds, which can appear as either (i) closed cells that reflect solar radiation back to space or (ii) open cells that allow solar radiation to reach the Earth's surface. Here we show that these clouds regimes -- open versus closed cells -- fit the paradigm of a phase transition. In addition, this paradigm characterizes pockets of open cells as the interface between the open- and closed-cell regimes, and it identifies shallow cumulus clouds as a regime of higher variability. This behavior can be understood using an idealized model for the dynamics of atmospheric water as a stochastic diffusion process. With this new conceptual viewpoint, ideas from statistical mechanics could potentially be used for understanding uncertainties related to clouds in the climate system and climate predictions.

  19. Density functional theory of the Seebeck coefficient in the Coulomb blockade regime

    NASA Astrophysics Data System (ADS)

    Yang, Kaike; Perfetto, Enrico; Kurth, Stefan; Stefanucci, Gianluca; D'Agosta, Roberto

    2016-08-01

    The Seebeck coefficient plays a fundamental role in identifying the efficiency of a thermoelectric device. Its theoretical evaluation for atomistic models is routinely based on density functional theory calculations combined with the Landauer-Büttiker approach to quantum transport. This combination, however, suffers from serious drawbacks for devices in the Coulomb blockade regime. We show how to cure the theory through a simple correction in terms of the temperature derivative of the exchange correlation potential. Our results compare well with both rate equations and experimental findings on carbon nanotubes.

  20. An Experimental Investigation of Swelling and Elastic Property Changes Resulting from Carbon Dioxide Injection into Prismatic Coal Specimens

    NASA Astrophysics Data System (ADS)

    Dlamini, Bongani

    The world currently relies heavily on fossil fuels to meet its energy needs. The demand from a growing population for energy continues to increase and cannot be met solely by renewable sources of energy. As a result of this high dependence on fossil fuels, various methods of reducing emissions are under investigation. Carbon dioxide Capture and Storage (CCS) has been identified as a potential technique that can be employed to reduce emissions. Unmineable coal seams have been identified as a possible carbon dioxide geologic storage formation. The behavior of coal in response to CO 2 injection is not yet fully understood or well documented. There is a need to understand and quantify the physical changes of coal in response to CO2 injection. These physical changes include properties such as strain (swelling), sonic velocity (compressional and shear velocity), and elastic moduli. Understanding the physical changes undergone by coal during CO2 injection is crucial in evaluating the efficiency and integrity of coal as a potential geologic storage formation. To study and quantify the effect of CO2 injection on adsorption induced strain (swelling) and coal elastic properties, specifically ultrasonic velocity (compressional and shear velocity) and elastic moduli, an experimental approach was followed. Two prismatic coal samples with approximate dimensions of 25cm (9.8 inches) x 17cm (6.7 inches) x 6cm (2.4 inches) were prepared. The coal samples used were from the Lower Sunnyside Coal Seam of the Books Cliffs Coalfields in Utah. A specially designed steel frame was used to contain the samples. Two extreme cases were tested using the samples. For case one, a high (4 MPa) injection pressure and high confining pressure (12 MPa) was used and in case two, both injection pressure and confining pressure were dramatically decreased. The conventional pulse transmission method was used to determine sonic velocities. This method uses transducers to send an ultrasonic wave through the

  1. The influence of temperature calibration on the OC-EC results from a dual optics thermal carbon analyzer

    NASA Astrophysics Data System (ADS)

    Pavlovic, J.; Kinsey, J. S.; Hays, M. D.

    2014-04-01

    Thermal-optical analysis (TOA) is a widely used technique that fractionates carbonaceous aerosol particles into organic and elemental carbon (OC and EC), or carbonate. Thermal sub-fractions of evolved OC and EC are also used for source identification and apportionment; thus, oven temperature accuracy during TOA analysis is essential. Evidence now indicates that the "actual" sample (filter) temperature and the temperature measured by the built-in oven thermocouple (or set-point temperature) can differ by as much as 50 °C. This difference can affect the OC-EC split point selection and consequently the OC and EC fraction and sub-fraction concentrations being reported, depending on the sample composition and in-use TOA method and instrument. The present study systematically investigates the influence of an oven temperature calibration procedure for TOA. A dual-optical carbon analyzer that simultaneously measures transmission and reflectance (TOT and TOR) is used, functioning under the conditions of both the NIOSH 5040 and IMPROVE protocols. Application of the oven calibration procedure to our dual optics instrument significantly changed NIOSH 5040 carbon fractions (OC and EC) and the IMPROVE OC fraction. In addition, the well-known OC-EC split difference between NIOSH and IMPROVE methods is even further perturbed following the instrument calibration. Further study is needed to determine if the wide-spread application of this oven temperature calibration procedure will indeed improve accuracy and our ability to compare among carbonaceous aerosol studies that use TOA.

  2. 78 FR 16252 - Certain Hot-Rolled Carbon Steel Flat Products From India, Indonesia, and Thailand: Final Results...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-14

    ... International Trade Administration Certain Hot-Rolled Carbon Steel Flat Products From India, Indonesia, and... Department'') initiated the second sunset reviews of the countervailing duty (``CVD'') orders on certain hot...). Scope of the Orders The merchandise subject to these orders is hot-rolled steel of a rectangular...

  3. 78 FR 55241 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-10

    ... International Trade Administration Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea...) is conducting an administrative review of the countervailing duty (CVD) order on corrosion-resistant.... SUPPLEMENTARY INFORMATION: Scope of the Order The merchandise covered by this Order \\2\\ is certain...

  4. Using a Class to Conduct a Carbon Inventory: A Case Study with Practical Results at Macalester College

    ERIC Educational Resources Information Center

    Wells, Christopher W.; Savanick, Suzanne; Manning, Christie

    2009-01-01

    Purpose: The purpose of this paper is to discuss the practical realities of using a college seminar to fulfill the carbon audit requirement for signatories to the American College and University Presidents Climate Commitment (ACUPCC) and presents evidence of this approach's advantages as an educational and practical tool.…

  5. 75 FR 47777 - Certain Cut-to-Length Carbon-Quality Steel Plate Products From Italy: Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-09

    ... steels (i.e., USS AR 400, USS AR 500); (5) products made to ASTM A202, A225, A514 grade S, A517 grade S, or their proprietary equivalents; (6) ball bearing steels; (7) tool steels; and (8) silicon manganese... International Trade Administration Certain Cut-to-Length Carbon-Quality Steel Plate Products From Italy:...

  6. Flamelet Regime Diagram for Turbulent Combustion Simulations

    NASA Astrophysics Data System (ADS)

    Chan, Wai Lee; Ihme, Matthias; Kolla, Hemanth; Chen, Jacqueline

    2016-11-01

    The flamelet model has been widely used in numerical combustion investigations, particularly for the closure of large-eddy simulations (LES) of turbulent reacting flows. In most cases, the simulation results demonstrated good agreements with their experimental counterparts. However, a systematic analysis of the flamelet model's applicability, as well as its potential limitations, is seldom conducted, and the model performance is usually based only on a-posteriori comparisons. The objective of this work is to derive a metric that can formally quantify the suitability of the flamelet model in different flame configurations. For this purpose, a flamelet regime diagram has been developed and studied in the context of direct numerical simulations (DNS) of a turbulent lifted jet flame. The implementation of the regime diagram in LES has been investigated through explicit filtering of the DNS results.

  7. Photoelectron circular dichroism in different ionization regimes

    NASA Astrophysics Data System (ADS)

    Wollenhaupt, Matthias

    2016-12-01

    Photoelectron circular dichroism (PECD) describes an asymmetry in the photoelectron angular distribution (PAD) from photoionization of randomly oriented enantiomers with circularly polarized light. Baulieu et al present a comprehensive set of measured PADs from multiphoton ionization of limonene and fenchone in different ionization regimes (multiphoton and tunneling) and analyze the resulting PECD (Baulieu et al 2016 New J. Phys. 18 102002). From their observations the authors conclude that the PECD is universal in the sense that the molecular chirality is encoded in the PAD independent of the ionization regime. The analysis is supplemented by a classical model based on electron scattering in a chiral potential. The paper presents beautiful data and is an important step towards a more complete physical picture of PECD. The results and their interpretation stimulate the ongoing vivid debate on the role of resonances in multiphoton PECD.

  8. Detecting spatial regimes in ecosystems | Science Inventory ...

    EPA Pesticide Factsheets

    Research on early warning indicators has generally focused on assessing temporal transitions with limited application of these methods to detecting spatial regimes. Traditional spatial boundary detection procedures that result in ecoregion maps are typically based on ecological potential (i.e. potential vegetation), and often fail to account for ongoing changes due to stressors such as land use change and climate change and their effects on plant and animal communities. We use Fisher information, an information theory based method, on both terrestrial and aquatic animal data (US Breeding Bird Survey and marine zooplankton) to identify ecological boundaries, and compare our results to traditional early warning indicators, conventional ecoregion maps, and multivariate analysis such as nMDS (non-metric Multidimensional Scaling) and cluster analysis. We successfully detect spatial regimes and transitions in both terrestrial and aquatic systems using Fisher information. Furthermore, Fisher information provided explicit spatial information about community change that is absent from other multivariate approaches. Our results suggest that defining spatial regimes based on animal communities may better reflect ecological reality than do traditional ecoregion maps, especially in our current era of rapid and unpredictable ecological change. Use an information theory based method to identify ecological boundaries and compare our results to traditional early warning

  9. Carbonate clumped isotope paleothermometry and stable isotope results from the Eocene Fenghuo Shan Group, Hoh Xil Basin, Central Tibet

    NASA Astrophysics Data System (ADS)

    Snell, K. E.; Lippert, P. C.; Eiler, J. M.

    2009-12-01

    We present preliminary clumped isotope temperatures, calcite δ13C and δ18O values, and reconstructed water δ18O values from paleosol carbonates and calcite cemented siltstones and mudstones of the Fenghuo Shan Group from stratigraphic sections in the TouTou He subbasin of Hoh Xil Basin on the northern Tibetan Plateau. Models of plateau growth vary in the timing of initial plateau growth, and in their description of the spatial distribution of the plateau through time. Oxygen isotope paleoaltimetry studies have been used to estimate the elevation of the plateau in the past, but this technique requires assumptions about the temperature of mineral formation. Independent estimates of the temperature of mineral formation are potentially useful for identifying samples in which carbonate has undergone post-depositional recrystallization and/or isotopic exchange, and, when plausible primary depositional temperatures are found, for making more accurate estimates of δ18O of the waters from which the calcite precipitated. The calcite δ18O and δ13C values for the cements are relatively invariant with stratigraphic level, averaging -10.1±1.2‰ and -4.5±2.5‰ (PDB), respectively. These values are similar to lacustrine carbonates of similar age from the same region. The paleosol carbonates, in contrast, are 18O- and 13C-enriched relative to the cements, with average δ18O and δ13C values of -2.4±0.8 and -2.8±0.7‰. Carbonate clumped isotope paleotemperatures for the cements and the paleosol carbonates are also markedly different. The cement samples vary from 26 to 83°C and increase consistently with increasing depth, at a steep gradient of ~100°C/km. Paleosol carbonates from depths at which cements recorded 60°C, preserve temperatures of 35°C and 41°C. A calcite spar-filled fracture in one paleosol carbonate had a temperature of 41°C. Finally the reconstructed cement water δ18O values range from 2.8 to -7.6‰(SMOW), with a trend of 0.2‰/°C. The

  10. Changes in mineralogical and leaching properties of converter steel slag resulting from accelerated carbonation at low CO{sub 2} pressure

    SciTech Connect

    Zomeren, Andre van; Laan, Sieger R. van der; Kobesen, Hans B.A.; Huijgen, Wouter J.J.; Comans, Rob N.J.

    2011-11-15

    Highlights: > Accelerated carbonation studied to improve environmental properties of steel slag. > Carbonation found to occur predominantly at surface of the steel slag grains. > Combined geochemical modelling and mineral analysis revealed controlling processes. > Enhanced V-leaching with di-Ca silicate (C2S) dissolution identified as major source. > Identified mineral transformations provide guidance for further quality improvement. - Abstract: Steel slag can be applied as substitute for natural aggregates in construction applications. The material imposes a high pH (typically 12.5) and low redox potential (Eh), which may lead to environmental problems in specific application scenarios. The aim of this study is to investigate the potential of accelerated steel slag carbonation, at relatively low pCO{sub 2} pressure (0.2 bar), to improve the environmental pH and the leaching properties of steel slag, with specific focus on the leaching of vanadium. Carbonation experiments are performed in laboratory columns with steel slag under water-saturated and -unsaturated conditions and temperatures between 5 and 90 {sup o}C. Two types of steel slag are tested; free lime containing (K3) slag and K1 slag with a very low free lime content. The fresh and carbonated slag samples are investigated using a combination of leaching experiments, geochemical modelling of leaching mechanisms and microscopic/mineralogical analysis, in order to identify the major processes that control the slag pH and resulting V leaching. The major changes in the amount of sequestered CO{sub 2} and the resulting pH reduction occurred within 24 h, the free lime containing slag (K3-slag) being more prone to carbonation than the slag with lower free lime content (K1-slag). While carbonation at these conditions was found to occur predominantly at the surface of the slag grains, the formation of cracks was observed in carbonated K3 slag, suggesting that free lime in the interior of slag grains had also reacted

  11. Determination of the Kinetic Oxidation Constants of Carbon Materials on the Basis of Analysis of Experiments on Their Ablation

    NASA Astrophysics Data System (ADS)

    Gorskii, V. V.; Koval‧skii, M. G.; Olenicheva, A. A.

    2017-01-01

    A new approach to the determination of the ablation properties of a heat-shield carbon material on the basis of analysis of the results of an experimental investigation of its ablation in the jet of an electric-arc plant in the nonstationary regime has been formulated. Original data on the kinetic constants of oxidation of carbon by atomic oxygen have been obtained.

  12. Anterior cervical corpectomy: review and comparison of results using titanium mesh cages and carbon fibre reinforced polymer cages.

    PubMed

    Kabir, Syed M R; Alabi, J; Rezajooi, Kia; Casey, Adrian T H

    2010-10-01

    Different types of cages have recently become available for reconstruction following anterior cervical corpectomy. We review the results using titanium mesh cages (TMC) and stackable CFRP (carbon fibre reinforced polymer) cages. Forty-two patients who underwent anterior cervical corpectomy between November 2001 and September 2008 were retrospectively reviewed. Pathologies included cervical spondylotic myelopathy (CSM), cervical radiculopathy, OPLL (ossified posterior longitudinal ligament), metastasis/primary bone tumour, rheumatoid arthritis and deformity correction. All patients were evaluated clinically and radiologically. Outcome was assessed on the basis of the Odom's criteria, neck disability index (NDI) and myelopathy disability index (MDI). Mean age was 60 years and mean follow-up was 1½ years. Majority of the patients had single-level corpectomy. Twenty-three patients had TMC cages while 19 patients had CFRP cages. The mean subsidence noted with TMC cage was 1.91 mm, while with the stackable CFRP cage it was 0.5 mm. This difference was statistically significant (p < 0.05). However, there was no statistically significant correlation noted between subsidence and clinical outcome (p > 0.05) or between subsidence and post-operative sagittal alignment (p > 0.05) in either of the groups. Three patients had significant subsidence (> 3 mm), one of whom was symptomatic. There were no hardware-related complications. On the basis of the Odom's criterion, 9 patients (21.4%) had an excellent outcome, 14 patients (33.3%) had a good outcome, 9 patients (21.4%) had a fair outcome and 5 patients (11.9%) had a poor outcome, i.e. symptoms and signs unchanged or exacerbated. Mean post-operative NDI was 26.27% and mean post-operative MDI was 19.31%. Fusion was noted in all 42 cases. Both TMC and stackable CFRP cages provide solid anterior column reconstruction with good outcome following anterior cervical corpectomy. However, more subsidence is noted with TMC cages though

  13. Global regime shift dynamics of catastrophic sea urchin overgrazing

    PubMed Central

    Ling, S. D.; Scheibling, R. E.; Rassweiler, A.; Johnson, C. R.; Shears, N.; Connell, S. D.; Salomon, A. K.; Norderhaug, K. M.; Pérez-Matus, A.; Hernández, J. C.; Clemente, S.; Blamey, L. K.; Hereu, B.; Ballesteros, E.; Sala, E.; Garrabou, J.; Cebrian, E.; Zabala, M.; Fujita, D.; Johnson, L. E.

    2015-01-01

    A pronounced, widespread and persistent regime shift among marine ecosystems is observable on temperate rocky reefs as a result of sea urchin overgrazing. Here, we empirically define regime-shift dynamics for this grazing system which transitions between productive macroalgal beds and impoverished urchin barrens. Catastrophic in nature, urchin overgrazing in a well-studied Australian system demonstrates a discontinuous regime shift, which is of particular management concern as recovery of desirable macroalgal beds requires reducing grazers to well below the initial threshold of overgrazing. Generality of this regime-shift dynamic is explored across 13 rocky reef systems (spanning 11 different regions from both hemispheres) by compiling available survey data (totalling 10 901 quadrats surveyed in situ) plus experimental regime-shift responses (observed during a total of 57 in situ manipulations). The emergent and globally coherent pattern shows urchin grazing to cause a discontinuous ‘catastrophic’ regime shift, with hysteresis effect of approximately one order of magnitude in urchin biomass between critical thresholds of overgrazing and recovery. Different life-history traits appear to create asymmetry in the pace of overgrazing versus recovery. Once shifted, strong feedback mechanisms provide resilience for each alternative state thus defining the catastrophic nature of this regime shift. Importantly, human-derived stressors can act to erode resilience of desirable macroalgal beds while strengthening resilience of urchin barrens, thus exacerbating the risk, spatial extent and irreversibility of an unwanted regime shift for marine ecosystems.

  14. Towards Extreme Field Physics: Relativistic Optics and Particle Acceleration in the Transparent-Overdense Regime

    NASA Astrophysics Data System (ADS)

    Hegelich, B. Manuel

    2011-10-01

    A steady increase of on-target laser intensity with also increasing pulse contrast is leading to light-matter interactions of extreme laser fields with matter in new physics regimes which in turn enable a host of applications. A first example is the realization of interactions in the transperent-overdense regime (TOR), which is reached by interacting a highly relativistic (a0 >10), ultra high contrast laser pulse [1] with a solid density target, turning it transparent to the laser by the relativistic mass increase of the electrons. Thus, the interactions becomes volumetric, increasing the energy coupling from laser to plasma, facilitating a range of effects, including relativistic optics and pulse shaping, mono-energetic electron acceleration [3], highly efficient ion acceleration in the break-out afterburner regime [4], and the generation of relativistic and forward directed surface harmonics. Experiments at the LANL 130TW Trident laser facility successfully reached the TOR, and show relativistic pulse shaping beyond the Fourier limit, the acceleration of mono-energetic ~40 MeV electron bunches from solid targets, forward directed coherent relativistic high harmonic generation >1 keV Break-Out Afterburner (BOA) ion acceleration of Carbon to >1 GeV and Protons to >100 MeV. Carbon ions were accelerated with a conversion efficiency of >10% for ions >20 MeV and monoenergetic carbon ions with an energy spread of <20%, have been accelerated at up to ~500 MeV, demonstrating 3 out of 4 for key requirements for ion fast ignition. The shown results now approach or exceed the limits set by many applications from ICF diagnostics over ion fast ignition to medical physics. Furthermore, TOR targets traverse a wide range of HEDP parameter space during the interaction ranging from WDM conditions (e.g. brown dwarfs) to energy densities of ~1011 J/cm3 at peak, then dropping back to the underdense but extremely hot parameter range of gamma-ray bursts. Whereas today this regime can

  15. The influence of temperature calibration on the OC-EC results from a dual-optics thermal carbon analyzer

    NASA Astrophysics Data System (ADS)

    Pavlovic, J.; Kinsey, J. S.; Hays, M. D.

    2014-09-01

    Thermal-optical analysis (TOA) is a widely used technique that fractionates carbonaceous aerosol particles into organic and elemental carbon (OC and EC), or carbonate. Thermal sub-fractions of evolved OC and EC are also used for source identification and apportionment; thus, oven temperature accuracy during TOA analysis is essential. Evidence now indicates that the "actual" sample (filter) temperature and the temperature measured by the built-in oven thermocouple (or set-point temperature) can differ by as much as 50 °C. This difference can affect the OC-EC split point selection and consequently the OC and EC fraction and sub-fraction concentrations being reported, depending on the sample composition and in-use TOA method and instrument. The present study systematically investigates the influence of an oven temperature calibration procedure for TOA. A dual-optical carbon analyzer that simultaneously measures transmission and reflectance (TOT and TOR) is used, functioning under the conditions of both the National Institute of Occupational Safety and Health Method 5040 (NIOSH) and Interagency Monitoring of Protected Visual Environment (IMPROVE) protocols. The application of the oven calibration procedure to our dual-optics instrument significantly changed NIOSH 5040 carbon fractions (OC and EC) and the IMPROVE OC fraction. In addition, the well-known OC-EC split difference between NIOSH and IMPROVE methods is even further perturbed following the instrument calibration. Further study is needed to determine if the widespread application of this oven temperature calibration procedure will indeed improve accuracy and our ability to compare among carbonaceous aerosol studies that use TOA.

  16. Dominant takeover regimes for genetic algorithms

    NASA Technical Reports Server (NTRS)

    Noever, David; Baskaran, Subbiah

    1995-01-01

    The genetic algorithm (GA) is a machine-based optimization routine which connects evolutionary learning to natural genetic laws. The present work addresses the problem of obtaining the dominant takeover regimes in the GA dynamics. Estimated GA run times are computed for slow and fast convergence in the limits of high and low fitness ratios. Using Euler's device for obtaining partial sums in closed forms, the result relaxes the previously held requirements for long time limits. Analytical solution reveal that appropriately accelerated regimes can mark the ascendancy of the most fit solution. In virtually all cases, the weak (logarithmic) dependence of convergence time on problem size demonstrates the potential for the GA to solve large N-P complete problems.

  17. Results of the TTF-TCNQ- and the calcium carbonate-crystallization on the Long Duration Exposure Facility

    NASA Technical Reports Server (NTRS)

    Nielsen, Kjeld Flemming; Lind, M. David

    1991-01-01

    Experiment AO139A on the Long Duration Exposure Facility (LDEF) carried four large containers into orbit for five years with crystal growth solutions for lead sulfide, calcium carbonate, and tetra thiafulvalene- tetra cyanoquino methane (TTF-TCNQ). The LDEF was in excellent condition after the long orbital stay, and although the temperature data was lost, the experiment program had been working since the valves in all containers were opened. All four experiments produced crystals; however, they were of varying quality. The calcium carbonate crystals had the best appearance. The TTF-TCNQ crystals were packed together near the valve openings of the container. When taken apart, the single crystals showed some unusual morphological properties. X-ray investigations as well as conductivity measurements on the long duration space grown TTF-TCNQ crystals are presented, and pictures of the calcium carbonate are shown. Comparisons are made with previous space solution growth experiments on the European Spacelab Mission and the Apollo-Soyuz Test Project.

  18. Measurement of contemporary and fossil carbon contents of PM 2.5 aerosols: results from Turtleback Dome, Yosemite National Park

    SciTech Connect

    Bench, G

    2003-10-17

    The impact of aerosol particulate matter of mean mass aerodynamic diameter {le} 2.5 {proportional_to}m (PM 2.5 aerosols), on health, visibility, and compliance with EPA's regional haze regulations is a growing concern. Techniques that can help better characterize particulate matter are required to better understand the constituents, causes and sources of PM 2.5 aerosols. Measurement of the {sup 14}C/C ratio of the PM 2.5 aerosols, the absence of {sup 14}C in fossil carbon materials and the known {sup 14}C/C levels in contemporary carbon materials allows use of a two-component model to derive contemporary and fossil carbon contents of the particulate matter. Such data can be used to estimate the relative contributions of fossil fuels and biogenic aerosols to the total aerosol loading. Here, the methodology for performing such an assessment using total suspended particulate Hi-vol aerosol samplers to collect PM 2.5 aerosols on quartz fiber filters and the technique of accelerator mass spectrometry to measure {sup 14}C/C ratios is presented and illustrated using PM 2.5 aerosols collected at Yosemite National Park.

  19. Constructing an interdisciplinary flow regime recommendation

    USGS Publications Warehouse

    Bartholow, J.M.

    2010-01-01

    It is generally agreed that river rehabilitation most often relies on restoring a more natural flow regime, but credibly defining the desired regime can be problematic. I combined four distinct methods to develop and refine month-by-month and event-based flow recommendations to protect and partially restore the ecological integrity of the Cache la Poudre River through Fort Collins, Colorado. A statistical hydrologic approach was used to summarize the river's natural flow regime and set provisional monthly flow targets at levels that were historically exceeded 75% of the time. These preliminary monthly targets were supplemented using results from three Poudre-specific disciplinary studies. A substrate maintenance flow model was used to better define the high flows needed to flush accumulated sediment from the river's channel and help sustain the riparian zone in this snowmelt-dominated river. A hydraulic/habitat model and a water temperature model were both used to better define the minimum flows necessary to maintain a thriving cool water fishery. The result is a range of recommended monthly flows and daily flow guidance illustrating the advantage of combining a wide range of available disciplinary information, supplemented by judgment based on ecological principles and a general understanding of river ecosystems, in a highly altered, working river. ?? 2010 American Water Resources Association.

  20. Vegetation management with fire modifies peatland soil thermal regime.

    PubMed

    Brown, Lee E; Palmer, Sheila M; Johnston, Kerrylyn; Holden, Joseph

    2015-05-01

    Vegetation removal with fire can alter the thermal regime of the land surface, leading to significant changes in biogeochemistry (e.g. carbon cycling) and soil hydrology. In the UK, large expanses of carbon-rich upland environments are managed to encourage increased abundance of red grouse (Lagopus lagopus scotica) by rotational burning of shrub vegetation. To date, though, there has not been any consideration of whether prescribed vegetation burning on peatlands modifies the thermal regime of the soil mass in the years after fire. In this study thermal regime was monitored across 12 burned peatland soil plots over an 18-month period, with the aim of (i) quantifying thermal dynamics between burned plots of different ages (from <2 to 15 + years post burning), and (ii) developing statistical models to determine the magnitude of thermal change caused by vegetation management. Compared to plots burned 15 + years previously, plots recently burned (<2-4 years) showed higher mean, maximum and range of soil temperatures, and lower minima. Statistical models (generalised least square regression) were developed to predict daily mean and maximum soil temperature in plots burned 15 + years prior to the study. These models were then applied to predict temperatures of plots burned 2, 4 and 7 years previously, with significant deviations from predicted temperatures illustrating the magnitude of burn management effects. Temperatures measured in soil plots burned <2 years previously showed significant statistical disturbances from model predictions, reaching +6.2 °C for daily mean temperatures and +19.6 °C for daily maxima. Soil temperatures in plots burnt 7 years previously were most similar to plots burned 15 + years ago indicating the potential for soil temperatures to recover as vegetation regrows. Our findings that prescribed peatland vegetation burning alters soil thermal regime should provide an impetus for further research to understand the consequences of thermal regime

  1. 75 FR 10207 - Certain Cut-to-Length Carbon-Quality Steel Plate From the Republic of Korea: Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-05

    ... their proprietary equivalents; (4) abrasion-resistant steels (i.e., USS AR 400, USS AR 500); (5) products made to ASTM A202, A225, A514 grade S, A517 grade S, or their proprietary equivalents; (6) ball...-to-Length Carbon-Quality Steel Plate From the Republic of Korea: Final Results of Antidumping...

  2. Carbon dioxide on the satellites of Saturn: Results from the Cassini VIMS investigation and revisions to the VIMS wavelength scale

    USGS Publications Warehouse

    Cruikshank, D.P.; Meyer, A.W.; Brown, R.H.; Clark, R.N.; Jaumann, R.; Stephan, K.; Hibbitts, C.A.; Sandford, S.A.; Mastrapa, R.M.E.; Filacchione, G.; Ore, C.M.D.; Nicholson, P.D.; Buratti, B.J.; McCord, T.B.; Nelson, R.M.; Dalton, J.B.; Baines, K.H.; Matson, D.L.

