WorldWideScience

Sample records for belowground processes limitations

  1. Above- and belowground competition from longleaf pine plantations limits performance of reintroduced herbaceous species.

    Energy Technology Data Exchange (ETDEWEB)

    T.B. Harrington; C.M. Dagley; M.B. Edwards.

    2003-10-01

    Although overstory trees limit the abundance and species richness of herbaceous vegetation in longleaf pine (Pinus palustris Mill.) plantations, the responsible mechanisms are poorly understood because of confounding among limiting factors. In fall 1998, research was initiated to determine the separate effects of above- and belowground competition and needlefall from overstory pines on understory plant performance. Three 13- to 15-yr-old plantations near Aiken, SC, were thinned to 0, 25, 50, or 100% of nonthinned basal area (19.5 m2 ha-1). Combinations of trenching (to eliminate root competition) and needlefall were applied to areas within each plot, and containerized seedlings of 14 perennial herbaceous species and longleaf pine were planted within each. Overstory crown closure ranged from 0 to 81%, and soil water and available nitrogen varied consistently with pine stocking, trenching, or their combination. Cover of planted species decreased an average of 16.5 and 14.1% as a result of above- and below-ground competition, respectively. Depending on species, needlefall effects were positive, negative, or negligible. Results indicate that understory restoration will be most successful when herbaceous species are established within canopy openings (0.1-0.2 ha) managed to minimize negative effects from above- and belowground competition and needlefall.

  2. Below-ground herbivory limits induction of extrafloral nectar by above-ground herbivores

    OpenAIRE

    Huang, Wei; Siemann, Evan; Carrillo, Juli; Ding, Jianqing

    2015-01-01

    Background and Aims Many plants produce extrafloral nectar (EFN), and increase production following above-ground herbivory, presumably to attract natural enemies of the herbivores. Below-ground herbivores, alone or in combination with those above ground, may also alter EFN production depending on the specificity of this defence response and the interactions among herbivores mediated through plant defences. To date, however, a lack of manipulative experiments investigating EFN production induc...

  3. Belowground Carbon Cycling Processes at the Molecular Scale: An EMSL Science Theme Advisory Panel Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Hess, Nancy J.; Brown, Gordon E.; Plata, Charity

    2014-02-21

    As part of the Belowground Carbon Cycling Processes at the Molecular Scale workshop, an EMSL Science Theme Advisory Panel meeting held in February 2013, attendees discussed critical biogeochemical processes that regulate carbon cycling in soil. The meeting attendees determined that as a national scientific user facility, EMSL can provide the tools and expertise needed to elucidate the molecular foundation that underlies mechanistic descriptions of biogeochemical processes that control carbon allocation and fluxes at the terrestrial/atmospheric interface in landscape and regional climate models. Consequently, the workshop's goal was to identify the science gaps that hinder either development of mechanistic description of critical processes or their accurate representation in climate models. In part, this report offers recommendations for future EMSL activities in this research area. The workshop was co-chaired by Dr. Nancy Hess (EMSL) and Dr. Gordon Brown (Stanford University).

  4. Above- and below-ground responses of Calamagrostis purpurea to UV-B radiation and elevated CO{sub 2} under phosphorus limitation

    Energy Technology Data Exchange (ETDEWEB)

    Bussell, J.S.; Gwynn-Jones, D.; Griffith, G.W.; Scullion, J. (Aberystwyth Univ., IBERS, Wales (United Kingdom))

    2012-08-15

    UV-B radiation and elevated CO{sub 2} may impact rhizosphere processes through altered below-ground plant resource allocation and root exudation, changes that may have implications for nutrient acquisition. As nutrients limit plant growth in many habitats, their supply may dictate plant response under elevated CO{sub 2}. This study investigated UV-B exposure and elevated CO{sub 2} effects, including interactions, on plant growth, tissue chemistry and rooting responses relating to P acquisition. The sub-arctic grass Calamagrostis purpurea was subjected to UV-B (0 or 3.04 kJ m-2day-1) and CO{sub 2} (ambient 380 or 650 ppmv) treatments in a factorial glasshouse experiment, with sparingly soluble P (0 or 0.152 mg P per plant as FePO{sub 4}) a further factor. It was hypothesized that UV-B exposure and elevated CO{sub 2} would change plant resource allocation, with CO{sub 2} mitigating adverse responses to UV-B exposure and aiding P uptake. Plant biomass and morphology, tissue composition and rhizosphere leachate properties were measured. UV-B directly affected chemical composition of shoots and interacted with CO{sub 2} to give a greater root biomass. Elevated CO{sub 2} altered the composition of both shoots and roots and increased shoot biomass and secondary root length, while leachate pH decreased. Below-ground responses to CO{sub 2} did not affect P acquisition although P limitation progressively reduced leachate pH and increased secondary root length. Although direct plant growth, foliar composition and below-ground nutrient acquisition responses were dominated by CO{sub 2} treatments, UV-B modified these CO{sub 2} responses significantly. These interactions have implications for plant responses to future atmospheric conditions. (Author)

  5. Redefining fine roots improves understanding of below-ground contributions to terrestrial biosphere processes.

    Science.gov (United States)

    McCormack, M Luke; Dickie, Ian A; Eissenstat, David M; Fahey, Timothy J; Fernandez, Christopher W; Guo, Dali; Helmisaari, Heljä-Sisko; Hobbie, Erik A; Iversen, Colleen M; Jackson, Robert B; Leppälammi-Kujansuu, Jaana; Norby, Richard J; Phillips, Richard P; Pregitzer, Kurt S; Pritchard, Seth G; Rewald, Boris; Zadworny, Marcin

    2015-08-01

    Fine roots acquire essential soil resources and mediate biogeochemical cycling in terrestrial ecosystems. Estimates of carbon and nutrient allocation to build and maintain these structures remain uncertain because of the challenges of consistently measuring and interpreting fine-root systems. Traditionally, fine roots have been defined as all roots ≤ 2 mm in diameter, yet it is now recognized that this approach fails to capture the diversity of form and function observed among fine-root orders. Here, we demonstrate how order-based and functional classification frameworks improve our understanding of dynamic root processes in ecosystems dominated by perennial plants. In these frameworks, fine roots are either separated into individual root orders or functionally defined into a shorter-lived absorptive pool and a longer-lived transport fine-root pool. Using these frameworks, we estimate that fine-root production and turnover represent 22% of terrestrial net primary production globally - a c. 30% reduction from previous estimates assuming a single fine-root pool. Future work developing tools to rapidly differentiate functional fine-root classes, explicit incorporation of mycorrhizal fungi into fine-root studies, and wider adoption of a two-pool approach to model fine roots provide opportunities to better understand below-ground processes in the terrestrial biosphere. PMID:25756288

  6. Dynamic belowground ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Harris, W. F.; Santantonio, D.; McGinty, D.

    1979-01-01

    Roots comprise the primary interface between plant and soil for uptake of water and nutrients. Much is known about the biochemistry, cell physiology and membrane physics associated with these important processes. In this paper we discuss the role of the belowground ecosystem, especially the autotrophic root component, in the structure and function of forest ecosystems. Beyond recognizing roles of anchoring terrestrial plants and uptake of water and nutrients, this component of the forest has been largely neglected in an ecosystem context. In order to focus discussion on the properties of the belowground ecosystem, we use the term rhizosphere to include roots, mycorrhizae, microbes, and rhizophagus invertebrates.

  7. Belowground competition among invading detritivores.

    Science.gov (United States)

    Chang, Chih-Han; Szlavecz, Katalin; Filley, Timothy; Buyer, Jeffrey S; Bernard, Michael J; Pitz, Scott L

    2016-01-01

    The factors regulating soil animal communities are poorly understood. Current theory favors niche complementarity and facilitation over competition as the primary forms of non-trophic interspecific interaction in soil fauna; however, competition has frequently been suggested as an important community-structuring factor in earthworms, ecosystem engineers that influence belowground processes. To date, direct evidence of competition in earthworms is lacking due to the difficulty inherent in identifying a limiting resource for saprophagous animals. In the present study, we offer the first direct evidence of interspecific competition for food in this dominant soil detritivore group by combining field observations with laboratory mesocosm experiments using 13C and 15N double-enriched leaf litter to track consumption patterns. In our experiments, the Asian invasive species Amynthas hilgendorfi was a dominant competitor for leaf litter against two European species currently invading the temperate deciduous forests in North America. This competitive advantage may account for recent invasion success of A. hilgendorfi in forests with established populations of European species, and we hypothesize that specific phenological differences play an important role in determining the outcome of the belowground competition. In contrast, Eisenoides lonnbergi, a common native species in the Eastern United States, occupied a unique trophic position with limited interactions with other species, which may contribute to its persistence in habitats dominated by invasive species. Furthermore, our results supported neither the hypothesis that facilitation occurs between species of different functional groups nor the hypothesis that species in the same group exhibit functional equivalency in C and N translocation in the soil. We propose that species identity is a more powerful approach to understand earthworm invasion and its impacts on belowground processes. PMID:27008785

  8. Advancing Understanding of the Role of Belowground Processes in Terrestrial Carbon Sinks trhrough Ground-Penetrating Radar. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Day, Frank P. [Old Dominion Univ., Norfolk, VA (United States)

    2015-02-06

    Coarse roots play a significant role in belowground carbon cycling and will likely play an increasingly crucial role in belowground carbon sequestration as atmospheric CO2 levels continue to rise, yet they are one of the most difficult ecosystem parameters to quantify. Despite promising results with ground-penetrating radar (GPR) as a nondestructive method of quantifying biomass of coarse roots, this application of GPR is in its infancy and neither the complete potential nor limitations of the technology have been fully evaluated. The primary goals and questions of this study fell into four groups: (1) GPR methods: Can GPR detect change in root biomass over time, differentiate live roots from dead roots, differentiate between coarse roots, fine roots bundled together, and a fine root mat, remain effective with varied soil moisture, and detect shadowed roots (roots hidden below larger roots); (2) CO2 enrichment study at Kennedy Space Center in Brevard County, Florida: Are there post-fire legacy effects of CO2 fertilization on plant carbon pools following the end of CO2application ? (3) Disney Wilderness Study: What is the overall coarse root biomass and potential for belowground carbon storage in a restored longleaf pine flatwoods system? Can GPR effectively quantify coarse roots in soils that are wetter than the previous sites and that have a high percentage of saw palmetto rhizomes present? (4) Can GPR accurately represent root architecture in a three-dimensional model? When the user is familiar with the equipment and software in a setting that minimizes unsuitable conditions, GPR is a relatively precise, non-destructive, useful tool for estimating coarse root biomass. However, there are a number of cautions and guidelines that should be followed to minimize inaccuracies or situations that are untenable for GPR use. GPR appears to be precise as it routinely predicts highly similar values for a given area across multiple

  9. Relationships at the aboveground-belowground interface: plants, soil biota and soil processes

    NARCIS (Netherlands)

    Porazinska, D.L.; Bardgett, R.D.; Postma-Blaauw, M.B.; Hunt, H.W.; Parsons, A.N.; Seastedt, T.R.; Wall, D.M.

    2003-01-01

    Interactions at the aboveground-below ground interface provide important feedbacks that regulate ecosystem processes. Organisms within soil food webs are involved in processes of decomposition and nutrient mineralization, and their abundance and activity have been linked to plant ecophysiological tr

  10. Belowground biodiversity and ecosystem functioning

    NARCIS (Netherlands)

    Bardgett, R.D.; Putten, van der W.H.

    2014-01-01

    Evidence is mounting that the immense diversity of microorganisms and animals that live belowground contributes significantly to shaping aboveground biodiversity and the functioning of terrestrial ecosystems. Our understanding of how this belowground biodiversity is distributed, and how it regulates

  11. Issues and prospects of belowground ecology with special reference to global climate change

    Institute of Scientific and Technical Information of China (English)

    HE Jinsheng; WANG Zhengquan; FANG Jingyun

    2004-01-01

    The theory of ecology is based on over 100 a of research and investigation, all centered on aboveground patterns and processes. However, as contemporary ecologists are increasingly acknowledging, belowground structures, functions, and processes are some of the most poorly understood areas in ecology. This lack of understanding of belowground ecological processes seriously restricts the advance of global change research. The interdisciplinary field of belowground ecology began to flourish in the 1990s, along with the expansion of global change research, and quickly gained momentum. Belowground ecology aims to investigate belowground structures, functions, and processes, as well as their relationships with corresponding aboveground features, emphasizing the responses of belowground systems under global change conditions. Key research areas include root ecology,belowground animals, and soil microorganisms. This review summarizes and analyzes the relationships between aboveand belowground ecosystems, root ecology, root biogeography, belowground biodiversity, as well as research areas with particular challenges and progress. This commentary emphasizes certain theoretical issues concerning the responses of belowground processes to global change, and concludes that belowground ecology is a critical research priority in the 21st century.

  12. Belowground Competition Directs Spatial Patterns of Seedling Growth in Boreal Pine Forests in Fennoscandia

    Directory of Open Access Journals (Sweden)

    E. Petter Axelsson

    2014-09-01

    Full Text Available Aboveground competition is often argued to be the main process determining patterns of natural forest regeneration. However, the theory of multiple resource limitation suggests that seedling performance also depends on belowground competition and, thus, that their relative influence is of fundamental importance. Two approaches were used to address the relative importance of above- and below-ground competition on regeneration in a nutrient-poor pine (Pinus sylvestris boreal forest. Firstly, seedling establishment beneath trees stem-girdled 12 years ago show that a substantial proportion of the seedlings were established within two years after girdling, which corresponds to a time when nutrient uptake by tree roots was severely reduced without disrupting water transport to the tree canopy, which consequently was maintained. The establishment during these two years also corresponds to abundances high enough for normal stand replacement. Secondly, surveys of regeneration within forest gaps showed that surrounding forests depressed seedlings, so that satisfactory growth occurred only more than 5 m from forest edges and that higher solar radiation in south facing edges was not enough to mediate these effects. We conclude that disruption of belowground competitive interactions mediates regeneration and, thus, that belowground competition has a strong limiting influence on seedling establishment in these forests.

  13. Limitations of Agile Software Processes

    OpenAIRE

    Turk, Dan; France, Robert; Rumpe, Bernhard

    2014-01-01

    Software developers and project managers are struggling to assess the appropriateness of agile processes to their development environments. This paper identifies limitations that apply to many of the published agile processes in terms of the types of projects in which their application may be problematic.

  14. The link between assimilation and below-ground processes - stable isotopes as tools to assess carbon transfer

    Science.gov (United States)

    Gessler, A.; Wingate, L.; Ogeé, J.; Offermann, C.; Kodama, N.

    2011-12-01

    At present, there is lack of knowledge on how plant physiological processes, the transfer of carbon within the plant, carbon storage and remobilization in the plant tissues as well as the release of carbon from the roots to the soil interact with ecosystem-scale processes. On the background of global climate change, we need to mechanistically link plant physiology, CO2 net exchange between ecosystems and the atmosphere and plant biomass accumulation. This is the basis for predicting productivity of forests as well as their carbon sequestration potential in future. This paper will give an overview on how stable isotope studies can give insights into the fate of newly assimilated carbon transported within trees and transferred to the soil and atmosphere. The paper includes assessments characterizing temporal and spatial variation in the natural abundance of carbon and oxygen isotopes or applying isotopically enriched tracers. In addition, it highlights the fact that the stable isotope composition of assimilates transported within the plant contains important time integrated information on environmental conditions, leaf physiology, and post-photosynthetic metabolism. The paper on the one hand focuses on the fast turn over carbon pools, which fuel plant respiration and soil microbial activity and on the other hand explores the transfer of the isotope information to long-lived compounds in plant archives such as tree rings.

  15. Impacts of farming practice within organic farming systems on below-ground ecology and ecosystem function

    OpenAIRE

    Stockdale, E A; Phillips, L; Watson, C. A.

    2006-01-01

    Maintaining ecosystem function is a key issue for sustainable farming systems which contribute broadly to global ecosystem health. A focus simply on the diversity of belowground organisms is not sufficient and there is a need to consider the contribution of below-ground biological processes to the maintenance and enhancement of soil function and ecosystem services. A critical literature review on the impacts of land management practices on below-ground ecology and function shows that farm man...

  16. Belowground carbon allocation dynamics in changing environments: insights from in situ pulse labeling studies

    Science.gov (United States)

    Bahn, M.

    2012-12-01

    Belowground carbon (C) allocation is a key process in ecosystems: it plays an important role for plant C storage, fuels root metabolism and provides substrates for soil microorganisms, with strong implications for microbial community composition and activity and thus soil organic matter turnover. Belowground C allocation has been well studied in young plants and mesocosms, and as long-term patterns in ecosystems. Much less is known on the short-term dynamics of C allocation in mature plants and ecosystems, which reflect more closely the actual processes underlying observed C allocation patterns and the mechanisms determining responses to changing environmental conditions. C allocation dynamics can best be analyzed with isotopic pulse labeling experiments, which permit a tracing of recently photo-assimilated C to carbohydrate pools, microbial communities and respiratory fluxes. This overview talk will highlight the potential and limitations of in situ isotopic tracer experiments for assessing belowground C allocation dynamics in changing environments, summarize some major recent findings and point towards emerging research questions.

  17. The importance of aboveground–belowground interactions on the evolution and maintenance of variation in plant defense traits

    Science.gov (United States)

    van Geem, Moniek; Gols, Rieta; van Dam, Nicole M.; van der Putten, Wim H.; Fortuna, Taiadjana; Harvey, Jeffrey A.

    2013-01-01

    Over the past two decades a growing body of empirical research has shown that many ecological processes are mediated by a complex array of indirect interactions occurring between rhizosphere-inhabiting organisms and those found on aboveground plant parts. Aboveground–belowground studies have thus far focused on elucidating processes and underlying mechanisms that mediate the behavior and performance of invertebrates in opposite ecosystem compartments. Less is known about genetic variation in plant traits such as defense as that may be driven by above- and belowground trophic interactions. For instance, although our understanding of genetic variation in aboveground plant traits and its effects on community-level interactions is well developed, little is known about the importance of aboveground–belowground interactions in driving this variation. Plant traits may have evolved in response to selection pressures from above- and below-ground interactions from antagonists and mutualists. Here, we discuss gaps in our understanding of genetic variation in plant-related traits as they relate to aboveground and belowground multitrophic interactions. When metabolic resources are limiting, multiple attacks by antagonists in both domains may lead to trade-offs. In nature, these trade-offs may critically depend upon their effects on plant fitness. Natural enemies of herbivores may also influence selection for different traits via top–down control. At larger scales these interactions may generate evolutionary “hotspots” where the expression of various plant traits is the result of strong reciprocal selection via direct and indirect interactions. The role of abiotic factors in driving genetic variation in plant traits is also discussed. PMID:24348484

  18. Physical limits on information processing

    CERN Document Server

    Hsu, S D H

    2006-01-01

    We derive a fundamental upper bound on the rate at which a device can process information (i.e., the number of logical operations per unit time), arising from quantum mechanics and general relativity. In Planck units a device of volume V can execute no more than the cube root of V operations per unit time. We compare this to the rate of information processing performed by nature in the evolution of physical systems, and find a connection to black hole entropy and the holographic principle.

  19. Physical limits on information processing

    International Nuclear Information System (INIS)

    We derive a fundamental upper bound on the rate at which a device can process information (i.e., the number of logical operations per unit time), arising from quantum mechanics and general relativity. In Planck units a device of volume V can execute no more than the cube root of V operations per unit time. We compare this to the rate of information processing performed by nature in the evolution of physical systems, and find a connection to black hole entropy and the holographic principle

  20. Empirical and theoretical challenges in aboveground–belowground ecology

    NARCIS (Netherlands)

    Van der Putten, W.H.; Bardgett, R.D.; de Ruiter, P.C.; Hol, W.H.G.; Meyer, K.M.; Bezemer, T.M.; Bradford, M.A.; Christensen, S.; Eppinga, M.B.; Fukami, T.; Hemerik, L.; Molofsky, J.; Schädler, M.; Scherber, C.; Strauss, S.Y.; Vos, M.; Wardle, D.A.

    2009-01-01

    A growing body of evidence shows that aboveground and belowground communities and processes are intrinsically linked, and that feedbacks between these subsystems have important implications for community structure and ecosystem functioning. Almost all studies on this topic have been carried out from

  1. Empirical and theoretical challenges in aboveground-belowground ecology

    NARCIS (Netherlands)

    Putten, van der W.H.; Bardgett, R.D.; Ruiter, de P.C.; Hol, W.H.G.; Meyer, K.M.; Bezemer, T.M.; Bradford, M.A.; Christensen, S.; Eppinga, M.B.; Fukami, T.; Hemerik, L.; Molofsky, J.; Schädler, M.; Scherber, C.; Strauss, S.Y.; Vos, M.; Wardle, D.A.