    2010-01-01

    Several of the icy satellites of Saturn show the spectroscopic signature of the asymmetric stretching mode of C-O in carbon dioxide (CO2) at or near the nominal solid-phase laboratory wavelength of 4.2675 ??m (2343.3 cm-1), discovered with the Visible-Infrared Mapping Spectrometer (VIMS) on the Cassini spacecraft. We report here on an analysis of the variation in wavelength and width of the CO2 absorption band in the spectra of Phoebe, Iapetus, Hyperion, and Dione. Comparisons are made to laboratory spectra of pure CO2, CO2 clathrates, ternary mixtures of CO2 with other volatiles, implanted and adsorbed CO2 in non-volatile materials, and ab initio theoretical calculations of CO2 * nH2O. At the wavelength resolution of VIMS, the CO2 on Phoebe is indistinguishable from pure CO2 ice (each molecule's nearby neighbors are also CO2) or type II clathrate of CO2 in H2O. In contrast, the CO2 band on Iapetus, Hyperion, and Dione is shifted to shorter wavelengths (typically ???4.255 ??m (???2350.2 cm-1)) and broadened. These wavelengths are characteristic of complexes of CO2 with different near-neighbor molecules that are encountered in other volatile mixtures such as with H2O and CH3OH, and non-volatile host materials like silicates, some clays, and zeolites. We suggest that Phoebe's CO2 is native to the body as part of the initial inventory of condensates and now exposed on the surface, while CO2 on the other three satellites results at least in part from particle or UV irradiation of native H2O plus a source of C, implantation or accretion from external sources, or redistribution of native CO2 from the interior. The analysis presented here depends on an accurate VIMS wavelength scale. In preparation for this work, the baseline wavelength calibration for the Cassini VIMS was found to be distorted around 4.3 ??m, apparently as a consequence of telluric CO2 gas absorption in the pre-launch calibration. The effect can be reproduced by convolving a sequence of model detector

  3. Differentially Rotating White Dwarfs I: Regimes of Internal Rotation

    NASA Astrophysics Data System (ADS)

    Ghosh, Pranab; Wheeler, J. Craig

    2017-01-01

    Most viable models of Type Ia supernovae (SNe Ia) require the thermonuclear explosion of a carbon/oxygen white dwarf that has evolved in a binary system. Rotation could be an important aspect of any model for SNe Ia, whether single or double degenerate, with the white dwarf mass at, below, or above the Chandrasekhar limit. Differential rotation is specifically invoked in attempts to account for the apparent excess mass in the super-Chandrasekhar events. Some earlier work has suggested that only uniform rotation is consistent with the expected mechanisms of angular momentum transport in white dwarfs, while others have found pronounced differential rotation. We show that if the baroclinic instability is active in degenerate matter and the effects of magnetic fields are neglected, both nearly uniform rotation and strongly differential rotation are possible. We classify rotation regimes in terms of the Richardson number, Ri. At small values of Ri ≤slant 0.1, we find both the low-viscosity Zahn regime with a nonmonotonic angular velocity profile and a new differential rotation regime for which the viscosity is high and scales linearly with the shear, σ. Employment of Kelvin–Helmholtz viscosity alone yields differential rotation. Large values of Ri ≫ 1 produce a regime of nearly uniform rotation for which the baroclinic viscosity is of intermediate value and scales as {σ }3. We discuss the gap in understanding of the behavior at intermediate values of Ri and how observations may constrain the rotation regimes attained by nature.

  4. Regimes of Internal Rotation in Differentially Rotating White Dwarfs

    NASA Astrophysics Data System (ADS)

    Wheeler, J. Craig; Ghosh, Pranab

    2017-01-01

    Most viable models of Type Ia supernovae (SN Ia) require the thermonuclear explosion of a carbon/oxygen white dwarf that has evolved in a binary system. Rotation could be an important aspect of any model for SN Ia, whether single or double degenerate, with the white dwarf mass at, below, or above the Chandrasekhar limit. Differential rotation is specifically invoked in attempts to account for the apparent excess mass in the super--Chandrasekhar events. Some earlier work has suggested that only uniform rotation is consistent with the expected mechanisms of angular momentum transport in white dwarfs, while others have found pronounced differential rotation. We show that if the baroclinic instability is active in degenerate matter and the effects of magnetic fields are neglected, both nearly-uniform and strongly-differential rotation are possible. We classify rotation regimes in terms of the Richardson number, Ri. At small values of Ri < 0.1, we find both the low-viscosity Zahn regime with a non-monotonic angular velocity profile and a new differential rotation regime for which the viscosity is high and scales linearly with the shear, σ. Employment of Kelvin-Helmholtz viscosity alone yields differential rotation. Large values of Ri >> 1 produce a regime of nearly-uniform rotation for which the baroclinic viscosity is of intermediate value and scales as σ3. We discuss the gap in understanding of the behavior at intermediate values of Ri and how observations may constrain the rotation regimes attained by nature.

  5. Impact of hydrological variations on modeling of peatland CO2 fluxes: Results from the North American Carbon Program site synthesis

    NASA Astrophysics Data System (ADS)

    Sulman, Benjamin N.; Desai, Ankur R.; Schroeder, Nicole M.; Ricciuto, Dan; Barr, Alan; Richardson, Andrew D.; Flanagan, Lawrence B.; Lafleur, Peter M.; Tian, Hanqin; Chen, Guangsheng; Grant, Robert F.; Poulter, Benjamin; Verbeeck, Hans; Ciais, Philippe; Ringeval, Bruno; Baker, Ian T.; Schaefer, Kevin; Luo, Yiqi; Weng, Ensheng

    2012-03-01

    Northern peatlands are likely to be important in future carbon cycle-climate feedbacks due to their large carbon pools and vulnerability to hydrological change. Use of non-peatland-specific models could lead to bias in modeling studies of peatland-rich regions. Here, seven ecosystem models were used to simulate CO2fluxes at three wetland sites in Canada and the northern United States, including two nutrient-rich fens and one nutrient-poor,sphagnum-dominated bog, over periods between 1999 and 2007. Models consistently overestimated mean annual gross ecosystem production (GEP) and ecosystem respiration (ER) at all three sites. Monthly flux residuals (simulated - observed) were correlated with measured water table for GEP and ER at the two fen sites, but were not consistently correlated with water table at the bog site. Models that inhibited soil respiration under saturated conditions had less mean bias than models that did not. Modeled diurnal cycles agreed well with eddy covariance measurements at fen sites, but overestimated fluxes at the bog site. Eddy covariance GEP and ER at fens were higher during dry periods than during wet periods, while models predicted either the opposite relationship or no significant difference. At the bog site, eddy covariance GEP did not depend on water table, while simulated GEP was higher during wet periods. Carbon cycle modeling in peatland-rich regions could be improved by incorporating wetland-specific hydrology and by inhibiting GEP and ER under saturated conditions. Bogs and fens likely require distinct plant and soil parameterizations in ecosystem models due to differences in nutrients, peat properties, and plant communities.

  6. Utilizing Surface Sensors to Identify Wake Regimes

    NASA Astrophysics Data System (ADS)

    Wang, Mengying; Hemati, Maziar S.

    2016-11-01

    Marine swimmers often exploit external flow structures to reduce locomotive effort. To achieve this advantage, these swimmers utilize mechanosensory organs on the surface of their bodies to detect hydrodynamic signals from the surrounding fluid, which can then be used to inform the control task. Recently, there has been a growing interest in developing similar flow sensing systems to achieve enhanced propulsive efficiency and maneuverability in human-engineered underwater vehicles. In particular, much attention has been given to the problem of wake sensing; however, these investigations have concentrated on a restricted class of wakes-i.e., Kármán-type vortex streets-whereas more complicated wake structures can arise in practice. In this talk, we will explore the possibility of identifying wake regimes through the use of surface sensors. Potential flow theory is adopted to simulate the interactions of various wakes with a fish-like body. Wakes in different dynamical regimes impart distinct hydrodynamic signatures on the body, which permits these regimes to be distinguished from one another in an automated fashion. Our results can provide guidance for improving flow sensing capabilities in human-engineered systems and hint at how marine swimmers may sense their hydrodynamic surroundings.

  7. Dynamical Response of Continuum Regime Langmuir Probe

    NASA Astrophysics Data System (ADS)

    Rappaport, H. L.

    2009-11-01

    Probe dynamic response is sometimes used as a way to increase the amount of information obtained from Langmuir probes [1]. In this poster, the effects of frequency dependent probe capacitance and coupling of probe fields to damped Langmuir waves and damped ion acoustic waves are considered. In the continuum regime, with small Debye length to spherical probe radius ratio, the probe DC current vs. voltage characteristic displays a hard saturation at sufficiently large probe potential [2]. In this regime, the sheath thickness varies little with the applied voltage although the plasma response can still be measured. A goal of the present investigation is to show that the probe dynamical response is richer as a result of modulation of sheath thickness or shielding particularly in the larger Debye length to probe radius ratio regime. Inertia inhibits ion response at sufficiently high frequency and deviation from the DC characteristic is shown.[4pt] [1] D. N. Walker, R.F. Fernsler, D.D. Blackwell, and W.E. Amatucci, Phys. Plasmas 15, 123506 (2008).[0pt] [2] E. Baum and R.L. Chapkis, AIAA J. 8, 1073 (1970).

  8. Cellular polyethylene-naphthalate ferroelectrets: Foaming in supercritical carbon dioxide, structural and electrical preparation, and resulting piezoelectricity

    NASA Astrophysics Data System (ADS)

    Fang, P.; Wegener, M.; Wirges, W.; Gerhard, R.; Zirkel, L.

    2007-05-01

    Polymer foams with electrically charged cellular voids, the so-called ferroelectrets, are soft piezoelectric transducer materials. Several polymers such as polyethylene terephthalate or cyclo-olefin copolymers are under investigation with respect to their suitability as ferroelectrets. Here, the authors report an additional ferroelectret polymer, cellular polyethylene-naphthalate (PEN), which was prepared from commercial uniform polymer films by means of foaming in supercritical carbon dioxide, inflation, biaxial stretching, electrical charging, and metallization. Piezoelectric d33 coefficients of up to 140pC/N demonstrate the suitability of such cellular PEN films for transducer applications. Their piezoelectricity is partially stable at elevated temperatures as high as 100°C.

  9. River flow regimes and vegetation dynamics along a river transect

    NASA Astrophysics Data System (ADS)

    Doulatyari, Behnam; Basso, Stefano; Schirmer, Mario; Botter, Gianluca

    2014-11-01

    Ecohydrological processes occurring within fluvial landscapes are strongly affected by natural streamflow variability. In this work the patterns of vegetation biomass in two rivers characterized by contrasting flow regimes were investigated by means of a comprehensive stochastic model which explicitly couples catchment-scale hydroclimatic processes, morphologic attributes of the river transect and in-stream bio-ecological features. The hydrologic forcing is characterized by the probability distribution (pdf) of streamflows and stages resulting from stochastic precipitation dynamics, rainfall-runoff transformation and reach scale morphologic attributes. The model proved able to reproduce the observed pdf of river flows and stages, as well as the pattern of exposure/inundation along the river transect in both regimes. Our results suggest that in persistent regimes characterized by reduced streamflow variability, mean vegetation biomass is chiefly controlled by the pattern of groundwater availability along the transect, leading to a marked transition between aquatic and terrestrial environments. Conversely, erratic regimes ensure wider aquatic-terrestrial zones in which optimal elevation ranges for species with different sensitivity to flooding and access to groundwater are separated. Patterns of mean biomass in erratic regimes were found to be more sensitive to changes in the underlying hydroclimatic conditions, notwithstanding the reduced responsiveness of the corresponding flow regimes. The framework developed highlights the important role played by streamflow regimes in shaping riverine environments, and may eventually contribute to identifying the influence of landscape, climate and morphologic features on in-stream ecological dynamics.

  10. Impacts of altered precipitation regimes on soil communities and biogeochemistry in arid and semi-arid ecosystems.

    PubMed

    Nielsen, Uffe N; Ball, Becky A

    2015-04-01

    Altered precipitation patterns resulting from climate change will have particularly significant consequences in water-limited ecosystems, such as arid to semi-arid ecosystems, where discontinuous inputs of water control biological processes. Given that these ecosystems cover more than a third of Earth's terrestrial surface, it is important to understand how they respond to such alterations. Altered water availability may impact both aboveground and belowground communities and the interactions between these, with potential impacts on ecosystem functioning; however, most studies to date have focused exclusively on vegetation responses to altered precipitation regimes. To synthesize our understanding of potential climate change impacts on dryland ecosystems, we present here a review of current literature that reports the effects of precipitation events and altered precipitation regimes on belowground biota and biogeochemical cycling. Increased precipitation generally increases microbial biomass and fungal:bacterial ratio. Few studies report responses to reduced precipitation but the effects likely counter those of increased precipitation. Altered precipitation regimes have also been found to alter microbial community composition but broader generalizations are difficult to make. Changes in event size and frequency influences invertebrate activity and density with cascading impacts on the soil food web, which will likely impact carbon and nutrient pools. The long-term implications for biogeochemical cycling are inconclusive but several studies suggest that increased aridity may cause decoupling of carbon and nutrient cycling. We propose a new conceptual framework that incorporates hierarchical biotic responses to individual precipitation events more explicitly, including moderation of microbial activity and biomass by invertebrate grazing, and use this framework to make some predictions on impacts of altered precipitation regimes in terms of event size and frequency as

  11. Results of high temperature processing of high-carbon materials from the lower Cambrian period of the Earth's history

    NASA Astrophysics Data System (ADS)

    Maslov, O. D.

    2016-07-01

    The paper reports on the observation of spontaneous fission of nuclides, concentrated in fly ash during the combustion of high-carbon (graphite) material, chemogenic siliceous-carbonaceous rocks and carbonaceous shale in the mixture with brown coal. In the samples obtained, the spontaneous fission was measured by track method. The zones of precipitation of spontaneous fission of nuclides and their lighter homologues on thermochromatographic column were determined. A nuclide with a half-life of 62 days was detected in the alkaline trap. The chemical treatment procedure included co-precipitation with iron hydroxide, dissolution in NH4OH + H2O2 solution and distillation by heating up to 100°C followed by AgI co-precipitation. Based on the chemical behavior it can be concluded that the detected radionuclide belongs to the halides. The content of the parent nuclide in high-carbon (graphite) material and chemogenic siliceous-carbonaceous rock corresponds to 10-14 g/g.

  12. Water level changes affect carbon turnover and microbial community composition in lake sediments.

    PubMed

    Weise, Lukas; Ulrich, Andreas; Moreano, Matilde; Gessler, Arthur; Kayler, Zachary E; Steger, Kristin; Zeller, Bernd; Rudolph, Kristin; Knezevic-Jaric, Jelena; Premke, Katrin

    2016-05-01

    Due to climate change, many lakes in Europe will be subject to higher variability of hydrological characteristics in their littoral zones. These different hydrological regimes might affect the use of allochthonous and autochthonous carbon sources. We used sandy sediment microcosms to examine the effects of different hydrological regimes (wet, desiccating, and wet-desiccation cycles) on carbon turnover. (13)C-labelled particulate organic carbon was used to trace and estimate carbon uptake into bacterial biomass (via phospholipid fatty acids) and respiration. Microbial community changes were monitored by combining DNA- and RNA-based real-time PCR quantification and terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA. The shifting hydrological regimes in the sediment primarily caused two linked microbial effects: changes in the use of available organic carbon and community composition changes. Drying sediments yielded the highest CO2 emission rates, whereas hydrological shifts increased the uptake of allochthonous organic carbon for respiration. T-RFLP patterns demonstrated that only the most extreme hydrological changes induced a significant shift in the active and total bacterial communities. As current scenarios of climate change predict an increase of drought events, frequent variations of the hydrological regimes of many lake littoral zones in central Europe are anticipated. Based on the results of our study, this phenomenon may increase the intensity and amplitude in rates of allochthonous organic carbon uptake and CO2 emissions.

  13. Water level changes affect carbon turnover and microbial community composition in lake sediments

    PubMed Central

    Weise, Lukas; Ulrich, Andreas; Moreano, Matilde; Gessler, Arthur; E. Kayler, Zachary; Steger, Kristin; Zeller, Bernd; Rudolph, Kristin; Knezevic-Jaric, Jelena; Premke, Katrin

    2016-01-01

    Due to climate change, many lakes in Europe will be subject to higher variability of hydrological characteristics in their littoral zones. These different hydrological regimes might affect the use of allochthonous and autochthonous carbon sources. We used sandy sediment microcosms to examine the effects of different hydrological regimes (wet, desiccating, and wet-desiccation cycles) on carbon turnover. 13C-labelled particulate organic carbon was used to trace and estimate carbon uptake into bacterial biomass (via phospholipid fatty acids) and respiration. Microbial community changes were monitored by combining DNA- and RNA-based real-time PCR quantification and terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA. The shifting hydrological regimes in the sediment primarily caused two linked microbial effects: changes in the use of available organic carbon and community composition changes. Drying sediments yielded the highest CO2 emission rates, whereas hydrological shifts increased the uptake of allochthonous organic carbon for respiration. T-RFLP patterns demonstrated that only the most extreme hydrological changes induced a significant shift in the active and total bacterial communities. As current scenarios of climate change predict an increase of drought events, frequent variations of the hydrological regimes of many lake littoral zones in central Europe are anticipated. Based on the results of our study, this phenomenon may increase the intensity and amplitude in rates of allochthonous organic carbon uptake and CO2 emissions. PMID:26902802

  14. Film thickness for different regimes of fluid-film lubrication. [elliptical contacts

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1983-01-01

    Mathematical formulas are presented which express the dimensionless minimum film thickness for the four lubrication regimes found in elliptical contacts: isoviscous-rigid regime; piezoviscous-rigid regime; isoviscous-elastic regime; and piezoviscous-elastic regime. The relative importance of pressure on elastic distortion and lubricant viscosity is the factor that distinguishes these regimes for a given conjunction geometry. In addition, these equations were used to develop maps of the lubrication regimes by plotting film thickness contours on a log-log grid of the dimensionless viscosity and elasticity parameters for three values of the ellipticity parameter. These results present a complete theoretical film thickness parameter solution for elliptical constants in the four lubrication regimes. The results are particularly useful in initial investigations of many practical lubrication problems involving elliptical conjunctions.

  15. Rheology of cohesive granular materials across multiple dense-flow regimes.

    PubMed

    Gu, Yile; Chialvo, Sebastian; Sundaresan, Sankaran

    2014-09-01

    We investigate the dense-flow rheology of cohesive granular materials through discrete element simulations of homogeneous, simple shear flows of frictional, cohesive, spherical particles. Dense shear flows of noncohesive granular materials exhibit three regimes: quasistatic, inertial, and intermediate, which persist for cohesive materials as well. It is found that cohesion results in bifurcation of the inertial regime into two regimes: (a) a new rate-independent regime and (b) an inertial regime. Transition from rate-independent cohesive regime to inertial regime occurs when the kinetic energy supplied by shearing is sufficient to overcome the cohesive energy. Simulations reveal that inhomogeneous shear band forms in the vicinity of this transition, which is more pronounced at lower particle volume fractions. We propose a rheological model for cohesive systems that captures the simulation results across all four regimes.

  16. An Examination of the Nature of Global MODIS Cloud Regimes

    NASA Technical Reports Server (NTRS)

    Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin; Kato, Seiji; Huffman, George J.

    2014-01-01

    We introduce global cloud regimes (previously also referred to as "weather states") derived from cloud retrievals that use measurements by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard the Aqua and Terra satellites. The regimes are obtained by applying clustering analysis on joint histograms of retrieved cloud top pressure and cloud optical thickness. By employing a compositing approach on data sets from satellites and other sources, we examine regime structural and thermodynamical characteristics. We establish that the MODIS cloud regimes tend to form in distinct dynamical and thermodynamical environments and have diverse profiles of cloud fraction and water content. When compositing radiative fluxes from the Clouds and the Earth's Radiant Energy System instrument and surface precipitation from the Global Precipitation Climatology Project, we find that regimes with a radiative warming effect on the atmosphere also produce the largest implied latent heat. Taken as a whole, the results of the study corroborate the usefulness of the cloud regime concept, reaffirm the fundamental nature of the regimes as appropriate building blocks for cloud system classification, clarify their association with standard cloud types, and underscore their distinct radiative and hydrological signatures.

  17. Toward a Physical Characterization of Raindrop Collision Outcome Regimes

    NASA Technical Reports Server (NTRS)

    Testik, F. Y.; Barros, Ana P.; Bilven, Francis L.

    2011-01-01

    A comprehensive raindrop collision outcome regime diagram that delineates the physical conditions associated with the outcome regimes (i.e., bounce, coalescence, and different breakup types) of binary raindrop collisions is proposed. The proposed diagram builds on a theoretical regime diagram defined in the phase space of collision Weber numbers We and the drop diameter ratio p by including critical angle of impact considerations. In this study, the theoretical regime diagram is first evaluated against a comprehensive dataset for drop collision experiments representative of raindrop collisions in nature. Subsequently, the theoretical regime diagram is modified to explicitly describe the dominant regimes of raindrop interactions in (We, p) by delineating the physical conditions necessary for the occurrence of distinct types of collision-induced breakup (neck/filament, sheet, disk, and crown breakups) based on critical angle of impact consideration. Crown breakup is a subtype of disk breakup for lower collision kinetic energy that presents distinctive morphology. Finally, the experimental results are analyzed in the context of the comprehensive collision regime diagram, and conditional probabilities that can be used in the parameterization of breakup kernels in stochastic models of raindrop dynamics are provided.

  18. Summary of 1978 Southeastern Virginia Urban Plume study: Aircraft results for carbon monoxide, methane, nonmethane hydrocarbons, and ozone

    NASA Technical Reports Server (NTRS)

    Hill, G. F.; Sachse, G. W.; Cofer, W. R., III

    1981-01-01

    The characteristics of the Southeastern Virginia urban plume were defined with emphasis on the photon-oxidant species. The measurement area was a rectangle, approximately 150 km by 100 km centered around Cape Charles, Virginia. Included in this area are the cities of Norfolk, Virginia Beach, Chesapeake, Newport News, and Hampton. The area is bounded on the north by Wallops Island, Virginia, and on the south by the Hampton Roads area of Tidewater Virginia. The major axis of the rectangle is oriented in the southwest-northeast direction. The data set includes aircraft measurements for carbon monoxide, methane, nonmethane hydrocarbons, and ozone. The experiment shows that CO can be successfully measured as a tracer gas and used as an index for determining localized and urban plumes. The 1978 data base provided sufficient data to assess an automated chromatograph with flame ionization detection used for measuring methane and nonmethane hydrocarbons in flight.

  19. Using Aerocom Results to Constrain Black Carbon, Sulphate and Total Direct Aerosol Radiative Forcing and Their Uncertainties

    NASA Astrophysics Data System (ADS)

    Samset, B. H.; Myhre, G.

    2014-12-01

    Aerosols affect the global radiative balance, and hence the climate, through a multitude of processes. However, even the direct interaction of aerosols with incoming sunlight is at present insufficiently constrained. Here we compare the output of 15 recent aerosol climate models (AeroCom Phase II), both column averaged and vertically resolved. Through a simple MonteCarlo approach, we show that the model based total anthropogenic aerosol direct radiative forcing (DRF) uncertainty may be underestimated. Constraining modelled vertical profiles of black carbon (BC) concentration to aircraft measurements in remote regions, we further show that recent BC DRF estimates may be biased high. A short modelled BC lifetime is indicated as a necessary, though not sufficient, requirement for reproducing measurements. Finally, modeled sulphate aerosol DRF is discussed in the context of differences in representation of humidity and hygroscopic growth in the models.

  20. Historical and projected changes in carbon and nutrient exports to the Gulf of Mexico as resulted from climate change and land use: 1850-2099

    NASA Astrophysics Data System (ADS)

    Tao, B.; Tian, H.; Yang, Q.; Lu, C.; Ren, W.; Yang, J.; Pan, S.; Lohrenz, S. E.; Cai, W.

    2012-12-01

    The transport of nutrients from terrestrial ecosystems to the coastal ocean represents a globally significant carbon flux and a critical biogeochemical linkage between land and coastal ecosystems. As one of the most productive agricultural regions in the world, the Mississippi River basin has experienced profound changes in climate and land use over the past century, fueled by food demand and growing population, and is likely to undergo further rapid development in the coming decades. These changes have greatly influenced carbon and nitrogen exports from land to the Gulf of Mexico (GOM). However, most existing associated studies in this region focused on either terrestrial or aquatic ecosystems separately and overlooked linkage between them, therefore potentially hinder the sustainability of ecosystems and efforts to mitigate and adapt to future environmental change. In this study, we used an integrated ecosystem model (Dynamic Land Ecosystem Model, DLEM) and new-developed gridded climate and land use/cover data as well as other ancillary data to assess historical changes in nutrient exports from Mississippi River basin to the GOM in responses to climate change and land use change during 1850-2010 and predict future changes through 2099 by off-line coupling with general circulation models (GCMs). We specifically quantified spatial patterns and interannual variations of carbon and nutrient exports (TOC, DOC, DIC, DIN, TON and TN, etc.) in responses to climate change and land use. The results indicated that carbon exports exhibited a significant inter-annual variations and land use change, characterized by crop expansion, has substantially increased nutrient exports in the study area. Based on different simulation experiments, our results further demonstrated how management practices (irrigation, nitrogen fertilizer application), the distribution of croplands, and patterns of climate can influence the biogeochemical cycles of carbon and nutrient exports.

  1. Changes in Forest Production, Biomass and Carbon: Results From the 2015 UN FAO Global Forest Resource Assessment

    NASA Astrophysics Data System (ADS)

    Navar, J.

    2015-12-01

    Forests are important sources of livelihoods to millions of people and contribute to national economic development of many countries. In addition, they are vital sources and sinks of carbon and contribute to the rate of climate change. The UN Food and Agriculture Organization has been collecting and presenting data on global forest resources and forest cover since 1948. This paper builds on data from FAO's 2015 Global Forest Resource Assessment (FRA) and presents information on growing stock, biomass, carbon stock, wood removals, and changes of forest area primarily designated for production and multiple use of the world's forests. Between 1990 and 2015, the total growing stock volume has increased in East Asia, Caribbean, Western and Central Asia, North America, Europe (including the Russian Federation), and Oceania with the highest relative increase in East Asia and the Caribbean. In all other subregions the total growing stock volume decreased. North and Central America, Europe and Asia report forest C stock increases while South America and Africa report strong decreases and Oceania reports stable forest C stocks. The annual rate of decrease of forest C stock weakened between 1990 and 2015. The total volume of annual wood removals including wood fuel removals increased between 1990 and 2011, but shows a remarkable decline during the 2008-2009 economic crisis. Forest areas designated for production purposes differ considerably between subregions. The percentage of production area out of total forest area ranges between 16 percent in South America and 53 percent in Europe. Globally about one quarter of the forest area is designated to multiple use forestry. The balance between biomass growth and removals shows considerable sub-regional differences and related implications for the sustainable use of forests.

  2. QUANTIFYING FOREST ABOVEGROUND CARBON POOLS AND FLUXES USING MULTI-TEMPORAL LIDAR A report on field monitoring, remote sensing MMV, GIS integration, and modeling results for forestry field validation test to quantify aboveground tree biomass and carbon

    SciTech Connect

    Lee Spangler; Lee A. Vierling; Eva K. Stand; Andrew T. Hudak; Jan U.H. Eitel; Sebastian Martinuzzi

    2012-04-01

    Sound policy recommendations relating to the role of forest management in mitigating atmospheric carbon dioxide (CO{sub 2}) depend upon establishing accurate methodologies for quantifying forest carbon pools for large tracts of land that can be dynamically updated over time. Light Detection and Ranging (LiDAR) remote sensing is a promising technology for achieving accurate estimates of aboveground biomass and thereby carbon pools; however, not much is known about the accuracy of estimating biomass change and carbon flux from repeat LiDAR acquisitions containing different data sampling characteristics. In this study, discrete return airborne LiDAR data was collected in 2003 and 2009 across {approx}20,000 hectares (ha) of an actively managed, mixed conifer forest landscape in northern Idaho, USA. Forest inventory plots, established via a random stratified sampling design, were established and sampled in 2003 and 2009. The Random Forest machine learning algorithm was used to establish statistical relationships between inventory data and forest structural metrics derived from the LiDAR acquisitions. Aboveground biomass maps were created for the study area based on statistical relationships developed at the plot level. Over this 6-year period, we found that the mean increase in biomass due to forest growth across the non-harvested portions of the study area was 4.8 metric ton/hectare (Mg/ha). In these non-harvested areas, we found a significant difference in biomass increase among forest successional stages, with a higher biomass increase in mature and old forest compared to stand initiation and young forest. Approximately 20% of the landscape had been disturbed by harvest activities during the six-year time period, representing a biomass loss of >70 Mg/ha in these areas. During the study period, these harvest activities outweighed growth at the landscape scale, resulting in an overall loss in aboveground carbon at this site. The 30-fold increase in sampling density

  3. The effect of refrigerants in the mixed lubrication regime

    SciTech Connect

    Mizuhara, Kazuyuki; Tomimoto, Makoto

    1997-12-31

    Because of environmental concerns, CFC (chlorofluorocarbon) refrigerants must be replaced with HFCs (hydrofluorocarbons). As a result, many tribological problems are caused especially in rotary piston compressors. To solve the problem, the effects of refrigerants on friction and wear characteristics of the oil and refrigerant mixtures at the mixed lubrication regime are investigated. The difference in refrigerants are clearly observed not only in boundary but also in the mixed lubrication regime. The effects of operating conditions on sliding conditions and experimental results are also discussed. It is concluded that for practical application where long life is essential, experiments must be conducted under the mixed lubrication regime. Also, the importance of defining the lubrication regime in terms of film parameter is emphasized.

  4. Analysis of light regime in continuous light distributions in photobioreactors.

    PubMed

    Brindley, Celeste; Fernández, F G Acién; Fernández-Sevilla, J M

    2011-02-01

    Maximum photobioreactor (PBR) efficiency is a must in applications such as the obtention of microalgae-derived fuels. Improving PBR performance requires a better understanding of the "light regime", the varying irradiance that microalgal cells moving in a dense culture are exposed to. We propose a definition of light regime that can be used consistently to describe the continuously varying light patterns in PBRs as well as in light/dark cycles. Equivalent continuous and light/dark regimes have been experimentally compared and the results show that continuous variations are not well represented by light/dark cycles, as had been widely accepted. It has been shown that a correct light regime allows obtaining photosynthetic rates higher than the corresponding to continuous light, the so-called "flashing light effect" and that this is possible in commercial PBRs. A correct PBR operation could result in photosynthetic efficiency close to the optimum eight quanta per O(2).

  5. Pyrolysis result of polyethylene waste as fuel for solid oxide fuel cell with samarium doped-ceria (SDC)-carbonate as electrolyte

    NASA Astrophysics Data System (ADS)

    Syahputra, R. J. E.; Rahmawati, F.; Prameswari, A. P.; Saktian, R.

    2017-02-01

    In this research, the result of pyrolysis on polyethylene was used as fuel for a solid oxide fuel cell (SOFC). The pyrolysis result is a liquid which consists of hydrocarbon chains. According to GC-MS analysis, the hydrocarbons mainly consist of C7 to C20 hydrocarbon chain. Then, the liquid was applied to a single cell of NSDC-L | NSDC | NSDC-L. NSDC is a composite SDC (samarium doped-ceria) with sodium carbonate. Meanwhile, NSDC-L is a composite of NSDC with LiNiCuO (LNC). NSDC and LNC were analyzed by X-ray diffraction to understand their crystal structure. The result shows that presence of carbonate did not change the crystal structure of SDC. SEM EDX analysis for fuel cell before and after being loaded with polyethylene oil to get information of element diffusion to the electrolyte. Meanwhile, the conductivity properties were investigated through impedance measurement. The presence of carbonate even increases the electrical conductivity. The single cell test with the pyrolysis result of polyethylene at 300 – 600 °C, found that the highest power density is at 600 °C with the maximum power density of 0.14 mW/cm2 and open circuit voltage of 0.4 Volt. Elemental analysis at three point spots of single cell NDSC-L |NSDC|NSDC-L found that a migration of ions was occurred during fuel operation at 300 – 600 °C.

  6. Overview of the regimes: CWC

    SciTech Connect

    1995-12-31

    The Chemical Weapons Convention`s (CWC) seeks to eradicate an entire category of catastrophic weapons and to ensure their continued non-production. Unlike the Non-Proliferation Treaty`s (NPT), the CWC requires disarmament. States Parties having chemical weapons (CW) must destroy them. The CWC has not adopted the NPT distinction between weapons and non-weapons states; the CWC`s prohibitions and obligations will apply identically to all States parties. In most other respects, the two treaties establish similar regimes with similar approaches. Included are objectives and primary obligations, legal bases, institutional oversight, trade restrictions, protection of information, penal consequences, and role of the United Nations.

  7. Preliminary Results from the First Year of Operations of the NASA Orbiting Carbon Observatory-2 (OCO-2)

    NASA Astrophysics Data System (ADS)

    Crisp, D.; Eldering, A.; O'Dell, C.; Fisher, B.; Wunch, D.; Wennberg, P. O.; Osterman, G. B.; Mandrake, L.; Payne, V.; Natraj, V.; Frankenberg, C.; Taylor, T.; Worden, J. R.; Bloom, A. A.; Nelson, R. R.; Schwandner, F. M.; Fu, D.; Braverman, A. J.; Chatterjee, A.; Baker, I. T.; Avis, C.; Livermore, T. R.

    2015-12-01

    On September 6, 2014, OCO-2 began routinely returning almost 106 soundings over the sunlit hemisphere each day. Over 10% of these soundings are sufficiently cloud free to yield full-column estimates of the column-averaged CO2 dry air mole fraction, XCO2. Nadir soundings over land yield XCO2 estimates with single-sounding random errors of 0.5 - 1 ppm at solar zenith angles (SZA) < 60° while ocean glint soundings yield precisions near 0.5 ppm at SZA < 70°. Nadir soundings over the ocean and glint soundings over high-latitude land are less precise. Initially, OCO-2 recorded only nadir soundings or glint soundings on alternate, 16-day ground-track repeat cycles. This provided adequate coverage of the globe each month, but produced 16-day gaps in ocean coverage while observing nadir, and similar gaps over high-latitude land while observing glint. In July 2015, this strategy was modified to alternate between glint and nadir soundings on consecutive orbits to yield more continuous coverage each day. While XCO2 and other products are being validated to identify and correct biases, global XCO2 maps are starting to reveal the most robust features of the atmospheric carbon cycle. XCO2 enhancements co-located with intense fossil fuel emissions in eastern U.S. and eastern China are most obvious in the fall, when the north-south XCO2 gradient is small. Enhanced XCO2 coincident with biomass burning in the Amazon, central Africa, and Indonesian is also obvious in the fall. In mid spring, when the north-south XCO2 gradient was largest, these sources were less apparent in global maps. From late May to mid-July, OCO-2 maps show a 2-3% reduction in XCO2 across the northern hemisphere, as the land biosphere rapidly absorbs CO2. As the carbon cycle community continues to analyze these OCO-2 data, quantitative estimates of regional-scale emission sources and natural sinks are expected to emerge. This presentation will summarize the OCO-2 mission status, early products, and near

  8. The New English Quality Assurance Regime

    ERIC Educational Resources Information Center

    Brown, Roger

    2011-01-01

    England is developing a new quality assurance regime that will come into effect in October 2011. A new funding regime will operate from the following year, together with new rules to ease the participation of private higher education providers. This article describes and analyses the new quality and funding regimes. It argues that the greater…

  9. Bose Polarons in the Strongly Interacting Regime

    NASA Astrophysics Data System (ADS)

    Hu, Ming-Guang; Van de Graaff, Michael J.; Kedar, Dhruv; Corson, John P.; Cornell, Eric A.; Jin, Deborah S.

    2016-07-01

    When an impurity is immersed in a Bose-Einstein condensate, impurity-boson interactions are expected to dress the impurity into a quasiparticle, the Bose polaron. We superimpose an ultracold atomic gas of 87Rb with a much lower density gas of fermionic 40 impurities. Through the use of a Feshbach resonance and radio-frequency spectroscopy, we characterize the energy, spectral width, and lifetime of the resultant polaron on both the attractive and the repulsive branches in the strongly interacting regime. The width of the polaron in the attractive branch is narrow compared to its binding energy, even as the two-body scattering length diverges.

  10. Mitochondrial Carbonic Anhydrase VA Deficiency Resulting from CA5A Alterations Presents with Hyperammonemia in Early Childhood

    PubMed Central

    van Karnebeek, Clara D.; Sly, William S.; Ross, Colin J.; Salvarinova, Ramona; Yaplito-Lee, Joy; Santra, Saikat; Shyr, Casper; Horvath, Gabriella A.; Eydoux, Patrice; Lehman, Anna M.; Bernard, Virginie; Newlove, Theresa; Ukpeh, Henry; Chakrapani, Anupam; Preece, Mary Anne; Ball, Sarah; Pitt, James; Vallance, Hilary D.; Coulter-Mackie, Marion; Nguyen, Hien; Zhang, Lin-Hua; Bhavsar, Amit P.; Sinclair, Graham; Waheed, Abdul; Wasserman, Wyeth W.; Stockler-Ipsiroglu, Sylvia

    2014-01-01

    Four children in three unrelated families (one consanguineous) presented with lethargy, hyperlactatemia, and hyperammonemia of unexplained origin during the neonatal period and early childhood. We identified and validated three different CA5A alterations, including a homozygous missense mutation (c.697T>C) in two siblings, a homozygous splice site mutation (c.555G>A) leading to skipping of exon 4, and a homozygous 4 kb deletion of exon 6. The deleterious nature of the homozygous mutation c.697T>C (p.Ser233Pro) was demonstrated by reduced enzymatic activity and increased temperature sensitivity. Carbonic anhydrase VA (CA-VA) was absent in liver in the child with the homozygous exon 6 deletion. The metabolite profiles in the affected individuals fit CA-VA deficiency, showing evidence of impaired provision of bicarbonate to the four enzymes that participate in key pathways in intermediary metabolism: carbamoylphosphate synthetase 1 (urea cycle), pyruvate carboxylase (anaplerosis, gluconeogenesis), propionyl-CoA carboxylase, and 3-methylcrotonyl-CoA carboxylase (branched chain amino acids catabolism). In the three children who were administered carglumic acid, hyperammonemia resolved. CA-VA deficiency should therefore be added to urea cycle defects, organic acidurias, and pyruvate carboxylase deficiency as a treatable condition in the differential diagnosis of hyperammonemia in the neonate and young child. PMID:24530203

  11. Methanol Droplet Extinction in Oxygen/Carbon-dioxide/Nitrogen Mixtures in Microgravity: Results from the International Space Station Experiments

    NASA Technical Reports Server (NTRS)

    Nayagam, Vedha; Dietrich, Daniel L.; Ferkul, Paul V.; Hicks, Michael C.; Williams, Forman A.

    2012-01-01

    Motivated by the need to understand the flammability limits of condensed-phase fuels in microgravity, isolated single droplet combustion experiments were carried out in the Combustion Integrated Rack Facility onboard the International Space Station. Experimental observations of methanol droplet combustion and extinction in oxygen/carbon-dioxide/nitrogen mixtures at 0.7 and 1 atmospheric pressure in quiescent microgravity environment are reported for initial droplet diameters varying between 2 mm to 4 mm in this study.The ambient oxygen concentration was systematically lowered from test to test so as to approach the limiting oxygen index (LOI) at fixed ambient pressure. At one atmosphere pressure, ignition and some burning were observed for an oxygen concentration of 13% with the rest being nitrogen. In addition, measured droplet burning rates, flame stand-off ratios, and extinction diameters are presented for varying concentrations of oxygen and diluents. Simplified theoretical models are presented to explain the observed variations in extinction diameter and flame stand-off ratios.

  12. The effect of carbon credits on savanna land management and priorities for biodiversity conservation.

    PubMed

    Douglass, Lucinda L; Possingham, Hugh P; Carwardine, Josie; Klein, Carissa J; Roxburgh, Stephen H; Russell-Smith, Jeremy; Wilson, Kerrie A

    2011-01-01

    Carbon finance offers the potential to change land management and conservation planning priorities. We develop a novel approach to planning for improved land management to conserve biodiversity while utilizing potential revenue from carbon biosequestration. We apply our approach in northern Australia's tropical savanna, a region of global significance for biodiversity and carbon storage, both of which are threatened by current fire and grazing regimes. Our approach aims to identify priority locations for protecting species and vegetation communities by retaining existing vegetation and managing fire and grazing regimes at a minimum cost. We explore the impact of accounting for potential carbon revenue (using a carbon price of US$14 per tonne of carbon dioxide equivalent) on priority areas for conservation and the impact of explicitly protecting carbon stocks in addition to biodiversity. Our results show that improved management can potentially raise approximately US$5 per hectare per year in carbon revenue and prevent the release of 1-2 billion tonnes of carbon dioxide equivalent over approximately 90 years. This revenue could be used to reduce the costs of improved land management by three quarters or double the number of biodiversity targets achieved and meet carbon storage targets for the same cost. These results are based on generalised cost and carbon data; more comprehensive applications will rely on fine scale, site-specific data and a supportive policy environment. Our research illustrates that the duel objective of conserving biodiversity and reducing the release of greenhouse gases offers important opportunities for cost-effective land management investments.

  13. Adaptation in Collaborative Governance Regimes

    NASA Astrophysics Data System (ADS)

    Emerson, Kirk; Gerlak, Andrea K.

    2014-10-01

    Adaptation and the adaptive capacity of human and environmental systems have been of central concern to natural and social science scholars, many of whom characterize and promote the need for collaborative cross-boundary systems that are seen as flexible and adaptive by definition. Researchers who study collaborative governance systems in the public administration, planning and policy literature have paid less attention to adaptive capacity specifically and institutional adaptation in general. This paper bridges the two literatures and finds four common dimensions of capacity, including structural arrangements, leadership, knowledge and learning, and resources. In this paper, we focus on institutional adaptation in the context of collaborative governance regimes and try to clarify and distinguish collaborative capacity from adaptive capacity and their contributions to adaptive action. We posit further that collaborative capacities generate associated adaptive capacities thereby enabling institutional adaptation within collaborative governance regimes. We develop these distinctions and linkages between collaborative and adaptive capacities with the help of an illustrative case study in watershed management within the National Estuary Program.

  14. Adaptation in collaborative governance regimes.

    PubMed

    Emerson, Kirk; Gerlak, Andrea K

    2014-10-01

    Adaptation and the adaptive capacity of human and environmental systems have been of central concern to natural and social science scholars, many of whom characterize and promote the need for collaborative cross-boundary systems that are seen as flexible and adaptive by definition. Researchers who study collaborative governance systems in the public administration, planning and policy literature have paid less attention to adaptive capacity specifically and institutional adaptation in general. This paper bridges the two literatures and finds four common dimensions of capacity, including structural arrangements, leadership, knowledge and learning, and resources. In this paper, we focus on institutional adaptation in the context of collaborative governance regimes and try to clarify and distinguish collaborative capacity from adaptive capacity and their contributions to adaptive action. We posit further that collaborative capacities generate associated adaptive capacities thereby enabling institutional adaptation within collaborative governance regimes. We develop these distinctions and linkages between collaborative and adaptive capacities with the help of an illustrative case study in watershed management within the National Estuary Program.

  15. Computer generated holograms for carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Montelongo, Yunuen; Butt, Haider; Butler, Tim; Wilkinson, Timothy D.; Amaratunga, Gehan A. J.

    2013-05-01

    Multiwalled carbon nanotubes are highly diffractive structures in the optical regime. Their metallic character and large scattering cross-section allow their usage as diffractive elements in Fraunhofer holograms. This work elaborates some important features of the far field diffraction patterns produced from periodic arrays of nanotubes. A theoretical approach for the interaction of arrays of nanotubes with light is presented and a computer generated hologram is calculated by means of periodical patterns. Based on the results, fabrication of carbon nanotube arrays (in holographic patterns) was performed. Experimentally measured diffraction patterns were in good agreement with the calculations.

  16. Computer generated holograms for carbon nanotube arrays.

    PubMed

    Montelongo, Yunuen; Butt, Haider; Butler, Tim; Wilkinson, Timothy D; Amaratunga, Gehan A J

    2013-05-21

    Multiwalled carbon nanotubes are highly diffractive structures in the optical regime. Their metallic character and large scattering cross-section allow their usage as diffractive elements in Fraunhofer holograms. This work elaborates some important features of the far field diffraction patterns produced from periodic arrays of nanotubes. A theoretical approach for the interaction of arrays of nanotubes with light is presented and a computer generated hologram is calculated by means of periodical patterns. Based on the results, fabrication of carbon nanotube arrays (in holographic patterns) was performed. Experimentally measured diffraction patterns were in good agreement with the calculations.

  17. Regime shifts and resilience in China's coastal ecosystems.

    PubMed

    Zhang, Ke

    2016-02-01

    Regime shift often results in large, abrupt, and persistent changes in the provision of ecosystem services and can therefore have significant impacts on human wellbeing. Understanding regime shifts has profound implications for ecosystem recovery and management. China's coastal ecosystems have experienced substantial deterioration within the past decades, at a scale and speed the world has never seen before. Yet, information about this coastal ecosystem change from a dynamics perspective is quite limited. In this review, I synthesize existing information on coastal ecosystem regime shifts in China and discuss their interactions and cascading effects. The accumulation of regime shifts in China's coastal ecosystems suggests that the desired system resilience has been profoundly eroded, increasing the potential of abrupt shifts to undesirable states at a larger scale, especially given multiple escalating pressures. Policy and management strategies need to incorporate resilience approaches in order to cope with future challenges and avoid major losses in China's coastal ecosystem services.

  18. Fixed points, stable manifolds, weather regimes, and their predictability

    DOE PAGES

    Deremble, Bruno; D'Andrea, Fabio; Ghil, Michael

    2009-10-27

    In a simple, one-layer atmospheric model, we study the links between low-frequency variability and the model’s fixed points in phase space. The model dynamics is characterized by the coexistence of multiple ''weather regimes.'' To investigate the transitions from one regime to another, we focus on the identification of stable manifolds associated with fixed points. We show that these manifolds act as separatrices between regimes. We track each manifold by making use of two local predictability measures arising from the meteorological applications of nonlinear dynamics, namely, ''bred vectors'' and singular vectors. These results are then verified in the framework of ensemblemore » forecasts issued from clouds (ensembles) of initial states. The divergence of the trajectories allows us to establish the connections between zones of low predictability, the geometry of the stable manifolds, and transitions between regimes.« less

  19. Spacetime-noncommutativity regime of loop quantum gravity

    NASA Astrophysics Data System (ADS)

    Amelino-Camelia, Giovanni; Da Silva, Malú Maira; Ronco, Michele; Cesarini, Lorenzo; Lecian, Orchidea Maria

    2017-01-01

    A recent study by Bojowald and Paily [M. Bojowald and G. M. Paily, Phys. Rev. D 87, 044044 (2013)., 10.1103/PhysRevD.87.044044] provided a path toward the identification of an effective quantum-spacetime picture of loop quantum gravity, applicable in the "Minkowski regime," the regime where the large-scale (coarse-grained) spacetime metric is flat. A pivotal role in the analysis is played by loop-quantum-gravity-based modifications to the hypersurface deformation algebra, which leave a trace in the Minkowski regime. We here show that the symmetry-algebra results reported by Bojowald and Paily are consistent with a description of spacetime in the Minkowski regime given in terms of the κ -Minkowski noncommutative spacetime, whose relevance for the study of the quantum-gravity problem had already been proposed for independent reasons.

  20. Fixed points, stable manifolds, weather regimes, and their predictability

    SciTech Connect

    Deremble, Bruno; D'Andrea, Fabio; Ghil, Michael

    2009-10-27

    In a simple, one-layer atmospheric model, we study the links between low-frequency variability and the model’s fixed points in phase space. The model dynamics is characterized by the coexistence of multiple ''weather regimes.'' To investigate the transitions from one regime to another, we focus on the identification of stable manifolds associated with fixed points. We show that these manifolds act as separatrices between regimes. We track each manifold by making use of two local predictability measures arising from the meteorological applications of nonlinear dynamics, namely, ''bred vectors'' and singular vectors. These results are then verified in the framework of ensemble forecasts issued from clouds (ensembles) of initial states. The divergence of the trajectories allows us to establish the connections between zones of low predictability, the geometry of the stable manifolds, and transitions between regimes.

  1. Regime change and oscillation thresholds in recorder-like instruments.

    PubMed

    Auvray, Roman; Fabre, Benoît; Lagrée, Pierre-Yves

    2012-02-01

    Based on results from the literature, a description of sound generation in a recorder is developed. Linear and non-linear analysis are performed to study the dependence of the frequency on the jet velocity. The linear analysis predicts that the frequency is a function of the jet velocity. The non-linear resolution provides information about limit cycle oscillation and hysteretic regime change thresholds. A comparison of the frequency between linear theory and experiments on a modified recorder shows good agreement except at very low jet velocities. Although the predicted threshold for the onset of the first regime shows an important deviation from experiments, the hysteresis of threshold to higher regimes is accurately estimated. Furthermore, a qualitative analysis of the influence of different parameters in the model on the sound generation and regime changes is presented.

  2. Initial Results from the Los Angeles Megacity Carbon Project: Exploring Spatial and Temporal Variability of the In Situ CO2 Observations

    NASA Astrophysics Data System (ADS)

    Verhulst, K. R.; Feng, S.; Kim, J.; Salameh, P.; Sloop, C.; Rao, P.; Hopkins, F. M.; Yadav, V.; Keeling, R. F.; Weiss, R. F.; Miller, J. B.; Miller, C. E.; Duren, R. M.

    2015-12-01

    The Megacities Carbon Project (megacities.jpl.nasa.gov) is a multi-national, multi-institution project aimed at quantifying multi-year carbon emissions trends from large urban areas. The Los Angeles Megacity greenhouse gas observation network includes fifteen surface in situ sites and was designed to capture spatial and temporal variability in carbon emissions across the South Coast Air Basin. The surface sites include a combination of towers and rooftops equipped with laser absorption spectrometers measuring carbon dioxide (CO2), with methane and carbon monoxide measurement capability at a subset of the sites. In this study, we report intial results from January-April 2015 collected at four tower sites: two "urban" sites, which predominantly exhibit urban CO2 enhancements, and two "background" sites, which are primarily influenced by unpolluted maritime or continental air masses and reflect local background CO2 levels. During January-April 2015, hourly-averaged in situ measurements ranged from roughly 395-650 ppm CO2, with the urban sites reflecting systematically higher CO2 levels compared to the background sites. The average CO2 enhancement observed at midday (12-4pm PST) ranged from 15-23 ppm CO2 excess at the urban sites, Compton and Granada Hills. The tower measurements also show diurnal, day of week, and monthly variability. Overall, the results from the in situ network are consistent with prior studies that utilized ground-based and space-based remote sensing data to demonstrate that the "urban CO2 dome" hypothesis applies to Los Angeles. The continuous measurement capability provided by the in situ network also highlights the fact that atmospheric CO2 enhancements vary in both space and time and are not uniform throughout the South Coast Air Basin. Future work will involve sectoral attribution of the emissions sources contributing to the urban CO2 enhancements using the Hestia high-resolution fossil fuel carbon emissions inventory. A forward model

  3. Quantity and quality of black carbon molecular markers as obtained by two chromatographic methods (GC-FID and HPLC-DAD) - How do results compare?

    NASA Astrophysics Data System (ADS)

    Schneider, M. P. W.; Smittenberg, R. H.; Dittmar, T.; Schmidt, M. W. I.

    2009-04-01

    Chars produced by wildfires are an important source of black carbon (BC) in the environment. After their deposition on the soil surface they can be distributed into rivers, marine waters and sediments. The analysis of benzenepolycarboxylic acids (BPCAs) as a quantitative measure for black carbon (BC) in soil and sediment samples is a well-established method (Glaser et al., 1998; Brodowski et al., 2005). Briefly, the nitric acid oxidation of fused aromatic ring systems in BC forms eight molecular markers (BPCAs), which can be assigned to BC, and which subsequently can be quantified by GC-FID (gas chromatography with flame ionization detector). Recently, this method was modified for the quantification of BC in seawater samples using HPLC-DAD (High performance liquid chromatography with diode array detector) for the determination of individual BPCAs (Dittmar, 2008). A direct comparison of both analytical techniques is lacking but would be important for future data comparison aimed at the calculation of global BC budgets. Here we present a systematic comparison of the two BPCA quantification methods. We prepared chars under well-defined laboratory conditions. In order to cover a broad spectrum of char properties we used two sources of biomass and a wide range of pyrolysis temperatures. Chestnut hardwood chips (Castanea sativa) and rice straw (Oryza sativa) were pyrolysed at temperatures between 200 and 1000°C under a constant N2 stream. The maximum temperatures were held constant for 5 hours (Hammes et al., 2006). The BC contents of the chars have been analysed using the BPCA extraction method followed by either GC-FID or HPLC-DAD quantification. Preliminary results suggest that both methods yield similar total quantities of BPCA, and also the proportions of the individual markers are similar. Ongoing experiments will allow for a more detailed comparison of the two methods. The BPCA composition of chars formed at different temperatures and from different precursor

  4. Wavelength Dependence of the Absorption of Black Carbon Particles: Predictions and Results from the TARFOX Experiment and Implications for the Aerosol Single Scattering Albedo

    NASA Technical Reports Server (NTRS)

    Bergstrom, Robert W.; Russell, Philip B.; Hignett, Phillip

    2002-01-01

    Measurements are presented of the wavelength dependence of the aerosol absorption coefficient taken during the Tropical Aerosol Radiative Forcing Observational Experiment (TARFOX) over the northern Atlantic. The data show an approximate lamda(exp -1) variation between 0.40 and 1.0 micrometers. The theoretical basis of the wavelength variation of the absorption of solar radiation by elemental carbon [or black carbon (BC)] is explored. For a wavelength independent refractive index the small particle absorption limit simplifies to a lambda(exp -1) variation in relatively good agreement with the data. This result implies that the refractive indices of BC were relatively constant in this wavelength region, in agreement with much of the data on refractive indices of BC. However, the result does not indicate the magnitude of the refractive indices. The implications of the wavelength dependence of BC absorption for the spectral behavior of the aerosol single scattering albedo are discussed. It is shown that the single scattering albedo for a mixture of BC and nonabsorbing material decreases with wavelength in the solar spectrum (i.e., the percentage amount of absorption increases). This decease in the single scattering albedo with wavelength for black carbon mixtures is different from the increase in single scattering allied for most mineral aerosols (dusts). This indicates that, if generally true, the spectral variation of the single- scattering albedo can be used to distinguish aerosol types. It also highlights the importance of measurements of the spectral variation of the aerosol absorption coefficient and single scattering albedo.

  5. Corrosion of low-carbon steel under environmental conditions at Hanford: Two-year soil corrosion test results

    SciTech Connect

    Anantatmula, R.P.; Divine, J.R.

    1995-11-01

    At the Hanford Site, located in southeastern Washington state, nuclear production reactors were operated from 1944 to 1970. The handling and processing of radioactive nuclear fuels produced a large volume of low-level nuclear wastes, chemical wastes, and a combination of the two (mixed wastes). These materials have historically been packaged in US Department of Transportation (DOT) approved drums made from low-carbon steel, then handled in one of three ways: (A) Before 1970, the drums were buried in the dry desert soil. It was assumed that chemical and radionuclide mobility would be low and that the isolated, government-owned site would provide sufficient protection for employees and the public. (B) After 1970, the drums containing long-lived transuranic radionuclides were protected from premature failure by stacking them in an ordered array on an asphalt concrete pad in the bottom of a burial trench. The array was then covered with a large, 0.28-mm- (011-in.-) thick polyethylene tarp and the trench was backfilled with 1.3 m (4 ft) of soil cover. This burial method is referred to as soil-shielded burial . Other configurations were also employed but the soil-shielded burial method contains most of the transuranic drums. (C) Since 1987, US Department of Energy sites have complied with the Resource Conservation and Recovery Act of 1976 (RCRA) regulations. These regulations require mixed waste drums to be stored in RCRA compliant large metal sheds with provisions for monitoring. These sheds are provided with forced ventilation but are not heated or cooled.

  6. Synchronous marine pelagic regime shifts in the Northern Hemisphere

    PubMed Central

    Beaugrand, G.; Conversi, A.; Chiba, S.; Edwards, M.; Fonda-Umani, S.; Greene, C.; Mantua, N.; Otto, S. A.; Reid, P. C.; Stachura, M. M.; Stemmann, L.; Sugisaki, H.

    2015-01-01

    Regime shifts are characterized by sudden, substantial and temporally persistent changes in the state of an ecosystem. They involve major biological modifications and often have important implications for exploited living resources. In this study, we examine whether regime shifts observed in 11 marine systems from two oceans and three regional seas in the Northern Hemisphere (NH) are synchronous, applying the same methodology to all. We primarily infer marine pelagic regime shifts from abrupt shifts in zooplankton assemblages, with the exception of the East Pacific where ecosystem changes are inferred from fish. Our analyses provide evidence for quasi-synchronicity of marine pelagic regime shifts both within and between ocean basins, although these shifts lie embedded within considerable regional variability at both year-to-year and lower-frequency time scales. In particular, a regime shift was detected in the late 1980s in many studied marine regions, although the exact year of the observed shift varied somewhat from one basin to another. Another regime shift was also identified in the mid- to late 1970s but concerned less marine regions. We subsequently analyse the main biological signals in relation to changes in NH temperature and pressure anomalies. The results suggest that the main factor synchronizing regime shifts on large scales is NH temperature; however, changes in atmospheric circulation also appear important. We propose that this quasi-synchronous shift could represent the variably lagged biological response in each ecosystem to a large-scale, NH change of the climatic system, involving both an increase in NH temperature and a strongly positive phase of the Arctic Oscillation. Further investigation is needed to determine the relative roles of changes in temperature and atmospheric pressure patterns and their resultant teleconnections in synchronizing regime shifts at large scales.

  7. Varying Inundation Regimes Differentially Affect Natural and ...

    EPA Pesticide Factsheets

    Climate change is altering sea-level rise rates and precipitation patterns worldwide. Coastal wetlands are vulnerable to these changes. System responses to stressors are important for resource managers and environmental stewards to understand in order to best manage them. Thin layer sand or sediment application to drowning and eroding marshes is one approach to build elevation and resilience. The above- and below-ground structure, soil carbon dioxide emissions, and pore water constituents in vegetated natural marsh sediments and sand-amended sediments were examined at varying inundation regimes between mean sea level and mean high water (0.82 m NAVD88 to 1.49 m NAVD88) in a field experiment at Laws Point, part of the Plum Island Sound Estuary (MA). Significantly lower salinities, pH, sulfides, phosphates, and ammonium were measured in the sand-amended sediments than in the natural sediments. In natural sediments there was a pattern of increasing salinity with increasing elevation while in the sand-amended sediments the trend was reversed, showing decreasing salinity with increasing elevation. Sulfide concentrations generally increased from low to high inundation with highest concentrations at the highest inundation (i.e., at the lowest elevations). High pore water phosphate concentrations were measured at low elevations in the natural sediments, but the sand-amended treatments had mostly low concentrations of phosphate and no consistent pattern with elevation. A

  8. River Flow Regimes and Effective Discharge

    NASA Astrophysics Data System (ADS)

    Basso, S.; Sprocati, R.; Frascati, A.; Marani, M.; Schirmer, M.; Botter, G.