    2009-01-01

    A growing body of evidence shows that aboveground and belowground communities and processes are intrinsically linked, and that feedbacks between these subsystems have important implications for community structure and ecosystem functioning. Almost all studies on this topic have been carried out from

  2. Central Limit Theorem for Nonlinear Hawkes Processes

    CERN Document Server

    Zhu, Lingjiong

    2012-01-01

    Hawkes process is a self-exciting point process with clustering effect whose jump rate depends on its entire past history. It has wide applications in neuroscience, finance and many other fields. Linear Hawkes process has an immigration-birth representation and can be computed more or less explicitly. It has been extensively studied in the past and the limit theorems are well understood. On the contrary, nonlinear Hawkes process lacks the immigration-birth representation and is much harder to analyze. In this paper, we obtain a functional central limit theorem for nonlinear Hawkes process.

  3. Limit theorems for fragmentation processes with immigration

    CERN Document Server

    Knobloch, Robert

    2012-01-01

    In this paper we extend two limit theorems which were recently obtained for fragmentation processes to such processes with immigration. More precisely, in the setting with immigration we consider a limit theorem for the process counted with a random characteristic as well as the asymptotic behaviour of an empirical measure associated with the stopping line corresponding to the first blocks, in their respective line of descent, that are smaller than a given size. In addition, we determine the asymptotic decay rate of the size of the largest block in a homogeneous fragmentation process with immigration. The techniques used to proves these results are based on submartingale arguments.

  4. Interactions between above- and belowground organisms modified in climate change experiments

    DEFF Research Database (Denmark)

    Stevnsbak, Karen; Scherber, Christoph; Gladbach, David;

    2012-01-01

    a multifactor, field-scale climate change experiment and independently manipulate atmospheric CO2 concentration, air and soil temperature and drought in all combinations since 2005. We show that changes in these factors modify the interaction between above- and belowground organisms.We use an insect herbivore......Climate change has been shown to affect ecosystem process rates and community composition, with direct and indirect effects on belowground food webs. In particular, altered rates of herbivory under future climate4 can be expected to influence above–belowground interactions. Here, we use...... to experimentally increase aboveground herbivory in grass phytometers exposed to all eight combinations of climate change factors for three years. Aboveground herbivory increased the abundance of belowground protozoans, microbial growth and microbial nitrogen availability. Increased CO2 modified these links through...

  5. Belowground Biomass Sampling to Estimate Fine Root Mass across NEON Sites

    Science.gov (United States)

    Spencer, J. J.; Meier, C. L.; Abercrombie, H.; Everhart, J. C.

    2013-12-01

    Production of belowground biomass is an important and relatively uncharacterized component of the net primary productivity (NPP) of ecosystems. Fine root productivity makes up a significant portion of total belowground production because fine roots turn over rapidly, and therefore contribute disproportionately to annual estimates of belowground net primary productivity (BNPP). One of the major goals of the National Ecological Observatory Network (NEON) is to quantify above- and below-ground NPP at 60 sites within 20 different eco-climactic regions. NEON's Terrestrial Observation System will carry out belowground biomass sampling throughout the life of the observatory to estimate fine root production. However, belowground biomass sampling during NEON operations will be constrained to a maximum depth of 50cm. This limited depth range leaves the question of what proportion of total fine root mass is being collected and how to optimally characterize belowground biomass given sampling depth limitations. During the construction period, NEON is characterizing fine root biomass distribution at depth down to 2m at each site, as well as physical and chemical properties in each soil horizon. Each sampling unit is a pit (2m deep and approximately 1.5m wide), dug in the site's dominant vegetation type where fine root biomass sampling will also occur during Operations. To sample fine root biomass in each pit, soil samples of a known volume are taken from three vertical profiles down the face of the pit. Samples are then wet sieved to extract fine root mass, and roots are dried at 65°C for 48 hours and then weighed. The soil pit data are used to estimate the proportion of total fine root biomass from each site as a function of depth. Non-linear curves are fitted to the data to calculate total fine root mass at depth and to provide estimates of the proportion of the total fine root mass that is sampled at each site during NEON's 30 year operational sampling. The belowground

  6. Limit processes of non-equilibrium TASEP

    CERN Document Server

    Corwin, I; Péché, S

    2010-01-01

    We consider the totally asymmetric simple exclusion process (TASEP) with two-sided Bernoulli initial condition, i.e., with left density rho_- and right density rho_+. We consider the associated height function, whose discrete gradient is given by the particle occurrences. Macroscopically one has a deterministic limit shape with a shock or a rarefaction fan depending on the values of rho_{+/-}. We characterize the large time scaling limit of the fluctuations as a function of the densities rho_{+/-} and of the different macroscopic regions. Moreover, using a slow decorrelation phenomena, the results are extended from fixed time to the whole space-time, except along the characteristic lines where the problem is still open. On the way to proving the results for TASEP, we obtain the limit processes for the fluctuations in a class of corner growth processes with external sources, of equivalently for the last passage time in a directed percolation model with two-sided boundary conditions. Additionally, we provide an...

  7. Stability of above-ground and below-ground processes to extreme drought in model grassland ecosystems: Interactions with plant species diversity and soil nitrogen availability.

    OpenAIRE

    Bloor, Juliette; Bardgett, R. D.

    2012-01-01

    Extreme drought events have the potential to cause dramatic changes in ecosystem structure and function, but the controls upon ecosystem stability to drought remain poorly understood. Here we used model systems of two commonly occurring, temperate grassland communities to investigate the shortterm interactive effects of a simulated 100-year summer drought event, soil nitrogen (N) availability and plant species diversity (low/high) on key ecosystem processes related to carbon (C) and N cycling...

  8. Color management: printing processes - opportunities and limitations

    Science.gov (United States)

    Ingram, Samuel T.

    2002-06-01

    Digital tools have impacted traditional methods employed to reproduce color images during the past decade. The shift from a purely photomechanical process in color reproduction to colorimetric reproduction offers tremendous opportunity in the graphic arts industry. But good things do not necessarily come to all in the same package. Printing processes possess different reproduction attributes: tone reproduction, gray balance and color correction requirements are as different as the ingredient sets selected for color reproduction. This paper will provide insight toward understanding advantages and limitations offered by the new digital technologies in printing, publishing and packaging. For the past five years the Clemson University Graphic Communications Department has conducted numerous color projects using the new digital colorimetric tools during the previous decade. Several approaches have been used including experimental research and typical production workflows. The use of colorimetric data in color reproduction has given an opportunity to realize real gains in color use, predictability and consistency. Meeting an image's separation and reproduction requirements for a specified printing process can involve disruption of the anticipated workflow. Understanding the printing process requirements and the fit within the specifications of a colorimetric workflow are critical to the successful adoption of a color managed workflow. The paper will also provide an insight into the issues and challenges experienced with a color managed workflow. The printing processes used include offset litho, narrow and wide-web flexography (paper, liner board, corrugated and film), screen printing (paper board and polycarbonates), and digital imaging with toner, ink and inkjet systems. A proposal for technology integration will be the focus of the presentation drawn from documented experiences in over 300 applications of color management tools. Discussion will include the structure of

  9. The importance of aboveground-belowground interactions on the evolution and maintenance of variation in plant defence traits

    Directory of Open Access Journals (Sweden)

    Moniek evan Geem

    2013-11-01

    Full Text Available Over the past two decades a growing body of empirical research has shown that many ecological processes are mediated by a complex array of indirect interactions occurring between rhizosphere-inhabiting organisms and those found on aboveground plant parts. Aboveground - belowground studies have thus far focused on elucidating processes and underlying mechanisms that mediate the behavior and performance of invertebrates in opposite compartments. Less is known about genetic variation in plant traits as this applies to an above- belowground framework. For instance, although the field of genetic variation in aboveground plant traits on community-level interactions is well developed, most studies have ignored genetic variation in plant traits – such as defence - that may have evolved in response to pressures from the combined effects of above- and below ground interactions from antagonists and mutualists. Here, we discuss gaps in our understanding of genetic variation in plant- and consumer-related traits as they relate to aboveground and belowground multitrophic interactions. When metabolic resources are limiting, then multiple attack by antagonists in both domains may lead to trade-offs in where these resources are optimally invested. In nature, these trade-offs may critically depend upon their effects on plant fitness. Natural enemies of herbivores may also influence selection for different traits via top-down control. At larger scales these interactions may generate evolutionary ‘hotspots’ where the expression of various plant traits is the result of strong reciprocal selection via direct and indirect interactions. The role of abiotic factors in driving genetic variation in plant traits is also discussed.

  10. Belowground plant development measured with magnetic resonance imaging (MRI: exploiting the potential for non-invasive trait quantification using sugar beet as a proxy

    Directory of Open Access Journals (Sweden)

    Ralf eMetzner

    2014-09-01

    Full Text Available Both structural and functional properties of belowground plant organs are critical for the development and yield of plants but, compared to the shoot, much more difficult to observe due to soil opacity. Many processes concerning the belowground plant performance are not fully understood, in particular spatial and temporal dynamics and their interrelation with environmental factors. We used Magnetic Resonance Imaging (MRI as a noninvasive method to evaluate which traits can be measured when a complex plant organ is monitored in-vivo while growing in the soil. We chose sugar beet (Beta vulgaris ssp. vulgaris as a model system. The beet consists mainly of root tissues, is rather complex regarding tissue structure and responses to environmental factors, and thereby a good object to test the applicability of MRI for 3D phenotyping approaches. Over a time period of up to 3 months, traits such as beet morphology or anatomy were followed in the soil and the effect of differently sized pots on beet fresh weight calculated from MRI data was studied. There was a clear positive correlation between the pot size and the increase in fresh weight of a sugar beet over time. Since knowledge of the development of internal beet structures with several concentric cambia, vascular and parenchyma rings is still limited, we consecutively acquired 3D volumetric images on individual plants using the MRI contrast parameter T2 to map the development of rings at the tissue level. This demonstrates that MRI provides versatile protocols to non-invasively measure plant traits in the soil. It opens new avenues to investigate belowground plant performance under adverse environmental conditions such as drought, nutrient shortage or soil compaction to seek for traits of belowground organs making plants more resilient to stress.

  11. Above-ground and below-ground plant responses to fertilization in two subarctic ecosystems

    NARCIS (Netherlands)

    Veen, G.F.; Sundqvist, Maja K.; Metcalfe, D.; Wilson, S.D.

    2015-01-01

    Soil nutrient supply is likely to change in the Arctic due to altered process rates associated with climate change. Here, we compare the responses of herbaceous tundra and birch forest understory to fertilization, considering both above- and below-ground responses. We added nitrogen and phosphorus t

  12. Belowground heathland responses after 2 years of combined warming, elevated CO2 and summer drought

    DEFF Research Database (Denmark)

    Andresen, Louise C.; Michelsen, Anders; Ambus, Per;

    2010-01-01

    scale experiment on temperate heathland, manipulation of precipitation and temperature was performed with retractable curtains, and atmospheric CO2 concentration was increased by FACE. The combination of elevated CO2 and warming was expected to affect belowground processes additively, through increased...

  13. Are limit cycle calculations a stochastic process?

    International Nuclear Information System (INIS)

    Stochasticity is typically associated with processes that produce uncertain results which, in many cases, are due to process nonlinearities and/or extreme sensitivity to initial conditions. By its name, a stochastic process should have a probabilistic or random nature; however, it is well known that many if not all, of the processes that behave stochasticly are indeed deterministic. This is the case with computer calculations to predict the stability of boiling water reactors (BWRs). This paper attempts to introduce the reader to some of the ''stochastic'' uncertainties involved in this topic, and in particular the errors introduced by the approximations used to integrate numerically the solutions in the time domain. The knowledge of this type of errors is relevant not only in BWR stability calculations but also in time domain calculations involving nonlinear or stochastic processes

  14. Processes regulating progressive nitrogen limitation under elevated carbon dioxide: a meta-analysis

    Science.gov (United States)

    Liang, Junyi; Qi, Xuan; Souza, Lara; Luo, Yiqi

    2016-05-01

    The nitrogen (N) cycle has the potential to regulate climate change through its influence on carbon (C) sequestration. Although extensive research has explored whether or not progressive N limitation (PNL) occurs under CO2 enrichment, a comprehensive assessment of the processes that regulate PNL is still lacking. Here, we quantitatively synthesized the responses of all major processes and pools in the terrestrial N cycle with meta-analysis of CO2 experimental data available in the literature. The results showed that CO2 enrichment significantly increased N sequestration in the plant and litter pools but not in the soil pool, partially supporting one of the basic assumptions in the PNL hypothesis that elevated CO2 results in more N sequestered in organic pools. However, CO2 enrichment significantly increased the N influx via biological N fixation and the loss via N2O emission, but decreased the N efflux via leaching. In addition, no general diminished CO2 fertilization effect on plant growth was observed over time up to the longest experiment of 13 years. Overall, our analyses suggest that the extra N supply by the increased biological N fixation and decreased leaching may potentially alleviate PNL under elevated CO2 conditions in spite of the increases in plant N sequestration and N2O emission. Moreover, our syntheses indicate that CO2 enrichment increases soil ammonium (NH4+) to nitrate (NO3-) ratio. The changed NH4+/NO3- ratio and subsequent biological processes may result in changes in soil microenvironments, above-belowground community structures and associated interactions, which could potentially affect the terrestrial biogeochemical cycles. In addition, our data synthesis suggests that more long-term studies, especially in regions other than temperate ones, are needed for comprehensive assessments of the PNL hypothesis.

  15. Limiting liability via high resolution image processing

    Energy Technology Data Exchange (ETDEWEB)

    Greenwade, L.E.; Overlin, T.K.

    1996-12-31

    The utilization of high resolution image processing allows forensic analysts and visualization scientists to assist detectives by enhancing field photographs, and by providing the tools and training to increase the quality and usability of field photos. Through the use of digitized photographs and computerized enhancement software, field evidence can be obtained and processed as `evidence ready`, even in poor lighting and shadowed conditions or darkened rooms. These images, which are most often unusable when taken with standard camera equipment, can be shot in the worst of photographic condition and be processed as usable evidence. Visualization scientists have taken the use of digital photographic image processing and moved the process of crime scene photos into the technology age. The use of high resolution technology will assist law enforcement in making better use of crime scene photography and positive identification of prints. Valuable court room and investigation time can be saved and better served by this accurate, performance based process. Inconclusive evidence does not lead to convictions. Enhancement of the photographic capability helps solve one major problem with crime scene photos, that if taken with standard equipment and without the benefit of enhancement software would be inconclusive, thus allowing guilty parties to be set free due to lack of evidence.

  16. Links between belowground and aboveground resource-related traits reveal species growth strategies that promote invasive advantages.

    Directory of Open Access Journals (Sweden)

    Maria S Smith

    Full Text Available Belowground processes are rarely considered in comparison studies of native verses invasive species. We examined relationships between belowground fine root production and lifespan, leaf phenology, and seasonal nitrogen dynamics of Lonicera japonica (non-native versus L. sempervirens (native and Frangula alnus (non-native versus Rhamnus alnifolia (native, over time. First and second order fine roots were monitored from 2010 to 2012 using minirhizotron technology and rhizotron windows. 15N uptake of fine roots was measured across spring and fall seasons. Significant differences in fine root production across seasons were seen between Lonicera species, but not between Frangula and Rhamnus, with both groups having notable asynchrony in regards to the timing of leaf production. Root order and the number of root neighbors at the time of root death were the strongest predictors of root lifespan of both species pairs. Seasonal 15N uptake was higher in spring than in the fall, which did not support the need for higher root activity to correspond with extended leaf phenology. We found higher spring 15N uptake in non-native L. japonica compared to native L. sempervirens, although there was no difference in 15N uptake between Frangula and Rhamnus species. Our findings indicate the potential for fast-growing non-native Lonicera japonica and Frangula alnus to outcompete native counterparts through differences in biomass allocation, root turnover, and nitrogen uptake, however evidence that this is a general strategy of invader dominance is limited.

  17. Effects of canopy tree species on belowground biogeochemistry in a lowland wet tropical forest

    Science.gov (United States)

    Keller, Adrienne B.; Reed, Sasha C.; Townsend, Alan R.; Cleveland, Cory C.

    2013-01-01

    Tropical rain forests are known for their high biological diversity, but the effects of plant diversity on important ecosystem processes in this biome remain unclear. Interspecies differences in both the demand for nutrients and in foliar and litter nutrient concentrations could drive variations in both the pool sizes and fluxes of important belowground resources, yet our understanding of the effects and importance of aboveground heterogeneity on belowground biogeochemistry is poor, especially in the species-rich forests of the wet tropics. To investigate the effects of individual tree species on belowground biogeochemical processes, we used both field and laboratory studies to examine how carbon (C), nitrogen (N), and phosphorus (P) cycles vary under nine different canopy tree species – including three legume and six non-legume species – that vary in foliar nutrient concentrations in a wet tropical forest in southwestern Costa Rica. We found significant differences in belowground C, N and P cycling under different canopy tree species: total C, N and P pools in standing litter varied by species, as did total soil and microbial C and N pools. Rates of soil extracellular acid phosphatase activity also varied significantly among species and functional groups, with higher rates of phosphatase activity under legumes. In addition, across all tree species, phosphatase activity was significantly positively correlated with litter N/P ratios, suggesting a tight coupling between relative N and P inputs and resource allocation to P acquisition. Overall, our results suggest the importance of aboveground plant community composition in promoting belowground biogeochemical heterogeneity at relatively small spatial scales.

  18. Empirical and theoretical challenges in aboveground-belowground ecology

    DEFF Research Database (Denmark)

    W.H. van der Putten,; R.D. Bardgett; P.C. de Ruiter;

    2009-01-01

    from an empirical perspective and in specific ecological settings or contexts. Belowground interactions operate at different spatial and temporal scales. Due to the relatively low mobility and high survival of organisms in the soil, plants have longer lasting legacy effects belowground than aboveground...... and environmental settings, we explore where and how they can be supported by theoretical approaches to develop testable predictions and to generalise empirical results. We review four key areas where a combined aboveground-belowground approach offers perspectives for enhancing ecological...

  19. Is the wash-off process of road-deposited sediment source limited or transport limited?

    Science.gov (United States)

    Zhao, Hongtao; Chen, Xuefei; Hao, Shaonan; Jiang, Yan; Zhao, Jiang; Zou, Changliang; Xie, Wenxia

    2016-09-01

    An in-depth understanding of the road-deposited sediments (RDS) wash-off process is essential to estimation of urban surface runoff pollution load and to designing methods to minimize the adverse impacts on the receiving waters. There are two debatable RDS wash-off views: source limited and transport limited. The RDS build-up and wash-off process was characterized to explore what determines the wash-off process to be source limited or transport limited based on twelve RDS sampling activities on an urban road in Beijing. The results showed that two natural rain events (2.0mm and 23.2mm) reduced the total RDS mass by 30%-40%, and that finer particles (wash-off load. Both single- and multi-rain events caused the RDS particle grain size to become coarser, while dry days made the RDS particle grain size finer. These findings indicated that the bulk RDS particles wash-off tends to be transport limited, but that finer particles tend to be source limited. To further explore and confirm the results of the field experiment, a total of 40 simulated rain events were designed to observe the RDS wash-off with different particle size fractions. The finer particles have a higher wash-off percentage (Fw) than the coarser particles, and the Fw values provide a good view to characterize the wash-off process. The key conclusions drawn from the combined field and simulated experiments data are: (i) Finer and coarser particle wash-off processes tend to be source limited and transport limited, respectively. (ii) The source and transport limited processes occur during the initial period (the first flush) and later periods, respectively. (iii) The smaller and larger rain events tend to be transport limited and source limited, respectively. Overall, the wash-off process is generally a combination of source and transport limited processes. PMID:27135567

  20. Plant Host Species and Geographic Distance Affect the Structure of Aboveground Fungal Symbiont Communities, and Environmental Filtering Affects Belowground Communities in a Coastal Dune Ecosystem.