    2015-12-01

    The concept of effective discharge is widespread in geomorphology and river engineering and restoration. For example, it is used to design the most stable channel configuration, to estimate sedimentation rate and lifespan of reservoirs and to characterize the hydrologic forcing in models studying long-term evolution of rivers. Accordingly, the effective discharge has been the focus of countless empirical, theoretical and numerical studies, which found it to vary among catchments as a function of climate, landscape and river morphology, type of transport (dissolved, suspended or bedload), and of streamflow variability. The heterogeneity of the effective discharge values observed in different catchments challenges a thorough understanding of its pivotal drivers, and a consistent framework which explains observations carried out in different geographic areas is still lacking. In the present work, the observed diversity is explained in terms of the underlying heterogeneity of river flow regimes, by linking effective discharge to attributes of the sediment rating curve and to streamflow variability, as resulting from climatic and landscape drivers. An analytic expression of the effective ratio (i.e. the ratio between effective discharge and mean streamflow) is provided, which captures observed values of effective discharge for suspended sediment transport in a set of catchments of the continental United States. The framework disentangles hydrologic and landscape controls on effective discharge, and highlights distinct effective ratios of persistent and erratic hydrologic regimes (respectively characterized by low and high flow variability), attributable to intrinsically different streamflow dynamics. Clusters of river catchments characterized by similar streamflow dynamics can be identified. The framework provides an opportunity for first-order estimates of effective discharge in rivers belonging to different areas, based on the type of flow regime.

  9. The discrete regime of flame propagation

    NASA Astrophysics Data System (ADS)

    Tang, Francois-David; Goroshin, Samuel; Higgins, Andrew

    The propagation of laminar dust flames in iron dust clouds was studied in a low-gravity envi-ronment on-board a parabolic flight aircraft. The elimination of buoyancy-induced convection and particle settling permitted measurements of fundamental combustion parameters such as the burning velocity and the flame quenching distance over a wide range of particle sizes and in different gaseous mixtures. The discrete regime of flame propagation was observed by substitut-ing nitrogen present in air with xenon, an inert gas with a significantly lower heat conductivity. Flame propagation in the discrete regime is controlled by the heat transfer between neighbor-ing particles, rather than by the particle burning rate used by traditional continuum models of heterogeneous flames. The propagation mechanism of discrete flames depends on the spa-tial distribution of particles, and thus such flames are strongly influenced by local fluctuations in the fuel concentration. Constant pressure laminar dust flames were observed inside 70 cm long, 5 cm diameter Pyrex tubes. Equally-spaced plate assemblies forming rectangular chan-nels were placed inside each tube to determine the quenching distance defined as the minimum channel width through which a flame can successfully propagate. High-speed video cameras were used to measure the flame speed and a fiber optic spectrometer was used to measure the flame temperature. Experimental results were compared with predictions obtained from a numerical model of a three-dimensional flame developed to capture both the discrete nature and the random distribution of particles in the flame. Though good qualitative agreement was obtained between model predictions and experimental observations, residual g-jitters and the short reduced-gravity periods prevented further investigations of propagation limits in the dis-crete regime. The full exploration of the discrete flame phenomenon would require high-quality, long duration reduced gravity environment

  10. Fate of organic carbon in paddy soils - results of Alisol and Andosol incubation with 13C marker

    NASA Astrophysics Data System (ADS)

    Winkler, Pauline; Cerli, Chiara; Fiedler, Sabine; Woche, Susanne; Rahayu Utami, Sri; Jahn, Reinhold; Kalbitz, Karsten; Kaiser, Klaus

    2016-04-01

    For a better understanding of organic carbon (OC) decomposition in paddy soils an incubation experiment was performed. Two soil types with contrasting mineralogy (Alisol and Andosol) were exposed to 8 anoxic‒oxic cycles over 1 year. Soils received rice straw marked with 13C (228 ‰) at the beginning of each cycle. A second set of samples without straw addition was used as control. Headspaces of the incubation vessels were regularly analysed for CO2 and CH4. In soil solutions, redox potential, pH, dissolved organic C (DOC), and Fe2+ were measured after each anoxic and each oxic phase. Soils were fractionated by density at the end of the experiment and the different fractions were isotopically analysed. Samples of genuine paddy soils that developed from the test soils were used as reference. During anoxic cycles, soils receiving rice straw released large amounts of CO2 and CH4, indicating strong microbial activity. Consequently, Eh values dropped and pH as well as Fe2+ concentrations increased. Concentrations of DOC were relatively small, indicating either strong consumption and/or strong retention of dissolved organic compounds. During oxic cycles, concentrations of dissolved Fe dropped in both soils while DOC concentrations remained constant in the Alisol and decreased in the Andosol. Density fractionation revealed increased contents of mineral associated OC for the Andosol incubated with straw addition as compared to the parent soil. No changes were found for the Alisol. However, the mineral-associated OC fraction of both soil types contained 13C of the added straw. Hence, fresh organic matter is incorporated while part of the older organic matter has been released or mineralized. The increase in the Andosol might be due to effective binding of fresh OC to minerals and/or stronger retention/preservation of older OC. Both could be explained by the more reactive mineralogy of the Andosol than of the Alisol. XPS analyses of the soils are currently performed and

  11. Environmental and Physiological Influences on the TEX86 Proxy: Results from Continuous Culture Studies and Stable Carbon Isotope Analyses

    NASA Astrophysics Data System (ADS)

    Pearson, A.; Hurley, S.; Elling, F. J.; Koenneke, M.; Santoro, A. E.; Buchwald, C.; Wankel, S. D.; Hinrichs, K. U.; Zhang, Y.; Shah Walter, S. R.

    2015-12-01

    Membrane lipids of marine Archaea - known as GDGTs - are the basis of the TEX86 sea surface temperature (SST) paleoproxy. GDGTs are ubiquitous in marine sediments, and their broad distribution and high preservation potential have led to an ever-increasing use of TEX86. The planktonic Thaumarchaeota that are believed to be the major sources of GDGTs to marine sediments are autotrophic nitrifiers, assimilating carbon directly from dissolved CO2. Therefore the δ13C values of GDGTs additionally provide information about the DIC system and paleoproductivity. However, as for all biological proxies, understanding the physiology and biochemistry of the responsible organisms is essential to understanding how the proxies work. From this perspective, the TEX86-SST proxy is uniquely perplexing: How is it possible that multiple approaches to calibration show a good correlation between TEX86 and SSTs, when maximum activity of Thaumarchaeota is near and below the base of the photic zone? Here we show data from two studies that help address this question. Analyses of GDGT δ13C values show that the dominant GDGT flux to sediments is not from the sea surface. The data are measured on intact GDGTs purified by orthogonal dimensions of HPLC, followed by measurement of δ13C values on a Spooling Wire Microcombustion (SWiM)-IRMS with 1σ precision of ±0.2‰ and accuracy of ±0.3‰. Using this approach, we confirm that GDGTs, generally around -19.0‰ to -18.5‰, are isotopically "heavy" compared to other marine lipids, and that crenarchaeol in particular is a good tracer of water column GDGT export. In parallel, we investigated the mechanistic underpinning of the TEX86 proxy using isothermal culture studies of the ammonia-oxidizing thaumarchaeon Nitrosopumilus maritimus SCM1 to explore the relationship between TEX86 and growth conditions. Evidence suggests that growth rate and electron donor supply are important controls on GDGT ratios and that TEX86 scales with the in-situ rate of

  12. The effect of abrupt permafrost thaw on the water table, vegetation and carbon feedback: results from a sub-arctic peatland

    NASA Astrophysics Data System (ADS)

    Malhotra, A.; Roulet, N. T.

    2015-12-01

    Uncertainty in estimating the carbon loss from thawing ice-rich permafrost is attributed, in part, to the abrupt changes in ecosystem structure and function after thaw. In a thawing peat plateau in the discontinuous permafrost zone (Stordalen, Mire, Sweden; ST), we tested for the occurrence of abrupt changes in hydrology and the effects of these changes on the water table and vegetation feedback. Using a chronosequence approach along three transects that capture several transitional thaw stages, we found abrupt hydrological changes following thaw, wherein adjacent areas (1 m apart) had unrelated water table depth (WTD) fluctuations. Despite these abrupt changes, surprisingly, the same Gaussian model of plant abundance explained by WTD could be applied to data from both ST and an undisturbed ombrotrophic peatland (Mer Bleue Bog, Canada; MB). However, the Gaussian model fit was better at MB than at ST. Furthermore, explanatory power of the model at ST decreased with increasing permafrost thaw. While water table and vegetation feedback in a thawing landscape is similar to that of a peatland without transitional land cover types, the vegetation and carbon feedback is complicated by non-linear shifts in the partitioning of gaseous effluxes between CO2 and CH4. These results will be presented along with key implications for modeling carbon loss from thawing landscapes.

  13. Evaluation of interregional variability in MODIS cloud regimes

    NASA Astrophysics Data System (ADS)

    Leinonen, J. S.; Lebsock, M. D.; Oreopoulos, L.; Cho, N.

    2015-12-01

    Clustering techniques have been used in the last few decades to classify cloud types automatically from satellite observations, most commonly using cloud top pressure and cloud optical depth. The underlying assumption is that the resulting clusters, called "cloud regimes" or "weather states", represent some type of basic states of the atmosphere, and thus that their occurrence can be used as a proxy for related variables such as radiative balance or precipitation. We have examined the validity of these assumptions by using independent measurements from the CloudSat and CALIPSO satellites. The CloudSat radar yields a reflectivity product that is sensitive to many aspects of the physics of the clouds, while CloudSat together with the CALIPSO lidar can retrieve the vertical structure of the cloud column, including multi-layer clouds. These observations have been separated into groups according to the recently published cloud regimes based on data from the MODIS instrument, deployed on the Aqua satellite orbiting in the same constellation with CloudSat and CALIPSO. The distributions of these observations have been constructed both globally and in a number of regions in different parts of the Earth. By analyzing the differences in the distributions between these regions, we can evaluate the usefulness of the cloud regimes as a proxy for the measured variables. Some cloud regimes have been found to be rather stable between regions, while others display considerable variability. Moreover, some cloud regimes appear much more similar to each other in CloudSat observations than they do using the MODIS regimes. We analyze the implications of these differences for the usability of the cloud regimes as climate indicators. We also explore various filtering techniques and different clustering methods that can potentially be used to reduce these differences, and thus to improve the universality of the cloud regimes.

  14. Assessing Ecosystem Drought Response in CLM 4.5 Using Site-Level Flux and Carbon-Isotope Measurements: Results From a Pacific Northwest Coniferous Forest

    NASA Astrophysics Data System (ADS)

    Duarte, H.; Raczka, B. M.; Koven, C. D.; Ricciuto, D. M.; Lin, J. C.; Bowling, D. R.; Ehleringer, J. R.

    2015-12-01

    The frequency, extent, and severity of droughts are expected to increase in the western United States as climate changes occur. The combination of warmer temperature, larger vapor pressure deficit, reduced snowfall and snow pack, earlier snow melt, and extended growing seasons is expected to lead to an intensification of summer droughts, with a direct impact on ecosystem productivity and therefore on the carbon budget of the region. In this scenario, an accurate representation of ecosystem drought response in land models becomes fundamental, but the task is challenging, especially in regards to stomatal response to drought. In this study we used the most recent release of the Community Land Model (CLM 4.5), which now includes photosynthetic carbon isotope discrimination and revised photosynthesis and hydrology schemes, among an extensive list of updates. We evaluated the model's performance at a coniferous forest site in the Pacific northwest (Wind River AmeriFlux Site), characterized by a climate that has a strong winter precipitation component followed by a summer drought. We ran the model in offline mode (i.e., decoupled from an atmospheric model), forced by observed meteorological data, and used site observations (e.g., surface fluxes, biomass values, and carbon isotope data) to assess the model. Previous field observations indicated a significant negative correlation between soil water content and the carbon isotope ratio of ecosystem respiration (δ13CR), suggesting that δ13CR was closely related to the photosynthetic discrimination against 13CO2 as controlled by stomatal conductance. We used these observations and latent-heat flux measurements to assess the modeled stomatal conductance values and their responses to extended summer drought. We first present the model results, followed by a discussion of potential CLM model improvements in stomatal conductance responses and in the representation of soil water stress (parameter βt) that would more precisely

  15. O-regime dynamics and modeling in Tore Supra

    NASA Astrophysics Data System (ADS)

    Turco, F.; Giruzzi, G.; Imbeaux, F.; Udintsev, V. S.; Artaud, J. F.; Barana, O.; Dumont, R.; Mazon, D.; Ségui, J.-L.

    2009-06-01

    The regime of nonlinear temperature oscillations (O-regime), characteristic of noninductive discharges on Tore Supra [Équipe Tore Supra, Proceedings of the 12th International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Nice, France, 1988 (International Atomic Energy Agency, Vienna, 1989), Vol. 1, p. 9], is investigated in its triggering and suppressing mechanism. This regime can be described by two nonlinearly coupled equations for the current density j(r ) and the electron temperature Te(r) where the equation coefficients are functions of j and Te themselves. Both the integrated modeling code CRONOS [V. Basiuk et al., Nucl. Fusion 43, 822 (2003)] and a two-patch predator-prey system with diffusion and noise have been used and results have been compared to the experimental observations of the O-regime. A database of discharges is analyzed which features monotonic, flat, and reversed safety factor (q) profiles in order to characterize the action of external actuators on the regime dynamics with the widest generality. Electron cyclotron current drive and neutral beam injections have been used in order to induce localized perturbations in the total current profile j(r ) as well as to change the plasma confinement conditions in the central region. Magnetic shear perturbations and modifications of the heat transport turn out to be the central parameters governing the dynamics of the O-regime.

  16. O-regime dynamics and modeling in Tore Supra

    SciTech Connect

    Turco, F.; Giruzzi, G.; Imbeaux, F.; Udintsev, V. S.; Artaud, J. F.; Barana, O.; Dumont, R.; Mazon, D.; Segui, J.-L.

    2009-06-15

    The regime of nonlinear temperature oscillations (O-regime), characteristic of noninductive discharges on Tore Supra [Equipe Tore Supra, Proceedings of the 12th International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Nice, France, 1988 (International Atomic Energy Agency, Vienna, 1989), Vol. 1, p. 9], is investigated in its triggering and suppressing mechanism. This regime can be described by two nonlinearly coupled equations for the current density j(r) and the electron temperature T{sub e}(r) where the equation coefficients are functions of j and T{sub e} themselves. Both the integrated modeling code CRONOS[V. Basiuk et al., Nucl. Fusion 43, 822 (2003)] and a two-patch predator-prey system with diffusion and noise have been used and results have been compared to the experimental observations of the O-regime. A database of discharges is analyzed which features monotonic, flat, and reversed safety factor (q) profiles in order to characterize the action of external actuators on the regime dynamics with the widest generality. Electron cyclotron current drive and neutral beam injections have been used in order to induce localized perturbations in the total current profile j(r) as well as to change the plasma confinement conditions in the central region. Magnetic shear perturbations and modifications of the heat transport turn out to be the central parameters governing the dynamics of the O-regime.

  17. Detonation wave driven by condensation of supersaturated carbon vapor.

    PubMed

    Emelianov, A; Eremin, A; Fortov, V; Jander, H; Makeich, A; Wagner, H Gg

    2009-03-01

    An experimental observation of a detonation wave driven by the energy of condensation of supersaturated carbon vapor is reported. The carbon vapor was formed by the thermal decay of unstable carbon suboxide C3O2 behind shock waves in mixtures containing 10-30% C3O2 in Ar. In the mixture 10% C3O2+Ar the insufficient heat release resulted in a regime of overdriven detonation. In the mixture 20% C3O2+Ar measured values of the pressure and wave velocity coincident with calculated Chapman-Jouguet parameters were attained. In the richest mixture 30% C3O2+Ar an excess heat release caused the slowing down of the condensation rate and the regime of underdriven detonation was observed.

  18. 76 FR 31938 - Certain Hot-Rolled Carbon Steel Flat Products From India: Notice of Preliminary Results of 2009...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-02

    ... Trade Compliance Analyst, through Melissa Skinner, Office Director, concerning ``Certain Hot Rolled... Trade Compliance Analyst, through Melissa Skinner, Office Director, concerning ``Certain Hot-Rolled....224(b). Comments Interested parties are invited to comment on the preliminary results and may...

  19. Oxygen isotope analysis of carbonates in the calcite-dolomite-magnesite solid-solution by high-temperature pyrolysis: initial results.

    PubMed

    Crowley, Stephen F; Spero, Howard J; Winter, David A; Sloane, Hilary J; Croudace, Ian W

    2008-06-01

    Accurate and efficient measurement of the oxygen isotope composition of carbonates (delta(C) (18)O) based on the mass spectrometric analysis of CO(2) produced by reacting carbonate samples with H(3)PO(4) is compromised by: (1) uncertainties associated with fractionation factors (alpha(CO)(2)C) used to correct measured oxygen isotope values of CO(2)(delta(CO(2)(18)O) to delta(C) (18)O; and (2) the slow reaction rates of many carbonates of geological and environmental interest with H(3)PO(4). In contrast, determination of delta(C) (18)O from analysis of CO produced by high-temperature (>1400 degrees C) pyrolytic reduction, using an elemental analyser coupled to continuous-flow isotope-ratio mass spectrometry (TC/EA CF-IRMS), offers a potentially efficient alternative that measures the isotopic composition of total carbonate oxygen and should, therefore, theoretically be free of fractionation effects. The utility of the TC/EA CF-IRMS technique was tested by analysis of carbonates in the calcite-dolomite-magnesite solid-solution and comparing the results with delta(C) (18)O measured by conventional thermal decomposition/fluorination (TDF) on the same materials. Initial results show that CO yields are dependent on both the chemical composition of the carbonate and the specific pyrolysis conditions. Low gas yields (<100% of predicted yield) are associated with positive (>+0.2 per thousand) deviations in delta(C(TC/EA) (18)O compared with delta(C(TDF) (18)O. At a pyrolysis temperature of 1420 degrees C the difference between delta(C) (18)O measured by TC/EA CF-IRMS and TDF (Delta(C(TC/EA,TDF) (18)O) was found to be negatively correlated with gas yield (r = -0.785) and this suggests that delta(C) (18)O values (with an estimated combined standard uncertainty of +/-0.38 per thousand) could be derived by applying a yield-dependent correction. Increasing the pyrolysis temperature to 1500 degrees C also resulted in a statistically significant correlation with gas yield (r = -0

  20. Acid neutralizing capacity and leachate results for igneous rocks, with associated carbon contents of derived soils, Animas River AML site, Silverton, Colorado

    USGS Publications Warehouse

    Yager, Douglas B.; Stanton, Mark R.; Choate, LaDonna M.; Burchell,

    2009-01-01

    Mine planning efforts have historically overlooked the possible acid neutralizing capacity (ANC) that local igneous rocks can provide to help neutralize acidmine drainage. As a result, limestone has been traditionally hauled to mine sites for use in neutralizing acid drainage. Local igneous rocks, when used as part of mine life-cycle planning and acid mitigation strategy, may reduce the need to transport limestone to mine sites because these rocks can contain acid neutralizing minerals. Igneous hydrothermal events often introduce moderately altered mineral assemblages peripheral to more intensely altered rocks that host metal-bearing veins and ore bodies. These less altered rocks can contain ANC minerals (calcite-chlorite-epidote) and are referred to as a propylitic assemblage. In addition, the carbon contents of soils in areas of new mining or those areas undergoing restoration have been historically unknown. Soil organic carbon is an important constituent to characterize as a soil recovery benchmark that can be referred to during mine cycle planning and restoration.
    This study addresses the mineralogy, ANC, and leachate chemistry of propylitic volcanic rocks that host polymetallic mineralization in the Animas River watershed near the historical Silverton, Colorado, mining area. Acid titration tests on volcanic rocks containing calcite (2 – 20 wt %) and chlorite (6 – 25 wt %), have ANC ranging from 4 – 146 kg/ton CaCO3 equivalence. Results from a 6-month duration, kinetic reaction vessel test containing layered pyritic mine waste and underlying ANC volcanic rock (saturated with deionized water) indicate that acid generating mine waste (pH 2.4) has not overwhelmed the ANC of propylitic volcanic rocks (pH 5.8). Sequential leachate laboratory experiments evaluated the concentration of metals liberated during leaching. Leachate concentrations of Cu-Zn-As-Pb for ANC volcanic rock are one-to-three orders of magnitude lower when compared to leached

  1. 75 FR 26927 - Certain Activated Carbon From the People's Republic of China: Notice of Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-13

    ... attempting to manipulate the respondent selection process. Petitioners argue that the Department's selection... (CO 2 ) in place of steam in this process. The vast majority of the internal porosity developed during the high temperature steam (or CO 2 gas) activated process is a direct result of oxidation of...

  2. 76 FR 33204 - Certain Welded Carbon Steel Pipe and Tube From Turkey; Notice of Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-08

    ... Results of Antidumping Duty Administrative Review, 75 FR 6627 (February 10, 2010) (``SSSS from Mexico... the cost changes and the sales prices during the POR. See SSSS from Mexico at Comment 6 and SSPC from... between Borusan's changing costs and sales prices during the POR. See id. See also SSSS from Mexico...

  3. 78 FR 76279 - Certain Cut-to-Length Carbon Steel Plate From the People's Republic of China: Final Results and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-17

    ...; 2011-2012, 78 FR 44525 (July 24, 2013) (``Preliminary Results''). DATES: Effective Date: December 17... shape, neither clad, plated nor coated with metal, whether or not painted, varnished, or coated with... coils, of rectangular shape, hot-rolled, neither clad, plated nor coated with metal, whether or...

  4. 77 FR 67337 - Certain Activated Carbon From the People's Republic of China; 2010-2011; Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-09

    ... made changes to the margin calculations for these final results and partial rescission of antidumping... to the margin calculations for Jacobi, DJAC, and Cherishmet. For the reasons explained in the Issues... made other changes to the margin calculations of Cherishmet, DJAC, and Jacobi.\\10\\ Finally,...

  5. Experimental results with fuel cell start-up and shut-down. Impact of type of carbon for cathode catalyst support

    DOE PAGES

    Lottin, Olivier; Dillet, Jerome; Maranzana, Gael; ...

    2015-09-14

    Separate testing protocols for fuel cell startups and shutdowns were developed to distinguish between their effects on reverse currents and CO2 evolution. The internal currents and the local potentials were measured with different membrane-electrode assemblies (MEAs): we examined the influence of the type of carbon for cathode catalyst support as well as the mitigating effect of low anode Pt loading. In conclusion, significant differences were observed and the experiments also confirmed previous results that the evolved CO2 accounts for less than 25% of the total exchanged charge.

  6. Experimental results with fuel cell start-up and shut-down. Impact of type of carbon for cathode catalyst support

    SciTech Connect

    Lottin, Olivier; Dillet, Jerome; Maranzana, Gael; Abbou, Sofyane; Didierjean, Sophie; Lamibrac, Adrien; Borup, Rodney L.; Mukundan, Rangachary; Spernjak, Dusan

    2015-09-14

    Separate testing protocols for fuel cell startups and shutdowns were developed to distinguish between their effects on reverse currents and CO2 evolution. The internal currents and the local potentials were measured with different membrane-electrode assemblies (MEAs): we examined the influence of the type of carbon for cathode catalyst support as well as the mitigating effect of low anode Pt loading. In conclusion, significant differences were observed and the experiments also confirmed previous results that the evolved CO2 accounts for less than 25% of the total exchanged charge.

  7. Modeling the spatiotemporal variability in subsurface thermal regimes across a low-relief polygonal tundra landscape

    SciTech Connect

    Kumar, Jitendra; Collier, Nathan; Bisht, Gautam; Mills, Richard T.; Thornton, Peter E.; Iversen, Colleen M.; Romanovsky, Vladimir

    2016-09-27

    Vast carbon stocks stored in permafrost soils of Arctic tundra are under risk of release to the atmosphere under warming climate scenarios. Ice-wedge polygons in the low-gradient polygonal tundra create a complex mosaic of microtopographic features. This microtopography plays a critical role in regulating the fine-scale variability in thermal and hydrological regimes in the polygonal tundra landscape underlain by continuous permafrost. Modeling of thermal regimes of this sensitive ecosystem is essential for understanding the landscape behavior under the current as well as changing climate. Here, we present an end-to-end effort for high-resolution numerical modeling of thermal hydrology at real-world field sites, utilizing the best available data to characterize and parameterize the models. We also develop approaches to model the thermal hydrology of polygonal tundra and apply them at four study sites near Barrow, Alaska, spanning across low to transitional to high-centered polygons, representing a broad polygonal tundra landscape. A multiphase subsurface thermal hydrology model (PFLOTRAN) was developed and applied to study the thermal regimes at four sites. Using a high-resolution lidar digital elevation model (DEM), microtopographic features of the landscape were characterized and represented in the high-resolution model mesh. The best available soil data from field observations and literature were utilized to represent the complex heterogeneous subsurface in the numerical model. Simulation results demonstrate the ability of the developed modeling approach to capture – without recourse to model calibration – several aspects of the complex thermal regimes across the sites, and provide insights into the critical role of polygonal tundra microtopography in regulating the thermal dynamics of the carbon-rich permafrost soils. Moreover, areas of significant disagreement between model results and observations highlight the importance of field

  8. Modeling the spatiotemporal variability in subsurface thermal regimes across a low-relief polygonal tundra landscape

    DOE PAGES

    Kumar, Jitendra; Collier, Nathan; Bisht, Gautam; ...

    2016-09-27

    Vast carbon stocks stored in permafrost soils of Arctic tundra are under risk of release to the atmosphere under warming climate scenarios. Ice-wedge polygons in the low-gradient polygonal tundra create a complex mosaic of microtopographic features. This microtopography plays a critical role in regulating the fine-scale variability in thermal and hydrological regimes in the polygonal tundra landscape underlain by continuous permafrost. Modeling of thermal regimes of this sensitive ecosystem is essential for understanding the landscape behavior under the current as well as changing climate. Here, we present an end-to-end effort for high-resolution numerical modeling of thermal hydrology at real-world fieldmore » sites, utilizing the best available data to characterize and parameterize the models. We also develop approaches to model the thermal hydrology of polygonal tundra and apply them at four study sites near Barrow, Alaska, spanning across low to transitional to high-centered polygons, representing a broad polygonal tundra landscape. A multiphase subsurface thermal hydrology model (PFLOTRAN) was developed and applied to study the thermal regimes at four sites. Using a high-resolution lidar digital elevation model (DEM), microtopographic features of the landscape were characterized and represented in the high-resolution model mesh. The best available soil data from field observations and literature were utilized to represent the complex heterogeneous subsurface in the numerical model. Simulation results demonstrate the ability of the developed modeling approach to capture – without recourse to model calibration – several aspects of the complex thermal regimes across the sites, and provide insights into the critical role of polygonal tundra microtopography in regulating the thermal dynamics of the carbon-rich permafrost soils. Moreover, areas of significant disagreement between model results and observations highlight the importance of field

  9. Propagation Regime of Iron Dust Flames

    NASA Technical Reports Server (NTRS)

    Tang, Francois-David; Goroshin, Samuel; Higgins, Andrew J.

    2012-01-01

    A flame propagating through an iron-dust mixture can propagate in two asymptotic regimes. When the characteristic time of heat transfer between particles is much smaller than the characteristic time of particle combustion, the flame propagates in the continuum regime where the heat released by reacting particles can be modelled as a space-averaged function. In contrast, when the characteristic time of heat transfer is much larger than the particle reaction time, the flame can no longer be treated as a continuum due to dominating effects associated with the discrete nature of the particle reaction. The discrete regime is characterized by weak dependence of the flame speed on the oxygen concentration compared to the continuum regime. The discrete regime is observed in flames propagating through an iron dust cloud within a gas mixture containing xenon, while the continuum regime is obtained when xenon is substituted with helium.

  10. 77 FR 58512 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-21

    ... resulting benefit by POSCO's total free on board (f.o.b.) sales. See 19 CFR 351.525(b)(3). On this basis, we... attributable to the POR by Dongbu's total f.o.b. sales for the POR. On this basis, we determine a net... of exemptions by Dongbu's total f.o.b. sales for the POR. On this basis, we preliminarily...

  11. Evolution of the water regime of Phobos

    SciTech Connect

    Fanale, F.P.; Salvail, J.R. )

    1990-12-01

    In the present model of Phobos water regime evolution, a time-dependent solar insolation is influenced by both decreasing solar output over geologic time and the Mars and Phobos cycles of eccentricity and obliquity, which vary over 100,000-1,000,000 year time scales. The results presented address model cases which assume (1) a homogeneous distribution of water ice, and (2) a driving of water ice toward the surface by the internal thermal gradient near the poles. A two-dimensional model is used to compute temperatures, heat and vapor fluxes, and ice removal/deposition rates, for the case of uniform ice distribution throughout Phobos. The results obtained indicate that a substantial amount of vapor is produced within 1 km of the surface. 15 refs.