    Science.gov (United States)

    David, Aaron S; Seabloom, Eric W; May, Georgiana

    2016-05-01

    Microbial symbionts inhabit tissues of all plants and animals. Their community composition depends largely on two ecological processes: (1) filtering by abiotic conditions and host species determining the environments that symbionts are able to colonize and (2) dispersal-limitation determining the pool of symbionts available to colonize a given host and community spatial structure. In plants, the above- and belowground tissues represent such distinct habitats for symbionts that we expect different effects of filtering and spatial structuring on their symbiont communities. In this study, we characterized above- and belowground communities of fungal endophytes-fungi living asymptomatically within plants-to understand the contributions of filtering and spatial structure to endophyte community composition. We used a culture-based approach to characterize endophytes growing in leaves and roots of three species of coastal beachgrasses in dunes of the USA Pacific Northwest. For leaves, endophyte isolation frequency and OTU richness depended primarily on plant host species. In comparison, for roots, both isolation frequency and OTU richness increased from the nutrient-poor front of the dune to the higher-nutrient backdune. Endophyte community composition in leaves exhibited a distance-decay relationship across the region. In a laboratory assay, faster growth rates and lower spore production were more often associated with leaf- than root-inhabiting endophytes. Overall, our results reveal a greater importance of biotic filtering by host species and dispersal-limitation over regional geographic distances for aboveground leaf endophyte communities and stronger effects of abiotic environmental filtering and locally patchy distributions for belowground root endophyte communities. PMID:26626912

  1. Belowground consequences of vegetation change and their treatment in models

    OpenAIRE

    Jackson, R.B.; Schenk, H J; Jobbagy, E G; Canadell, J.; Colello, G D; Dickinson, R E; Dunne, T.; Field, C.B.; Friedlingstein, P.; Heimann, M.; Hibbard, K.; Kicklighter, D W; A. Kleidon; R. P. Neilson; Parton, W.J.

    2000-01-01

    The extent and consequences of global land-cover and land-use change are increasingly apparent. One consequence not so apparent is the altered structure of plants belowground. This paper examines such belowground changes, emphasizing the interaction of altered root distributions with other factors and their treatment in models. Shifts of woody and herbaceous vegetation with deforestation, afforestation, and woody plant encroachment typically alter the depth and distribution of plant rests, in...

  2. Aboveground-belowground biodiversity linkages differ in early and late successional temperate forests

    OpenAIRE

    Hui Li; Xugao Wang; Chao Liang; Zhanqing Hao; Lisha Zhou; Sam Ma; Xiaobin Li; Shan Yang; Fei Yao; Yong Jiang

    2015-01-01

    Understanding ecological linkages between above- and below-ground biota is critical for deepening our knowledge on the maintenance and stability of ecosystem processes. Nevertheless, direct comparisons of plant-microbe diversity at the community level remain scarce due to the knowledge gap between microbial ecology and plant ecology. We compared the α- and β- diversities of plant and soil bacterial communities in two temperate forests that represented early and late successional stages. We do...

  3. Investigation of density limit processes in DIII-D

    International Nuclear Information System (INIS)

    A series of experiments has been conducted in DIII-D to investigate density-limiting processes. We have studied divertor detachment and MARFEs on closed field lines and find semi-quantitative agreement with theoretical calculations of onset conditions. We have shown that the critical density for MARFE onset at low edge temperature scales as Ip/a2, i.e. similar to Greenwald scaling. We have also shown that the scaling of the critical separatrix density with heating power at partial detachment onset agrees with Borass' model. Both of these processes yield high edge density limits for reactors such as ITER. By using divertor pumping and pellet fueling we have avoided these and other processes and accessed densities >1.5x Greenwald limit scaling with H-mode confinement, demonstrating that the Greenwald limit is not a fundamental limit on the core density. (author)

  4. Scaling Limits of Coalescent Processes Near Time Zero

    OpenAIRE

    Sengul, Bati

    2013-01-01

    In this paper we obtain scaling limits of $\\Lambda$-coalescents near time zero under a regularly varying assumption. In particular this covers the case of Kingman's coalescent and beta coalescents. The limiting processes are coalescents with infinite mass, obtained geometrically as tangent cones of Evans metric space associated with the coalescent. In the case of Kingman's coalescent we are able to obtain a simple construction of the limiting space using a two-sided Brownian motion.

  5. Estimation of limiting availability for a stationary bivariate process

    OpenAIRE

    Abraham, B.; Balakrishna, N

    2000-01-01

    We estimate the limiting availability of a system when the operating and repair times form a stationary bivariate sequence. These estimators are shown to be consistent and asymptotically normal under certain conditions. In particular, we estimate the limiting availability for a bivariate exponential autoregressive process.

  6. Above- and belowground interactions drive habitat segregation between two cryptic species of tropical trees.

    Science.gov (United States)

    Pizano, Camila; Mangan, Scott A; Herre, Edward Allen; Eom, Ahn-Heum; Dalling, James W

    2011-01-01

    In the lowlands of central Panama, the Neotropical pioneer tree Trema micrantha (sensu lato) exists as two cryptic species: "landslide" Trema is restricted to landslides and road embankments, while "gap" Trema occurs mostly in treefall gaps. In this study, we explored the relative contributions of biotic interactions and physical factors to habitat segregation in T. micrantha. Field surveys showed that soils from landslides were significantly richer in available phosphorus and harbored distinct arbuscular mycorrhizal fungal (AMF) communities compared to gap soils. Greenhouse experiments designed to determine the effect of these abiotic and biotic differences showed that: (1) both landslide and gap species performed better in sterilized soil from their own habitat, (2) the availability of phosphorus and nitrogen was limiting in gap and landslide soils, respectively, (3) a standardized AMF inoculum increased performance of both species, but primarily on gap soils, and (4) landslide and gap species performed better when sterilized soils were inoculated with the microbial inoculum from their own habitat. A field experiment confirmed that survival and growth of each species was highest in its corresponding habitat. This experiment also showed that browsing damage significantly decreased survival of gap Trema on landslides. We conclude that belowground interactions with soil microbes and aboveground interactions with herbivores contribute in fundamental ways to processes that may promote and reinforce adaptive speciation. PMID:21560675

  7. Limit process of stationary TASEP near the characteristic line

    CERN Document Server

    Baik, Jinho; Péché, Sandrine

    2009-01-01

    The totally asymmetric simple exclusion process (TASEP) on Z with the Bernoulli-rho measure as initial conditions, 0limiting distribution has also been obtained explicitly. In this paper we determine the limiting multi-point distribution of the current fluctuations moving away from the characteristics by the order t^{2/3}. The main tool is the analysis of a related directed last percolation model. We also discuss the process limit in tandem queues in equilibrium.

  8. Effects of above- and belowground herbivory on growth, pollination, and reproduction in cucumber.

    Science.gov (United States)

    Barber, Nicholas A; Adler, Lynn S; Bernardo, Holly L

    2011-02-01

    Plants experience unique challenges due to simultaneous life in two spheres, above- and belowground. Interactions with other organisms on one side of the soil surface may have impacts that extend across this boundary. Although our understanding of plant-herbivore interactions is derived largely from studies of leaf herbivory, belowground root herbivores may affect plant fitness directly or by altering interactions with other organisms, such as pollinators. In this study, we investigated the effects of leaf herbivory, root herbivory, and pollination on plant growth, subsequent leaf herbivory, flower production, pollinator attraction, and reproduction in cucumber (Cucumis sativus). We manipulated leaf and root herbivory with striped cucumber beetle (Acalymma vittatum) adults and larvae, respectively, and manipulated pollination with supplemental pollen. Both enhanced leaf and root herbivory reduced plant growth, and leaf herbivory reduced subsequent leaf damage. Plants with enhanced root herbivory produced 35% fewer female flowers, while leaf herbivory had no effect on flower production. While leaf herbivory reduced the time that honey bees spent probing flowers by 29%, probing times on root-damaged plants were over twice as long as those on control plants. Root herbivory increased pollen limitation for seed production in spite of increased honey bee preference for plants with root damage. Leaf damage and hand-pollination treatments had no effect on fruit production, but plants with enhanced root damage produced 38% fewer fruits that were 25% lighter than those on control plants. Despite the positive effect of belowground damage on honey bee visitation, root herbivory had a stronger negative effect on plant reproduction than leaf herbivory. These results demonstrate that the often-overlooked effects of belowground herbivores may have profound effects on plant performance. PMID:20859750

  9. Above and belowground controls on litter decomposition in semiarid ecosystems: effects of solar radiation, water availability and litter quality

    Science.gov (United States)

    Austin, A. T.; Araujo, P. I.; Leva, P. E.; Ballare, C. L.

    2008-12-01

    The integrated controls on soil organic matter formation in arid and semiarid ecosystems are not well understood and appear to stem from a number of interacting controls affecting above- and belowground carbon turnover. While solar radiation has recently been shown to have an important direct effect on carbon loss in semiarid ecosystems as a result of photochemical mineralization of aboveground plant material, the mechanistic basis for photodegradative losses is poorly understood. In addition, there are large potential differences in major controls on above- and belowground decomposition in low rainfall ecosystems. We report on a mesocosm and field study designed to examine the relative importance of different wavelengths of solar radiation, water availability, position of senescent material above- and belowground and the importance of carbon litter quality in determining rates of abiotic and biotic decomposition. In a factorial experiment of mesocosms, we incubated leaf and root litter simultaneously above- and belowground and manipulated water availability with large and small pulses. Significant interactions between position-litter type and position-pulse sizes demonstrated interactive controls on organic mass loss. Aboveground decomposition showed no response to pulse size or litter type, as roots and leaves decomposed equally rapidly under all circumstances. In contrast, belowground decomposition was significantly altered by litter type and water pulses, with roots decomposing significantly slower and small water pulses reducing belowground decomposition. In the field site, using plastic filters which attenuated different wavelengths of natural solar radiation, we found a highly significant effect of radiation exclusion on mass loss and demonstrated that both UV-A and short-wave visible light can have important impacts on photodegradative carbon losses. The combination of position and litter quality effects on litter decomposition appear to be critical for the

  10. FRACTURE LIMIT LOAD OF CONE SHAPE PART IN DRAWING PROCESS

    Institute of Scientific and Technical Information of China (English)

    Xu Jisheng; Gao Shiyou

    2005-01-01

    The deformation characters and load status of the blank's potential fracture zone are analyzed at the moment when blank is approaching to punch corner in drawing process of cone shape part. Based on tension instability theory, the formula for calculating fracture limit load of cone shape part in drawing process is derived. Also, the formula is analyzed and verified by experiment.

  11. Responses of belowground carbon allocation dynamics to extended shading in mountain grassland

    Science.gov (United States)

    Bahn, Michael; Lattanzi, Fernando A.; Hasibeder, Roland; Wild, Birgit; Koranda, Marianne; Danese, Valentina; Brüggemann, Nicolas; Schmitt, Michael; Siegwolf, Rolf; Richter, Andreas

    2014-05-01

    Carbon (C) allocation strongly influences plant and soil processes. Short-term C allocation dynamics in ecosystems and their responses to environmental changes are still poorly understood. Using in situ 13CO2 pulse labeling, we studied the effects of one week of shading on the transfer of recent photoassimilates between sugars and starch of above- and belowground plant organs and to soil microbial communities of a mountain meadow. C allocation to roots and microbial communities was rapid. Shading strongly reduced sucrose and starch concentrations in shoots, but not roots, and affected tracer dynamics in sucrose and starch of shoots, but not roots: recent C was slowly incorporated into root starch irrespective of the shading treatment. Shading reduced leaf respiration more strongly than root respiration. It caused no reduction in the amount of 13C incorporated into fungi and gram-negative bacteria, but increased its residence time. These findings suggest that, under interrupted C supply, belowground C allocation (as reflected by the amount of tracer allocated to root starch, soil microbial communities and belowground respiration) was maintained at the expense of aboveground C status, and that C source strength may affect the turnover of recent plant-derived C in soil microbial communities. (Reference: Bahn et al. 2013. New Phytologist 198:116-126)

  12. Brownian Motion as a Limit to Physical Measuring Processes

    DEFF Research Database (Denmark)

    Niss, Martin

    2016-01-01

    In this paper, we examine the history of the idea that noise presents a fundamental limit to physical measuring processes. This idea had its origins in research aimed at improving the accuracy of instruments for electrical measurements. Out of these endeavors, the Swedish physicist Gustaf A. Ising...... formulated a general conclusion concerning the nature of physical measurements, namely that there is a definite limit to the ultimate sensitivity of measuring instruments beyond which we cannot advance, and that this limit is determined by Brownian motion. Ising’s conclusion agreed with experiments and...... received widespread recognition, but his way of modeling the system was contested by his contemporaries. With the more embracing notion of noise that developed during and after World War II, Ising’s conclusion was reinterpreted as showing that noise puts a limit on physical measurement processes. Hence...

  13. The Process of Forming a Private Limited Liability Company

    OpenAIRE

    Horáková, Michaela

    2008-01-01

    The purpose of this dissertation is to describe the process of forming a private limited liability company (private L.L.C. or private LLC), which is the most common form of a legal business entity. The first part focuses on the general characteristics of a private LLC and summarizes the advantages and disadvantages of this form of legal entity. Next, the Commercial Register and a description of its benefits will be introduced during the "establishing process," which also explains the necessar...

  14. Scope and limitations of due process in administrative proceedings

    Directory of Open Access Journals (Sweden)

    Bernardo Carvajal Sánchez

    2010-12-01

    Full Text Available In order to explain in a better way the scope of Due Process in Administrative Law as a legal norm whose respect is essential to all government agencies, three points of view (formal, structural and material are proposed. Those items seem useful to understand “Administrative Due Process” in all its dimensions: as a constitutional norm developed by the enactment of laws and decrees; as a principle inspiring some conducts and new norms; and as an objective and subjective fundamental right. On the other hand, it is shown that Administrative Due Process is not an absolute rule because in some cases its full application is subject to normative relativism. Two opposite trends can be perceived at this point: in the first place, government agencies usually do not act the same way judges do, so Administrative Due Process should be distinguished from Judicial Due Process; therefore, it could actually have a more restricted scope. In the second place, some administrative authorities are nowadays playing a role more or less similar to what judges do. This means that new procedural guarantees will be claimed. In any case, admitting valid limitations to Administrative Due Process leads to the quest of the limits of these limitations. The application of the rule of Due Process cannot be totally suppressed; its scope cannot be completely reduced. This is the result of its fundamental nature as a legal norm that ensures justice and equity in all administrative procedures, and proscribes random decisions.

  15. Limit theorems for bifurcating integer-valued autoregressive processes

    CERN Document Server

    Blandin, Vassili

    2012-01-01

    We study the asymptotic behavior of the weighted least squares estimators of the unknown parameters of bifurcating integer-valued autoregressive processes. Under suitable assumptions on the immigration, we establish the almost sure convergence of our estimators, together with the quadratic strong law and central limit theorems. All our investigation relies on asymptotic results for vector-valued martingales.

  16. Functional State Modelling of Cultivation Processes: Dissolved Oxygen Limitation State

    Directory of Open Access Journals (Sweden)

    Olympia Roeva

    2015-04-01

    Full Text Available A new functional state, namely dissolved oxygen limitation state for both bacteria Escherichia coli and yeast Saccharomyces cerevisiae fed-batch cultivation processes is presented in this study. Functional state modelling approach is applied to cultivation processes in order to overcome the main disadvantages of using global process model, namely complex model structure and a big number of model parameters. Alongwith the newly introduced dissolved oxygen limitation state, second acetate production state and first acetate production state are recognized during the fed-batch cultivation of E. coli, while mixed oxidative state and first ethanol production state are recognized during the fed-batch cultivation of S. cerevisiae. For all mentioned above functional states both structural and parameter identification is here performed based on experimental data of E. coli and S. cerevisiae fed-batch cultivations.

  17. Belowground interactions with aboveground consequences: Invasive earthworms and arbuscular mycorrhizal fungi.

    Science.gov (United States)

    Paudel, Shishir; Longcore, Travis; MacDonald, Beau; McCormick, Melissa K; Szlavecz, Katalin; Wilson, Gail W T; Loss, Scot R

    2016-03-01

    A mounting body of research suggests that invasive nonnative earthworms substantially alter microbial communities, including arbuscular mycorrhizal fungi (AMF). These changes to AMF can cascade to affect plant communities and vertebrate populations. Despite these research advances, relatively little is known about (1) the mechanisms behind earthworms' effects on AMF and (2) the factors that determine the outcomes of earthworm-AMF interactions (i.e., whether AMF abundance is increased or decreased and subsequent effects on plants). We predict that AMF-mediated effects of nonnative earthworms on ecosystems are nearly universal because (1) AMF are important components of most terrestrial ecosystems, (2) nonnative earthworms have become established in nearly every type of terrestrial ecosystem, and (3) nonnative earthworms, due to their burrowing and feeding behavior, greatly affect AMF with potentially profound concomitant effects on plant communities. We highlight the multiple direct and indirect effects of nonnative earthworms on plants and review what is currently known about the interaction between earthworms and AMF. We also illustrate how the effects of nonnative earthworms on plant-AMF mutualisms can alter the structure and stability of aboveground plant communities, as well as the vertebrate communities relying on these habitats. Integrative studies that assess the interactive effects of earthworms and AMF can provide new insights into the role that belowground ecosystem engineers play in altering aboveground ecological processes. Understanding these processes may improve our ability to predict the structure of plant and animal communities in earthworm-invaded regions and to develop management strategies that limit the numerous undesired impacts of earthworms. PMID:27197388

  18. Species-specific defence responses facilitate conspecifics and inhibit heterospecifics in above–belowground herbivore interactions

    OpenAIRE

    Huang, Wei; Siemann, Evan; Xiao, Li; Yang, Xuefang; Ding, Jianqing

    2014-01-01

    Conspecific and heterospecific aboveground and belowground herbivores often occur together in nature and their interactions may determine community structure. Here we show how aboveground adults and belowground larvae of the tallow tree specialist beetle Bikasha collaris and multiple heterospecific aboveground species interact to determine herbivore performance. Conspecific aboveground adults facilitate belowground larvae, but other aboveground damage inhibits larvae or has no effect. Belowgr...

  19. Diffusion limits for shortest remaining processing time queues

    CERN Document Server

    Gromoll, H Christian; Puha, Amber L

    2010-01-01

    We present a heavy traffic analysis for a single server queue with renewal arrivals and generally distributed i.i.d. service times, in which the server employs the Shortest Remaining Processing Time (SRPT) policy. Under typical heavy traffic assumptions, we prove a diffusion limit theorem for a measure-valued state descriptor, from which we conclude a similar theorem for the queue length process. These results allow us to make some observations on the queue length optimality of SRPT. In particular, they provide the sharpest illustration of the well-known tension between queue length optimality and quality of service for this policy.

  20. Diffusion limits for shortest remaining processing time queues

    Directory of Open Access Journals (Sweden)

    Amber L. Puha

    2011-01-01

    Full Text Available We present a heavy traffic analysis for a single server queue with renewal arrivals and generally distributed i.i.d. service times, in which the server employs the Shortest Remaining Processing Time (SRPT policy. Under typical heavy traffic assumptions, we prove a diffusion limit theorem for a measure-valued state descriptor, from which we conclude a similar theorem for the queue length process. These results allow us to make some observations on the queue length optimality of SRPT. In particular, they provide the sharpest illustration of the well-known tension between queue length optimality and quality of service for this policy.

  1. Central limit theorem for Fourier transform of stationary processes

    CERN Document Server

    Peligrad, Magda

    2009-01-01

    We consider asymptotic behavior of Fourier transforms of stationary ergodic sequences with finite second moments. We establish the central limit theorem (CLT) for almost all frequencies and also the annealed CLT. The theorems hold for all regular sequences. Our results shed new light on the foundation of spectral analysis and on the asymptotic distribution of periodogram, and it provides a nice blend of harmonic analysis, theory of stationary processes and theory of martingales.

  2. Scaling limits for Hawkes processes and application to financial statistics

    CERN Document Server

    Bacry, Emmanuel; Hoffmann, Marc; Muzy, Jean François

    2012-01-01

    We prove a law of large numbers and a functional central limit theorem for multivariate Hawkes processes observed over a time interval $[0,T]$ in the limit $T \\rightarrow \\infty$. We further exhibit the asymptotic behaviour of the covariation of the increments of the components of a multivariate Hawkes process, when the observations are imposed by a discrete scheme with mesh $\\Delta$ over $[0,T]$ up to some further time shift $\\tau$. The behaviour of this functional depends on the relative size of $\\Delta$ and $\\tau$ with respect to $T$ and enables to give a full account of the second-order structure. As an application, we develop our results in the context of financial statistics. We introduced in a previous work a microscopic stochastic model for the variations of a multivariate financial asset, based on Hawkes processes and that is confined to live on a tick grid. We derive and characterise the exact macroscopic diffusion limit of this model and show in particular its ability to reproduce important empiric...