  12. North Sea wind climate in changing weather regimes

    NASA Astrophysics Data System (ADS)

    Anders, Ivonne; Rockel, Burkhardt

    2015-04-01

    Results from regional climate models (RCMs) are getting more and more important in future wind climate assessment. From RCMs often only the daily wind speed is available, but no information on prevailing wind direction of each day. Weather regime classification can close this gap and models ability of simulating surface wind speed can be analysed in detail. Several objective regime classifications have been investigated to be a sufficient diagnostic tool to evaluate the present wind climate at the German and Dutch coastal area of the North Sea. The classification by Jenkinson and Collison (1977) uses values for mean sea level pressure at 16 locations centered over the North Sea. Beside the predefined 8 prevailed wind directions and the two possibilities on cyclonic or anticyclonic turbulence, 2x8 hybrid weather types can be defined. In this way 27 different regimes can be distinguished including a class of non-classifiable cases. The 27 regimes could be reduced to a number of 11 by allotting the hybrid types to the directional or the centered types. As the classification is carried out for the North Sea based on ERA40 mean sea level pressure the different regimes clearly reflect the mean wind characteristics at the stations. Comparing the wind roses for the individual observations leads to the assumption that the regime classification described before fits the requirements to carry out the regime dependent evaluation of the RCMs with a focus on the German and Dutch coast. Trends in the occurrence of the regimes in the winter period of 1961 to 2000 show an increase of the regimes with Western and Southwestern wind directions and a decrease of wind events from Eastern directions in the North Sea. The trend is dominated by the strong positive phase of the NAO especially in the months January to March starting in the beginning of the 1980s. Due to the applied method ERA40 and the RCMs do not necessarily show the same regime at each day. The agreement among the RCM

  13. Longitudinal profiling of urinary steroids by gas chromatography/combustion/isotope ratio mass spectrometry: diet change may result in carbon isotopic variations.

    PubMed

    Saudan, Christophe; Kamber, Matthias; Barbati, Giulia; Robinson, Neil; Desmarchelier, Aurélien; Mangin, Patrice; Saugy, Martial

    2006-02-02

    Longitudinal profiling of urinary steroids was investigated by using a gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) method. The carbon isotope ratio of three urinary testosterone (T) metabolites: androsterone, etiocholanolone, 5beta-androstane-3alpha,17beta-diol (5beta-androstanediol) together with 16(5alpha)-androsten-3alpha-ol (androstenol) and 5beta-pregnane-3alpha,20alpha-diol (5beta-pregnanediol) were measured in urine samples collected from three top-level athletes over 2 years. Throughout the study, the subjects were living in Switzerland and were residing every year for a month or two in an African country. (13)C-enrichment larger than 2.5 per thousand was observed for one subject after a 2-month stay in Africa. Our findings reveal that (13)C-enrichment caused by a diet change might be reduced if the stay in Africa was shorter or if the urine sample was not collected within the days after return to Switzerland. The steroids of interest in each sample did not show significant isotopic fractionation that could lead to false positive results in anti-doping testing. In contrast to the results obtained with the carbon isotopic ratio, profiling of urinary testosterone/epitestosterone (T/E) ratios was found to be unaffected by a diet change.

  14. A model-data comparison of gross primary productivity: Results from the North American Carbon Program site synthesis

    NASA Astrophysics Data System (ADS)

    Schaefer, Kevin; Schwalm, Christopher R.; Williams, Chris; Arain, M. Altaf; Barr, Alan; Chen, Jing M.; Davis, Kenneth J.; Dimitrov, Dimitre; Hilton, Timothy W.; Hollinger, David Y.; Humphreys, Elyn; Poulter, Benjamin; Raczka, Brett M.; Richardson, Andrew D.; Sahoo, Alok; Thornton, Peter; Vargas, Rodrigo; Verbeeck, Hans; Anderson, Ryan; Baker, Ian; Black, T. Andrew; Bolstad, Paul; Chen, Jiquan; Curtis, Peter S.; Desai, Ankur R.; Dietze, Michael; Dragoni, Danilo; Gough, Christopher; Grant, Robert F.; Gu, Lianhong; Jain, Atul; Kucharik, Chris; Law, Beverly; Liu, Shuguang; Lokipitiya, Erandathie; Margolis, Hank A.; Matamala, Roser; McCaughey, J. Harry; Monson, Russ; Munger, J. William; Oechel, Walter; Peng, Changhui; Price, David T.; Ricciuto, Dan; Riley, William J.; Roulet, Nigel; Tian, Hanqin; Tonitto, Christina; Torn, Margaret; Weng, Ensheng; Zhou, Xiaolu

    2012-09-01

    Accurately simulating gross primary productivity (GPP) in terrestrial ecosystem models is critical because errors in simulated GPP propagate through the model to introduce additional errors in simulated biomass and other fluxes. We evaluated simulated, daily average GPP from 26 models against estimated GPP at 39 eddy covariance flux tower sites across the United States and Canada. None of the models in this study match estimated GPP within observed uncertainty. On average, models overestimate GPP in winter, spring, and fall, and underestimate GPP in summer. Models overpredicted GPP under dry conditions and for temperatures below 0°C. Improvements in simulated soil moisture and ecosystem response to drought or humidity stress will improve simulated GPP under dry conditions. Adding a low-temperature response to shut down GPP for temperatures below 0°C will reduce the positive bias in winter, spring, and fall and improve simulated phenology. The negative bias in summer and poor overall performance resulted from mismatches between simulated and observed light use efficiency (LUE). Improving simulated GPP requires better leaf-to-canopy scaling and better values of model parameters that control the maximum potential GPP, such asɛmax (LUE), Vcmax (unstressed Rubisco catalytic capacity) or Jmax (the maximum electron transport rate).

  15. Measurement of hydrogen, helium, carbon and oxygen cosmic ray primaries: Preliminary results from the CREAM II experiment

    NASA Astrophysics Data System (ADS)

    Mognet, S. A. Isaac

    The direct measurement of the energy spectrum and composition of the incoming cosmic-ray flux at multi-TeV energies is of great interest. A feature located somewhere between 1000-10,000 TeV in the all-particle spectrum, referred to as the 'knee' characterized by a steepening of the power-law flux, has been observed by ground-based detectors for many years. It is believed to be related to an upper limit or change in efficiency of the Galactic accelerators of cosmic rays and/or properties of the propagation of cosmic rays in the Galaxy. Presented here is a preliminary analysis of the flux of primary H, He, C and O cosmic-ray species measured using the CREAM II instrument. This analysis is conducted using the Penn State-built Timing Charge Detector, distinct from other charge detectors used in alternative published CREAM II results. The second Antarctic flight of the CREAM instrument had a ~ 28 day flight in the 2005-2006 Antarctic flight season. The instrument was launched on December 16 th 2005 from Williams Field near McMurdo Station, Antarctica. The analysis presented here used events collected throughout the flight to calibrate the charge response of the Timing Charge Detector. High-energy events collected during the entire flight time (except for the first ~ 3.5 days which were used for high-voltage tuning) are also analyzed here. Also presented in this thesis is a novel optical simulation of the Timing Charge Detector used in the various flights of the CREAM instrument. The model suggests fundamental limitations on the timing resolution of the detector arising purely from photon propagation physics in the scintillation and light- guide elements.

  16. Effects of acidic deposition on the erosion of carbonate stone - experimental results from the U.S. National Acid Precipitation Assessment Program (NAPAP)

    USGS Publications Warehouse

    Baedecker, P.A.; Reddy, M.M.; Reimann, K.J.; Sciammarella, C.A.

    1992-01-01

    One of the goals of NAPAP-sponsored research on the effects of acidic deposition on carbonate stone has been to quantify the incremental effects of wet and dry deposition of hydrogen ion, sulfur dioxide and nitrogen oxides on stone erosion. Test briquettes and slabs of freshly quarried Indiana limestone and Vermont marble have been exposed to ambient environmental conditions in a long-term exposure program. Physical measurements of the recession of test stones exposed to ambient conditions at an angle of 30?? to horizontal at the five NAPAP materials exposure sites range from ~15 to ~30?? ??m yr-1 for marble, and from ~25 to ~45 ??m yr -1 for limestone, and are approximately double the recession estimates based on the observed calcium content of run-off solutions from test slabs. The difference between the physical and chemical recession measurements is attributed to the loss of mineral grains from the stone surfaces that are not measured in the run-off experiments. The erosion due to grain loss does not appear to be influenced by rainfall acidity, however, preliminary evidence suggests that grain loss may be influenced by dry deposition of sulfur dioxide between rainfall events. Chemical analyses of the run-off solutions and associated rainfall blanks suggest that ~30% of erosion by dissolution can be attributed to the wet deposition of hydrogen ion and the dry deposition of sulfur dioxide and nitric acid between rain events. The remaining ~70% of erosion by dissolution is accounted for by the solubility of carbonate stone in rain that is in equilibrium with atmospheric carbon dioxide ('clean rain'). These results are for marble and limestone slabs exposed at an angle of 30?? from horizontal. The relative contribution of sulfur dioxide to chemical erosion is significantly enhanced for stone slabs having an inclination of 60?? or 85??. The dry deposition of alkaline particulate material has a mitigating effect at the two urban field exposure sites at Washington, DC

  17. Identification of absorbing organic (brown carbon) aerosols through Sun Photometry: results from AEROCAN / AERONET stations in high Arctic and urban Locations

    NASA Astrophysics Data System (ADS)

    Kerr, G. H.; Chaubey, J. P.; O'Neill, N. T.; Hayes, P.; Atkinson, D. B.

    2014-12-01

    Light absorbing organic aerosols or brown carbon (BrC) aerosols are prominent species influencing the absorbing aerosol optical depth (AAOD) of the total aerosol optical depth (AOD) in the UV wavelength region. They, along with dust, play an important role in modifying the spectral AAOD and the spectral AOD in the UV region: this property can be used to discriminate BrC aerosols from both weakly absorbing aerosols such as sulfates as well as strongly absorbing aerosols such as black carbon (BC). In this study we use available AERONET inversions (level 1.5) retrieved for the measuring period from 2009 to 2013, for the Arctic region (Eureka, Barrow and Hornsund), Urban/ Industrial regions (Kanpur, Beijing), and the forest regions (Alta Foresta and Mongu), to identify BrC aerosols. Using Dubovik's inversion algorithm results, we analyzed parameters that were sensitive to BrC presence, notably AAOD, AAODBrC estimated using the approach of Arola et al. [2011], the fine-mode-aerosol absorption derivative (αf, abs) and the fine-mode-aerosol absorption 2nd derivative (αf, abs'), all computed at a near UV wavelength (440 nm). Temporal trends of these parameters were investigated for all test stations and compared to available volume sampling surface data as a means of validating / evaluating the sensitivity of ostensible sunphotometer indicators of BrC aerosols to the presence of BrC as measured using independent indicators. Reference: Arola, A., Schuster, G., Myhre, G., Kazadzis, S., Dey, S., and Tripathi, S. N.: Inferring absorbing organic carbon content from AERONET data, Atmos. Chem. Phys., 11, 215-225, doi:10.5194/acp-11-215-2011, 2011

  18. Atlantic Ocean Carbon Experiment (acex): Implementation of Eddy Covariance Implementation of Eddy Covariance CO2 Flux Measurements on the SW Atlantic Ocean and Results from the Second Cruise

    NASA Astrophysics Data System (ADS)

    Schultz, C.; Pezzi, L. P.; Miller, S. D.; Martins, L. G.; Araujo, R. G.; Acevedo, O. C.; Moller, O.; Souza, R.; Tavano, V. M.; Farias, P.; Casagrande, F.

    2013-05-01

    The project observational and numerical study of heat, momentum and CO2 fluxes at the ocean-atmosphere interface in the South Atlantic Ocean - Atlantic Ocean Carbon Experiment (ACEx) combines observational and modeling approaches to characterize heat, momentum and CO2 fluxes at the ocean-atmosphere interface in the South Atlantic Ocean. This project is part of an innovative initiative aimed at providing a better understanding of the chemical, physical and dynamic processes of ocean-atmosphere interaction in micro and meso-scales at the South Atlantic Ocean, as well as fluxes across this interface. The ACEx project has performed three cruises so far, collecting measurements with CTDs and XBTs, launching radiosondes, and deploying a micro-meteorological tower to make in situ measurements of heat, momentum and CO2 fluxes. Our successful deployment of this tower represents the first use of a CO2 flux measurement system using eddy covariance technique in the Southwestern Atlantic Ocean. In this work, we present results from the second ACEx cruise, in which the crew onboard the Hydro-oceanographic Vessel Cruzeiro do Sul took measurements at 31 stations between Paranaguá (PR) and Chuí (RS). In addition to physical data, this cruise collected phytoplankton and nutrient data, allowing carbonic gas fluxes to be analyzed and compared with both physical and biological forcings. The highest chlorophyll concentrations were found in water derived from the La Plata River, which showed low salinity waters close to the surface. The influence of these waters was observed mainly at the southernmost stations of the cruise, coincident with increases on the CO2 fluxes that had remained slightly negative until then. This suggests that the biological forcings might have a significant impact on the gas fluxes in this area, through both respiration and the consumption of organic matter. We are currently working to apply circulation and biogeochemical models to evaluate the importance of

  19. Organic sulfur compounds resulting from the interaction of iron sulfide, hydrogen sulfide and carbon dioxide in an anaerobic aqueous environment.

    PubMed

    Heinen, W; Lauwers, A M

    1996-04-01

    The reaction of iron sulfide (FeS) with H2S in water, in presence of CO2 under anaerobic conditions was found to yield H2 and a variety of organic sulfur compounds, mainly thiols and small amounts of CS2 and dimethyldisulfide. The same compounds were produced when H2S was replaced by HCl, in the H2S-generating system FeS/HCl/CO2. The identification of the products was confirmed by GC-MS analyses and the incorporation of H2 in the organic sulfur compounds was demonstrated by experiments in which all hydrogen compounds were replaced by deuterium compounds. Generation of H2 and the synthesis of thiols were both dependent upon the relative abundance of FeS and HCl or H2S, i.e. the FeS/HCl- or FeS/H2S-proportions. Whether thiols or CS2 were formed as the main products depended also on the FeS/HCl-ratio: All conditions which create a H2 deficiency were found to initiate a proportional increase in the amount of CS2. The quantities of H2 and thiols generated depended on temperature: the production of H2 was significantly accelerated from 50 degrees C onward and thiol synthesis above 75 degrees C. The yield of thiols increased with the amount of FeS and HCl (H2S), given a certain FeS/HCl-ratio and a surplus of CO2. A deficiency of CO2 results in lower thiol synthesis. The end product, pyrite (FeS2), was found to appear as a silvery granular layer floating on the aqueous surface. The identity of the thiols was confirmed by mass spectrometry, and the reduction of CO2 demonstrated by the determination of deuterium incorporation with DCl and D2O. The described reactions can principally proceed under the conditions comparable to those obtaining around submarine hydrothermal vents, or the global situation about 4 billion years ago, before the dawn of life, and could replace the need for a reducing atmosphere on the primitive earth.

  20. Ocean Wave Energy Regimes of the Circumpolar Coastal Zones

    NASA Astrophysics Data System (ADS)

    Atkinson, D. E.

    2004-12-01

    Ocean wave activity is a major enviromental forcing agent of the ice-rich sediments that comprise large sections of the arctic coastal margins. While it is instructive to possess information about the wind regimes in these regions, direct application to geomorphological and engineering needs requires knowledge of the resultant wave-energy regimes. Wave energy information has been calculated at the regional scale using adjusted reanalysis model windfield data. Calculations at this scale are not designed to account for local-scale coastline/bathymetric irregularities and variability. Results will be presented for the circumpolar zones specified by the Arctic Coastal Dynamics Project.

  1. Effects of atmospheric carbon dioxide on insect herbivores and their host plants. Technical progress report

    SciTech Connect

    Lincoln, D.E.

    1984-01-01

    The goal was to examine and confirm the observation that leaf eting insects feed at higher rates on plants grown under elevated carbon dioxide regimes. Results confirm and refine the preliminary observation. Subsequent experiments are designd to examine the basis for the increased feeding and examine the generality by testing another plant/herbivore system. (ACR)

  2. Diffusive Transport Properties Across Coupling Regimes

    NASA Astrophysics Data System (ADS)

    Dharuman, G.; Murillo, M. S.; Verboncoeur, J.; Christlieb, A.

    2014-10-01

    Transport properties are poorly known across coupling regimes, therefore understanding them is of importance for theoretical and practical reasons. A useful tool is an ultracold plasma system because of the experimental capability to tune the system to attain Coulomb coupling Γ ranging from 0.1 to 1 to 10 with the screening parameter κ ranging from 0 to 4 to 8, spanning the regions of the phase diagram from weak to moderate to strongly coupled and screened systems. Strong coupling is possible if Disorder Induced Heating is mitigated which requires a correlated initial ion state. Of particular interest is Rydberg blockaded gas of ultracold atoms where the local blockade effect results in correlations. Predictions of higher coupling in ultracold plasma created from a Rydberg blockaded gas have been reported. In this work we examine the diffusive transport properties of ultracold plasma system using molecular dynamics simulations for experimentally realizable values of Γ and κ as discussed above.

  3. Capillary underwater discharges in repetitive pulse regime

    NASA Astrophysics Data System (ADS)

    de Baerdemaeker, F.; Monte, M.; Leys, C.

    2004-03-01

    In this study a capillary underwater discharge, that is sustained with AC (50 Hz) voltages up to 7.5 kV, is investigated. In a capillary discharge scheme, the current is, at some point along its path between two submerged electrodes, flowing through a narrow elongated bore in a dielectric material. When the current density is sufficiently high, local boiling and subsequent vapour breakdown results in the formation of a plasma within this capillary. At the same time the capillary emits an intense jet of vapour bubbles. Time-dependent electrical current, voltage and light emission curves are recorded for discharges in solutions of NaCl in distilled water and reveal different discharge regimes, depending on the conductivity and the excitation voltage, ranging from repetitive microsecond discharge pulses to a quasi-continuous discharge with a glow-like voltage-current characteristic.

  4. Regime Changes in California Temperature Trends

    NASA Astrophysics Data System (ADS)

    Cordero, E. C.; Kessomkiat, W.; Mauget, S.

    2008-12-01

    Annual and seasonal temperature trends are analyzed for California using surface data from the US Historical Climate Network and the larger COOP network. While trends in Tmax and Tmin both show warming over the last 50 years, the temporal and spatial structure of these trends is quite different. An analysis using Mann Whitney U statistics reveals that the patterns of warming and cooling from individual stations have a distinct temporal signature that differs between Tmax and Tmin. Significant cooling trends in Tmin are found between 1920-1958, while significant warming only starts after the 1970s. In contrast, Tmax trends show a more variable pattern of warming and cooling between 1920-1980, with California wide warming only occurring after 1980. These results suggest regime changes in California temperature trends that could only occur through large scale forcing. A discussion of the various forcing mechanisms contributing to California trends and their spatial and temporal variability will be presented.

  5. Anomalous Transport in the Superfluid Fluctuation Regime

    NASA Astrophysics Data System (ADS)

    Uchino, Shun; Ueda, Masahito

    2017-03-01

    Motivated by a recent experiment in ultracold atoms [S. Krinner et al., Proc. Natl. Acad. Sci. U.S.A. 113, 8144 (2016), 10.1073/pnas.1601812113], we analyze transport of attractively interacting fermions through a one-dimensional wire near the superfluid transition. We show that in a ballistic regime where the conductance is quantized in the absence of interaction, the conductance is renormalized by superfluid fluctuations in reservoirs. In particular, the particle conductance is strongly enhanced, and the conductance plateau is blurred by emergent bosonic pair transport. For spin transport, in addition to the contact resistance, the wire itself is resistive, leading to a suppression of the measured spin conductance. Our results are qualitatively consistent with the experimental observations.

  6. Varying results using the shell weights of different planktonic foraminiferal species as a proxy for changing carbonate ion concentrations in the Cariaco Basin, Venezuela

    NASA Astrophysics Data System (ADS)

    Marshall, B. J.; McConnell, M. C.; Thunell, R.; Astor, Y.

    2011-12-01

    Ocean acidification, due in part to increased atmospheric CO2, is thought to reduce calcification rates of planktonic foraminifera. A positive linear relationship has been found between foraminiferal shell weight and the carbonate ion concentrations [CO32-] of the waters in which they calcify (Barker and Elderfield, 2002). Such a relationship provides a useful proxy for determining past changes in ocean carbonate chemistry. The Cariaco Basin, Venezuela (10°30' N, 65°31 W) is an ideal study area to determine the relationship between seawater [CO32-] and planktonic foraminiferal shell weight as the region is characterized by the seasonal upwelling of low pH, low temperature, and low carbonate ion concentrated waters. In this study we use biweekly sediment trap samples and concurrent hydrographic measurements collected between January 2005 and May 2010 in the Cariaco Basin to assess the relationship between [CO32-] and shell weight of three planktonic foraminiferal species, Globigerinoides ruber, Orbulina universa and Globigerinoides sacculifer. Measured salinity, pH, sea surface temperature (SST) and total alkalinity (TA) were used to estimate pCO2 and [CO32-]. Size-normalized shells of G. ruber, O. universa and G. sacculifer were picked (> 10 per sample), photographed for size analysis and weighed. Globigerinoides ruber shell weights varied from 10.4 μg to 17.7 μg, with an average weight of 14.62 μg from 2005 to 2007, with concurrent surface water [CO32-] ranging from ~220-280 μmol/kg. Orbulina universa shell weights ranged from 35.4 μg to 67.8 μg with an average shell weight of 50.1 μg. Preliminary data reveal a strong positive linear relationship between foraminiferal shell weight and [CO32-] for G. ruber (R2 = 0.52, 99% confidence level; p = 0.007) but no significant relationship for O. universa (R2 = 0.05, ; p = 0.4). The initial results suggest that the foraminiferal shell weight changes of certain planktonic foraminiferal species may reflect changes

  7. Is Thawing Permafrost as a Result of Global Warming a Possible Significant Source of Degradable Carbon for Microbiota Residing In Situ and in Arctic Rivers?

    NASA Astrophysics Data System (ADS)

    Zhu, E. Y.; Coolen, M. J.

    2008-12-01

    Northern high-latitude ecosystems contain about half of the world's soil carbon, most of which is stored in permanently frozen soil (permafrost). Global warming through the 21st century is expected to induce permafrost thaw, which will increase microbial organic matter (OM) decomposition and release large amounts of the greenhouse gasses methane and carbon dioxide into the atmosphere. In addition, Arctic rivers are a globally important source of terrestrial organic carbon to the ocean and further permafrost melting will impact surface runoff, directly affecting groundwater storage and river discharge. Up to now, it remains largely unknown to what extent the ancient OM stored in newly thawing permafrost can be consumed by microbes in situ or by microbes residing in Arctic rivers which become exposed to newly discharged permafrost OM. In addition, we know little about which microbes are capable of degrading permafrost OM. During a field trip to the Toolik Lake Arctic Long Term Ecological Research (LTER) field station in northern Alaska in August 2008, we cored permafrost located near the Kuparuk River down to 110 cm below the active layer (i.e. the top layer which melts each summer) and analyzed the initial microbial enzymatic cleavage of particulate OM (POM) stored in permafrost. Alkaline phosphatase activity remained fairly constant throughout the permafrost and was only one order of magnitude lower than in the active layer. The latter enzyme cleaves organic phosphoesters into phosphate, which could cause eutrophication of lakes and rivers via ground water discharge. Similar results were found for β-glucosidase, which cleaves cellobiose into glucose. This process could fuel heterotrophic bacteria to produce carbon dioxide which, in return, could be converted to the stronger greenhouse gas methane by methanogenic archaea. Leucine aminopeptidase activities, on the other hand, were highest in the top Sphagnum root layer and quickly dropped to below detection limit

  8. Measuring carbon and oxygen isotope signals of photosynthesis and respiration: first field results from a chamber system coupled to tunable diode laser spectrometers

    NASA Astrophysics Data System (ADS)

    Wingate, L.; Burlett, R.; Bosc, A.; Cross, A.; Devaux, M.; Grace, J.; Loustau, D.; Seibt, U.; Ogée, J.

    2007-12-01

    Studying the carbon and oxygen stable isotope signals from plants and soils can help us gain insight to mechanistic processes responsible for the net exchange of CO2 and water cycled between terrestrial ecosystems and the atmosphere. Chamber field measurements of component fluxes and their isotopic composition have been reported for a few ecosystems. These observations have revealed that isotopic signals for carbon and oxygen are dynamic over relatively short time scales (hrs and days) for both branches and soils (Seibt et al., 2006a; 2006b; Wingate et al., 2007), and not fully explained by currently available models (Seibt et al., 2006b; Wingate et al., 2007). Ecosystem isotope studies have been limited by flask sampling requirements in the past. To evaluate and refine our models of isotopic fractionation by plants and soil, we need high resolution continuous isotopic measurements over the growing season for different ecosystems. In this study, we coupled chambers with tunable diode laser spectroscopy techniques in the field to continuously capture the isotopic signals from the most important component fluxes contributing to the net ecosystem exchange of CO2 in a Pinus pinaster forest in south-west France. We obtained profiles of the carbon and oxygen isotope content of CO2 within and above the forest canopy. In addition, we measured branch photosynthetic 13C and 18O discrimination alongside the 13C and 18O isotopic composition of the branch, stem and soil respiration during a 6-month period in 2007. In this talk, we will present the first results from this field campaign. References Seibt, U., Wingate, L., Berry, J.A. and Lloyd, J. (2006a) Non steady state effects in diurnal 18O discrimination by Picea sitchensis branches in the field. Plant, Cell and Environment Vol 29, 928-939. Seibt, U., Wingate, L., Lloyd, J. and Berry, J.A. (2006b) Diurnally variable δ18O signatures of soil CO2 fluxes indicate carbonic anhydrase activity in a forest soil. JGR

  9. Final Progress Report for Collaborative Research: Aging of Black Carbon during Atmospheric Transport: Understanding Results from the DOE’s 2010 CARES and 2012 ClearfLo Campaigns

    SciTech Connect

    Mazzoleni, Claudio; Subramanian, R.

    2016-08-31

    Over the course of this project, we have analyzed data and samples from the Carbonaceous Aerosol and Radiative Effects Study (CARES) and the Clear air for London (ClearfLo) campaign, as well as conducted or participated in laboratory experiments designed to better understand black carbon mixing state and climate-relevant properties. The laboratory campaigns took place at the Pacific Northwest National Laboratory and Carnegie Mellon University to study various climate-relevant aerosol properties of different sources of soot mixing with secondary organic aerosol precursors. Results from some of these activities were summarized in the previous progress report. This final report presents the manuscripts that have been published (many in the period since the last progress report), lists presentations at different conferences based on grant-related activities, and presents some results that are likely to be submitted for publication in the near future.

  10. FISHER INFORMATION AND ECOSYSTEM REGIME CHANGES

    EPA Science Inventory

    Following Fisher’s work, we propose two different expressions for the Fisher Information along with Shannon Information as a means of detecting and assessing shifts between alternative ecosystem regimes. Regime shifts are a consequence of bifurcations in the dynamics of an ecosys...

  11. Testing new approaches to carbonate system simulation at the reef scale: the ReefSam model first results, application to a question in reef morphology and future challenges.

    NASA Astrophysics Data System (ADS)

    Barrett, Samuel; Webster, Jody

    2016-04-01

    Numerical simulation of the stratigraphy and sedimentology of carbonate systems (carbonate forward stratigraphic modelling - CFSM) provides significant insight into the understanding of both the physical nature of these systems and the processes which control their development. It also provides the opportunity to quantitatively test conceptual models concerning stratigraphy, sedimentology or geomorphology, and allows us to extend our knowledge either spatially (e.g. between bore holes) or temporally (forwards or backwards in time). The later is especially important in determining the likely future development of carbonate systems, particularly regarding the effects of climate change. This application, by its nature, requires successful simulation of carbonate systems on short time scales and at high spatial resolutions. Previous modelling attempts have typically focused on the scales of kilometers and kilo-years or greater (the scale of entire carbonate platforms), rather than at the scale of centuries or decades, and tens to hundreds of meters (the scale of individual reefs). Previous work has identified limitations in common approaches to simulating important reef processes. We present a new CFSM, Reef Sedimentary Accretion Model (ReefSAM), which is designed to test new approaches to simulating reef-scale processes, with the aim of being able to better simulate the past and future development of coral reefs. Four major features have been tested: 1. A simulation of wave based hydrodynamic energy with multiple simultaneous directions and intensities including wave refraction, interaction, and lateral sheltering. 2. Sediment transport simulated as sediment being moved from cell to cell in an iterative fashion until complete deposition. 3. A coral growth model including consideration of local wave energy and composition of the basement substrate (as well as depth). 4. A highly quantitative model testing approach where dozens of output parameters describing the reef

  12. Evaluation of terrestrial carbon cycle models with atmospheric CO2 measurements: Results from transient simulations considering increasing CO2, climate, and land-use effects

    USGS Publications Warehouse

    Dargaville, R.J.; Heimann, Martin; McGuire, A.D.; Prentice, I.C.; Kicklighter, D.W.; Joos, F.; Clein, J.S.; Esser, G.; Foley, J.; Kaplan, J.; Meier, R.A.; Melillo, J.M.; Moore, B.; Ramankutty, N.; Reichenau, T.; Schloss, A.; Sitch, S.; Tian, H.; Williams, L.J.; Wittenberg, U.

    2002-01-01

    An atmospheric transport model and observations of atmospheric CO2 are used to evaluate the performance of four Terrestrial Carbon Models (TCMs) in simulating the seasonal dynamics and interannual variability of atmospheric CO2 between 1980 and 1991. The TCMs were forced with time varying atmospheric CO2 concentrations, climate, and land use to simulate the net exchange of carbon between the terrestrial biosphere and the atmosphere. The monthly surface CO2 fluxes from the TCMs were used to drive the Model of Atmospheric Transport and Chemistry and the simulated seasonal cycles and concentration anomalies are compared with observations from several stations in the CMDL network. The TCMs underestimate the amplitude of the seasonal cycle and tend to simulate too early an uptake of CO2 during the spring by approximately one to two months. The model fluxes show an increase in amplitude as a result of land-use change, but that pattern is not so evident in the simulated atmospheric amplitudes, and the different models suggest different causes for the amplitude increase (i.e., CO2 fertilization, climate variability or land use change). The comparison of the modeled concentration anomalies with the observed anomalies indicates that either the TCMs underestimate interannual variability in the exchange of CO2 between the terrestrial biosphere and the atmosphere, or that either the variability in the ocean fluxes or the atmospheric transport may be key factors in the atmospheric interannual variability.

  13. Microbial Communities as Environmental Indicators of Ecological Disturbance in Restored Carbonate Fen-Results of 10 Years of Studies.

    PubMed

    Mieczan, Tomasz; Tarkowska-Kukuryk, Monika

    2017-03-06

    Interactions between bacteria and protists are essential to the ecosystem ecology of fens. Until now, however, there has been almost no information on how restoration procedures in carbonate fens affect the functioning of microbial food webs. Changes in vegetation patterns resulting from restoration may take years to be observed, whereas microbial processes display effects even after short-term exposure to changes in environmental conditions caused by restoration. Therefore, microbial processes and patterns can be used as sensitive indicators of changes in environmental conditions. The present study attempts to verify the hypothesis that the species richness and abundance of microbial loop components would differ substantially before and after restoration. The effect of restoration processes on the functioning of the food web was investigated for a 10 years in a carbonate-rich fen, before and after restoration. The restoration procedure (particularly the improvement in hydrological conditions) distinctly modified the taxonomic composition and functioning of microbial food webs. This is reflected in the increased abundance and diversity of testate amoeba, i.e. top predators, within the microbial food web and in the pronounced increase in the abundance of bacteria. This study suggests potential use of microbial loop components as bio-indicators and bio-monitoring tools for hydrological status of fens and concentrations of nutrients. Better understanding of what regulates microbial populations and activity in fens and unravelling of these fundamental mechanisms are particularly critical in order to more accurately predict how fens will respond to global change or anthropogenic disturbances.

  14. Carbon dioxide emissions and the overshoot ratio change resulting from the implementation of 2nd Energy Master Plan in South Korea

    NASA Astrophysics Data System (ADS)

    Yeo, M. J.; Kim, Y. P.

    2015-12-01

    The direction of the energy policies of the country is important in the projection of environmental impacts of the country. The greenhouse gases (GHGs) emission of the energy sector in South Korea is very huge, about 600 MtCO2e in 2011. Also the carbon footprint due to the energy consumption contributes to the ecological footprint is also large, more than 60%. Based on the official plans (the national greenhouse gases emission reduction target for 2030 (GHG target for 2030) and the 2nd Energy Master Plan (2nd EMP)), several scenarios were proposed and the sensitivity of the GHG emission amount and 'overshoot ratio' which is the ratio of ecological footprint to biocapacity were estimated. It was found that to meet the GHG target for 2030 the ratio of non-emission energy for power generation should be over 71% which would be very difficult. We also found that the overshoot ratio would increase from 5.9 in 2009 to 7.6 in 2035. Thus, additional efforts are required to reduce the environmental burdens in addition to optimize the power mix configuration. One example is the conversion efficiency in power generation. If the conversion efficiency in power generation rises up 50% from the current level, 40%, the energy demand and resultant carbon dioxide emissions would decrease about 10%. Also the influence on the environment through changes in consumption behavior, for example, the diet choice is expected to be meaningful.

  15. Risk of lung cancer following exposure to carbon black, titanium dioxide and talc: results from two case-control studies in Montreal.

    PubMed

    Ramanakumar, Agnihotram V; Parent, Marie-Elise; Latreille, Benoit; Siemiatycki, Jack

    2008-01-01

    The International Agency for Research on Cancer (IARC) recently evaluated the carcinogenicity of three poorly soluble weakly-toxic substances: carbon black, titanium dioxide and talc. Though there is evidence of carcinogenity in experimental animals for these substances, the evidence in humans is sparse and equivocal. In the context of two large population based case-control studies of lung cancer carried out in Montreal, we were able to study the possible relationships between the exposure to each of these substances and subsequent risk of lung cancer. We were able to distinguish talc used for industrial purposes from that used for cosmetic purposes. Interviews for Study I were conducted in 1979-1986 (857 cases, 533 population controls, 1,349 cancer controls) and interviews for Study II were conducted in 1996-2001 (1,236 cases and 1,512 controls). Detailed lifetime job histories were elicited, and a team of hygienists and chemists evaluated the evidence of exposure to a host of occupational substances. Lung cancer risk was analysed in relation to each exposure, adjusting for several potential confounders, including smoking. Subjects with occupational exposure to carbon black, titanium dioxide, industrial talc and cosmetic talc did not experience any detectable excess risk of lung cancer. The results are consistent with the recent evaluations of the IARC Monographs.

  16. Experimental determination of heat transfer coefficient in the slip regime and its anomalously low value

    NASA Astrophysics Data System (ADS)

    Demsis, Anwar; Verma, Bhaskar; Prabhu, S. V.; Agrawal, Amit

    2009-07-01

    In this paper, the measurement of the heat transfer coefficient in rarefied gases is presented; these are among the first heat transfer measurements in the slip flow regime. The experimental setup is validated by comparing friction factor in the slip regime and heat transfer coefficient in the continuum regime. Experimental results suggest that the Nusselt number is a function of Reynolds and Knudsen numbers in the slip flow regime. The measured values for Nusselt numbers are smaller than that predicted by theoretical or simulation results, and can become a few orders of magnitude smaller than the theoretical values in the continuum regime. The results are repeatable and expected to be useful for further experimentation and modeling of flow in the slip and transition regimes.

  17. THE IMPACT OF THE GLOBAL NUCLEAR SAFETY REGIME IN BRAZIL

    SciTech Connect

    Almeida, C.

    2004-10-06

    A turning point of the world nuclear industry with respect to safety occurred due to the accident at Chernobyl, in 1986. A side from the tragic personal losses and the enormous financial damage, the Chernobyl accident has literally demonstrated that ''a nuclear accident anywhere is an accident everywhere''. The impact was felt immediately by the nuclear industry, with plant cancellations (e.g. Austria), elimination of national programs (e.g. Italy) and general construction delays. However, the reaction of the nuclear industry was equally immediate, which led to the proposal and establishment of a Global Nuclear Safety Regime. This regime is composed of biding international safety conventions, globally accepted safety standard, and a voluntary peer review system. In a previous work, the author has presented in detail the components of this Regime, and briefly discussed its impact in the Brazilian nuclear power organizations, including the Regulatory Body. This work, on the opposite, briefly reviews the Global Nuclear Safety Regime, and concentrates in detail in the discussion of its impact in Brazil, showing how it has produced some changes, and where the peer pressure regime has failed to produce real results.

  18. Early regimes of water capillary flow in slit silica nanochannels.

    PubMed

    Oyarzua, Elton; Walther, Jens H; Mejía, Andrés; Zambrano, Harvey A

    2015-06-14

    Molecular dynamics simulations are conducted to investigate the initial stages of spontaneous imbibition of water in slit silica nanochannels surrounded by air. An analysis is performed for the effects of nanoscopic confinement, initial conditions of liquid uptake and air pressurization on the dynamics of capillary filling. The results indicate that the nanoscale imbibition process is divided into three main flow regimes: an initial regime where the capillary force is balanced only by the inertial drag and characterized by a constant velocity and a plug flow profile. In this regime, the meniscus formation process plays a central role in the imbibition rate. Thereafter, a transitional regime takes place, in which, the force balance has significant contributions from both inertia and viscous friction. Subsequently, a regime wherein viscous forces dominate the capillary force balance is attained. Flow velocity profiles identify the passage from an inviscid flow to a developing Poiseuille flow. Gas density profiles ahead of the capillary front indicate a transient accumulation of air on the advancing meniscus. Furthermore, slower capillary filling rates computed for higher air pressures reveal a significant retarding effect of the gas displaced by the advancing meniscus.

  19. Regime switching model for financial data: Empirical risk analysis

    NASA Astrophysics Data System (ADS)

    Salhi, Khaled; Deaconu, Madalina; Lejay, Antoine; Champagnat, Nicolas; Navet, Nicolas

    2016-11-01

    This paper constructs a regime switching model for the univariate Value-at-Risk estimation. Extreme value theory (EVT) and hidden Markov models (HMM) are combined to estimate a hybrid model that takes volatility clustering into account. In the first stage, HMM is used to classify data in crisis and steady periods, while in the second stage, EVT is applied to the previously classified data to rub out the delay between regime switching and their detection. This new model is applied to prices of numerous stocks exchanged on NYSE Euronext Paris over the period 2001-2011. We focus on daily returns for which calibration has to be done on a small dataset. The relative performance of the regime switching model is benchmarked against other well-known modeling techniques, such as stable, power laws and GARCH models. The empirical results show that the regime switching model increases predictive performance of financial forecasting according to the number of violations and tail-loss tests. This suggests that the regime switching model is a robust forecasting variant of power laws model while remaining practical to implement the VaR measurement.

  20. Fatigue of Austempered Ductile Iron with Two Strength Grades in Very High Cycle Regime

    NASA Astrophysics Data System (ADS)

    Zhang, Jiwang; Li, Wei; Song, Qingpeng; Zhang, Ning; Lu, Liantao

    2016-03-01

    In this study, Austempered ductile irons (ADIs) with two different strength grades were produced and the fatigue properties were measured at 109 cycles. The results show that the S-N curves give a typical step-wise shape and there is no fatigue limit in the very high cycle fatigue regime. The two grades ADI have the similar fracture behaviors and fatigue failure can initiate from defects at specimen surface and subsurface zone. On the fracture surfaces of some specimens, the `granular-bright-facet' area with rich carbon distribution is observed in the vicinity of the defect. The microstructure affects the crack behaviors at the early propagation stage. The ADI with upper and lower bainite shows higher fatigue strength compared with the ADI with coarse upper bainite.

  1. Collimated proton acceleration in light sail regime with a tailored pinhole target

    NASA Astrophysics Data System (ADS)

    Wang, H. Y.; Yan, X. Q.; Zepf, M.

    2014-06-01

    A scheme for producing collimated protons from laser interactions with a diamond-like-carbon + pinhole target is proposed. The process is based on radiation pressure acceleration in the multi-species light-sail regime [B. Qiao et al., Phys. Rev. Lett. 105, 155002 (2010); T. P. Yu et al., Phys. Rev. Lett. 105, 065002 (2010)]. Particle-in-cell simulations demonstrate that transverse quasistatic electric field at TV/m level can be generated in the pinhole. The transverse electric field suppresses the transverse expansion of protons effectively, resulting in a higher density and more collimated proton beam compared with a single foil target. The dependence of the proton beam divergence on the parameters of the pinhole is also investigated.

  2. L-[METHYL-{sup 11}C] Methionine Positron Emission Tomography for Target Delineation in Malignant Gliomas: Impact on Results of Carbon Ion Radiotherapy

    SciTech Connect

    Mahasittiwat, Pawinee; Mizoe, Jun-etsu Hasegawa, Azusa; Ishikawa, Hiroyuki; Yoshikawa, Kyosan; Mizuno, Hideyuki; Yanagi, Takeshi; Takagi, Ryou D.D.S.; Pattaranutaporn, Pittayapoom; Tsujii, Hirohiko

    2008-02-01

    Purpose: To assess the importance of {sup 11}C-methionine (MET)-positron emission tomography (PET) for clinical target volume (CTV) delineation. Methods and Materials: This retrospective study analyzed 16 patients with malignant glioma (4 patients, anaplastic astrocytoma; 12 patients, glioblastoma multiforme) treated with surgery and carbon ion radiotherapy from April 2002 to Nov 2005. The MET-PET target volume was compared with gross tumor volume and CTV, defined by using computed tomography/magnetic resonance imaging (MRI). Correlations with treatment results were evaluated between positive and negative extended volumes (EVs) of the MET-PET target for CTV. Results: Mean volumes of the MET-PET targets, CTV1 (defined by means of high-intensity volume on T2-weighted MRI), and CTV2 (defined by means of contrast-enhancement volume on T1-weighted MRI) were 6.35, 264.7, and 117.7 cm{sup 3}, respectively. Mean EVs of MET-PET targets for CTV1 and CTV2 were 0.6 and 2.2 cm{sup 3}, respectively. The MET-PET target volumes were included in CTV1 and CTV2 in 13 (81.3%) and 11 patients (68.8%), respectively. Patients with a negative EV for CTV1 had significantly greater survival rate (p = 0.0069), regional control (p = 0.0047), and distant control time (p = 0.0267) than those with a positive EV. Distant control time also was better in patients with a negative EV for CTV2 than those with a positive EV (p = 0.0401). Conclusions: For patients with malignant gliomas, MET-PET has a possibility to be a predictor of outcome in carbon ion radiotherapy. Direct use of MET-PET fused to planning computed tomography will be useful and yield favorable results for the therapy.

  3. The history of research into improved confinement regimes

    NASA Astrophysics Data System (ADS)

    Wagner, F.

    2017-01-01

    Increasing the pressure by additional heating of magnetically confined plasmas had the consequence that turbulent processes became more violent and plasma confinement degraded. Since this experience from the early 1980ies, fusion research was dominated by the search for confinement regimes with improved properties. It was a gratifying experience that toroidally confined plasmas are able to self-organise in such a way that turbulence diminishes, resulting in a confinement with good prospects to reach the objectives of fusion R&D. The understanding of improved confinement regimes revolutionized the understanding of turbulent transport in high-temperature plasmas. In this paper the story of research into improved confinement regimes will be narrated starting with 1980.

  4. Suspended-sediment concentration regimes in Tennessee biological reference streams

    USGS Publications Warehouse

    Diehl, Timothy H.; Wolfe, William J.

    2010-01-01

    Suspended-sediment-concentration (SSC) regimes of five biological reference streams in Tennessee were characterized from 15-minute SSC records spanning 1 to 4 water years (October 1 through September 30) between 2004 and 2008. These streams represent least disturbed conditions for their respective ecoregions and have exceptional biodiversity in terms of fish or aquatic invertebrates. SSC regimes in streams, when plotted in terms of duration above a given SSC at a given annual frequency such as the annual maximum or the annual tenth longest duration, can be compared directly to published biological impairment thresholds derived from experimental trials. Based on such comparison, the SSC regimes of all five reference streams reached published impairment thresholds at least 10 times per water year for all years of record. The results suggest that the published impairment thresholds are not directly applicable to streams in Tennessee and, by extension, the southeastern United States.

  5. Hydrodynamic interaction of swimming organisms in an inertial regime

    NASA Astrophysics Data System (ADS)

    Li, Gaojin; Ostace, Anca; Ardekani, Arezoo M.

    2016-11-01

    We numerically investigate the hydrodynamic interaction of swimming organisms at small to intermediate Reynolds number regimes, i.e., Re˜O (0.1 -100 ) , where inertial effects are important. The hydrodynamic interaction of swimming organisms in this regime is significantly different from the Stokes regime for microorganisms, as well as the high Reynolds number flows for fish and birds, which involves strong flow separation and detached vortex structures. Using an archetypal swimmer model, called a "squirmer," we find that the inertial effects change the contact time and dispersion dynamics of a pair of pusher swimmers, and trigger hydrodynamic attraction for two pullers. These results are potentially important in investigating predator-prey interactions, sexual reproduction, and the encounter rate of marine organisms such as copepods, ctenophora, and larvae.

  6. Hydrodynamic interaction of swimming organisms in an inertial regime.

    PubMed

    Li, Gaojin; Ostace, Anca; Ardekani, Arezoo M

    2016-11-01

    We numerically investigate the hydrodynamic interaction of swimming organisms at small to intermediate Reynolds number regimes, i.e., Re∼O(0.1-100), where inertial effects are important. The hydrodynamic interaction of swimming organisms in this regime is significantly different from the Stokes regime for microorganisms, as well as the high Reynolds number flows for fish and birds, which involves strong flow separation and detached vortex structures. Using an archetypal swimmer model, called a "squirmer," we find that the inertial effects change the contact time and dispersion dynamics of a pair of pusher swimmers, and trigger hydrodynamic attraction for two pullers. These results are potentially important in investigating predator-prey interactions, sexual reproduction, and the encounter rate of marine organisms such as copepods, ctenophora, and larvae.

  7. Geothermal regimes at Clearlake California: A preliminary review

    SciTech Connect

    Burns, K.L.; Potter, R.M.; Zyvoloski, G.

    1992-08-01

    Three distinct geothermal regimes are inferred in the vicinity of the city of Clearlake, California. The first is a conductive heat flow regime, the second is a fault-controlled hot spring flow of ``magmatic`` fluids, and the third is a resurgent flow of meteoric warm water. The conductive heat flow results in flat, horizontal isotherms. The hot spring generates a localized spike in the isotherms. The advective disturbance carries heat laterally to a fault-line resurgence, lowering the apparent heat flow at the surface.

  8. Reconciliation in Cambodia: thirty years after the terror of the Khmer Rouge regime.

    PubMed

    Bockers, Estelle; Stammel, Nadine; Knaevelsrud, Christine

    2011-01-01

    During the Khmer Rouge regime one quarter of the Cambodian population was killed as a result of malnutrition, overwork and mass killings. Although the regime ended 30 years ago, its legacy continues to affect Cambodians. Mental health problems as well as feelings of anger and revenge resulting from traumatic events experienced during the Khmer Rouge regime are still common in Cambodia. These conditions continue to impede social coexistence and the peace-building process in society. Thirty years after the Khmer Rouge regime this article gives an overview on the status of the country's current reconciliation process and recommends potential future steps.

  9. THE WIDESPREAD OCCURRENCE OF WATER VAPOR IN THE CIRCUMSTELLAR ENVELOPES OF CARBON-RICH ASYMPTOTIC GIANT BRANCH STARS: FIRST RESULTS FROM A SURVEY WITH HERSCHEL /HIFI

    SciTech Connect

    Neufeld, D. A.; Gonzalez-Alfonso, E.; Melnick, G.; Szczerba, R.; Schmidt, M.; Decin, L.; Alcolea, J.; De Koter, A.; Dominik, C.; Waters, L. B. F. M.; Schoeier, F. L.; Justtanont, K.; Olofsson, H.; Bujarrabal, V.; Planesas, P.; Cernicharo, J.; Teyssier, D.; Marston, A. P.; Menten, K.

    2011-02-01

    We report the preliminary results of a survey for water vapor in a sample of eight C stars with large mid-IR continuum fluxes: V384 Per, CIT 6, V Hya, Y CVn, IRAS 15194-5115, V Cyg, S Cep, and IRC+40540. This survey, performed using the HIFI instrument on board the Herschel Space Observatory, entailed observations of the lowest transitions of both ortho- and para-water: the 556.936 GHz 1{sub 10}-1{sub 01} and 1113.343 GHz 1{sub 11}-0{sub 00} transitions, respectively. Water vapor was unequivocally detected in all eight of the target stars. Prior to this survey, IRC+10216 was the only carbon-rich asymptotic giant branch (AGB) star from which thermal water emissions had been discovered, in that case with the use of the Submillimeter Wave Astronomy Satellite (SWAS). Our results indicate that IRC+10216 is not unusual, except insofar as its proximity to Earth leads to a large line flux that was detectable with SWAS. The water spectral line widths are typically similar to those of CO rotational lines, arguing against the vaporization of a Kuiper Belt analog being the general explanation for water vapor in carbon-rich AGB stars. There is no apparent correlation between the ratio of the integrated water line fluxes to the 6.3 {mu}m continuum flux-a ratio which measures the water outflow rate-and the total mass-loss rate for the stars in our sample.

  10. On the characteristics of aerosol indirect effect based on dynamic regimes in global climate models

    NASA Astrophysics Data System (ADS)

    Zhang, Shipeng; Wang, Minghuai; Ghan, Steven J.; Ding, Aijun; Wang, Hailong; Zhang, Kai; Neubauer, David; Lohmann, Ulrike; Ferrachat, Sylvaine; Takeamura, Toshihiko; Gettelman, Andrew; Morrison, Hugh; Lee, Yunha; Shindell, Drew T.; Partridge, Daniel G.; Stier, Philip; Kipling, Zak; Fu, Congbin

    2016-03-01

    Aerosol-cloud interactions continue to constitute a major source of uncertainty for the estimate of climate radiative forcing. The variation of aerosol indirect effects (AIE) in climate models is investigated across different dynamical regimes, determined by monthly mean 500 hPa vertical pressure velocity (ω500), lower-tropospheric stability (LTS) and large-scale surface precipitation rate derived from several global climate models (GCMs), with a focus on liquid water path (LWP) response to cloud condensation nuclei (CCN) concentrations. The LWP sensitivity to aerosol perturbation within dynamic regimes is found to exhibit a large spread among these GCMs. It is in regimes of strong large-scale ascent (ω500 < -25 hPa day-1) and low clouds (stratocumulus and trade wind cumulus) where the models differ most. Shortwave aerosol indirect forcing is also found to differ significantly among different regimes. Shortwave aerosol indirect forcing in ascending regimes is close to that in subsidence regimes, which indicates that regimes with strong large-scale ascent are as important as stratocumulus regimes in studying AIE. It is further shown that shortwave aerosol indirect forcing over regions with high monthly large-scale surface precipitation rate (> 0.1 mm day-1) contributes the most to the total aerosol indirect forcing (from 64 to nearly 100 %). Results show that the uncertainty in AIE is even larger within specific dynamical regimes compared to the uncertainty in its global mean values, pointing to the need to reduce the uncertainty in AIE in different dynamical regimes.

  11. On the characteristics of aerosol indirect effect based on dynamic regimes in global climate models

    SciTech Connect

    Zhang, S.; Wang, Minghuai; Ghan, Steven J.; Ding, A.; Wang, Hailong; Zhang, Kai; Neubauer, David; Lohmann, U.; Ferrachat, S.; Takeamura, Toshihiko; Gettelman, A.; Morrison, H.; Lee, Y. H.; Shindell, D. T.; Partridge, Daniel; Stier, P.; Kipling, Z.; Fu, Congbin

    2016-03-04

    Aerosol-cloud interactions continue to constitute a major source of uncertainty for the estimate of climate radiative forcing. The variation of aerosol indirect effects (AIE) in climate models is investigated across different dynamical regimes, determined by monthly mean 500 hPa vertical pressure velocity (ω500), lower-tropospheric stability (LTS) and large-scale surface precipitation rate derived from several global climate models (GCMs), with a focus on liquid water path (LWP) response to cloud condensation nuclei (CCN) concentrations. The LWP sensitivity to aerosol perturbation within dynamic regimes is found to exhibit a large spread among these GCMs. It is in regimes of strong large-scale ascend (ω500 < -25 hPa/d) and low clouds (stratocumulus and trade wind cumulus) where the models differ most. Shortwave aerosol indirect forcing is also found to differ significantly among different regimes. Shortwave aerosol indirect forcing in ascending regimes is as large as that in stratocumulus regimes, which indicates that regimes with strong large-scale ascend are as important as stratocumulus regimes in studying AIE. 42" It is further shown that shortwave aerosol indirect forcing over regions with high monthly large-scale surface precipitation rate (> 0.1 mm/d) contributes the most to the total aerosol indirect forcing (from 64% to nearly 100%). Results show that the uncertainty in AIE is even larger within specific dynamical regimes than that globally, pointing to the need to reduce the uncertainty in AIE in different dynamical regimes.

  12. Welfare state regimes, health and health inequalities in adolescence: a multilevel study in 32 countries.

    PubMed

    Richter, Matthias; Rathman, Katharina; Nic Gabhainn, Saoirse; Zambon, Alessio; Boyce, William; Hurrelmann, Klaus

    2012-07-01

    Comparative research on health and health inequalities has recently started to establish a welfare regime perspective. The objective of this study was to determine whether different welfare regimes are associated with health and health inequalities among adolescents. Data were collected from the 'Health Behaviour in School-aged Children' study in 2006, including 11- to 15-year-old students from 32 countries (N = 141,091). Prevalence rates and multilevel logistic regression models were calculated for self-rated health (SRH) and health complaints. The results show that between 4 per cent and 7 per cent of the variation in both health outcomes is attributable to differences between countries. Compared to the Scandinavian regime, the Southern regime had lower odds ratios for SRH, while for health complaints the Southern and Eastern regime showed high odds ratios. The association between subjective health and welfare regime was largely unaffected by adjusting for individual socioeconomic position. After adjustment for the welfare regime typology, the country-level variations were reduced to 4.6 per cent for SRH and to 2.9 per cent for health complaints. Regarding cross-level interaction effects between welfare regimes and socioeconomic position, no clear regime-specific pattern was found. Consistent with research on adults this study shows that welfare regimes are important in explaining variations in adolescent health across countries.

  13. Initial results of comparing cold-seep carbonates from mussel- and tubeworm-associated environments at Atwater Valley lease block 340, northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Feng, Dong; Roberts, Harry H.

    2010-11-01

    Chemosymbiotic macrofauna (such as mussels and tubeworms) and authigenic carbonates are typical of many hydrocarbon seeps. To address whether mussels and tubeworms could impact the sediment geochemistry of their habitat where authigenic carbonates are precipitated, a comparative study of petrographic and geochemical features of the authigenic carbonates from mussel- and tubeworm-associated environments at hydrocarbon seeps in Atwater Valley lease area block 340 (AT340) of the Gulf of Mexico was undertaken. Both mussel- and tubeworm-associated carbonates are dominated by high-magnesium calcite (HMC) and aragonite, and two tubeworm-associated carbonate samples have minor amounts of dolomite. The δ13C values of all carbonates are low, ranging from -60.8‰ to -35.5‰ PDB. Although there is much overlap, surprisingly the δ13C values of mussel-associated carbonates are generally higher than those of tubeworm-associated carbonates (-51.8‰ vs. -54.8‰ for an average of over 60 subsamples). It is suggested that (1) carbon isotopic vital effect of seep mussels and tubeworms, (2) fluid physical pumping of mussels, and (3) release of sulfate by tubeworm roots may be responsible for the relatively lower δ13C values of tubeworm-associated carbonates. It has been suggested that the heterogeneities in mineralogy and stable carbon isotope geochemistry of the seep carbonates may be attributed to the activity of macrofauna (mussels and tubeworms) and associated microbes. Our observations also suggest that at AT340 the geochemical evolution of seep macrofauna is from a mussel-dominated environment to a mixed mussel-tubeworm environment, and finally to a mostly tubeworm-dominated environment. This evolution is controlled mainly by the habitat, e.g., hydrocarbon seep flux.

  14. Abrupt climate-independent fire regime changes

    USGS Publications Warehouse

    Pausas, Juli G.; Keeley, Jon E.

    2014-01-01

    Wildfires have played a determining role in distribution, composition and structure of many ecosystems worldwide and climatic changes are widely considered to be a major driver of future fire regime changes. However, forecasting future climatic change induced impacts on fire regimes will require a clearer understanding of other drivers of abrupt fire regime changes. Here, we focus on evidence from different environmental and temporal settings of fire regimes changes that are not directly attributed to climatic changes. We review key cases of these abrupt fire regime changes at different spatial and temporal scales, including those directly driven (i) by fauna, (ii) by invasive plant species, and (iii) by socio-economic and policy changes. All these drivers might generate non-linear effects of landscape changes in fuel structure; that is, they generate fuel changes that can cross thresholds of landscape continuity, and thus drastically change fire activity. Although climatic changes might contribute to some of these changes, there are also many instances that are not primarily linked to climatic shifts. Understanding the mechanism driving fire regime changes should contribute to our ability to better assess future fire regimes.

  15. Magnetised Kelvin-Helmholtz instability in the intermediate regime between subsonic and supersonic regimes

    SciTech Connect

    Henri, P.; Califano, F.; Pegoraro, F.; Faganello, M.