  3. Failure mechanism and forming limit of tube axial compressive process

    Institute of Scientific and Technical Information of China (English)

    SUN Zhi-chao; YANG He

    2006-01-01

    Based on minimum energy principle for plastic forming,tearing and buckling failures mechanisms are explored and criteria for them are developed by theoretical analysis and experiment. Combined with finite element software developed forming limit and effects of process parameters on failures are investigated and proper parameters for stable forming are determined. The results show that: 1) The failures and forming limit are mainly determined by geometry and materials parameters of tube blank,fillet radius or half conical angle of die. For the process under fillet die,there exists a maximum fillet radius within which no tearing failure happens,and a maximum radius and a minimum radius range within which no buckling failure happens. For the process under conical die,there exists a maximum and minimum half conical angle range within which no tearing and buckling failures occur. 2) For both forming processes,the higher the value of material strain hardening exponent or the lower the value of relative thickness,the more impossible for tearing and buckling failures to occur,and the larger the ranges of fillet radius and half conical angle. The experiment results verify the reliability and practicability of this research.

  4. Identifying qualitative effects of different grazing types on below-ground communities and function in a long-term field experiment

    DEFF Research Database (Denmark)

    Macdonald, Catriona A.; Crawley, Michael J.; Wright, Denis J.;

    2015-01-01

    on some soil functions involved in carbon cycling, microbial diversity, structure and functional composition. Both rabbit and invertebrate grazing impacted soil functions and microbial community structure. All functional community measures (functions, biogeochemical cycling genes, network association......Herbivory is an important modulator of plant biodiversity and productivity in grasslands, but our understanding of herbivore-induced changes on below-ground processes and communities is limited. Using a long-term (17 years) experimental site, we evaluated impacts of rabbit and invertebrate grazers...... between different taxa) were more strongly affected by invertebrate grazers than rabbits. Furthermore, our results suggest that exclusion of invertebrate grazers decreases both microbial biomass and abundance of genes associated with key biogeochemical cycles, and could thus have long-term consequences...

  5. The rate-limiting process of hydrogen transport in Mo

    Energy Technology Data Exchange (ETDEWEB)

    Ohkoshi, Keishiro; Chikazawa, Yoshitaka; Bandourko, V.; Yamaguchi, Kenji; Yamawaki, Michio [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

    1996-10-01

    Hydrogen isotope transport characteristics of Mo, whose refractory properties are considered to be suitable as plasma facing material, was investigated by applying 3 keV D{sub 2}{sup +} beam to the membrane specimen. The Arrhenius plot of deuterium permeation probability showed linear increase against the reciprocal temperature and its apparent activation energy was determined as 41.5 kJ/mol. The simultaneous irradiation of 3 keV Ar{sup +} onto backside surface of specimen had little effect on the deuterium permeation rate. According to these results, the rate-limiting process of deuterium transport in Mo was determined. (author)

  6. Some distance bounds of branching processes and their diffusion limits

    CERN Document Server

    Kammerer, Niels B

    2010-01-01

    We compute exact values respectively bounds of "distances" - in the sense of (transforms of) power divergences and relative entropy - between two discrete-time Galton-Watson branching processes with immigration GWI for which the offspring as well as the immigration is arbitrarily Poisson-distributed (leading to arbitrary type of criticality). Implications for asymptotic distinguishability behaviour in terms of contiguity and entire separation of the involved GWI are given, too. Furthermore, we determine the corresponding limit quantities for the context in which the two GWI converge to Feller-type branching diffusion processes, as the time-lags between observations tend to zero. Some applications to (static random environment like) Bayesian decision making and Neyman-Pearson testing are presented as well.

  7. New limits on double beta processes in 106-Cd

    CERN Document Server

    Tretyak, V I; Bernabei, R; Brudanin, V B; Cappella, F; Caracciolo, V; Cerulli, R; Chernyak, D M; Danevich, F A; d'Angelo, S; Di Marco, A; Incicchitti, A; Laubenstein, M; Mokina, V M; Poda, D V; Polischuk, O G; Tupitsyna, I A

    2016-01-01

    A radiopure cadmium tungstate crystal scintillator, enriched in 106-Cd to 66%, with mass of 216 g (106-CdWO4) was used in coincidence with four ultra-low background HPGe detectors contained in a single cryostat to search for double beta decay processes in 106-Cd. New improved half-life limits on the double beta processes in 106-Cd have been set on the level of 1e20-1e21 yr after 13085 h of data taking deep underground (3600 m w.e.) at the Gran Sasso National Laboratories of INFN (Italy). In particular, the limit on the two neutrino electron capture with positron emission T1/2 >1.1e21 yr, has reached the region of theoretical predictions. The resonant neutrinoless double electron captures to the 2718, 2741 and 2748 keV excited states of 106-Pd are restricted on the level of T1/2 > 8.5e20 - 1.4e21 yr.

  8. Limit Theorems for Competitive Density Dependent Population Processes

    CERN Document Server

    Parsons, Todd L

    2010-01-01

    Near the beginning of the century, Wright and Fisher devised an elegant, mathematically tractable model of gene reproduction and replacement that laid the foundation for contemporary population genetics. The Wright-Fisher model and its extensions have given biologists powerful tools of statistical inference that enabled the quantification of genetic drift and selection. Given the utility of these tools, we often forget that their model - for mathematical, and not biological reasons - makes assumptions that are violated in most real-world populations. In this paper, I consider an alternative framework that merges P. A. P. Moran's continuous-time Markov chain model of allele frequency with the density dependent models of ecological competition proposed by Gause, Lotka and Volterra, that, unlike Moran's model allow for a stochastically varying -- but bounded -- population size. I require that allele numbers vary according to a density-dependent population process, for which the limiting law of large numbers is a...

  9. A limit process for partial match queries in random quadtrees

    CERN Document Server

    Broutin, Nicolas; Sulzbach, Henning

    2012-01-01

    We consider the problem of recovering items matching a partially specified pattern in multidimensional trees (quad trees and k-d trees). We assume the classical model where the data consist of independent and uniform points in the unit square. For this model, in a structure on $n$ points, it is known that the complexity, measured as the number of nodes $C_n(\\xi)$ to visit in order to report the items matching a random query $\\xi$, independent and uniformly distributed on $[0,1]$, satisfies $E{C_n(\\xi)}\\sim \\kappa n^{\\beta}$, where $\\kappa$ and $\\beta$ are explicit constants. We develop an approach based on the analysis of the cost $C_n(s)$ of any fixed query $s\\in [0,1]$, and give precise estimates for the variance and limit distribution. Moreover, a functional limit law for a rescaled version of the process $(C_n(s))_{0\\le s\\le 1}$ is derived in the space of c\\`{a}dl\\`{a}g functions with the Skorokhod topology. For the worst case complexity $\\max_{s\\in [0,1]} C_n(s)$ the order of the expectation as well as a...

  10. Soil microbial nutrient constraints along a tropical forest elevation gradient: a belowground test of a biogeochemical paradigm

    Science.gov (United States)

    Nottingham, A. T.; Turner, B. L.; Whitaker, J.; Ostle, N. J.; McNamara, N. P.; Bardgett, R. D.; Salinas, N.; Meir, P.

    2015-10-01

    Aboveground primary productivity is widely considered to be limited by phosphorus (P) availability in lowland tropical forests and by nitrogen (N) availability in montane tropical forests. However, the extent to which this paradigm applies to belowground processes remains unresolved. We measured indices of soil microbial nutrient status in lowland, sub-montane and montane tropical forests along a natural gradient spanning 3400 m in elevation in the Peruvian Andes. With increasing elevation there were marked increases in soil concentrations of total N, total P, and readily exchangeable P, but a decrease in N mineralization determined by in situ resin bags. Microbial carbon (C) and N increased with increasing elevation, but microbial C : N : P ratios were relatively constant, suggesting homeostasis. The activity of hydrolytic enzymes, which are rich in N, decreased with increasing elevation, while the ratio of enzymes involved in the acquisition of N and P increased with increasing elevation, further indicating an increase in the relative demand for N compared to P with increasing elevation. We conclude that soil microorganisms shift investment in nutrient acquisition from P to N between lowland and montane tropical forests, suggesting that different nutrients regulate soil microbial metabolism and the soil carbon balance in these ecosystems.

  11. When CO2 kills: effects of magmatic CO2 flux on belowground biota at Mammoth Mountain, CA

    Science.gov (United States)

    McFarland, J.; Waldrop, M. P.; Mangan, M.

    2011-12-01

    The biomass, composition, and activity of the soil microbial community is tightly linked to the composition of the aboveground plant community. Microorganisms in aerobic surface soils, both free-living and plant-associated are largely structured by the availability of growth limiting carbon (C) substrates derived from plant inputs. When C availability declines following a catastrophic event such as the death of large swaths of trees, the number and composition of microorganisms in soil would be expected to decline and/or shift to unique microorganisms that have better survival strategies under starvation conditions. High concentrations of volcanic cold CO2 emanating from Mammoth Mountain near Horseshoe Lake on the southwestern edge of Long Valley Caldera, CA has resulted in a large kill zone of tree species, and associated soil microbial species. In July 2010, we assessed belowground microbial community structure in response to disturbance of the plant community along a gradient of soil CO2 concentrations grading from 80% (no plant life). We employed a microbial community fingerprinting technique (automated ribosomal intergenic spacer analysis) to determine changes in overall community composition for three broad functional groups: fungi, bacteria, and archaea. To evaluate changes in ectomycorrhizal fungal associates along the CO2 gradient, we harvested root tips from lodgepole pine seedlings collected in unaffected forest as well as at the leading edge of colonization into the kill zone. We also measured soil C fractions (dissolved organic C, microbial biomass C, and non-extractable C) at 10 and 30 cm depth, as well as NH4+. Not surprisingly, our results indicate a precipitous decline in soil C, and microbial C with increasing soil CO2; phospholipid fatty acid analysis in conjunction with community fingerprinting indicate both a loss of fungal diversity as well as a dramatic decrease in biomass as one proceeds further into the kill zone. This observation was

  12. Will anticipated future climatic conditions affect belowground C utilization? - Insights into the role of microbial functional groups in a temperate heath/grassland.

    Science.gov (United States)

    Reinsch, Sabine; Michelsen, Anders; Sárossy, Zsuzsa; Egsgaard, Helge; Kappel Schmidt, Inger; Jakobsen, Iver; Ambus, Per

    2013-04-01

    The global terrestrial soil organic matter stock is the biggest terrestrial carbon pool (1500 Pg C) of which about 4 % is turned over annually. Thus, terrestrial ecosystems have the potential to accelerate or diminish atmospheric climate change effects via belowground carbon processes. We investigated the effect of elevated CO2 (510 ppm), prolonged spring/summer droughts and increased temperature (1 ˚C) on belowground carbon allocation and on the recovery of carbon by the soil microbial community. An in-situ 13C-carbon pulse-labeling experiment was carried out in a temperate heath/grassland (Denmark) in May 2011. Recently assimilated 13C-carbon was traced into roots, soil and microbial biomass 1, 2 and 8 days after pulse-labeling. The importance of the microbial community in C utilization was investigated using 13C enrichment patterns in microbial functional groups on the basis of phospholipid fatty acids (PLFAs) in roots. Gram-negative and gram-positive bacteria were distinguished from the decomposer groups of actinomycetes (belonging to the group of gram-positive bacteria) and saprophytic fungi. Mycorrhizal fungi specific PLFAs were not detected probably due to limited sample size in combination with restricted sensitivity of the used GC-c-IRMS setup. Climate treatments did not affect 13C allocation into roots, soil and microbial biomass carbon and also the total microbial biomass size stayed unchanged as frequently observed. However, climate treatments changed the composition of the microbial community: elevated CO2 significantly reduced the abundance of gram-negative bacteria (17:0cy) but did not affect the abundance of decomposers. Drought favored the bacterial community whereas increased temperatures showed reduced abundance of gram-negative bacteria (19:0cy) and changed the actinomycetes community (10Me16:0, 10Me18:0). However, not only the microbial community composition was affected by the applied climatic conditions, but also the activity of microbial

  13. 40 CFR Table 2 to Subpart Ddddd of... - Operating Limits for Boilers and Process Heaters With Particulate Matter Emission Limits

    Science.gov (United States)

    2010-07-01

    ... emission limit for particulate matter. 2. Fabric filter control a. Install and operate a bag leak detection... Process Heaters With Particulate Matter Emission Limits 2 Table 2 to Subpart DDDDD of Part 63 Protection... Heaters With Particulate Matter Emission Limits As stated in § 63.7500, you must comply with...

  14. The Limited Impact of Exposure Duration on Holistic Word Processing

    Science.gov (United States)

    Chen, Changming; Abbasi, Najam ul Hasan; Song, Shuang; Chen, Jie; Li, Hong

    2016-01-01

    The current study explored the impact of stimuli exposure duration on holistic word processing measured by the complete composite paradigm (CPc paradigm). The participants were asked to match the cued target parts of two characters which were presented for either a long (600 ms) or a short duration (170 ms). They were also tested by two popular versions of the CPc paradigm: the “early-fixed” task where the attention cue was visible from the beginning of each trial at a fixed position, and the “delayed-random” task where the cue showed up after the study character at random locations. The holistic word effect, as indexed by the alignment × congruency interaction, was identified in both tasks and was unaffected by the stimuli duration in both tasks. Meanwhile, the “delayed-random” task did not bring about larger holistic word effect than the “early-fixed” task. These results suggest the exposure duration (from around 150 to 600 ms) has a limited impact on the holistic word effect, and have methodological implications for experiment designs in this field. PMID:27375504

  15. Belowground carbon balance and carbon accumulation rate in the successional series of monsoon evergreen broad-leaved forest

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The balance, accumulation rate and temporal dynamics of belowground carbon in the successional series of monsoon evergreen broadleaved forest are obtained in this paper, based on long-term observations to the soil organic matter, input and standing biomass of litter and coarse woody debris, and dissolved organic carbon carried in the hydrological process of subtropical climax forest ecosystem-monsoon evergreen broad-leaved forest, and its two successional forests of natural restoration-coniferous and broad-leaved mixed forest and Pinus massoniana forest, as well as data of root biomass obtained once every five years and respiration measurement of soil, litter and coarse woody debris respiration for 1 year. The major results include: the belowground carbon pools of monsoon evergreen broad-leaved forest, coniferous and broad-leaved mixed forest, and Pinus massoniana forest are 23191 ± 2538 g·m?2, 16889 ± 1936 g·m?2 and 12680 ± 1854 g·m?2, respectively, in 2002. Mean annual carbon accumulation rates of the three forest types during the 24a from 1978 to 2002 are 383 ± 97 g·m?2·a?1, 193 ± 85 g·m?2·a?1 and 213 ± 86 g·m?2·a?1, respectively. The belowground carbon pools in the three forest types keep increasing during the observation period, suggesting that belowground carbon pools are carbon sinks to the atmosphere. There are seasonal variations, namely, they are strong carbon sources from April to June, weak carbon sources from July to September; while they are strong carbon sinks from October to November, weak carbon sinks from December to March.

  16. Process mining in auditing: from current limitations to future challenges

    OpenAIRE

    Jans, Mieke J.

    2011-01-01

    In the first book on process mining, Wil van de Aalst densely defines the goal of process mining “to use event data to extract process-related information”, like automatically discovering a process model by observing events that are recorded by some information system. This definition is broad, since it addresses the mining of all processes that are supported by an information system, revealing the wide range of possible applications of process mining. With the growing of the digital universe...

  17. Designing an Iterative Learning Control Algorithm Based on Process History using limited post process geometrical information

    DEFF Research Database (Denmark)

    Endelt, Benny Ørtoft; Volk, Wolfram

    2013-01-01

    , the reaction speed may be insufficient compared to the production rate in an industrial application. We propose to design an iterative learning control (ILC) algorithm which can control and update the blank-holder force as well as the distribution of the blank-holder force based on limited geometric data from......, there is a number of obstacles which need to be addressed before an industrial implementation is possible, e.g. the proposed control algorithms are often limited by the ability to sample process data with both sufficient accuracy and robustness - this lack of robust sampling technologies is one of the main barriers...

  18. Demographic processes limiting seedling recruitment in arid grassland restoration

    Science.gov (United States)

    Seeding is commonly used in plant community restoration to overcome recruitment limitations. In arid systems, seeding is a particularly important management tool because plant community recovery following disturbance is slow and often inhibited by invasive species. While important in arid systems,...

  19. Stochastic Modeling and Deterministic Limit of Catalytic Surface Processes

    DEFF Research Database (Denmark)

    Starke, Jens; Reichert, Christian; Eiswirth, Markus;

    2007-01-01

    Three levels of modeling, microscopic, mesoscopic and macroscopic are discussed for the CO oxidation on low-index platinum single crystal surfaces. The introduced models on the microscopic and mesoscopic level are stochastic while the model on the macroscopic level is deterministic. It can...... be derived rigorously for low-pressure conditions from the microscopic model, which is characterized as a moderately interacting many-particle system, in the limit as the particle number tends to infinity. Also the mesoscopic model is given by a many-particle system. However, the particles move on a lattice......, such that in contrast to the microscopic model the spatial resolution is reduced. The derivation of deterministic limit equations is in correspondence with the successful description of experiments under low-pressure conditions by deterministic reaction-diffusion equations while for intermediate pressures phenomena...

  20. Limit Theorems for some Branching Measure-Valued Processes

    CERN Document Server

    Cloez, Bertrand

    2011-01-01

    We consider a particles system, where, the particles move independently according to a Markov process and branching event occurs at an inhomogeneous time. The offspring locations and their number may depend on the position of the mother. Our setting capture, for instance, the processes indexed by Galton-Watson tree. We first determine the asymptotic behaviour of the empirical measure. The proof is based on an expression of the empirical measure using an auxiliary process. This latter is not distributed as a one cell lineage, there is a biased phenomenon. Our model is a microscopic description of a random (discrete) population of individuals. We then obtain a large population approximation as weak solution of a growth- fragmentation equation. We illustrate our result with two examples. The first one is a size-structured population model which describes the mitosis and the second one can model a parasite infection.

  1. Leaching from cementitious waste forms in belowground vaults

    International Nuclear Information System (INIS)

    Solidification and/or stabilization with cementitious materials prior to burial is one option for disposal of liquid hazardous and radioactive wastes. A common design for disposal of cementitious waste forms is to pour the material into large belowground vaults. The leaching performance of partially degraded monolithic vaults is examined quantitatively for facilities located in humid to semiarid climates. Development of perched water on the vault roof leading to fracture flow through the structure is predicted for a wide range of climate and design conditions. Leaching controlled by diffusion in matrix blocks out to fractures is examined parametrically in relation to water flux rate and crack spacing. Depending upon the parameters examined, release rate may be controlled by water flux rate or diffusion. Under some circumstances, contaminant release rates and exit concentrations are predicted to be inversely related. In this situation, minimization of release does not result in the lowest predicted groundwater concentrations below the vault

  2. Statistical Process Control: Going to the Limit for Quality.

    Science.gov (United States)

    Training, 1987

    1987-01-01

    Defines the concept of statistical process control, a quality control method used especially in manufacturing. Generally, concept users set specific standard levels that must be met. Makes the point that although employees work directly with the method, management is responsible for its success within the plant. (CH)

  3. Coupling and Hydrodynamic Limit for the Inclusion Process

    Science.gov (United States)

    Opoku, Alex; Redig, Frank

    2015-08-01

    We show propagation of local equilibrium for the symmetric inclusion process (SIP) after diffusive rescaling of space and time, as well as the local equilibrium property of the non-equilibrium steady state in the boundary driven SIP. The main tool is self-duality and a coupling between SIP particles and independent random walkers.

  4. Harmonisation of licensing processes for decommissioning. Options and limitations

    International Nuclear Information System (INIS)

    The shutdown of eight reactors in Germany in the wake of Fukushima 2011 and the scheduled phase-out of the remaining units in several steps ending 2022 has obviously triggered a wave of applications for decommissioning and dismantling licences. It would seem natural to strive for a harmonised handling of these processes, analogous to the 'convoi' concept which was successfully employed for licensing and construction of the three most recent German NPPs in the 1980s. However, a comparative analysis shows that the motivation of all players is much different from that of earlier times and that harmonisation of licensing processes for dismantling is not as crucial for operators, authorities and technical support organisations as it was for construction.

  5. Belowground plant biomass allocation in tundra ecosystems and its relationship with temperature

    Science.gov (United States)

    Wang, Peng; Heijmans, Monique M. P. D.; Mommer, Liesje; van Ruijven, Jasper; Maximov, Trofim C.; Berendse, Frank

    2016-05-01

    Climate warming is known to increase the aboveground productivity of tundra ecosystems. Recently, belowground biomass is receiving more attention, but the effects of climate warming on belowground productivity remain unclear. Enhanced understanding of the belowground component of the tundra is important in the context of climate warming, since most carbon is sequestered belowground in these ecosystems. In this study we synthesized published tundra belowground biomass data from 36 field studies spanning a mean annual temperature (MAT) gradient from ‑20 °C to 0 °C across the tundra biome, and determined the relationships between different plant biomass pools and MAT. Our results show that the plant community biomass–temperature relationships are significantly different between above and belowground. Aboveground biomass clearly increased with MAT, whereas total belowground biomass and fine root biomass did not show a significant increase over the broad MAT gradient. Our results suggest that biomass allocation of tundra vegetation shifts towards aboveground in warmer conditions, which could impact on the carbon cycling in tundra ecosystems through altered litter input and distribution in the soil, as well as possible changes in root turnover.

  6. Two ARCH Models and Their Limitations as Diffusion Processes

    Institute of Scientific and Technical Information of China (English)

    杨海波; 叶俊

    2002-01-01

    Two typical ARCH models: the ASDARCH model and the APARCH model are analyzed. Let Yk and σ2k denote the log returns and the volatility. When the time interval h goes to zero, (Yk,σ2k), as a discrete time Markov chain system, weakly converges to a continuous time diffusion process. The continuous time approximation of the ASDARCH model is done using two different methods. With some transformation, these two results are equivalent to high frequency data. The continuous time approximation of the APARCH model is obtained by a different procedure.

  7. Limits to meritocracy? Gender in academic recruitment and promotion processes

    DEFF Research Database (Denmark)

    Nielsen, Mathias Wullum

    2015-01-01

    According to the literature, women researchers are sometimes at a disadvantage in academic recruitment due to insufficient network ties and subtle gender biases among evaluators. But how exactly do highly formal recruitment procedures allow space for mobilizing informal, potentially gendered...... beliefs among managers in the meritocracy and the de facto functioning of the recruitment procedures. Of the vacancies for associate- and full professorships, 40% have one applicant, and 19% are announced under closed procedures with clear implications for gender stratification. The interviews reveal a...... myriad of factors explaining these patterns showing how department heads sometimes exploit decoupling processes to reduce external constraints on management function and ensure organizational certainty....

  8. Marital processes, arranged marriage, and contraception to limit fertility.

    Science.gov (United States)

    Ghimire, Dirgha J; Axinn, William G

    2013-10-01

    An international transition away from familially arranged marriages toward participation in spouse choice has endured for decades and continues to spread through rural Asia today. Although we know that this transformation has important consequences for childbearing early in marriage, we know much less about longer-term consequences of this marital revolution. Drawing on theories of family and fertility change and a rural Asian panel study designed to measure changes in both marital and childbearing behaviors, this study seeks to investigate these long-term consequences. Controlling for social changes that shape both marital practices and childbearing behaviors, and explicitly considering multiple dimensions of marital processes, we find evidence consistent with an independent, long-standing association of participation in spouse choice with higher rates of contraception to terminate childbearing. These results add a new dimension to the evidence linking revolutions in marital behavior to long-term declines in fertility and suggest that new research should consider a broader range of long-term consequences of changing marital processes. PMID:23709184

  9. Evaluation of Process Capability in Gas Carburizing Process to Achieve Quality through Limit Design Concept

    Institute of Scientific and Technical Information of China (English)

    K. Palaniradja; N. Alagumurthi; V. Soundararajan

    2004-01-01

    Steel is the most important metallic material used in industry. This is because of the versatility of its engineering properties under different conditions. In one condition it can be very mild, soft and suitable for any forming operation. In another condition the same steel can be very hard and strong. This versatility is made possible by the different heat treatments that the steel can be subject to. One such treatment is Gas carburizing. This is the most widely used process for surface hardening of low carbon steels. In this method the surface composition of the steel changes by diffusion of carbon and or nitrogen and result in hard outer surface with good wear resistance properties. A striking feature of Gas Carburizing process is that in this process the original toughness and ductility remains unaffected even after heat treatment. 3% nickel chromium case hardened low carbon steels are widely used for critical automotive and machine applications such as rack and pinion, gears, camshaft, valve rocker shafts and axles which requires high fatigue resistance. Fatigue behaviour of case carburized parts depends to a great extent on the correct combination of Hardness Penetration Depth (HPD) and the magnitude of hardness at the surface and beneath the surface with low size and shape distortion. In order to reduce the manufacturing costs in terms of material consumption and elimination of the number of processing steps, the effect of Gas carburizing parameters on the fatigue behaviour should already be considered in the parameter design stage. Therefore it is of importance to optimize the gas carburizing process variables to attain quality products with respect to hardness and case depth. In the present paper, the evaluation of process capability was carried out through a Limit Design Concept called orthogonal array design of experiment. To optimize the process variables the influence of several parameters (Holding time,Carbon potential, Furnace temperature and Quench

  10. General limitations on trajectories suitable for super-Penrose process

    CERN Document Server

    Zaslavskii, O B

    2015-01-01

    Collisions of particles near a rotating black hole can lead to unbound energies E_{c.m.} in their centre of mass frame. There are indications that the Killing energy of debris at infinity can also be unbound for some scenarios of collisions near the extremal black hole horizon (so-called super-Penrose process). They include participation of a particle that (i) has generic (not fine-tuned) parameters and (ii) moves away from a black hole after collision. We show that for any finite particle's mass, such a particle cannot be obtained as a result of preceding collision. However, this can be done if one of initial infalling particles has the mass of the order $N^{-2}$ that generalizes previous observation made in literature for radial infall in the Kerr background.

  11. An orthographic effect in phoneme processing, and its limitations

    Directory of Open Access Journals (Sweden)

    Anne eCutler

    2012-02-01

    Full Text Available To examine whether lexically stored knowledge about spelling influences phoneme evaluation, we conducted three experiments with a low-level phonetic judgement task: phoneme goodness rating. In each experiment, listeners heard phonetic tokens varying along a continuum centred on /s/, occurring finally in isolated word or nonword tokens. An effect of spelling appeared in Experiment 1: Native English speakers’ goodness ratings for the best /s/ tokens were significantly higher in words spelled with S (e.g., bless than in words spelled with C (e.g., voice. No such difference appeared when nonnative speakers rated the same materials in Experiment 2, indicating that the difference could not be due to acoustic characteristics of the S- versus C-words. In Experiment 3, nonwords with lexical neighbours consistently spelled with S (e.g., pless versus with C (e.g., floice failed to elicit orthographic neighbourhood effects; no significant difference appeared in native English speakers’ ratings for the S-consistent versus the C-consistent sets. Obligatory influence of lexical knowledge on phonemic processing would have predicted such neighbourhood effects; the findings are thus better accommodated by models in which phonemic decisions draw strategically upon lexical information.

  12. 40 CFR 63.1036 - Alternative means of emission limitation: Batch processes.

    Science.gov (United States)

    2010-07-01

    ... limitation: Batch processes. 63.1036 Section 63.1036 Protection of Environment ENVIRONMENTAL PROTECTION... § 63.1036 Alternative means of emission limitation: Batch processes. (a) General requirement. As an... operator of a batch process that operates in regulated material service during the calendar year may...

  13. 40 CFR Table 1 of Subpart Aaaaaaa... - Emission Limits for Asphalt Processing (Refining) Operations

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 14 2010-07-01 2010-07-01 false Emission Limits for Asphalt Processing... Area Sources: Asphalt Processing and Asphalt Roofing Manufacturing Other Requirements and Information... of Part 63—Emission Limits for Asphalt Processing (Refining) Operations For * * * You must meet...

  14. A Fluctuation Limit Theorem of Branching Processes with Immigration and Statistical Applications

    CERN Document Server

    Ma, Chunhua

    2009-01-01

    We prove a general fluctuation limit theorem for Galton-Watson branching processes with immigration. The limit is a time-inhomogeneous OU type process driven by a spectrally positive Levy process. As applications of this result, we obtain some asymptotic estimates for the conditional least-squares estimator of the offspring mean.

  15. Above- and belowground herbivory jointly impact defense and seed dispersal traits in Taraxacum officinale

    OpenAIRE

    de la Pena, Eduardo; Bonte, Dries

    2014-01-01

    Plants are able to cope with herbivores by inducing defensive traits or growth responses that allow them to reduce or avoid the impact of herbivores. Since above- and belowground herbivores differ substantially in life-history traits, for example feeding types, and their spatial distribution, it is likely that they induce different responses in plants. Moreover, strong interactive effects on defense and plant growth are expected when above- and belowground herbivores are jointly present. The ...

  16. Below-ground herbivory in natural communities: a review emphasizing fossorial animals

    Science.gov (United States)

    Andersen, Douglas C.

    1987-01-01

    Roots, bulbs, corms, and other below-ground organs are almost universally present in communities containing vascular plants. A large and taxonomically diverse group of herbivores uses these below-ground plant parts as its sole or primary source of food. Important within this group are plant-parasitic nematodes and several fossorial taxa that affect plants through their soil-disturbing activities as well as by consuming plant tissue. The fossorial taxa are probably best exemplified by fossorial rodents, which are distributed on all continents except Australia. All other fossorial herbivores are insects. The impact of below-groud herbivory on individual plant fitness will depend upon the extent to which, and under what circumstances, the consumption of plant tissue disrupts one or more of the six functions of below-ground plant parts. Below-ground herbivory is probably more often chronic than acute. Indirect evidence suggests that plants have responded evolutionarily to herbivory by enhancing the functional capacities of below-ground organs, thus developing a degree of tolerance, and by producing compounds that serve as feeding deterrents. Many plant species respond to the removal of root tissues by increasing the growth rate of the remaining roots and initiating new roots. Soil movement and mixing by fossorial rodents infleuce the environment of other below-ground herbivores as well as that of plants and plant propagules. The relationships among the various groups of below-ground herbivores, and between below-ground herbivores and plants, are at best poorly known, yet they appear to have major roles in determining the structure and regulating the functioning of natural communities.

  17. Belowground legacies of Pinus contorta invasion and removal result in multiple mechanisms of invasional meltdown

    OpenAIRE

    Dickie, Ian A.; St John, Mark G.; Yeates, Gregor W.; Morse, Chris W.; Bonner, Karen I; Orwin, Kate; Peltzer, Duane A.

    2013-01-01

    Plant invasions can change soil biota and nutrients in ways that drive subsequent plant communities, particularly when co-invading with belowground mutualists such as ectomycorrhizal fungi. These effects can persist following removal of the invasive plant and, combined with effects of removal per se, influence subsequent plant communities and ecosystem functioning. We used field observations and a soil bioassay with multiple plant species to determine the belowground effects and post-removal ...

  18. Uncertainty in below-ground carbon biomass for major land covers in Southeast Asia

    OpenAIRE

    Yuen, Jia Qi; Ziegler, Alan D.; Edward L Webb; Ryan, Casey M.

    2013-01-01

    Owing to difficulties associated with measuring root biomass accurately in space and time, below-ground root biomass is often calculated indirectly from above-ground biomass measurements via general allometric equations. Of concern is that general equations may not provide accurate site-specific calculations for accurate carbon stock assessments. This review comparing more than 100 root-related studies conducted in SE Asia shows highly variable and uncertain below-ground woody carbon (BGC) bi...

  19. Understory Plant Community Composition Is Associated with Fine-Scale Above- and Below-Ground Resource Heterogeneity in Mature Lodgepole Pine (Pinus contorta) Forests

    OpenAIRE

    McIntosh, Anne C. S.; Ellen Macdonald, S.; Sylvie A Quideau

    2016-01-01

    Understory plant communities play critical ecological roles in forest ecosystems. Both above- and below-ground ecosystem properties and processes influence these communities but relatively little is known about such effects at fine (i.e., one to several meters within-stand) scales, particularly for forests in which the canopy is dominated by a single species. An improved understanding of these effects is critical for understanding how understory biodiversity is regulated in such forests and f...

  20. 40 CFR 65.117 - Alternative means of emission limitation: Batch processes.

    Science.gov (United States)

    2010-07-01

    ... limitation: Batch processes. 65.117 Section 65.117 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... of emission limitation: Batch processes. (a) General requirement. As an alternative to complying with the requirements of §§ 65.106 through 65.114 and § 65.116, an owner or operator of a batch...

  1. 40 CFR 63.178 - Alternative means of emission limitation: Batch processes.

    Science.gov (United States)

    2010-07-01

    ... limitation: Batch processes. 63.178 Section 63.178 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Alternative means of emission limitation: Batch processes. (a) As an alternative to complying with the requirements of §§ 63.163 through 63.171 and §§ 63.173 through 63.176, an owner or operator of a batch...

  2. Simulations and a conditional limit theorem for intermediately subcritical branching processes in random environment

    OpenAIRE

    Böinghoff, Christian; Kersting, Götz

    2012-01-01

    Intermediately subcritical branching processes in random environment are at the borderline between two subcritical regimes and exhibit a particularly rich behavior. In this paper, we prove a functional limit theorem for these processes. It is discussed together with two other recently proved limit theorems for the intermediately subcritical case and illustrated by several computer simulations.

  3. Responses of aboveground and belowground forest carbon stocks to disturbances in boreal forests of Northeastern China

    Science.gov (United States)

    Huang, Chao; He, Hong S.; Hawbaker, Todd J.; Liang, Yu; Gong, Peng; Wu, Wuzhiwei; Zhu, Zhiliang

    2016-04-01

    Boreal forests represents about 1/3 of forest area and 1/3 of forest carbon on earth. Carbon dynamics of boreal forests are sensitive to climate change, natural (e.g., fire) and anthropogenic (e.g., harvest) disturbances. Field-based studies suggest that disturbances alter species composition, stand structure, and litter decomposition, and have significant effects on boreal forest carbon dynamics. Most of these studies, however, covered a relatively short period of time (e.g., few decades), which is limited in revealing such long-term effects of disturbances. Models are therefore developed as important tools in exploring the long-term (e.g., hundreds of years) effects of disturbances on forest carbon dynamics. In this study, we applied a framework of coupling forest ecosystem and landscape model to evaluating the effect of fire, harvest and their interactions on carbon stocks in a boreal forest landscape of Northeastern China. We compared the simulation results under fire, harvest and fire-harvest interaction scenarios with the simulated value of succession scenario at 26 landtypes over 150 years at a 10-year time step. Our results suggest that aboveground and belowground carbon are significantly reduced by fire and harvest over 150years. Fire reduced aboveground carbon by 2.3±0.6 ton/ha, harvest by 6.0±1.4 ton/ha, and fire and harvest interaction by 8.0±1.9 tons/ha. Fire reduced belowground carbon by 4.6±3.4 ton/ha, harvest by 5.0±3.5 ton/ha, and fire-harvest interaction by 5.7±3.7 tons/ha. The divergent response of carbon stocks among landtypes and between disturbance scenarios was due to the spatial interactions between fire, harvest, and species composition. Our results indicated that boreal forests carbon stocks prediction needs to consider the effects of fire and harvest for improving the estimation accuracy.

  4. A RANDOM FUNCTIONAL CENTRAL LIMIT THEOREM FOR PROCESSES OF PRODUCT SUMS OF LINEAR PROCESSES GENERATED BY MARTINGALE DIFFERENCES

    Institute of Scientific and Technical Information of China (English)

    WANG YUEBAO; YANG YANG; ZHOU HAIYANG

    2003-01-01

    A random functional central limit theorem is obtained for processes of partial sums andproduct sums of linear processes generated by non-stationary martingale differences. It devel-ops and improves some corresponding results on processes of partial sums of linear processesgenerated by strictly stationary martingale differences, which can be found in [5].

  5. 40 CFR Table 3 to Subpart Ddddd of... - Operating Limits for Boilers and Process Heaters With Mercury Emission Limits and Boilers and...

    Science.gov (United States)

    2010-07-01

    ... Process Heaters With Mercury Emission Limits and Boilers and Process Heaters That Choose To Comply With... Heaters With Mercury Emission Limits and Boilers and Process Heaters That Choose To Comply With the... operating limits: If you demonstrate compliance with applicable mercury and/or total selected...

  6. Understory Plant Community Composition Is Associated with Fine-Scale Above- and Below-Ground Resource Heterogeneity in Mature Lodgepole Pine (Pinus contorta Forests.

    Directory of Open Access Journals (Sweden)

    Anne C S McIntosh

    Full Text Available Understory plant communities play critical ecological roles in forest ecosystems. Both above- and below-ground ecosystem properties and processes influence these communities but relatively little is known about such effects at fine (i.e., one to several meters within-stand scales, particularly for forests in which the canopy is dominated by a single species. An improved understanding of these effects is critical for understanding how understory biodiversity is regulated in such forests and for anticipating impacts of changing disturbance regimes. Our primary objective was to examine the patterns of fine-scale variation in understory plant communities and their relationships to above- and below-ground resource and environmental heterogeneity within mature lodgepole pine forests. We assessed composition and diversity of understory vegetation in relation to heterogeneity of both the above-ground (canopy tree density, canopy and tall shrub basal area and cover, downed wood biomass, litter cover and below-ground (soil nutrient availability, decomposition, forest floor thickness, pH, and phospholipid fatty acids (PLFAs and multiple carbon-source substrate-induced respiration (MSIR of the forest floor microbial community environment. There was notable variation in fine-scale plant community composition; cluster and indicator species analyses of the 24 most commonly occurring understory species distinguished four assemblages, one for which a pioneer forb species had the highest cover levels, and three others that were characterized by different bryophyte species having the highest cover. Constrained ordination (distance-based redundancy analysis showed that two above-ground (mean tree diameter, litter cover and eight below-ground (forest floor pH, plant available boron, microbial community composition and function as indicated by MSIR and PLFAs properties were associated with variation in understory plant community composition. These results provide

  7. Understory Plant Community Composition Is Associated with Fine-Scale Above- and Below-Ground Resource Heterogeneity in Mature Lodgepole Pine (Pinus contorta) Forests.

    Science.gov (United States)

    McIntosh, Anne C S; Macdonald, S Ellen; Quideau, Sylvie A

    2016-01-01

    Understory plant communities play critical ecological roles in forest ecosystems. Both above- and below-ground ecosystem properties and processes influence these communities but relatively little is known about such effects at fine (i.e., one to several meters within-stand) scales, particularly for forests in which the canopy is dominated by a single species. An improved understanding of these effects is critical for understanding how understory biodiversity is regulated in such forests and for anticipating impacts of changing disturbance regimes. Our primary objective was to examine the patterns of fine-scale variation in understory plant communities and their relationships to above- and below-ground resource and environmental heterogeneity within mature lodgepole pine forests. We assessed composition and diversity of understory vegetation in relation to heterogeneity of both the above-ground (canopy tree density, canopy and tall shrub basal area and cover, downed wood biomass, litter cover) and below-ground (soil nutrient availability, decomposition, forest floor thickness, pH, and phospholipid fatty acids (PLFAs) and multiple carbon-source substrate-induced respiration (MSIR) of the forest floor microbial community) environment. There was notable variation in fine-scale plant community composition; cluster and indicator species analyses of the 24 most commonly occurring understory species distinguished four assemblages, one for which a pioneer forb species had the highest cover levels, and three others that were characterized by different bryophyte species having the highest cover. Constrained ordination (distance-based redundancy analysis) showed that two above-ground (mean tree diameter, litter cover) and eight below-ground (forest floor pH, plant available boron, microbial community composition and function as indicated by MSIR and PLFAs) properties were associated with variation in understory plant community composition. These results provide novel insights

  8. Short-Term Belowground Responses to Thinning and Burning Treatments in Southwestern Ponderosa Pine Forests of the USA

    Directory of Open Access Journals (Sweden)

    Steven T. Overby

    2016-02-01

    Full Text Available Microbial-mediated decomposition and nutrient mineralization are major drivers of forest productivity. As landscape-scale fuel reduction treatments are being implemented throughout the fire-prone western United States of America, it is important to evaluate operationally how these wildfire mitigation treatments alter belowground processes. We quantified these important belowground components before and after management-applied fuel treatments of thinning alone, thinning combined with prescribed fire, and prescribed fire in ponderosa pine (Pinus ponderosa stands at the Southwest Plateau, Fire and Fire Surrogate site, Arizona. Fuel treatments did not alter pH, total carbon and nitrogen (N concentrations, or base cations of the forest floor (O horizon or mineral soil (0–5 cm during this 2-year study. In situ rates of net N mineralization and nitrification in the surface mineral soil (0–15 cm increased 6 months after thinning with prescribed fire treatments; thinning only resulted in net N immobilization. The rates returned to pre-treatment levels after one year. Based on phospholipid fatty acid composition, microbial communities in treated areas were similar to untreated areas (control in the surface organic horizon and mineral soil (0–5 cm after treatments. Soil potential enzyme activities were not significantly altered by any of the three fuel treatments. Our results suggest that a variety of one-time alternative fuel treatments can reduce fire hazard without degrading soil fertility.