    2012-07-15

    The understanding of the dynamics at play at the Earth's Magnetopause, the boundary separating the Earth's magnetosphere and the solar wind plasmas, is of primary importance for space plasma modeling. We focus our attention on the low latitude flank of the magnetosphere where the velocity shear between the magnetosheath and the magnetospheric plasmas is the energetic source of Kelvin-Helmholtz instability. On the shoulder of the resulting vortex chain, different secondary instabilities are at play depending on the local plasma parameters and compete with the vortex pairing process. Most important, secondary instabilities, among other magnetic reconnection, control the plasma mixing as well as the entry of solar wind plasma in the magnetosphere. We make use of a two-fluid model, including the Hall term and the electron mass in the generalized Ohm's law, to study the 2D non-linear evolution of the Kelvin-Helmholtz instability at the magnetosheath-magnetosphere interface, in the intermediate regime between subsonic and supersonic regimes. We study the saturation mechanisms, depending on the density jump across the shear layer and the magnetic field strength in the plane. In the presence of a weak in-plane magnetic field, the dynamics of the Kelvin-Helmholtz rolled-up vortices self-consistently generates thin current sheets where reconnection instability eventually enables fast reconnection to develop. Such a system enables to study guide field multiple-island collisionless magnetic reconnection as embedded in a large-scale dynamic system, unlike the classical static, ad hoc reconnection setups. In this regime, reconnection is shown to inhibit the vortex pairing process. This study provides a clear example of nonlinear, cross-scale, collisionless plasma dynamics.

  16. Properties and regimes of vertisols with gilgai microtopography (a review)

    NASA Astrophysics Data System (ADS)

    Khitrov, N. B.

    2016-03-01

    Data on the morphology and spatial distribution of slickensides and cracks, particle-size distribution, the organic carbon content, the content and forms of carbonate concentrations, and physical and physicochemical properties of Vertisols with the gilgai microtopography are systematized. Relatively scarce information on the functioning regimes of gilgai soil complexes (their temperature and moisture conditions, redox potential, vertical and horizontal deformations, and soil density changes) is discussed. Common properties of gilgai soils are the clayey texture of their profiles and the high portion of smectitic minerals specifying the high shrink-swell capacity of the soil material. The most important specificity of soils with the gilgai microtopography is a significant horizontal differentiation of the soil profiles with alternation of bowl-shaped morphostructures with a thick dark layer without carbonates in microlows and diapiric morphostructures composed of the rising material of the lower layers with diverse carbonate concentrations on microhighs. Data on the spatial distribution of soil properties within the gilgai microcatenas can be applied in the studies of the genesis and evolution stages of the gilgai soil complexes.

  17. Distinct Turbulence Saturation Regimes in Stellarators

    NASA Astrophysics Data System (ADS)

    Plunk, G. G.; Xanthopoulos, P.; Helander, P.

    2017-03-01

    In the complex 3D magnetic fields of stellarators, ion-temperature-gradient turbulence is shown to have two distinct saturation regimes, as revealed by petascale numerical simulations and explained by a simple turbulence theory. The first regime is marked by strong zonal flows and matches previous observations in tokamaks. The newly observed second regime, in contrast, exhibits small-scale quasi-two-dimensional turbulence, negligible zonal flows, and, surprisingly, a weaker heat flux scaling. Our findings suggest that key details of the magnetic geometry control turbulence in stellarators.

  18. Seasonal and interannual variations of carbon and oxygen isotopes of respired CO2 in a tallgrass prairie: Measurements and modeling results from 3 years with contrasting water availability

    NASA Astrophysics Data System (ADS)

    Lai, Chun-Ta; Riley, William; Owensby, Clenton; Ham, Jay; Schauer, Andrew; Ehleringer, James R.

    2006-04-01

    We made weekly measurements of carbon (δ13C) and oxygen (δ18O) isotopes of atmospheric CO2 in a C3/C4 tallgrass prairie during the growing season for 3 years with contrasting soil moisture conditions. Air samples above and within canopies were collected using 100-ml flasks at night to characterize isotopic composition of ecosystem respiration. We used a two-source mixing line (Keeling plot) approach to estimate isotope ratios of ecosystem respired CO2 for both carbon (δ13CR) and oxygen (δ18OR). Measured net ecosystem CO2 exchange (NEE) showed the largest net carbon uptake in 2004, followed by 2003 and 2002. This interannual difference in NEE strongly depends on the amount and distribution of precipitation received by this tallgrass prairie. Precipitation also affects the timing of the seasonal transition from C3 dominance in spring to C4 dominance in summer. Variations of δ13CR showed that C4 plants dominated ecosystem respiration in 2003 and 2004, except in early spring when C3 plants were more active. In contrast, contributions of C3 plants were relatively higher for an extended period in the summer of 2002, when a severe drought occurred. Typically, C3 forbs extract water and nutrients from soil layers below that of the C4 grasses and remain photosynthetically active in periods when C4 grasses have water stress that limits photosynthesis. Drought-reduced C4 grass photosynthesis was lower than temperature-limited C3 forb growth during this period. We used an integrated isotope land surface model (ISOLSM) to simulate (and compare to measurements) net CO2 fluxes, δ18O values of leaf and soil water, and δ18O values of aboveground and soil respiration. The Keeling plot analysis becomes less reliable for estimating δ18OR values when the surface soil is dry. We suspect this is due to low CO2 production in the soil when water is limiting, in which case the invasion (abiotic) effect is more significant. ISOLSM reasonably captured seasonal variations of measured

  19. Ten Years of Near-Surface-Sensitive Satellite Observations of Carbon Dioxide and Methane: Selected Results Related to Natural and Anthropogenic Sources and Sinks

    NASA Astrophysics Data System (ADS)

    Buchwitz, M. A.; Reuter, M.; Schneising, O.; Bovensmann, H.; Burrows, J. P.

    2014-12-01

    Prior to the recently successfully launched OCO-2 mission, global near-surface-sensitive satellite observations of carbon dioxide (CO2) have been made with SCIAMACHY/ENVISAT during 2002-2012 and are still being made since 2009 with TANSO-FTS/GOSAT, which also deliver atmospheric methane (CH4). The SCIAMACHY and GOSAT overlapping time series of atmospheric column-averaged mole fractions, i.e., XCO2 and XCH4, now cover more than 10 years. During the last years significant progress has been made in improving the quality of the XCO2 and XCH4 data products retrieved from SCIAMACHY and GOSAT and in extending the time series so that more and more applications can be addressed. In this presentation we present some recent results related to CO2 and CH4 sources and sinks. The SCIAMACHY products have been generated using retrieval algorithms developed at University of Bremen. For XCO2 we use an ensemble of data products generated using GOSAT retrieval algorithms developed in Japan (at NIES), in the US (at NASA/JPL and collaborating institutes) and at European institutions (University of Leicester, UK, and SRON, Netherlands, in collaboration with KIT, Germany). Focus will be on three applications: (i) An assessment of the strength of the European terrestrial carbon sink during 2003-2010 based on an ensemble of SCIAMACHY (2003-2010) and GOSAT (2010) XCO2 data products, (ii) an assessment of CO2 and NO2 anthropogenic emission and emission ratio trends using co-located SCIAMACHY XCO2 and NO2 observations over Europe, North America and East Asia, and (iii) an analysis of SCIAMACHY XCH4 retrievals during 2006-2011 over North America focusing on fugitive methane emissions from oil and gas production using tight geological formations ("fracking"). It will be shown that (i) the European terrestrial carbon sink appears to be stronger than expected, (ii) that recent Chinese CO2 and NO2 emissions are increasing but with a trend towards reduced NO2-to-CO2 emission ratios pointing to

  20. Oxidation Kinetics and Strength Degradation of Carbon Fibers in a Cracked Ceramic Matrix Composite

    NASA Technical Reports Server (NTRS)

    Halbig, Michael C.

    2003-01-01

    Experimental results and oxidation modeling will be presented to discuss carbon fiber susceptibility to oxidation, the oxidation kinetics regimes and composite strength degradation and failure due to oxidation. Thermogravimetric Analysis (TGA) was used to study the oxidation rates of carbon fiber and of a pyro-carbon interphase. The analysis was used to separately obtain activation energies for the carbon constituents within a C/SiC composite. TGA was also conducted on C/SiC composite material to study carbon oxidation and crack closure as a function of temperature. In order to more closely match applications conditions C/SiC tensile coupons were also tested under stressed oxidation conditions. The stressed oxidation tests show that C/SiC is much more susceptible to oxidation when the material is under an applied load where the cracks are open and allow for oxygen ingress. The results help correlate carbon oxidation with composite strength reduction and failure.

  1. The Isolated Bubble Regime in Pool Nucleate Boiling

    NASA Technical Reports Server (NTRS)

    Buyevich, Y. A.; Webbon, Bruce W.; Callaway, Robert (Technical Monitor)

    1995-01-01

    We consider an isolated bubble boiling regime in which vapour bubbles are intermittently produced at a prearranged set of nucleation site on an upward facing overheated wall plane. In this boiling regime, the bubbles depart from the wall and move as separate entities. Except in the matter of rise velocity, the bubbles do not interfere and are independent of one another. However, the rise velocity is dependent on bubble volume concentration in the bulk. Heat transfer properties specific to this regime cannot be described without bubble detachment size, and we apply our previously developed dynamic theory of vapour bubble growth and detachment to determine this size. Bubble growth is presumed to be thermally controlled. Two limiting cases of bubble evolution are considered: the one in which buoyancy prevails in promoting bubble detachment and the one in which surface tension prevails. We prove termination of the isolated regime of pool nucleate boiling to result from one of the four possible causes, depending on relevant parameters values. The first cause consists in the fact that the upward flow of rising bubbles hampers the downward liquid flow, and under certain conditions, prevents the liquid from coming to the wall in an amount that would be sufficient to compensate for vapour removal from the wall. The second cause is due to the lateral coalescence of growing bubbles that are attached to their corresponding nucleation sites, with ensuing generation of larger bubbles and extended vapour patches near the wall. The other two causes involve longitudinal coalescence either 1) immediately in the wall vicinity, accompanied by the establishment of the multiple bubble boiling regime, or 2) in the bulk, with the formation of vapour columns. The longitudinal coalescence in the bulk is shown to be the most important cause. The critical wall temperature and the heat flux density associated with isolated bubble regime termination are found to be functions of the physical and

  2. Early results from combined historic chlorofluorocarbon and first sulphur hexafluoride measurements in the Weddell Sea - variability of ventilation rates and anthropogenic carbon

    NASA Astrophysics Data System (ADS)

    Huhn, O.; Rhein, M.; Bulsiewicz, K.

    2012-04-01

    The Weddell Sea is a key area for the formation of deep and bottom water and, hence, a major driver of the deep part of the global ocean's conveyor belt. Furthermore, it provides an important sink for atmospheric gases like anthropogenic carbon. Its sensitivity to changing atmospheric conditions is under discussion. During the last three decades time series of anthropogenic transient tracer measurements (chlorofluorocarbons, CFCs) were obtained on a section crossing the Weddell Basin from the northern tip of the Antarctic Peninsula to Cape Norwegia and along the Prime Meridian from the Antarctic Continent to the Mid Atlantic Ridge (1984-2008). On our most recent RV POLARSTERN expedition from November 2010 to February 2011 we obtained for the first time sulphur hexafluoride (SF6) measurements in addition to CFCs in that area. The onset of the atmospheric SF6 history starts some decades after the CFCs, and the increase of SF6 in the atmosphere is steeper. The combination of CFC and SF6 may, hence, provide a better constraint for the quantification of very recently ventilated deep and bottom water and for the estimate of transport time scales or transit time distributions (TTDs). We discuss that new CFC and SF6 data set in comparison to the historic CFC data and show early results from our analysis. We use the extended CFC time series combined with the additional tracer SF6 to determine TTDs, from which we assess the ventilation rates of deep and bottom water and estimate the related content of anthropogenic carbon and their temporal variability in the Weddell Sea during the last three decades.

  3. IRECCSEM: Evaluating Clare Basin potential for onshore carbon sequestration using magnetotelluric data (Preliminary results). New approaches applied for processing, modeling and interpretation

    NASA Astrophysics Data System (ADS)

    Campanya i Llovet, J.; Ogaya, X.; Jones, A. G.; Rath, V.

    2014-12-01

    The IRECCSEM project (www.ireccsem.ie) is a Science Foundation Ireland Investigator Project that is funded to evaluate Ireland's potential for onshore carbon sequestration in saline aquifers by integrating new electromagnetic data with existing geophysical and geological data. The main goals of the project are to determine porosity-permeability values of the potential reservoir formation as well as to evaluate the integrity of the seal formation. During the Summer of 2014 a magnetotelluric (MT) survey was carried out at the Clare basin (Ireland). A total of 140 sites were acquired including audiomagnetotelluric (AMT), broadband magnetotelluric (BBMT) and long period magnetotelluric (LMT) data. The nominal space between sites is 0.6 km for AMT sites, 1.2 km for BBMT sites and 8 km for LMT sites. To evaluate the potential for carbon sequestration of the Clare basin three advances on geophysical methodology related to electromagnetic techniques were applied. First of all, processing of the MT data was improved following the recently published ELICIT methodology. Secondly, during the inversion process, the electrical resistivity distribution of the subsurface was constrained combining three different tensor relationships: Impedances (Z), induction arrows (TIP) and multi-site horizontal magnetic transfer-functions (HMT). Results from synthetic models were used to evaluate the sensitivity and properties of each tensor relationship. Finally, a computer code was developed, which employs a stabilized least squares approach to estimate the cementation exponent in the generalized Archie law formulated by Glover (2010). This allows relating MT-derived electrical resistivity models to porosity distributions. The final aim of this procedure is to generalize the porosity - permeability values measured in the boreholes to regional scales. This methodology will contribute to the evaluation of possible sequestration targets in the study area.

  4. Nonlinear transport processes in tokamak plasmas. I. The collisional regimes

    NASA Astrophysics Data System (ADS)

    Sonnino, Giorgio; Peeters, Philippe

    2008-06-01

    An application of the thermodynamic field theory (TFT) to transport processes in L-mode tokamak plasmas is presented. The nonlinear corrections to the linear ("Onsager") transport coefficients in the collisional regimes are derived. A quite encouraging result is the appearance of an asymmetry between the Pfirsch-Schlüter (P-S) ion and electron transport coefficients: the latter presents a nonlinear correction, which is absent for the ions, and makes the radial electron coefficients much larger than the former. Explicit calculations and comparisons between the neoclassical results and the TFT predictions for Joint European Torus (JET) plasmas are also reported. It is found that the nonlinear electron P-S transport coefficients exceed the values provided by neoclassical theory by a factor that may be of the order 102. The nonlinear classical coefficients exceed the neoclassical ones by a factor that may be of order 2. For JET, the discrepancy between experimental and theoretical results for the electron losses is therefore significantly reduced by a factor 102 when the nonlinear contributions are duly taken into account but, there is still a factor of 102 to be explained. This is most likely due to turbulence. The expressions of the ion transport coefficients, determined by the neoclassical theory in these two regimes, remain unaltered. The low-collisional regimes, i.e., the plateau and the banana regimes, are analyzed in the second part of this work.

  5. Chemistry of organic carbon in soil with relationship to the global carbon cycle

    SciTech Connect

    Post, W.M. III

    1988-01-01

    Various ecosystem disturbances alter the balances between production of organic matter and its decomposition and therefore change the amount of carbon in soil. The most severe perturbation is conversion of natural vegetation to cultivated crops. Conversion of natural vegetation to cultivated crops results in a lowered input of slowly decomposing material which causes a reduction in overall carbon levels. Disruption of soil matrix structure by cultivation leads to lowered physical protection of organic matter resulting in an increased net mineralization rate of soil carbon. Climate change is another perturbation that affects the amount and composition of plant production, litter inputs, and decomposition regimes but does not affect soil structure directly. Nevertheless, large changes in soil carbon storage are probable with anticipated CO2 induced climate change, particularly in northern latitudes where anticipated climate change will be greatest (MacCracken and Luther 1985) and large amounts of soil organic matter are found. It is impossible, given the current state of knowledge of soil organic matter processes and transformations to develop detailed process models of soil carbon dynamics. Largely phenomenological models appear to be developing into predictive tools for understanding the role of soil organic matter in the global carbon cycle. In particular, these models will be useful in quantifying soil carbon changes due to human land-use and to anticipated global climate and vegetation changes. 47 refs., 7 figs., 2 tabs.

  6. 75 FR 75455 - Certain Hot-Rolled Flat-Rolled Carbon-Quality Steel Products From Brazil: Final Results of Full...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-03

    ... International Trade Administration Certain Hot-Rolled Flat-Rolled Carbon-Quality Steel Products From Brazil... certain hot-rolled flat-rolled carbon-quality steel products (hot-rolled steel) from Brazil, pursuant to.../COSIPA) \\2\\ and Companhia Siderurgica Nacional (CSN), producers of hot-rolled steel, and the...

  7. 75 FR 47541 - Hot-Rolled Flat-Rolled Carbon-Quality Steel Products from Brazil and Japan: Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-06

    ... International Trade Administration Hot-Rolled Flat-Rolled Carbon-Quality Steel Products from Brazil and Japan... Commerce (the Department) initiated sunset reviews of the antidumping duty orders on hot-rolled flat-rolled... hot- rolled flat-rolled carbon-quality steel products from Brazil and Japan pursuant to section...

  8. Invited article summarizing the Science To Achieve Results research portfolio on Black Carbon for the journal EM of the Air and Waste Management Association.

    EPA Science Inventory

    Where there’s smoke, there’s fire – and black carbon. Black carbon is the sooty material emitted from combustion processes, including diesel engines and other sources that burn fossil fuels, biofuels, or biomass. This soot contributes to fine particulate matter,...

  9. Earth Regime Network Evolution Study (ERNESt)

    NASA Technical Reports Server (NTRS)

    Menrad, Bob

    2016-01-01

    Speaker and Presenter at the Lincoln Laboratory Communications Workshop on April 5, 2016 at the Massachusetts Institute of Technology Lincoln Laboratory in Lexington, MA. A visual presentation titled Earth Regimes Network Evolution Study (ERNESt).

  10. Prolonged instability prior to a regime shift.

    PubMed

    Spanbauer, Trisha L; Allen, Craig R; Angeler, David G; Eason, Tarsha; Fritz, Sherilyn C; Garmestani, Ahjond S; Nash, Kirsty L; Stone, Jeffery R

    2014-01-01

    Regime shifts are generally defined as the point of 'abrupt' change in the state of a system. However, a seemingly abrupt transition can be the product of a system reorganization that has been ongoing much longer than is evident in statistical analysis of a single component of the system. Using both univariate and multivariate statistical methods, we tested a long-term high-resolution paleoecological dataset with a known change in species assemblage for a regime shift. Analysis of this dataset with Fisher Information and multivariate time series modeling showed that there was a∼2000 year period of instability prior to the regime shift. This period of instability and the subsequent regime shift coincide with regional climate change, indicating that the system is undergoing extrinsic forcing. Paleoecological records offer a unique opportunity to test tools for the detection of thresholds and stable-states, and thus to examine the long-term stability of ecosystems over periods of multiple millennia.

  11. Soil Carbon Sequestration and Greenhouse Gas Emissions Under a Changing Climate at the Foodshed Scale - Preliminary Results from Diverse Cropping Systems

    NASA Astrophysics Data System (ADS)

    Kong, A. Y.; Shukla, S. P.; Rosenzweig, C.

    2011-12-01

    The term 'foodshed' is an analog to the concept of a 'watershed' and describes "the flow of foodstuffs to consuming markets." Our main goals in identifying a foodshed are to: determine sustainable regional production and develop ideas for regional/local distribution systems that increase market access for producers and fresh food access for consumers, while reducing the carbon footprint of the food choices within the foodshed. The latter can be achieved by establishing policies that protect agricultural land from development, conserve water, and promote the adoption of agricultural management practices that decrease disturbance and/or increase carbon sequestration in soils, all of which can play a role in mitigating climate change. Because few studies relate climate change and agriculture at the regional-scale, we lack a good understanding of which elements of a foodshed are most vulnerable to changes in climate. With this foodshed analysis, our overall aims are to utilize the latest methods of climate and agricultural scenario generation to conduct multi-scale and transdisciplinary assessments of climate change impacts on the production, distribution and consumption of agricultural crops within a foodshed and to evaluate the potential for mitigation [soil carbon sequestration and greenhouse gas (GHG) emissions reduction)] and design the framework for adaptation (policy incentives) to climate change within a foodshed. Here, we present the methodology and preliminary results for an integrated climate/ecosystem modeling approach to look at how agricultural management practices can contribute to climate change mitigation within the Hudson Valley, a sub-region of the New York City foodshed. First, cutting-edge CMIP5 GCMs were validated against historical climatic data (1979-present) to identify which GCMs best simulate the climate of the Northeastern US (which includes the New York City foodshed). Subsequently, the selected GCMs were forced with the IPCC's four newly

  12. Using Clustering to Establish Climate Regimes from PCM Output

    NASA Technical Reports Server (NTRS)

    Oglesby, Robert; Arnold, James E. (Technical Monitor); Hoffman, Forrest; Hargrove, W. W.; Erickson, D.

    2002-01-01

    A multivariate statistical clustering technique--based on the k-means algorithm of Hartigan has been used to extract patterns of climatological significance from 200 years of general circulation model (GCM) output. Originally developed and implemented on a Beowulf-style parallel computer constructed by Hoffman and Hargrove from surplus commodity desktop PCs, the high performance parallel clustering algorithm was previously applied to the derivation of ecoregions from map stacks of 9 and 25 geophysical conditions or variables for the conterminous U.S. at a resolution of 1 sq km. Now applied both across space and through time, the clustering technique yields temporally-varying climate regimes predicted by transient runs of the Parallel Climate Model (PCM). Using a business-as-usual (BAU) scenario and clustering four fields of significance to the global water cycle (surface temperature, precipitation, soil moisture, and snow depth) from 1871 through 2098, the authors' analysis shows an increase in spatial area occupied by the cluster or climate regime which typifies desert regions (i.e., an increase in desertification) and a decrease in the spatial area occupied by the climate regime typifying winter-time high latitude perma-frost regions. The patterns of cluster changes have been analyzed to understand the predicted variability in the water cycle on global and continental scales. In addition, representative climate regimes were determined by taking three 10-year averages of the fields 100 years apart for northern hemisphere winter (December, January, and February) and summer (June, July, and August). The result is global maps of typical seasonal climate regimes for 100 years in the past, for the present, and for 100 years into the future. Using three-dimensional data or phase space representations of these climate regimes (i.e., the cluster centroids), the authors demonstrate the portion of this phase space occupied by the land surface at all points in space and time

  13. Using Clustering to Establish Climate Regimes from PCM Output

    NASA Astrophysics Data System (ADS)

    Hoffman, F.; Oglesby, R.; Hargrove, W. W.; Erickson, D.

    2002-12-01

    A multivariate statistical clustering technique--based on the k-means algorithm of Hartigan--has been used to extract patterns of climatological significance from 200 years of general circulation model (GCM) output. Originally developed and implemented on a Beowulf-style parallel computer constructed by Hoffman and Hargrove from surplus commodity desktop PCs, the high performance parallel clustering algorithm was previously applied to the derivation of ecoregions from map stacks of 9 and 25 geophysical conditions or variables for the conterminous U.S. at a resolution of 1 sq km. Now applied both across space and through time, the clustering technique yields temporally-varying climate regimes predicted by transient runs of the Parallel Climate Model (PCM). Using a business-as-usual (BAU) scenario and clustering four fields of significance to the global water cycle (surface temperature, precipitation, soil moisture, and snow depth) from 1871 through 2098, the authors' analysis shows an increase in spatial area occupied by the cluster or climate regime which typifies desert regions (i.e., an increase in desertification) and a decrease in the spatial area occupied by the climate regime typifying winter-time high latitude perma-frost regions. The patterns of cluster changes have been analyzed to understand the predicted variability in the water cycle on global and continental scales. In addition, representative climate regimes were determined by taking three 10-year averages of the fields 100 years apart for northern hemisphere winter (December, January, and February) and summer (June, July, and August). The result is global maps of typical seasonal climate regimes for 100 years in the past, for the present, and for 100 years into the future. Using three-dimensional data or phase space representations of these climate regimes (i.e., the cluster centroids), the authors demonstrate the portion of this phase space occupied by the land surface at all points in space and

  14. Radiation build-up in laminar and turbulent regimes in quasi-CW Raman fiber laser.

    PubMed

    Smirnov, Sergey V; Tarasov, Nikita; Churkin, Dmitry V

    2015-10-19

    We study the radiation build-up in laminar and turbulent generation regimes in quasi-CW Raman fiber laser. We found the resulted spectral shape and generation type is defined by the total spectral broadening/narrowing balance over laser cavity round-trip, which is substantially different in different regimes starting from first round-trips of the radiation build-up. In turbulent regime, the steady-state is reached only after a few round-trips, while in the laminar regime the laser approaches the equilibrium spectrum shape asymptotically.

  15. Electron transport fluxes in potato plateau regime

    SciTech Connect

    Shaing, K.C.; Hazeltine, R.D.

    1997-12-01

    Electron transport fluxes in the potato plateau regime are calculated from the solutions of the drift kinetic equation and fluid equations. It is found that the bootstrap current density remains finite in the region close to the magnetic axis, although it decreases with increasing collision frequency. This finite amount of the bootstrap current in the relatively collisional regime is important in modeling tokamak startup with 100{percent} bootstrap current. {copyright} {ital 1997 American Institute of Physics.}

  16. Iranian Regime Reform: Opportunities and Consequences

    DTIC Science & Technology

    2010-12-01

    formal political access to mitigate the adverse effects of . . . the deterioration of quality of life .”70 Three broad sets of factors outlined by...demanding changes in the Iranian regime that mesh with U.S.. national interests. However, the Green Movement may not be successful in effecting change...viable threat to the Iranian regime. This thesis used game theory as a tool because game theory outcomes very often reflect real- life outcomes

  17. Dynamic Financial Constraints: Distinguishing Mechanism Design from Exogenously Incomplete Regimes*

    PubMed Central

    Karaivanov, Alexander; Townsend, Robert M.

    2014-01-01

    We formulate and solve a range of dynamic models of constrained credit/insurance that allow for moral hazard and limited commitment. We compare them to full insurance and exogenously incomplete financial regimes (autarky, saving only, borrowing and lending in a single asset). We develop computational methods based on mechanism design, linear programming, and maximum likelihood to estimate, compare, and statistically test these alternative dynamic models with financial/information constraints. Our methods can use both cross-sectional and panel data and allow for measurement error and unobserved heterogeneity. We estimate the models using data on Thai households running small businesses from two separate samples. We find that in the rural sample, the exogenously incomplete saving only and borrowing regimes provide the best fit using data on consumption, business assets, investment, and income. Family and other networks help consumption smoothing there, as in a moral hazard constrained regime. In contrast, in urban areas, we find mechanism design financial/information regimes that are decidedly less constrained, with the moral hazard model fitting best combined business and consumption data. We perform numerous robustness checks in both the Thai data and in Monte Carlo simulations and compare our maximum likelihood criterion with results from other metrics and data not used in the estimation. A prototypical counterfactual policy evaluation exercise using the estimation results is also featured. PMID:25246710

  18. On spinfoam models in large spin regime

    NASA Astrophysics Data System (ADS)

    Han, Muxin

    2014-01-01

    We study the semiclassical behavior of Lorentzian Engle-Pereira-Rovelli-Livine (EPRL) spinfoam model, by taking into account the sum over spins in the large spin regime. We also employ the method of stationary phase analysis with parameters and the so-called, almost analytic machinery, in order to find the asymptotic behavior of the contributions from all possible large spin configurations in the spinfoam model. The spins contributing the sum are written as Jf = λjf, where λ is a large parameter resulting in an asymptotic expansion via stationary phase approximation. The analysis shows that at least for the simplicial Lorentzian geometries (as spinfoam critical configurations), they contribute the leading order approximation of spinfoam amplitude only when their deficit angles satisfy \\gamma \\mathring{\\Theta }_f\\le \\lambda ^{-1/2} mod 4\\pi {Z}. Our analysis results in a curvature expansion of the semiclassical low energy effective action from the spinfoam model, where the UV modifications of Einstein gravity appear as subleading high-curvature corrections.

  19. Shifts from glucose to certain secondary carbon-sources result in activation of the extracytoplasmic function sigma factor sigmaE in Salmonella enterica serovar Typhimurium.