  9. Performance assessment for a below-ground vault low-level radioactive waste disposal facility

    International Nuclear Information System (INIS)

    The U.S. Department of Energy is responsible for assisting in the evaluation of alternative technologies for disposal of low-level radioactive waste (LLW). Part of this effort has included the development of a prototype Safety Analysis Report (SAR) for a below-ground vault (BGV) disposal facility. The SAR has been prepared following guidance provided by the U.S. Nuclear Regulatory Commission (NRC). The objectives of the project were to (a) extend the available body of knowledge on alternative LLW disposal technologies, (b) identify and address potential licensing issues, (c) provide for NRC review and comment, and (d) develop prototype license documentation using NRC guidance. The BGV LLW disposal facility is designed to accomplish all the performance objectives and functional requirements of 10CFR61. The principal design features provided to accomplish these functions include class A vaults, class B/C vaults, disposal unit cover systems, a surface water drainage system, and a percolating water drainage system. The results of this performance assessment show that the doses for all pathways assessed are below the current regulatory limit of 25 mrem/yr. While all possible exposure scenarios and pathways cannot be evaluated, a reasonable comprehensive set of scenarios has been addressed

  10. EXISTENCE OF UNIQUE LIMITING PROBABILITY VECTORS IN STOCHASTIC PROCESSES WITH MULTIPLE TRANSITION MATRICES

    OpenAIRE

    Mjelde, James W.; Harris, Wesley D.; Conner, J. Richard; Schnitkey, Gary D.; Glover, Michael K.; Garoian, Lee

    1992-01-01

    Concepts associated with stochastic process containing multiple transition matricies are discussed. It is proved that under certain conditions, a process with m transition matrices has m unique limiting probability vectors. This result extends the notion of discrete Markov processes to problems with intrayear and interyear dynamics. An example using a large DP model illustrates the usefulness of the concepts developed to applied problems.

  11. Agora: A proposal to overcome the limitations of the current knowledge creation process

    OpenAIRE

    ScientistFive

    2015-01-01

    Agora: A proposal to overcome the limitations of the current knowledge creation process ======================================================================================= By Scientistsfive () Abstract: The knowledge creation process is broken and can be improved by a combination of currently emerging tools. The rationale for this proposal is the notion that the current scientific process is not optimal: * Artificially staged competitions (g...

  12. 40 CFR Table 2 to Subpart Vvvvvv... - Emission Limits and Compliance Requirements for Batch Process Vents

    Science.gov (United States)

    2010-07-01

    ... Requirements for Batch Process Vents 2 Table 2 to Subpart VVVVVV of Part 63 Protection of Environment... of Part 63—Emission Limits and Compliance Requirements for Batch Process Vents As required in § 63.11496, you must comply with the requirements for batch process vents as shown in the following...

  13. Estimating Heat and Mass Transfer Processes in Green Roof Systems: Current Modeling Capabilities and Limitations (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Tabares Velasco, P. C.

    2011-04-01

    This presentation discusses estimating heat and mass transfer processes in green roof systems: current modeling capabilities and limitations. Green roofs are 'specialized roofing systems that support vegetation growth on rooftops.'

  14. New limits on the $\\beta^{+}$EC and ECEC processes in $^{120}$Te

    CERN Document Server

    Barabash, A S; Hubert, P; Umatov, V; Hubert, Ph

    2007-01-01

    New limits on the double beta processes for $^{120}$Te have been obtained using a 400 cm$^3$ HPGe detector and a source consisting of natural Te0$_2$ powder. At a confidence level of 90% the limits are $0.19\\times 10^{18}$ y for the $\\beta^+$EC$(0\

  15. Joint Limit Distributions of Exceedances Point Processes and Partial Sums of Gaussian Vector Sequence

    Institute of Scientific and Technical Information of China (English)

    Zuo Xiang PENG; Jin Jun TONG; Zhi Chao WENG

    2012-01-01

    In this paper,we study the joint limit distributions of point processes of exceedances and partial sums of multivariate Gaussian sequences and show that the point processes and partial sums are asymptotically independent under some mild conditions.As a result,for a sequence of standardized stationary Gaussian vectors,we obtain that the point process of exceedances formed by the sequence (centered at the sample mean) converges in distribution to a Poisson process and it is asymptotically independent of the partial sums.The asymptotic joint limit distributions of order statistics and partial sums are also investigated under different conditions.

  16. Scaling Limits of a Tagged Particle in the Exclusion Process with Variable Diffusion Coefficient

    Science.gov (United States)

    Gonçalves, Patrícia; Jara, Milton

    2008-09-01

    We prove a law of large numbers and a central limit theorem for a tagged particle in a symmetric simple exclusion process in ℤ with variable diffusion coefficient. The scaling limits are obtained from a similar result for the current through -1/2 for a zero-range process with bond disorder. For the CLT, we prove convergence to a fractional Brownian motion of Hurst exponent 1/4.

  17. Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests

    Energy Technology Data Exchange (ETDEWEB)

    Cusack, D.; Silver, W.L.; Torn, M.S.; McDowell, W.H.

    2011-04-15

    Anthropogenic nitrogen (N) deposition is increasing rapidly in tropical regions, adding N to ecosystems that often have high background N availability. Tropical forests play an important role in the global carbon (C) cycle, yet the effects of N deposition on C cycling in these ecosystems are poorly understood. We used a field N-fertilization experiment in lower and upper elevation tropical rain forests in Puerto Rico to explore the responses of above- and belowground C pools to N addition. As expected, tree stem growth and litterfall productivity did not respond to N fertilization in either of these Nrich forests, indicating a lack of N limitation to net primary productivity (NPP). In contrast, soil C concentrations increased significantly with N fertilization in both forests, leading to larger C stocks in fertilized plots. However, different soil C pools responded to N fertilization differently. Labile (low density) soil C fractions and live fine roots declined with fertilization, while mineral-associated soil C increased in both forests. Decreased soil CO2 fluxes in fertilized plots were correlated with smaller labile soil C pools in the lower elevation forest (R2 = 0.65, p\\0.05), and with lower live fine root biomass in the upper elevation forest (R2 = 0.90, p\\0.05). Our results indicate that soil C storage is sensitive to N deposition in tropical forests, even where plant productivity is not N-limited. The mineral-associated soil C pool has the potential to respond relatively quickly to N additions, and can drive increases in bulk soil C stocks in tropical forests.

  18. Above- and below-ground net primary productivity across ten Amazonian forests on contrasting soils

    Science.gov (United States)

    Aragão, L. E. O. C.; Malhi, Y.; Metcalfe, D. B.; Silva-Espejo, J. E.; Jiménez, E.; Navarrete, D.; Almeida, S.; Costa, A. C. L.; Salinas, N.; Phillips, O. L.; Anderson, L. O.; Alvarez, E.; Baker, T. R.; Goncalvez, P. H.; Huamán-Ovalle, J.; Mamani-Solórzano, M.; Meir, P.; Monteagudo, A.; Patiño, S.; Peñuela, M. C.; Prieto, A.; Quesada, C. A.; Rozas-Dávila, A.; Rudas, A.; Silva, J. A., Jr.; Vásquez, R.

    2009-12-01

    The net primary productivity (NPP) of tropical forests is one of the most important and least quantified components of the global carbon cycle. Most relevant studies have focused particularly on the quantification of the above-ground coarse wood productivity, and little is known about the carbon fluxes involved in other elements of the NPP, the partitioning of total NPP between its above- and below-ground components and the main environmental drivers of these patterns. In this study we quantify the above- and below-ground NPP of ten Amazonian forests to address two questions: (1) How do Amazonian forests allocate productivity among its above- and below-ground components? (2) How do soil and leaf nutrient status and soil texture affect the productivity of Amazonian forests? Using a standardized methodology to measure the major elements of productivity, we show that NPP varies between 9.3±1.3 Mg C ha-1 yr-1 (mean±standard error), at a white sand plot, and 17.0±1.4 Mg C ha-1 yr-1 at a very fertile Terra Preta site, with an overall average of 12.8±0.9 Mg C ha-1 yr-1. The studied forests allocate on average 64±3% and 36±3% of the total NPP to the above- and below-ground components, respectively. The ratio of above-ground and below-ground NPP is almost invariant with total NPP. Litterfall and fine root production both increase with total NPP, while stem production shows no overall trend. Total NPP tends to increase with soil phosphorus and leaf nitrogen status. However, allocation of NPP to below-ground shows no relationship to soil fertility, but appears to decrease with the increase of soil clay content.

  19. Aboveground insect herbivory increases plant competitive asymmetry, while belowground herbivory mitigates the effect.

    Science.gov (United States)

    Borgström, Pernilla; Strengbom, Joachim; Viketoft, Maria; Bommarco, Riccardo

    2016-01-01

    Insect herbivores can shift the composition of a plant community, but the mechanism underlying such shifts remains largely unexplored. A possibility is that insects alter the competitive symmetry between plant species. The effect of herbivory on competition likely depends on whether the plants are subjected to aboveground or belowground herbivory or both, and also depends on soil nitrogen levels. It is unclear how these biotic and abiotic factors interactively affect competition. In a greenhouse experiment, we measured competition between two coexisting grass species that respond differently to nitrogen deposition: Dactylis glomerata L., which is competitively favoured by nitrogen addition, and Festuca rubra L., which is competitively favoured on nitrogen-poor soils. We predicted: (1) that aboveground herbivory would reduce competitive asymmetry at high soil nitrogen by reducing the competitive advantage of D. glomerata; and (2), that belowground herbivory would relax competition at low soil nitrogen, by reducing the competitive advantage of F. rubra. Aboveground herbivory caused a 46% decrease in the competitive ability of F. rubra, and a 23% increase in that of D. glomerata, thus increasing competitive asymmetry, independently of soil nitrogen level. Belowground herbivory did not affect competitive symmetry, but the combined influence of above- and belowground herbivory was weaker than predicted from their individual effects. Belowground herbivory thus mitigated the increased competitive asymmetry caused by aboveground herbivory. D. glomerata remained competitively dominant after the cessation of aboveground herbivory, showing that the influence of herbivory continued beyond the feeding period. We showed that insect herbivory can strongly influence plant competitive interactions. In our experimental plant community, aboveground insect herbivory increased the risk of competitive exclusion of F. rubra. Belowground herbivory appeared to mitigate the influence of

  20. Critical Age-Dependent Branching Markov Processes and their Scaling Limits

    Indian Academy of Sciences (India)

    Krishna B Athreya; Siva R Athreya; Srikanth K Iyer

    2010-06-01

    This paper studies: (i) the long-time behaviour of the empirical distribution of age and normalized position of an age-dependent critical branching Markov process conditioned on non-extinction; and (ii) the super-process limit of a sequence of age-dependent critical branching Brownian motions.

  1. Central limit theorems for smoothed extreme value estimates of Poisson point processes boundaries

    OpenAIRE

    Girard, Stéphane; Menneteau, Ludovic

    2011-01-01

    In this paper, we give sufficient conditions to establish central limit theorems for boundary estimates of Poisson point processes. The considered estimates are obtained by smoothing some bias corrected extreme values of the point process. We show how the smoothing leads Gaussian asymptotic distributions and therefore pointwise confidence intervals. Some new unidimensional and multidimensional examples are provided.

  2. Central limit theorems for smoothed extreme value estimates of point processes boundaries

    OpenAIRE

    Girard, Stéphane; Menneteau, Ludovic

    2005-01-01

    In this paper, we give sufficient conditions to establish central limit theorems for boundary estimates of Poisson point processes. The considered estimates are obtained by smoothing some bias corrected extreme values of the point process. We show how the smoothing leads Gaussian asymptotic distributions and therefore pointwise confidence intervals. Some new unidimensional and multidimensional examples are provided.

  3. 43 CFR 46.160 - Limitations on actions during the NEPA analysis process.

    Science.gov (United States)

    2010-10-01

    ... analysis process. 46.160 Section 46.160 Public Lands: Interior Office of the Secretary of the Interior... Quality § 46.160 Limitations on actions during the NEPA analysis process. During the preparation of a... accordance with 40 CFR 1506.1 when that action is within the scope of, and analyzed in, an existing...

  4. LIMIT THEOREMS FOR WEIGHTED NONLINEAR TRANSFORMATIONS OF GAUSSIAN STATIONARY PROCESSES WITH SINGULAR SPECTRA

    OpenAIRE

    Ivanov, Alexander V.; Leonenko, Nikolai; Ruiz-Medina, María D.; Savich, Irina N.

    2013-01-01

    The limit Gaussian distribution of multivariate weighted functionals of nonlinear transformations of Gaussian stationary processes, having multiple singular spectra, is derived, under very general conditions on the weight function. This paper is motivated by its potential applications in nonlinear regression, and asymptotic inference on nonlinear functionals of Gaussian stationary processes with singular spectra.

  5. Central limit theorems for multivariate semi-Markov sequences and processes, with applications

    OpenAIRE

    Ball, Frank

    1999-01-01

    In this paper, central limit theorems for multivariate semi-Markov sequences and processes are obtained, both as the number of jumps of the associated Markov chain tends to infinity and, if appropriate, as the time for which the process has been running tends to infinity. The theorems are widely applicable since many functions defined on Markov or semi-Markov processes can be analysed by exploiting appropriate embedded multivariate semi-Markov sequences. An application to a ...

  6. Facilitation and inhibition: changes in plant nitrogen and secondary metabolites mediate interactions between above-ground and below-ground herbivores

    OpenAIRE

    Huang, Wei; Siemann, Evan; Yang, Xuefang; Wheeler, Gregory S.; Ding, Jianqing

    2013-01-01

    To date, it remains unclear how herbivore-induced changes in plant primary and secondary metabolites impact above-ground and below-ground herbivore interactions. Here, we report effects of above-ground (adult) and below-ground (larval) feeding by Bikasha collaris on nitrogen and secondary chemicals in shoots and roots of Triadica sebifera to explain reciprocal above-ground and below-ground insect interactions. Plants increased root tannins with below-ground herbivory, but above-ground herbivo...

  7. Plastic limit analysis with non linear kinematic strain hardening for metalworking processes applications

    International Nuclear Information System (INIS)

    Limit analysis approaches are widely used to deal with metalworking processes analysis; however, they are applied only for perfectly plastic materials and recently for isotropic hardening ones excluding any kind of kinematic hardening. In the present work, using Implicit Standard Materials concept, sequential limit analysis approach and the finite element method, our objective consists in extending the limit analysis application for including linear and non linear kinematic strain hardenings. Because this plastic flow rule is non associative, the Implicit Standard Materials concept is adopted as a framework of non standard plasticity modeling. The sequential limit analysis procedure which considers the plastic behavior with non linear kinematic strain hardening as a succession of perfectly plastic behavior with yielding surfaces updated after each sequence of limit analysis and geometry updating is applied. Standard kinematic finite element method together with a regularization approach is used for performing two large compression cases (cold forging) in plane strain and axisymmetric conditions

  8. Limit theorems for infinite-dimensional piecewise deterministic processes and applications to stochastic neuron models

    CERN Document Server

    Riedler, Martin G; Wainrib, Gilles

    2011-01-01

    In the present paper we present limit theorems for a sequence of Piecewise Deterministic Markov Processes taking values in Hilbert spaces. This class of processes provides a rigorous framework for stochastic spatial models in which discrete random events are globally coupled with continuous space-dependent variables solving partial differential equations, e.g., stochastic hybrid models of excitable membranes. We derive a law of large numbers which establishes a connection to deterministic macroscopic models and a martingale central limit theorem which connects the stochastic fluctuations to diffusion processes. As a prerequisite we carry out a thorough discussion of Hilbert space valued martingales associated to the PDMPs. Furthermore, these limit theorems provide the basis for a general Langevin approximation to PDMPs, i.e., certain stochastic partial differential equations that are expected to be similar in their dynamics to PDMPs. We apply these results to compartmental-type models of spatially extended ne...

  9. Stimulation of the Salicylic Acid Pathway Aboveground Recruits Entomopathogenic Nematodes Belowground

    Science.gov (United States)

    Filgueiras, Camila Cramer; Willett, Denis S.; Junior, Alcides Moino; Pareja, Martin; Borai, Fahiem El; Dickson, Donald W.; Stelinski, Lukasz L.; Duncan, Larry W.

    2016-01-01

    Plant defense pathways play a critical role in mediating tritrophic interactions between plants, herbivores, and natural enemies. While the impact of plant defense pathway stimulation on natural enemies has been extensively explored aboveground, belowground ramifications of plant defense pathway stimulation are equally important in regulating subterranean pests and still require more attention. Here we investigate the effect of aboveground stimulation of the salicylic acid pathway through foliar application of the elicitor methyl salicylate on belowground recruitment of the entomopathogenic nematode, Steinernema diaprepesi. Also, we implicate a specific root-derived volatile that attracts S. diaprepesi belowground following aboveground plant stimulation by an elicitor. In four-choice olfactometer assays, citrus plants treated with foliar applications of methyl salicylate recruited S. diaprepesi in the absence of weevil feeding as compared with negative controls. Additionally, analysis of root volatile profiles of citrus plants receiving foliar application of methyl salicylate revealed production of d-limonene, which was absent in negative controls. The entomopathogenic nematode S. diaprepesi was recruited to d-limonene in two-choice olfactometer trials. These results reinforce the critical role of plant defense pathways in mediating tritrophic interactions, suggest a broad role for plant defense pathway signaling belowground, and hint at sophisticated plant responses to pest complexes. PMID:27136916

  10. Interactive effects of above- and belowground herbivory and plant competition on plant growth and defence

    NARCIS (Netherlands)

    Jing, Jingying; Raaijmakers, Ciska; Kostenko, Olga; Kos, Martine; Mulder, P.P.J.; Bezemer, T. Martijn

    2015-01-01

    Competition and herbivory are two major factors that can influence plant growth and plant defence. Although these two factors are often studied separately, they do not operate independently. We examined how aboveground herbivory by beet armyworm larvae (Spodoptera exigua) and belowground herbivory b

  11. Investigation of physical processes limiting plasma density in H-mode on DIII-D

    International Nuclear Information System (INIS)

    A series of experiments was conducted on the DIII-D tokamak to investigate the physical processes which limit density in high confinement mode (H-mode) discharges. The typical H-mode to low confinement mode (L-mode) transition limit at high density near the empirical Greenwald density limit was avoided by divertor pumping, which reduced divertor neutral pressure and prevented formation of a high density, intense radiation zone (MARFE) near the X-point. It was determined that the density decay time after pellet injection was independent of density relative to the Greenwald limit and increased non-linearly with the plasma current. Magnetohydrodynamic (MHD) activity in pellet-fueled plasmas was observed at all power levels, and often caused unacceptable confinement degradation, except when the neutral beam injected (NBI) power was ≤ 3 MW. Formation of MARFEs on closed field lines was avoided with low safety factor (q) operation but was observed at high q, qualitatively consistent with theory. By using pellet fueling and optimizing discharge parameters to avoid each of these limits, an operational space was accessed in which density ∼ 1.5 x Greenwald limit was achieved for 600 ms, and good H-mode confinement was maintained for 300 ms of the density flattop. More significantly, the density was successfully increased to the limit where a central radiative collapse was observed, the most fundamental density limit in tokamaks

  12. Long-term variation in above and belowground plant inputs alters soil organic matter biogeochemistry at the molecular-level

    Science.gov (United States)

    Simpson, M. J.; Pisani, O.; Lin, L.; Lun, O.; Simpson, A.; Lajtha, K.; Nadelhoffer, K. J.

    2015-12-01

    The long-term fate of soil carbon reserves with global environmental change remains uncertain. Shifts in moisture, altered nutrient cycles, species composition, or rising temperatures may alter the proportions of above and belowground biomass entering soil. However, it is unclear how long-term changes in plant inputs may alter the composition of soil organic matter (SOM) and soil carbon storage. Advanced molecular techniques were used to assess SOM composition in mineral soil horizons (0-10 cm) after 20 years of Detrital Input and Removal Treatment (DIRT) at the Harvard Forest. SOM biomarkers (solvent extraction, base hydrolysis and cupric (II) oxide oxidation) and both solid-state and solution-state nuclear magnetic resonance (NMR) spectroscopy were used to identify changes in SOM composition and stage of degradation. Microbial activity and community composition were assessed using phospholipid fatty acid (PLFA) analysis. Doubling aboveground litter inputs decreased soil carbon content, increased the degradation of labile SOM and enhanced the sequestration of aliphatic compounds in soil. The exclusion of belowground inputs (No roots and No inputs) resulted in a decrease in root-derived components and enhanced the degradation of leaf-derived aliphatic structures (cutin). Cutin-derived SOM has been hypothesized to be recalcitrant but our results show that even this complex biopolymer is susceptible to degradation when inputs entering soil are altered. The PLFA data indicate that changes in soil microbial community structure favored the accelerated processing of specific SOM components with littler manipulation. These results collectively reveal that the quantity and quality of plant litter inputs alters the molecular-level composition of SOM and in some cases, enhances the degradation of recalcitrant SOM. Our study also suggests that increased litterfall is unlikely to enhance soil carbon storage over the long-term in temperate forests.

  13. On the scaling limits of Galton Watson processes in varying environment

    OpenAIRE

    Bansaye, Vincent; Simatos, Florian

    2011-01-01

    We establish a general sufficient condition for a sequence of Galton Watson branching processes in varying environment to converge weakly. This condition extends previous results by allowing offspring distributions to have infinite variance, which leads to a new and subtle phenomena when the process goes through a bottleneck and also in terms of time scales. Our assumptions are stated in terms of pointwise convergence of a triplet of two real-valued functions and a measure. The limiting proce...

  14. Territorial resources, limits and strategies of local development processes and agri-food productions of quality

    OpenAIRE

    Severino Romano; Francesco Marangon; Roberto Polidori

    2011-01-01

    The aim of this work is to analyse the role that typical products can play in the local development process. Territorial resources involved, limits and strategies for their enhancement are analysed; this analysis will permit both to define the results that have been achieved since nowadays in the local development process and to point out future themes for the research in the field of agricultural economics. The typicality of an agri-food product regards qualitative characteristics that deriv...

  15. A weak limit theorem for numerical approximation of Brownian semi-stationary processes

    DEFF Research Database (Denmark)

    Podolskij, Mark; Thamrongrat, Nopporn

    In this paper we present a weak limit theorem for a numerical approximation of Brownian semi-stationary processes studied in [14]. In the original work of [14] the authors propose to use Fourier transformation to embed a given one dimensional (Levy) Brownian semi-stationary process into a two-par....../drift process needs to be numerically simulated. In particular, weak approximation errors for smooth test functions can be obtained from our asymptotic theory.......In this paper we present a weak limit theorem for a numerical approximation of Brownian semi-stationary processes studied in [14]. In the original work of [14] the authors propose to use Fourier transformation to embed a given one dimensional (Levy) Brownian semi-stationary process into a two......-parameter stochastic field. For the latter they use a simple iteration procedure and study the strong approximation error of the resulting numerical scheme given that the volatility process is fully observed. In this work we present the corresponding weak limit theorem for the setting, where the volatility...

  16. Improved limits on {beta}{sup +}EC and ECEC processes in {sup 112}Sn

    Energy Technology Data Exchange (ETDEWEB)

    Barabash, A.S. [Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow (Russian Federation); Hubert, Ph.; Nachab, A. [Centre d' Etudes Nucleaires, IN2P3-CNRS et Universite de Bordeaux, 33170 Gradignan (France); Konovalov, S.I.; Umatov, V. [Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow (Russian Federation)

    2012-08-15

    Limits on {beta}{sup +}EC and ECEC processes in {sup 112}Sn have been obtained using a 380 cm{sup 3} HPGe detector and an external source consisting of 100 g enriched tin (94.32% of {sup 112}Sn). A limit with 90% C.L. on the {sup 112}Sn half-life of 1.3 Multiplication-Sign 10{sup 21} y for the ECEC(0{nu}) transition to the 0{sub 3}{sup +} excited state in {sup 112}Cd (1871 keV) has been established. This transition has been discussed in the context of a possible enhancement of the decay rate. The limits on other {beta}{sup +}EC and ECEC processes in {sup 112}Sn have also been obtained on the level of (0.1-1.6) Multiplication-Sign 10{sup 21} y at the 90% C.L.

  17. Wavefront curvature limitations and compensation to polar format processing for synthetic aperture radar images.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2006-01-01

    Limitations on focused scene size for the Polar Format Algorithm (PFA) for Synthetic Aperture Radar (SAR) image formation are derived. A post processing filtering technique for compensating the spatially variant blurring in the image is examined. Modifications to this technique to enhance its robustness are proposed.

  18. On the Limit Distributions of Continuous-State Branching Processes with Immigration

    CERN Document Server

    Keller-Ressel, Martin

    2011-01-01

    We consider the class of continuous-state branching processes with immigration (CBI-processes), introduced by Kawazu and Watanabe [1971], and give a deterministic characterisation for the convergence of a CBI-process to a limit distribution L, which also turns out to be the stationary distribution of the CBI-process, as time tends to infinity. We give an explicit description of the Levy-Khintchine triplet of L in terms of the characteristic triplets of the Levy subordinator and the spectrally positive Levy process, which arise in the definition of the CBI-process and determine it uniquely. We show that the Levy density of L is given by the generator of the Levy subordinator applied to the scale function of the spectrally positive Levy process. This formula allows us to describe the support of L and characterise the absolute continuity and the asymptotic behavior of the density of L at the boundary of the support. Finally we show that the class of limit distributions of CBI-processes is strictly larger (resp. ...

  19. Assessment of capability index of processes revealing significant asymmetry with respect to tolerance limits

    Directory of Open Access Journals (Sweden)

    L. Bukowski

    2010-07-01

    Full Text Available The paper presents an analysis of basic capability indices for production processes, Cp and Cpk, as well as the Cpm index for processes asymmetric with respect to tolerance limits. A method is presented for the estimation of process admissible asymmetry, when anappropriate PPM level of defective products is to be maintained. It is proved that an unbiased capability assessment for asymmetricprocesses is only feasible if the pair of indices Cp and Cpk is included in the assessment. An example is given of an analysis of data on the production of automotive bearings. The computations were performed with use of the KWSPP program.

  20. Modeling intermediate product selection under production and storage capacity limitations in food processing

    DEFF Research Database (Denmark)

    Kilic, Onur Alper; Akkerman, Renzo; Grunow, Martin;

    2009-01-01

    In the food industry products are usually characterized by their recipes, which are specified by various quality attributes. For end products, this is given by customer requirements, but for intermediate products, the recipes can be chosen in such a way that raw material procurement costs and pro...... production and inventory planning, thereby considering the production and storage capacity limitations. The resulting model can be used to solve an important practical problem typical for many food processing industries....... processing costs are minimized. However, this product selection process is bound by production and storage capacity limitations, such as the number and size of storage tanks or silos. In this paper, we present a mathematical programming approach that combines decision making on product selection with...

  1. Above- and below-ground net primary productivity across ten Amazonian forests on contrasting soils

    Directory of Open Access Journals (Sweden)

    L. E. O. C. Aragão

    2009-12-01

    Full Text Available The net primary productivity (NPP of tropical forests is one of the most important and least quantified components of the global carbon cycle. Most relevant studies have focused particularly on the quantification of the above-ground coarse wood productivity, and little is known about the carbon fluxes involved in other elements of the NPP, the partitioning of total NPP between its above- and below-ground components and the main environmental drivers of these patterns. In this study we quantify the above- and below-ground NPP of ten Amazonian forests to address two questions: (1 How do Amazonian forests allocate productivity among its above- and below-ground components? (2 How do soil and leaf nutrient status and soil texture affect the productivity of Amazonian forests? Using a standardized methodology to measure the major elements of productivity, we show that NPP varies between 9.3±1.3 Mg C ha−1 yr−1 (mean±standard error, at a white sand plot, and 17.0±1.4 Mg C ha−1 yr−1 at a very fertile Terra Preta site, with an overall average of 12.8±0.9 Mg C ha−1 yr−1. The studied forests allocate on average 64±3% and 36±3% of the total NPP to the above- and below-ground components, respectively. The ratio of above-ground and below-ground NPP is almost invariant with total NPP. Litterfall and fine root production both increase with total NPP, while stem production shows no overall trend. Total NPP tends to increase with soil phosphorus and leaf nitrogen status. However, allocation of NPP to below-ground shows no relationship to soil fertility, but appears to decrease with the increase of soil clay content.

  2. Above- and below-ground net primary productivity across ten Amazonian forests on contrasting soils

    Directory of Open Access Journals (Sweden)

    L. E. O. C. Aragão

    2009-02-01

    Full Text Available The net primary productivity (NPP of tropical forests is one of the most important and least quantified components of the global carbon cycle. Most relevant studies have focused particularly on the quantification of the above-ground coarse wood productivity, and little is known about the carbon fluxes involved in other elements of the NPP, the partitioning of total NPP between its above- and below-ground components and the main environmental drivers of these patterns. In this study we quantify the above- and below-ground NPP of ten Amazonian forests to address two questions: (1 How do Amazonian forests allocate productivity among its above- and below-ground components? (2 How do soil and leaf nutrient status and soil texture affect the productivity of Amazonian forests? Using a standardized methodology to measure the major elements of productivity, we show that NPP varies between 9.3±1.3 Mg C ha−1 yr−1 (mean±standard error, at a white sand plot, and 17.0±1.4 Mg C ha−1 yr−1 at a very fertile Terra Preta site, with an overall average of 12.8±0.9 Mg C ha−1 yr−1. The studied forests allocate on average 64±3% and 36±3% of the total NPP to the above- and below-ground components, respectively. The ratio of above-ground and below-ground NPP is almost invariant with total NPP. Litterfall and fine root production both increase with total NPP, while stem production shows no overall trend. Total NPP tends to increase with soil phosphorus and leaf nitrogen status. However, allocation of NPP to below-ground shows no relationship to soil fertility, but appears to decrease with the increase of soil clay content.

  3. On the Scaling Limits of Determinantal Point Processes with Kernels Induced by Sturm-Liouville Operators

    CERN Document Server

    Bornemann, Folkmar

    2011-01-01

    By applying an idea of Borodin and Olshanski (2007), we study the various scaling limits of determinantal point processes with trace class projection kernels given by a spectral projection of a selfadjoint Sturm-Liouville operator. Instead of studying the convergence of the kernels as functions, the method directly addresses the strong convergence of the induced integral operators. We show that, for this class of problems, the Dyson, Airy, and Bessel kernels are universal in the bulk, soft-edge, and hard-edge scaling limits. The result allows to give a simple and unified derivation of the known formulae for the scaling limits of the classical unitary random matrix ensembles (GUE, LUE/Wishart, JUE/MANOVA).

  4. Joint preprocesser-based detector for cooperative networks with limited hardware processing capability

    KAUST Repository

    Abuzaid, Abdulrahman I.

    2015-02-01

    In this letter, a joint detector for cooperative communication networks is proposed when the destination has limited hardware processing capability. The transmitter sends its symbols with the help of L relays. As the destination has limited hardware, only U out of L signals are processed and the energy of the remaining relays is lost. To solve this problem, a joint preprocessing based detector is proposed. This joint preprocessor based detector operate on the principles of minimizing the symbol error rate (SER). For a realistic assessment, pilot symbol aided channel estimation is incorporated for this proposed detector. From our simulations, it can be observed that our proposed detector achieves the same SER performance as that of the maximum likelihood (ML) detector with all participating relays. Additionally, our detector outperforms selection combining (SC), channel shortening (CS) scheme and reduced-rank techniques when using the same U. Our proposed scheme has low computational complexity.

  5. Limit theorems for Markov processes indexed by continuous time Galton-Watson trees

    CERN Document Server

    Bansaye, Vincent; Marsalle, Laurence; Tran, Viet Chi

    2009-01-01

    We study the evolution of a particle system whose genealogy is given by a supercritical continuous time Galton-Watson tree. The particles move independently according to a Markov process and when a branching event occurs, the offspring locations depend on the position of the mother and the number of offspring. We prove a law of large numbers for the empirical measure of individuals alive at time $t$. This relies on a probabilistic interpretation of its intensity by mean of an auxiliary process. This latter has the same generator as the Markov process along the branches plus additional branching events, associated with jumps of accelerated rate and biased distribution. This comes from the fact that choosing an individual uniformly at time $t$ favors lineages with more branching events and larger offspring number. The central limit theorem is considered on a special case. Several examples are developed, including applications to splitting diffusions, cellular aging, branching L\\'evy processes and ancestral line...

  6. Functional limit theorems for L\\'evy processes satisfying Cram\\'er's condition

    CERN Document Server

    Barczy, Matyas

    2011-01-01

    We consider a L\\'evy process that starts from $x<0$ and conditioned on having a positive maximum. When Cram\\'er's condition holds, we provide two weak limit theorems as $x\\to -\\infty$ for the law of the (two-sided) path shifted at the first instant when it enters $(0,\\infty)$, respectively shifted at the instant when its overall maximum is reached. The comparison of these two asymptotic results yields some interesting identities related to time-reversal, insurance risk, and self-similar Markov processes.

  7. Solar-thermal complex sample processing for nucleic acid based diagnostics in limited resource settings

    OpenAIRE

    Gumus, Abdurrahman; Ahsan, Syed; Dogan, Belgin; Jiang, Li; Snodgrass, Ryan; Gardner, Andrea; Lu, Zhengda; Simpson, Kenneth; Erickson, David

    2016-01-01

    The use of point-of-care (POC) devices in limited resource settings where access to commonly used infrastructure, such as water and electricity, can be restricted represents simultaneously one of the best application fits for POC systems as well as one of the most challenging places to deploy them. Of the many challenges involved in these systems, the preparation and processing of complex samples like stool, vomit, and biopsies are particularly difficult due to the high number and varied natu...

  8. Cellular automata simulations on nanocrystallization processes: From instantaneous growth approximation to limited growth

    OpenAIRE

    Blázquez, J.S.; Conde, C. F.; Conde, A.

    2011-01-01

    Cellular automata simulations have been performed to simulate the crystallization process under a limited growth approximation. This approximation resembles several characteristics exhibited by nanocrystalline microstructures and nanocrystallization kinetics. Avrami exponent decreases from a value n = 4 indicating interface controlled growth and constant nucleation rate to a value n ~ 1 indicating absence of growth. A continuous change of the growth contribution to the Avrami exponent from ze...

  9. Inventory of ionium (230Th) during uranium processing and its implications on operational limits

    International Nuclear Information System (INIS)

    The effluents from the Uranium Oxide Plant have shown significant levels of ionium. In view of its high radiotoxicity, a laboratory study was carried out to estimate its distribution in various process streams. This paper presents the analytical procedures employed in the study. The present air activity at the Nuclear Fuel Complex, Hyderabad, has been found to be below operational limits and the presence of ionium does not pose any additional hazard. (author)

  10. Above- and below-ground net primary productivity across ten Amazonian forests on contrasting soils

    OpenAIRE

    L. E. O. C. Aragão; Malhi, Y.; Metcalfe, D.B; Silva-Espejo, J. E.; E. Jiménez; Navarrete, D.; Almeida, S.; Costa, A. C. L.; N. Salinas; O. L. Phillips; L. O. Anderson; Alvarez, E.; T. R. Baker; P. H. Goncalvez; J. Huamán-Ovalle

    2009-01-01

    The net primary productivity (NPP) of tropical forests is one of the most important and least quantified components of the global carbon cycle. Most relevant studies have focused particularly on the quantification of the above-ground coarse wood productivity, and little is known about the carbon fluxes involved in other elements of the NPP, the partitioning of total NPP between its above- and below-ground components and the main environmental drivers of these patterns. In this study we quanti...

  11. Aboveground insect herbivory increases plant competitive asymmetry, while belowground herbivory mitigates the effect

    OpenAIRE

    Borgström, Pernilla; Strengbom, Joachim; Viketoft, Maria; Bommarco, Riccardo

    2016-01-01

    Insect herbivores can shift the composition of a plant community, but the mechanism underlying such shifts remains largely unexplored. A possibility is that insects alter the competitive symmetry between plant species. The effect of herbivory on competition likely depends on whether the plants are subjected to aboveground or belowground herbivory or both, and also depends on soil nitrogen levels. It is unclear how these biotic and abiotic factors interactively affect competition. In a greenho...

  12. Belowground induction by delia radicum or phytohormones affect aboveground herbivore communities on field-grown broccoli

    OpenAIRE

    Pierre, S.P.; Dugravot, S.; Hervé, M. R.; Hassan, H M; Dam, N.M. van; Cortesero, A. M.

    2013-01-01

    Induced plant defence in response to phytophagous insects is a well described phenomenon. However, so far little is known about the effect of induced plant responses on subsequently colonizing herbivores in the field. Broccoli plants were induced in the belowground compartment using (i) infestation by the root-herbivore Delia radicum, (ii) root application of jasmonic acid (JA) or (iii) root application of salicylic acid (SA). The abundance of D. radicum and six aboveground herbivores display...

  13. Belowground ectomycorrhizal fungal communities at fagus stands in differently polluted forest research plots

    OpenAIRE

    Al Sayegh-Petkovšek, Samar

    2005-01-01

    Belowground ectomycorrhizal fungal communities at fagus stands were analysed. Eectomycorrhiza types were identified in soil cores from differently polluted beech forest research plots in the 1998 - 2001 period by mycobioindication method. Forest research plots were situated in the vicinity of thermal power plants (polluted plots: Zavodnje - Prednji vrh and Zasavje - Dobovec) and in unpolluted areas (in the vicinity of Kočevska Reka: Preža and Moravške gredice). Eighty-eight different ectomyco...

  14. Stimulation of the Salicylic Acid Pathway Aboveground Recruits Entomopathogenic Nematodes Belowground

    OpenAIRE

    Filgueiras, Camila Cramer; Willett, Denis S.; Junior, Alcides Moino; Pareja, Martin; Borai, Fahiem El; Dickson, Donald W.; Lukasz L Stelinski; Duncan, Larry W

    2016-01-01

    Plant defense pathways play a critical role in mediating tritrophic interactions between plants, herbivores, and natural enemies. While the impact of plant defense pathway stimulation on natural enemies has been extensively explored aboveground, belowground ramifications of plant defense pathway stimulation are equally important in regulating subterranean pests and still require more attention. Here we investigate the effect of aboveground stimulation of the salicylic acid pathway through fol...

  15. Above- and belowground antifungal resistance in maize: aspects of organ-specific defense

    OpenAIRE

    Balmer, Dirk; Mauch-Mani, Brigitte

    2013-01-01

    The hemibiotrophic fungus Colletotrichum graminicola causes devastating anthracnose on maize (Zea mays) and is responsible for annual losses of up to 1 billion dollars in the U.S. A key factor for its success is the capability to infect different plant organs. The predominant symptoms are leaf blight and stalk rot, but C. graminicola also infects roots. The vast majority of phytopathological studies were conducted on aerial disease stages, and only little is known about belowground defense re...

  16. Signal signature of aboveground-induced resistance upon belowground herbivory in maize

    OpenAIRE

    Erb, Matthias; Flors, Victor; Karlen, Danielle; De Lange, Elvira S.; Planchamp, Chantal; D’Alessandro, Marco; Turlings, Ted C. J.; Ton, Jurriaan

    2012-01-01

    Plants activate local and systemic defence mechanisms upon exposure to stress. This innate immune response is partially regulated by plant hormones, and involves the accumulation of defensive metabolites. Although local defence reactions to herbivores are well studied, less is known about the impact of root herbivory on shoot defence. Here, we examined the effects of belowground infestation by the western corn rootworm Diabrotica virgifera virgifera on aboveground resistance in maize. Belowgr...