    PubMed

    Kenyon, William J; Thomas, Sheena M; Johnson, Erin; Pallen, Mark J; Spector, Michael P

    2005-07-01

    Salmonella enterica serovar Typhimurium (S. Typhimurium) elicits the starvation-stress response (SSR) due to starvation for an essential nutrient, e.g. a carbon/energy source (C-source). As part of the SSR, the alternative sigma factor sigma(E) is activated and induced. The authors suspect that this activation is, in part, triggered by changes in the S. Typhimurium cell envelope occurring during the adaptation from growth to carbon/energy starvation (C-starvation), and resulting in an increased need for sigma(E)-regulated factors involved in the proper folding and assembly of newly synthesized proteins destined for this extracytoplasmic compartment. This led to the hypothesis that a sigma(E) activation signal might arise during C-source shifts that cause the induction of proteins localized to the extracytoplasmic compartment, i.e. the outer membrane or periplasm, of the cell. To test this hypothesis, cultures were grown in minimal medium containing enough glucose to reach mid-exponential-phase, plus a non-limiting amount of a secondary 'less-preferred' but utilizable carbon/energy source. The sigma(E) activity was then monitored using plasmids carrying rpoEP1- and rpoEP2-lacZ transcriptional fusions, which exhibit sigma(E)-independent and -dependent lacZ expression, respectively. The secondary C-sources maltose, succinate and citrate, which have extracytoplasmic components involved in their utilization (e.g. LamB), resulted in a discernible diauxic lag period and a sustained increase in sigma(E) activity. Growth transition from glucose to other utilizable phosphotransferase (PTS) and non-PTS C-sources, such as trehalose, mannose, mannitol, fructose, glycerol, d-galactose or l-arabinose, did not cause a discernible diauxic lag period or a sustained increase in sigma(E) activity. Interestingly, a shift from glucose to melibiose, which does not use an extracytoplasmic-localized protein for uptake, did cause an observable diauxic lag period but did not result in a

  20. Ubiquity of Exciton Localization in Cryogenic Carbon Nanotubes

    PubMed Central

    2016-01-01

    We present photoluminescence studies of individual semiconducting single-wall carbon nanotubes at room and cryogenic temperatures. From the analysis of spatial and spectral features of nanotube photoluminescence, we identify characteristic signatures of unintentional exciton localization. Moreover, we quantify the energy scale of exciton localization potentials as ranging from a few to a few tens of millielectronvolts and stemming from both environmental disorder and shallow covalent side-wall defects. Our results establish disorder-induced crossover from the diffusive to the localized regime of nanotube excitons at cryogenic temperatures as a ubiquitous phenomenon in micelle-encapsulated and as-grown carbon nanotubes. PMID:27105355

  1. Ubiquity of Exciton Localization in Cryogenic Carbon Nanotubes.

    PubMed

    Hofmann, Matthias S; Noé, Jonathan; Kneer, Alexander; Crochet, Jared J; Högele, Alexander

    2016-05-11

    We present photoluminescence studies of individual semiconducting single-wall carbon nanotubes at room and cryogenic temperatures. From the analysis of spatial and spectral features of nanotube photoluminescence, we identify characteristic signatures of unintentional exciton localization. Moreover, we quantify the energy scale of exciton localization potentials as ranging from a few to a few tens of millielectronvolts and stemming from both environmental disorder and shallow covalent side-wall defects. Our results establish disorder-induced crossover from the diffusive to the localized regime of nanotube excitons at cryogenic temperatures as a ubiquitous phenomenon in micelle-encapsulated and as-grown carbon nanotubes.

  2. Aharonov-Bohm conductance modulation in ballistic carbon nanotubes.

    PubMed

    Lassagne, B; Cleuziou, J-P; Nanot, S; Escoffier, W; Avriller, R; Roche, S; Forró, L; Raquet, B; Broto, J-M

    2007-04-27

    We report on magnetoconductance experiments in ballistic multiwalled carbon nanotubes threaded by magnetic fields as large as 55 T. In the high temperature regime (100 K), giant modulations of the conductance, mediated by the Fermi level location, are unveiled. The experimental data are consistently analyzed in terms of the field-dependent density of states of the external shell that modulates the injection properties at the electrode-nanotube interface, and the resulting linear conductance. This is the first unambiguous experimental evidence of Aharonov-Bohm effect in clean multiwalled carbon nanotubes.

  3. Liquid-Vapor Flow Regime Transitions for Use in Design of Heat Transfer Loops in Spacecraft - An Investigation of Two-Phase Flow in Zero Gravity Conditions

    DTIC Science & Technology

    1985-05-01

    Horizontal Dukler -Taitel, Vertical Dukler -Taitel, Vertical Weisman and H1orizontal Weisman. None of these models when’ dxtrap- olated to zero-g...COMPARISON OF LAB RESULTS WITH THE FOUR FLOW 37 REGIME MAPS Dukler -Taitel Horizontal Flow Regime Map 37 Weisman Horizontal Flow Regime Map 50 Dukler -Taitel... Dukler -Taitel Horizontal Flow Regime Map 72 The Dukler -Taitel Vertical Flow Regime Map 72 VII. ANALYTICAL WORK 73 VIII.CONCLUSIONS 76 References 77

  4. Deciphering the evolution and origin of the lower Colorado River and uplift of the Colorado Plateau: Preliminary U-Pb carbonate dating results and future directions

    NASA Astrophysics Data System (ADS)

    Crow, R. S.; Karlstrom, K. E.; Crossey, L. J.; Polyak, V. J.; Asmerom, Y.; House, K.

    2014-12-01

    Long-standing debate has focused on the timing, mode, and direction of Colorado River integration, either down or up river. Miocene-Pliocene Colorado River deposits are well exposed in the lower Colorado River corridor (i.e. Bouse Fm and Bullhead Alluvium). There, improved geochronologic constraints have the potential to test integration models and improve our understanding of the inception of a continental-scale river system. In addition, timing and magnitude of regional uplift could be estimated if 5-6 Ma paleoelevation of any part of the system can be confidently identified (e.g. paleo sea level). Present data indicate that downward integration occurred in part through a series of lake basins that filled and spilled as fluvial-deltaic sediments prograded towards the Gulf of California. However, a possible marine connection and hence a near sea-level elevation for the lower Blythe basin of the Bouse Fm remains controversial. Non-marine Sr signatures in lower Bouse Fm carbonates are permissibly consistent with mixing in an estuary and conversely, limited assemblages of marine fossils are permissively explained by avian transport to inland saline lakes. Improved geochronology has the potential to discriminate between a < 100 ka episode of downward integration of short-lived lakes from a > 1 Ma longer-lived estuarine system. Improved geochronology can also help resolve controversy about the timing of the arrival of Colorado River sediment and water in each basin and, in particular in the Salton Trough. We present initial U/Pb results on Hualapai Limestone and Bouse Fm carbonates. Hualapai samples give linear 3D isochron ages of 9.3 ± 1.1 and 10.4 ± 3.1 Ma that are consistent with available stratigraphic controls. Preliminary attempts to date Bouse marl have so far yielded imprecise results. However generally high U/Pb ratios and U concentrations in Bouse samples are promising. Efforts are currently underway to date fine-grained banded Bouse tufas from lake margins.

  5. Characterization of fire regime in Sardinia (Italy)

    NASA Astrophysics Data System (ADS)

    Bacciu, V. M.; Salis, M.; Mastinu, S.; Masala, F.; Sirca, C.; Spano, D.

    2012-12-01

    In the last decades, a number of Authors highlighted the crucial role of forest fires within Mediterranean ecosystems, with impacts both negative and positive on all biosphere components and with reverberations on different scales. Fire determines the landscape structure and plant composition, but it is also the cause of enormous economic and ecological damages, beside the loss of human life. In Sardinia (Italy), the second largest island of the Mediterranean Basin, forest fires are perceived as one of the main environmental and social problems, and data are showing that the situation is worsening especially within the rural-urban peripheries and the increasing number of very large forest fires. The need for information concerning forest fire regime has been pointed out by several Authors (e.g. Rollins et al., 2002), who also emphasized the importance of understanding the factors (such as weather/climate, socio-economic, and land use) that determine spatial and temporal fire patterns. These would be used not only as a baseline to predict the climate change effect on forest fires, but also as a fire management and mitigation strategy. The main aim of this paper is, thus, to analyze the temporal and spatial patterns of fire occurrence in Sardinia (Italy) during the last three decades (1980-2010). For the analyzed period, fire statistics were provided by the Sardinian Forest Service (CFVA - Corpo Forestale e di Vigilanza Ambientale), while weather data for eight weather stations were obtained from the web site www.tutiempo.it. For each station, daily series of precipitation, mean, maximum and minimum temperature, relative humidity and wind speed were available. The present study firstly analyzed fire statistics (burned area and number of fires) according to the main fire regime characteristics (seasonality, fire return interval, fire incidence, fire size distribution). Then, fire and weather daily values were averaged to obtain monthly, seasonal and annual values, and

  6. Experimental Manipulation of Soil Moisture Regime Impacts Soil Microbial Community Abundance, Diversity, and Function in a Semi-Arid Sagebrush Steppe

    NASA Astrophysics Data System (ADS)

    Sorensen, P. O.; Feris, K. P.; Germino, M. J.

    2010-12-01

    labile soil carbon pools which were dependent on sampling depth and experimental precipitation regime. Our results provide a significant example of ecohydrological interactions structuring unique microbial communities in the semi-arid sagebrush steppe. Additionally, we observe precipitation regime as an important factor in governing the quality and quantity of soil carbon in this ecosystem, with feedback implications to a changing global climate.

  7. Regimes of flow induced vibration for tandem, tethered cylinders

    NASA Astrophysics Data System (ADS)

    Nave, Gary; Stremler, Mark

    2015-11-01

    In the wake of a bluff body, there are a number of dynamic response regimes that exist for a trailing bluff body depending on spacing, structural restoring forces, and the mass-damping parameter m* ζ . For tandem cylinders with low values of m* ζ , two such regimes of motion are Gap Flow Switching and Wake Induced Vibration. In this study, we consider the dynamics of a single degree-of-freedom rigid cylinder in the wake of another in these regimes for a variety of center-to-center cylinder spacings (3-5 diameters) and Reynolds numbers (4,000-11,000). The system consists of a trailing cylinder constrained to a circular arc around a fixed leading cylinder, which, for small angle displacements, bears a close resemblance to the transversely oscillating cylinders found more commonly in existing literature. From experiments on this system, we compare and contrast the dynamic response within these two regimes. Our results show sustained oscillations in the absence of a structural restoring force in all cases, providing experimental support for the wake stiffness assumption, which is based on the mean lift toward the center line of flow.

  8. Observed trends in the hydrologic regime of Alpine catchments

    NASA Astrophysics Data System (ADS)

    Bard, Antoine; Renard, Benjamin; Lang, Michel

    2010-05-01

    A European trans-national project, AdaptAlp, has been set up since 2008 in order to study the impacts of climate change in the Alps and to assess adaptation strategies. One of the objectives of this project is to study past and present changes in the hydrologic regime of Alpine rivers. This poster presents preliminary results of a trend analysis over the whole Alpine area. A new dataset of more than two hundred discharge time series has been collected over the six countries of the alpine space: Switzerland, Italy, Germany, Austria, Slovenia and France. These series are made up of at least forty years of daily record and are related to undisturbed catchments. This dataset covers the whole spectrum of hydrological regimes existing in the Alps (from glacier- to mixed rainfall/snow regimes). In a second step, a set of hydrologic indices has been defined to characterize the hydrologic regime in terms of low, medium and high flows. In particular, these indices describe the drought severity (in terms of duration, intensity and volume deficit) and seasonality, the volume and timing of snowmelt, floods intensity and seasonality. A statistical trend test is finally applied for each hydrologic indice at each site. Consistent trends affecting the timing of snowmelt-dominated streamflow are found all over the Alps. Spring floods appear earlier in the season and tend to be longer in duration. Winter droughts tend to be shorter and less severe in terms of volume deficit.

  9. Microgravity Flow Regime Data: Buoyancy and Mixing Apparatus Effects

    NASA Astrophysics Data System (ADS)

    Shephard, Adam; Best, Frederick

    2010-01-01

    Zero-g two-phase flow data set qualification and flight experiment design have not been standardized and as a result, agreement among researchers has not been reached regarding what experimental conditions adequately approximate those of microgravity. The effects of buoyancy forces and mixing apparatus on the flow regime transitions are presented in this study. The gravity conditions onboard zero-g aircraft are at best 10-3 g which is used to approximate the 10-5 g conditions of microgravity, thus the buoyancy forces present on zero-g aircraft can become significantly large and unrepresentative of microgravity. When buoyancy forces approach those of surface tension forces, buoyancy induced coalescence occurs. When discussing flow regime transitions, these large buoyancy forces lead to flow regime transitions which otherwise would not occur. The buoyancy attributes of the two-phase flow data sets available in the literature are evaluated to determine which data sets exhibit buoyancy induced transitions. Upon comparison of the representative data sets, the affects of different mixing apparatus can be seen in the superficial velocity flow regime maps.

  10. Greenland Meltwater and Arctic Circulation Regimes

    NASA Astrophysics Data System (ADS)

    Dukhovskoy, D. S.; Proshutinsky, A. Y.; Timmermans, M. L.; Myers, P. G.; Platov, G.

    2015-12-01

    Between 1948 and 1996, wind-driven components of ice drift and surface ocean currents experienced a well-pronounced decadal variability alternating between anticyclonic and cyclonic circulation regimes. During cyclonic regimes, low sea level atmospheric pressure dominated over the Arctic Ocean driving sea ice and the upper ocean clockwise; the Arctic atmosphere was relatively warm and humid and freshwater flux from the Arctic Ocean toward the sub-Arctic seas was intensified. During anticylonic circulation regimes, high sea level pressure dominated over the Arctic driving sea ice and ocean counter-clockwise; the atmosphere was cold and dry and the freshwater flux from the Arctic to the sub-Arctic seas was reduced. Since 1997, however, the Arctic system has been dominated by an anticyclonic circulation regime with a set of environmental parameters that are atypical for these regimes. Of essential importance is to discern the causes and consequences of the apparent break-down in the natural decadal variability of the Arctic climate system, and specifically: Why has the well-pronounced decadal variability observed in the 20th century been replaced by relatively weak interannual changes under anticyclonic circulation regime conditions in the 21st century? We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from Greenland impact environmental conditions and interrupt their decadal variability. In order to test this hypothesis, numerical experiments with several FAMOS (Forum for Arctic Modeling & Observational Synthesis) ice-ocean coupled models have been conducted. In these experiments, Greenland melt freshwater is tracked by passive tracers being constantly released along the Greenland coast. Propagation pathways and time scales of Greenland meltwater within the sub-Arctic seas are discussed.

  11. A holistic view of marine regime shifts

    PubMed Central

    Conversi, Alessandra; Dakos, Vasilis; Gårdmark, Anna; Ling, Scott; Folke, Carl; Mumby, Peter J.; Greene, Charles; Edwards, Martin; Blenckner, Thorsten; Casini, Michele; Pershing, Andrew; Möllmann, Christian

    2015-01-01

    Understanding marine regime shifts is important not only for ecology but also for developing marine management that assures the provision of ecosystem services to humanity. While regime shift theory is well developed, there is still no common understanding on drivers, mechanisms and characteristic of abrupt changes in real marine ecosystems. Based on contributions to the present theme issue, we highlight some general issues that need to be overcome for developing a more comprehensive understanding of marine ecosystem regime shifts. We find a great divide between benthic reef and pelagic ocean systems in how regime shift theory is linked to observed abrupt changes. Furthermore, we suggest that the long-lasting discussion on the prevalence of top-down trophic or bottom-up physical drivers in inducing regime shifts may be overcome by taking into consideration the synergistic interactions of multiple stressors, and the special characteristics of different ecosystem types. We present a framework for the holistic investigation of marine regime shifts that considers multiple exogenous drivers that interact with endogenous mechanisms to cause abrupt, catastrophic change. This framework takes into account the time-delayed synergies of these stressors, which erode the resilience of the ecosystem and eventually enable the crossing of ecological thresholds. Finally, considering that increased pressures in the marine environment are predicted by the current climate change assessments, in order to avoid major losses of ecosystem services, we suggest that marine management approaches should incorporate knowledge on environmental thresholds and develop tools that consider regime shift dynamics and characteristics. This grand challenge can only be achieved through a holistic view of marine ecosystem dynamics as evidenced by this theme issue.

  12. Enhanced carbon influx into TFTR supershots

    SciTech Connect

    Ramsey, A.T.; Bush, C.E.; Dylla, H.F.; Owens, D.K.; Pitcher, C.S.; Ulrickson, M.

    1990-12-01

    Under some conditions, a very large influx of carbon into TFTR occurs during beam injection into low recycling plasmas (the Supershot regime). These carbon blooms'' result in serious degradation of plasma parameters. The sources of this carbon have been identified as hot spots on the TFTR bumper limiter at or near the last closed flux surface. Two separate temperature thresholds have been identified. One, at about 1650{degree}C, is consistent with radiation enhanced sublimation. The other, at about 2300{degree}C, appears to be thermal sublimation of carbon from the limiter. To account for the increased density caused by the blooms, near unity recycling of the carbon at the limiter by physical sputtering is required; this effect is expected from laboratory measurements, and we believe we are seeing it on TFTR. The sources of the carbon blooms are sites which have either loosely attached fragments of limiter material (caused by damage) or surfaces nearly perpendicular to the magnetic field lines. Such surfaces may have local power depositions two orders of magnitude higher than usual. The TFTR team modified the limiter during the opening of Winter 1989--90. The modifications greatly reduced the number and magnitude of the blooms, so that they are no longer a problem.

  13. Global fishery prospects under contrasting management regimes

    PubMed Central

    Costello, Christopher; Ovando, Daniel; Clavelle, Tyler; Strauss, C. Kent; Hilborn, Ray; Melnychuk, Michael C.; Branch, Trevor A.; Gaines, Steven D.; Szuwalski, Cody S.; Cabral, Reniel B.; Rader, Douglas N.; Leland, Amanda

    2016-01-01

    Data from 4,713 fisheries worldwide, representing 78% of global reported fish catch, are analyzed to estimate the status, trends, and benefits of alternative approaches to recovering depleted fisheries. For each fishery, we estimate current biological status and forecast the impacts of contrasting management regimes on catch, profit, and biomass of fish in the sea. We estimate unique recovery targets and trajectories for each fishery, calculate the year-by-year effects of alternative recovery approaches, and model how alternative institutional reforms affect recovery outcomes. Current status is highly heterogeneous—the median fishery is in poor health (overfished, with further overfishing occurring), although 32% of fisheries are in good biological, although not necessarily economic, condition. Our business-as-usual scenario projects further divergence and continued collapse for many of the world’s fisheries. Applying sound management reforms to global fisheries in our dataset could generate annual increases exceeding 16 million metric tons (MMT) in catch, $53 billion in profit, and 619 MMT in biomass relative to business as usual. We also find that, with appropriate reforms, recovery can happen quickly, with the median fishery taking under 10 y to reach recovery targets. Our results show that commonsense reforms to fishery management would dramatically improve overall fish abundance while increasing food security and profits. PMID:27035953

  14. Direct linkage between dimethyl sulfide production and microzooplankton grazing, resulting from prey composition change under high partial pressure of carbon dioxide conditions.

    PubMed

    Park, Ki-Tae; Lee, Kitack; Shin, Kyoungsoon; Yang, Eun Jin; Hyun, Bonggil; Kim, Ja-Myung; Noh, Jae Hoon; Kim, Miok; Kong, Bokyung; Choi, Dong Han; Choi, Su-Jin; Jang, Pung-Guk; Jeong, Hae Jin

    2014-05-06

    Oceanic dimethyl sulfide (DMS) is the enzymatic cleavage product of the algal metabolite dimethylsulfoniopropionate (DMSP) and is the most abundant form of sulfur released into the atmosphere. To investigate the effects of two emerging environmental threats (ocean acidification and warming) on marine DMS production, we performed a large-scale perturbation experiment in a coastal environment. At both ambient temperature and ∼ 2 °C warmer, an increase in partial pressure of carbon dioxide (pCO2) in seawater (160-830 ppmv pCO2) favored the growth of large diatoms, which outcompeted other phytoplankton species in a natural phytoplankton assemblage and reduced the growth rate of smaller, DMSP-rich phototrophic dinoflagellates. This decreased the grazing rate of heterotrophic dinoflagellates (ubiquitous micrograzers), resulting in reduced DMS production via grazing activity. Both the magnitude and sign of the effect of pCO2 on possible future oceanic DMS production were strongly linked to pCO2-induced alterations to the phytoplankton community and the cellular DMSP content of the dominant species and its association with micrograzers.

  15. Terminating pre-ozonation prior to biological activated carbon filtration results in increased formation of nitrogenous disinfection by-products upon subsequent chlorination.

    PubMed

    Chu, Wenhai; Li, Changjun; Gao, Naiyun; Templeton, Michael R; Zhang, Yanshen

    2015-02-01

    Previous research demonstrated that ozone dosed before biological activated carbon (BAC) filtration reduces the formation of disinfection by-products (DBPs) upon subsequent chlorination. The current work aimed to evaluate the impact of terminating this pre-ozonation on the ability of the BAC to remove the precursors of N-DBPs. More N-DBP precursors passed into the post-BAC water when the pre-ozonation was terminated, resulting in greater formation of N-DBPs when the water was subsequently chlorinated, compared to a parallel BAC filter when the pre-ozonation was run continuously. Moreover, the N-DBP formation potential was significantly increased in the effluent of the BAC filter after terminating pre-ozonation, compared with the influent of the BAC filter (i.e. the effluent from the sand filter). Therefore, while selectively switching pre-ozonation on/off may have cost and other operational benefits for water suppliers, these should be weighed against the increased formation of N-DBPs and potential associated health risks.

  16. Nadir Measurements of Carbon Monoxide Distributions by the Tropospheric Emission Spectrometer Instrument Onboard the Aura Spacecraft: Overview of Analysis Approach and Examples of Initial Results

    NASA Technical Reports Server (NTRS)

    Rinsland, Curtis P.; Luo, Ming; Logan, Jennifer A.; Beer, Reinhard; Worden, Helen; Kulawik, Susan S.; Rider, David; Osterman, Greg; Gunson, Michael; Eldering, Annmarie; Goldman, Aaron; Shephard, Mark; Clough, Shepard A.; Rodgers, Clive; Lampel, Michael; Chiou, Linda

    2006-01-01

    We provide an overview of the nadir measurements of carbon monoxide (CO) obtained thus far by the Tropospheric Emission Spectrometer (TES). The instrument is a high resolution array Fourier transform spectrometer designed to measure infrared spectral radiances from low Earth orbit. It is one of four instruments successfully launched onboard the Aura platform into a sun synchronous orbit at an altitude of 705 km on July 15, 2004 from Vandenberg Air Force Base, California. Nadir spectra are recorded at 0.06/cm spectral resolution with a nadir footprint of 5 x 8 km. We describe the TES retrieval approach for the analysis of the nadir measurements, report averaging kernels for typical tropical and polar ocean locations, characterize random and systematic errors for those locations, and describe instrument performance changes in the CO spectral region as a function of time. Sample maps of retrieved CO for the middle and upper troposphere from global surveys during December 2005 and April 2006 highlight the potential of the results for measurement and tracking of global pollution and determining air quality from space.

  17. Experimental determination of carbon partitioning between upper mantle minerals and silicate melts: initial results and comparison to trace element partitioning (Nb, Rb, Ba, U, Th, K)

    NASA Astrophysics Data System (ADS)

    Rosenthal, A.; Hauri, E. H.; Hirschmann, M. M.; Davis, F. A.; Withers, A. C.; Fogel, M. L.

    2012-12-01

    ). Resulting D's indicate that C is highly incompatible in all major mantle mineral phases, with D's for OL, OPX and CPX of close to 5x10-4, and for GA ~2.2x10-4. D's for H2O (2x10-4 to ~3x10-2) and F (~2.3x10-3 to ~5.8x10-2) are comparable to those found in previous studies. Trace element partition determinations are in progress, but comparison to previous studies indicates that carbon is significantly more incompatible during mantle melting than Nb, U, or Th, and has behavior approximately similar to Ba. We therefore suggest that undegassed C/Ba ratios may be useful indicators of C fluxes and concentrations in basalt source regions where very low degrees of melting might fractionate C/Nb ratios. [1] Saal, A, Hauri, EH, Langmuir, CH, Perfit, M (2002) Nature 419, 451-455. [2] Cartigny, P, Pineau, F, Aubaud, C, Javoy, M (2008) Earth Planet Sci Lett 265, 672-685.

  18. Soil organic carbon dynamics and non-CO2 gas fluxes from agricultural soils under organic and non-organic management - results of two meta-studies

    NASA Astrophysics Data System (ADS)

    Gattinger, Andreas; Skinner, Colin; Müller, Adrian; Mäder, Paul; Niggli, Urs

    2015-04-01

    It is anticipated that organic farming systems provide benefits concerning soil conservation and climate protection. Therefore, meta-studies on soil organic carbon (SOC) and soil-derived greenhouse (GHG) fluxes, respectively, were conducted to proof this assumption. Datasets from 74 studies from pair wise comparisons of organic versus non-organic farming systems were subjected to meta-analysis to identify differences in soil organic carbon (SOC). We found significant differences and higher values for organically farmed soils of 0.18±0.06 % points (mean±95% confidence interval) for SOC concentrations, 3.50±1.08 Mg C ha-1 for stocks, and 0.45±0.21 Mg C ha-1 a-1 for sequestration rates compared to non-organic management. Meta-regression did not deliver clear results on drivers, but differences in external C inputs and crop rotations seemed important. Restricting the analysis to zero net input organic systems, i.e. without nutrient inputs from outside the system, and retaining only the datasets with highest data quality (measured soil bulk densities and external C and N inputs), the mean difference in SOC stocks between the farming systems was still significant (1.98±1.50 Mg C ha-1), while the difference in sequestration rates became insignificant (0.07±0.08 Mg C ha-1 a-1). The SOC dataset mainly covers top soil and temperate zones, while only few data from tropical regions and sub soil horizons exist. For the second meta-study measured soil-derived nitrous oxide and methane flux data from soils under organic and non-organic management from 19 farming system comparisons were analysed. Based on 12 studies that cover annual measurements, it appeared with a high significance that area-scaled nitrous oxide emissions from organically managed soils are 492±160 kg CO2 eq. ha-1 a-1 lower than from non-organically managed soils. For arable soils the difference amounts to 497±162 kg CO2 eq. ha-1 a-1. However, yield-scaled nitrous oxide emissions are higher by 41±34 kg

  19. Organic carbon compounds detected by the SAM instrument suite on Curiosity: results of the first year of exploration at Gale Crater (Invited)

    NASA Astrophysics Data System (ADS)

    Summons, R. E.; Miller, K.; Glavin, D. P.; Eigenbrode, J. L.; Freissinet, C.; Martin, M. G.; Team, M.

    2013-12-01

    A search for organic matter is a high priority in the search for habitable environments on Mars as it is in the quest for clues about the nature of early life on Earth. These endeavors are technically challenging because of the inherent instability of organic matter under conditions that exist in the regolith of both planets and the antiquity of the sediments of interest. In the case of the early Earth, exposure to ionizing radiation and the heat associated with burial and tectonism are the main obstacles to organic matter preservation. On Mars, exposure to ionizing radiation and chemical oxidation are the prime threats to organic matter preservation. It has been hypothesized that UV-generated hydroxyl radicals will almost certainly oxidize or highly alter any organic carbon of martian or meteoritic origin at Mars' surface. Also, there could be diagenetic processes peculiar to Mars, for which no terrestrial analogs are presently known. Thus, the search for organics on Mars must be informed by data from the entire Curiosity payload since the results are mutually informative. Sediments from the Rocknest aeolian drift and the probable fluvio-lacustrine sediments of Yellowknife Bay in Gale Crater, when analyzed by pyrolysis with evolved gas analysis (EGA) and gas chromatography mass spectrometry (GC-MS), afforded a number of chlorohydrocarbons including chloromethane, dichloromethane, trichloromethane, a chloromethylpropene, and chlorobenzene (1, 2). Some proportion of these compounds can be traced to instrument background from organic materials within the chromatographic columns, hydrocarbon traps and wet chemistry capability of SAM. N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) and dimethylformamide, compounds carried in SAM for chemical derivatization can react with gases released from the sediments to yield the C1 and C4 chlorohydrocarbons. However, we continue to explore the possibility that a portion of the C1 chlorohydrocarbons are derived

  20. Morphology, properties, and regimes of migrational-mycelial agrochernozems with different ground moistening (Belgorod oblast)

    NASA Astrophysics Data System (ADS)

    Lebedeva, I. I.; Bazykina, G. S.; Grebennikov, A. M.; Smirnova, L. G.; Tyutyunov, S. I.

    2016-12-01

    Agrochernozems of a catena (local divide, backslope, and footslope positions on a gentle slope of southern aspect) on the fields of Belgorodskoe farm were studied. The soils are developed from lithologically heterogeneous sediments with temporal accumulation of precipitation water above the lithological contact. A close correlation between the morphology and properties of the soils and the character of their water regime in different positions of the catena was found. Agrochernozems of the divide belong to the migrational-mycelial type of forest-steppe chernozems according to their humus profile, water regime, and slightly differentiated distribution of carbonates. Agrochernozems on the backslope with a higher ground moistening have a more contrasting water regime with the topsoil drying in the summer, a sharper decrease in the humus content down the soil profile, and a distinct carbonate-accumulative horizon with a smooth upper boundary, which makes them closer to the type of steppe agrochernozems. The soils of the footslope are characterized by alternation of the percolative and exudative water regimes; these soils are classified as quasigley agrochernozems with a shortened humus horizon and with dispersed and pendant forms of pedogenic carbonates. The character of moistening, morphology, and properties of the studied soils allow us to state that their genesis is controlled by the local ecological conditions with minimal influence of erosional processes on the slope.