  17. Estimation of Below-Ground Biomass in Natural and Replanted Mangroves in Gazi Bay, Kenya

    International Nuclear Information System (INIS)

    Estimation of belowground biomass in woody ecosystems is important because of it's relevance to nutrient turnover and the potential store in carbon. Most studies om mangroves biomass have concentrated on standing biomass with very little on belowground biomass; this is particularly true for he eastern African region. The present study was conducted at Gaza Bay in Southern Coast of Kenya. The main objective was to determine belowground biomass mangroves in natural and replanted plantations of Rhizophora mucronata, Avicennia marina and Sonneratia alba. The study in addition investigated horizontal and vertical root distribution. Sampling was carried out in 10m * 10m plots where cores (65 cm length and 15.6 cm diameter) were made at the present root base, between and away from the stem as far as the roots from individual stem could possibly extend based on the sampled tree canopy diameter. In R. mucronata belowground biomass from different stands ranged between 4.9 to 3.7 t ha-1, S. alba 50.8 to 87.3 t ha-1and A. marina 28.7 to 47.6 t ha-1. R mucronata showed a clear effect of age with the amount of biomass increasing with age. Vertical root distribution showed high root densities in the top 20 cm layer decreasing gradually with depth in all species under study. Fine root (<5 mm) density ranged between 20 to 52.8% of the total live root biomass among all species. The information generated is useful in complimenting previous studies on above-ground biomass in Gazi bay and therefore contribute to determination of the potential amount of carbon sequestered by mangroves total biomass within the entire Gazi bay hence improving on forest management

  18. Adopted levels and derived limits for Ra-226 and the decision making processes concerning TENORM releases

    International Nuclear Information System (INIS)

    A fraction of a primary dose limit can be, in general, agreed upon as a dose related level to be adopted in decision-making processes. In the case of TENORM releases, fractions of primary dose levels for 226Ra, 228Ra, and 210Po may be of particular importance to establish adopted levels and derived limits to guide decision making processes. Thus, for example, a registration level for 226Ra could be adopted at the highest portion of the natural background variation. Above such level, intervention and remedial action levels could also be adopted. All those levels would be fractions of the primary level, but translated in terms of derived limits expressed in practical units. Derived limits would then be calculated by using environmental models. In such approach 'critical groups' would have to be carefully defined and identified. In addition, the size of a critical group would be chosen to be used in environmental modeling. Site specific environmental models and parameters are desirable, though unavailable, or very difficult to obtain, in most cases. Thus, mathematical models and parameters of more generic nature are often used. A sensitive parametric analysis can make a ranking of the parameters used in a model, allowing one to choose how important each parameter will be for the model output. The paper will point out that when using the adopted levels and derived limits, as suggested above, the uncertainties and importance of the parameters entering an environmental model can make the difference for decision makers to take the right or wrong decision, as far as radiological protection is concerned. (author)

  19. Genetic Variation of the Host Plant Species Matters for Interactions with Above- and Belowground Herbivores

    Directory of Open Access Journals (Sweden)

    Dinesh Kafle

    2014-08-01

    Full Text Available Plants are challenged by both above- and belowground herbivores which may indirectly interact with each other via herbivore-induced changes in plant traits; however, little is known about how genetic variation of the host plant shapes such interactions. We used two genotypes (M4 and E9 of Solanum dulcamara (Solanaceae with or without previous experience of aboveground herbivory by Spodoptera exigua (Noctuidae to quantify its effects on subsequent root herbivory by Agriotes spp. (Elateridae. In the genotype M4, due to the aboveground herbivory, shoot and root biomass was significantly decreased, roots had a lower C/N ratio and contained significantly higher levels of proteins, while the genotype E9 was not affected. However, aboveground herbivory had no effects on weight gain or mortality of the belowground herbivores. Root herbivory by Agriotes increased the nitrogen concentration in the roots of M4 plants leading to a higher weight gain of conspecific larvae. Also, in feeding bioassays, Agriotes larvae tended to prefer roots of M4 over E9, irrespective of the aboveground herbivore treatment. Fourier-Transform Infrared Spectroscopy (FT-IR documented differences in metabolic profiles of the two plant genotypes and of the roots of M4 plants after aboveground herbivory. Together, these results demonstrate that previous aboveground herbivory can have genotype-specific effects on quantitative and qualitative root traits. This may have consequences for belowground interactions, although generalist root herbivores might not be affected when the root biomass offered is still sufficient for growth and survival.

  20. Belowground legacies of Pinus contorta invasion and removal result in multiple mechanisms of invasional meltdown.

    Science.gov (United States)

    Dickie, Ian A; St John, Mark G; Yeates, Gregor W; Morse, Chris W; Bonner, Karen I; Orwin, Kate; Peltzer, Duane A

    2014-01-01

    Plant invasions can change soil biota and nutrients in ways that drive subsequent plant communities, particularly when co-invading with belowground mutualists such as ectomycorrhizal fungi. These effects can persist following removal of the invasive plant and, combined with effects of removal per se, influence subsequent plant communities and ecosystem functioning. We used field observations and a soil bioassay with multiple plant species to determine the belowground effects and post-removal legacy caused by invasion of the non-native tree Pinus contorta into a native plant community. Pinus facilitated ectomycorrhizal infection of the co-occurring invasive tree, Pseudotsuga menziesii, but not conspecific Pinus (which always had ectomycorrhizas) nor the native pioneer Kunzea ericoides (which never had ectomycorrhizas). Pinus also caused a major shift in soil nutrient cycling as indicated by increased bacterial dominance, NO3-N (17-fold increase) and available phosphorus (3.2-fold increase) in soils, which in turn promoted increased growth of graminoids. These results parallel field observations, where Pinus removal is associated with invasion by non-native grasses and herbs, and suggest that legacies of Pinus on soil nutrient cycling thus indirectly promote invasion of other non-native plant species. Our findings demonstrate that multi-trophic belowground legacies are an important but hitherto largely unconsidered factor in plant community reassembly following invasive plant removal. PMID:25228312

  1. Belowground rhizomes in paleosols: The hidden half of an Early Devonian vascular plant.

    Science.gov (United States)

    Xue, Jinzhuang; Deng, Zhenzhen; Huang, Pu; Huang, Kangjun; Benton, Michael J; Cui, Ying; Wang, Deming; Liu, Jianbo; Shen, Bing; Basinger, James F; Hao, Shougang

    2016-08-23

    The colonization of terrestrial environments by rooted vascular plants had far-reaching impacts on the Earth system. However, the belowground structures of early vascular plants are rarely documented, and thus the plant-soil interactions in early terrestrial ecosystems are poorly understood. Here we report the earliest rooted paleosols (fossil soils) in Asia from Early Devonian deposits of Yunnan, China. Plant traces are extensive within the soil and occur as complex network-like structures, which are interpreted as representing long-lived, belowground rhizomes of the basal lycopsid Drepanophycus The rhizomes produced large clones and helped the plant survive frequent sediment burial in well-drained soils within a seasonal wet-dry climate zone. Rhizome networks contributed to the accumulation and pedogenesis of floodplain sediments and increased the soil stabilizing effects of early plants. Predating the appearance of trees with deep roots in the Middle Devonian, plant rhizomes have long functioned in the belowground soil ecosystem. This study presents strong, direct evidence for plant-soil interactions at an early stage of vascular plant radiation. Soil stabilization by complex rhizome systems was apparently widespread, and contributed to landscape modification at an earlier time than had been appreciated. PMID:27503883

  2. Belowground legacies of Pinus contorta invasion and removal result in multiple mechanisms of invasional meltdown

    Science.gov (United States)

    Dickie, Ian A.; St John, Mark G.; Yeates, Gregor W.; Morse, Chris W.; Bonner, Karen I.; Orwin, Kate; Peltzer, Duane A.

    2013-01-01

    Plant invasions can change soil biota and nutrients in ways that drive subsequent plant communities, particularly when co-invading with belowground mutualists such as ectomycorrhizal fungi. These effects can persist following removal of the invasive plant and, combined with effects of removal per se, influence subsequent plant communities and ecosystem functioning. We used field observations and a soil bioassay with multiple plant species to determine the belowground effects and post-removal legacy caused by invasion of the non-native tree Pinus contorta into a native plant community. Pinus facilitated ectomycorrhizal infection of the co-occurring invasive tree, Pseudotsuga menziesii, but not conspecific Pinus (which always had ectomycorrhizas) nor the native pioneer Kunzea ericoides (which never had ectomycorrhizas). Pinus also caused a major shift in soil nutrient cycling as indicated by increased bacterial dominance, NO3-N (17-fold increase) and available phosphorus (3.2-fold increase) in soils, which in turn promoted increased growth of graminoids. These results parallel field observations, where Pinus removal is associated with invasion by non-native grasses and herbs, and suggest that legacies of Pinus on soil nutrient cycling thus indirectly promote invasion of other non-native plant species. Our findings demonstrate that multi-trophic belowground legacies are an important but hitherto largely unconsidered factor in plant community reassembly following invasive plant removal. PMID:25228312

  3. Adopted levels and derived limits for Ra-226 and the decision making processes concerning TENORM releases

    International Nuclear Information System (INIS)

    A fraction of a primary dose limit can be, in general, agreed upon as a dose related level to be adopted in decision-making processes. In the case of TENORM releases, fractions of primary dose levels for 226Ra, 228Ra, and 210Po may be of particular importance to establish adopted levels for 226Ra could be adopted at the highest portion of the natural background variation. Above such level, intervention and remedial action levels could also be adopted. All those levels would be fractions of the primary level, but translated in terms of derived limits expressed in practical units. Derived limits would then be calculated by using environmental models. In such approach 'critical groups' would have to be carefully defined and identified. In addition, the size of a critical group would be chosen to be used in environmental modeling. Site specific environmental models and parameters are desirable, though unavailable, or very difficult to obtain, in most cases. Thus, mathematical models and parameters of more generic nature are often used. A sensitive parametric analysis can make a ranking of the parameters used in a model, allowing one to choose how important each parameter will be for the model output. The paper will point out that when using the adopted levels and derived limits, as suggested above, the uncertainties and importance of the parameters entering an environmental model can make the difference for decision makers to take the right or wrong decision, as far as radiological protection is concerned. (author)

  4. The top 50 commodity chemicals: Impact of catalytic process limitations on energy, environment, and economics

    Energy Technology Data Exchange (ETDEWEB)

    Tonkovich, A.L.Y.; Gerber, M.A.

    1995-08-01

    The production processes for the top 50 U.S. commodity chemicals waste energy, generate unwanted byproducts, and require more than a stoichiometric amount of feedstocks. Pacific Northwest Laboratory has quantified this impact on energy, environment, and economics for the catalytically produced commodity chemicals. An excess of 0.83 quads of energy per year in combined process and feedstock energy is required. The major component, approximately 54%, results from low per-pass yields and the subsequent separation and recycle of unreacted feedstocks. Furthermore, the production processes, either directly or through downstream waste treatment steps, release more than 20 billion pounds of carbon dioxide per year to the environment. The cost of the wasted feedstock exceeds 2 billion dollars per year. Process limitations resulting from unselective catalysis and unfavorable reaction thermodynamic constraints are the major contributors to this waste. Advanced process concepts that address these problems in an integrated manner are needed to improve process efficiency, which would reduce energy and raw material consumption, and the generation of unwanted byproducts. Many commodity chemicals are used to produce large volume polymer products. Of the energy and feedstock wasted during the production of the commodity chemicals, nearly one-third and one-half, respectively, represents chemicals used as polymer precursors. Approximately 38% of the carbon dioxide emissions are generated producing polymer feedstocks.

  5. Applications and limitations of very large-scale integration in SAR azimuth processing

    Science.gov (United States)

    Kuhler, D. G.

    1978-01-01

    The major limitation of a convolution processor designed with CCD memory chips is the inability to operate in real time except for slow aircraft speeds or coarse resolutions. Two methods of summing the products were evaluated with respect to speed, power, and space requirements. A convolution processor was designed, and the number of chips as well as the power and volume requirements were determined using 4, 6, and 8 bit data words. The processor is flexible because range samples may be traded for additional azimuth samples by altering the control signals. The processor is also modular, and additional range or azimuth may be processed by adding more cards.

  6. Figuring out the process of denitrification by stable isotope approaches - Prospects and limitations -

    Science.gov (United States)

    Stange, C. F.; Spott, O.

    2009-04-01

    Improvement in the analysis of stable isotopes, higher measurement capacity and faster and more complex analysis methods allow a more detailed insight into the complexity of N cycling in soils or sediments, in particular in the formation and emission of N2 gas. The knowledge about the site-specific N2 to N2O ratio of denitrification and perhaps other processes is important to develop sustainable land use strategies for reduction of GHG emissions. Adapted stable isotope approaches are an irreplaceable tool for process identification, process quantification and processes separation. In the last years a few of new processes were found (e.g. anammox, codenitrification) and new stable isotope approaches for quantification and processes separation were published (Wrage et al.). Source partitioning of N gas production in soils is inherently challenging, but is vital to better understand controls on the different processes, with a view to develope appropriate management practices for mitigation of harmful N gases (e.g.N2O) (Baggs, 2008). Recently dual-isotope labelling approaches (Wrage et al., 2005) and triplet 15N tracer experiments (TTE) with 15N labelling of different pools (e.g. Müller et al., 2006, Russow et al 2009) have been developed to differentiate between more than two processes. The high number of simultaneously occurring processes during soil N cycling (Hayatsu et al. 2008) limits an easy applicability of isotope approaches (Spott and Stange 2007 ;Wrage et al. 2005; Phillips and Gregg, 2003), and therefore partitioning and process quantification is often afflicted with high uncertainties (Ambus et al., 2006). Especially the heterogeneity of environmental conditions in soils caused by the soil structure is difficult to handle (e.g. homogeneously labelling a soil). Hence, spatially separated processes in combination with high turnover rates (gross production and consumption) can produce different pools of one substrate in the soil (Russow et al. 2009) and

  7. Limitations on the Activity Concentration of Mineral Processing Residues Used as Building Material

    International Nuclear Information System (INIS)

    The use of mineral processing residue as a building material accounts for a significant proportion of the various uses of such material. The activity concentrations of radionuclides of natural origin in the material can be significantly elevated, resulting in enhanced exposure of occupants of the buildings concerned unless some restriction is placed on the radioactivity content. Accordingly, in order to comply with the dose limitation requirements of the relevant laws and standards, the activity concentration in the material has to be restricted. The use of mineral processing residues in building material is controlled in three categories according to a parameter known as the equivalent concentration, which can guide the product specification of the building material and control the dose received by a building occupant. (author)

  8. Anomalous scaling due to correlations: limit theorems and self-similar processes

    International Nuclear Information System (INIS)

    We derive theorems which outline explicit mechanisms by which anomalous scaling for the probability density function of the sum of many correlated random variables asymptotically prevails. The results characterize general anomalous scaling forms, explain their universal character, and specify universality domains in the spaces of joint probability density functions of the summand variables. These density functions are assumed to be invariant under arbitrary permutations of their arguments. Examples from the theory of critical phenomena are discussed. The novel notion of stability implied by the limit theorems also allows us to define sequences of random variables whose sum satisfies anomalous scaling for any finite number of summands. If regarded as developing in time, the stochastic processes described by these variables are non-Markovian generalizations of Gaussian processes with uncorrelated increments, and provide, e.g., explicit realizations of a recently proposed model of index evolution in finance

  9. Limited ability driven phase transitions in the coevolution process in Axelrod's model

    International Nuclear Information System (INIS)

    We study the coevolution process in Axelrod's model by taking into account of agents' abilities to access information, which is described by a parameter α to control the geographical range of communication. We observe two kinds of phase transitions in both cultural domains and network fragments, which depend on the parameter α. By simulation, we find that not all rewiring processes pervade the dissemination of culture, that is, a very limited ability to access information constrains the cultural dissemination, while an exceptional ability to access information aids the dissemination of culture. Furthermore, by analyzing the network characteristics at the frozen states, we find that there exists a stage at which the network develops to be a small-world network with community structures.

  10. Limited ability driven phase transitions in the coevolution process in Axelrod's model

    Energy Technology Data Exchange (ETDEWEB)

    Wang Bing [ERATO Aihara Complexity Modelling Project, JST, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Institute of Industrial Science, University of Tokyo, Tokyo (Japan)], E-mail: bingbignmath@gmail.com; Han Yuexing [Graduate School of Information System, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu-Shi, Tokyo (Japan); Chen Luonan [Department of Electrical Engineering and Electronics, Osaka Sangyo University, Daito, Osaka 574-8530 (Japan); Aihara, Kazuyuki [ERATO Aihara Complexity Modelling Project, JST, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Institute of Industrial Science, University of Tokyo, Tokyo (Japan)

    2009-04-13

    We study the coevolution process in Axelrod's model by taking into account of agents' abilities to access information, which is described by a parameter {alpha} to control the geographical range of communication. We observe two kinds of phase transitions in both cultural domains and network fragments, which depend on the parameter {alpha}. By simulation, we find that not all rewiring processes pervade the dissemination of culture, that is, a very limited ability to access information constrains the cultural dissemination, while an exceptional ability to access information aids the dissemination of culture. Furthermore, by analyzing the network characteristics at the frozen states, we find that there exists a stage at which the network develops to be a small-world network with community structures.

  11. A PREDICTING MODEL OF THE LIMITING FLUX FOR THE CHARGED SOLUTE IN ULTRAFILTRATION PROCESS

    Institute of Scientific and Technical Information of China (English)

    LUO Ming-liang; GUO Yan; PU Chun-sheng; LU Feng-ji

    2004-01-01

    In the process of ultrafiltration , the occur-rence of the limiting flux is elucidated with the formation of a cake(gel) layer on the membrane surface. Before cake formation, the pressure drop on the concentration polarization layer, as well as the permeate flux, increases with the applied pressure. The pressure drop on the concentration polarization layer, however, will no longer change with the applied pressure after the formation of the cake layer. The limiting flux will be obtained if the hydrodynamic conditions in the filtration channel are not affected by the cake layer. A mathematics model for predicting the limiting flux for the charged solute in ultrafiltration is developed. In this model, a repulsive electric force is taken into account in addition to convection and diffusion when the solute is carrying the same charge as the membrane material. A procedure to correlate the model with experimental ultrafiltration data is also present. The results show that a model in this paper is developed on a more realistic perception of the ultrafiltration system and the predicting data agrees well with experimental data.

  12. Partitioning belowground CO2 emissions for a Miscanthus plantation in Lincolnshire, UK

    Science.gov (United States)

    Robertson, Andrew; Smith, Pete; Davies, Christian; Bottoms, Emily; McNamara, Niall

    2013-04-01

    Miscanthus is a lignocellulosic crop that uses the Hatch-Slack (C4) photosynthetic pathway as opposed to most C3 vegetation native to the UK. Miscanthus can be grown for a number of practical end-uses but recently interest has increased in its viability as a bioenergy crop; both providing a renewable source of energy and helping to limit climate change by reducing carbon (C) emissions associated with energy generation. Recent studies have shown that Miscanthus plantations may increase stocks of soil organic carbon (SOC), however full greenhouse gas (GHG) budgets must be calculated. Consequently, we monitored emissions of N2O, CH4 and CO2 from Miscanthus roots, decomposing plant litter and soil individually to quantify and partition these emissions and better understand the influence of abiotic factors on SOC and GHG dynamics under Miscanthus. In January 2009 twenty-five 2 m2 plots were set up in a three-year old 11 hectare Miscanthus plantation in Lincolnshire, UK; with five replicates of five treatments. These treatments varied plant input to the soil by way of controlled exclusion techniques. Treatments excluded roots only ("No Roots"), surface litter only ("No Litter"), both roots and surface litter ("No Roots or Litter") or had double the litter amount added to the soil surface ("Double Litter"). A fifth treatment was a control with undisturbed roots and an average amount of litter added. Monthly measurements of CO2, CH4 and N2O emissions were taken at the soil surface from each treatment between March 2009 and March 2013, and soil C from the top 30 cm was monitored in all plots over the same period. Miscanthus-derived SOC was determined using the isotopic discrimination between C4 plant matter and C3 soil, and the treatments were compared to assess their effects on C inputs and outputs to the soil. Both CH4 and N2O emissions were below detection limits, mainly due to a lack of fertiliser additions and limited management of the agricultural site. However

  13. Extension of the Limiting Quality Indexed Single Acceptance Sampling Plans for Attributes in High Precision Processes

    Directory of Open Access Journals (Sweden)

    Ma. Theresa Gomez

    1998-12-01

    Full Text Available This study investigated the extension of existing single acceptance sampling plans indexed by lot tolerance percent defective (LTPD or limiting quality (LQ with respect to their applicability to high precision processes. LTPD/LQ indexed sampling plans were extended to cover the very low fraction defective levels of high precision processes. Plans based on the ISO 2859-2 LQ indexed plans, Dodge-Romig LTPD indexed plans, and lot sensitive plans (LSP were used as bases for the extensions. Target levels for LTPD/LQ were set at defective parts per million levels ranging from 20 ppm to 5000 ppm. The performance of the extended plans was evaluated using measures relating to level of protection afforded by the plans and efficiency in terms of amount of required inspection. The extended Dodge-Romig LTPD plans showed best performance among the three plans generated. Three selected plans from the extended Dodge-Romig LTPD sampling scheme were then subjected to simulation studies. Comparison of the theoretical and simulation data indicated that the plans behave more strictly than expected from theoretical calculations. The specific demands of high precision processes for appropriate sampling inspection plans that cover lower fraction defective levels, and at the same time satisfy the requirement for economy and efficiency of inspection were shown to be provided by this plan. These results contributed significantly to the manufacturing industry as it continuously strives to improve process yields and decreases fraction defective levels to respond to customer demands of better quality and improved performance.

  14. The limits of feedforward vision: recurrent processing promotes robust object recognition when objects are degraded.

    Science.gov (United States)

    Wyatte, Dean; Curran, Tim; O'Reilly, Randall

    2012-11-01

    Everyday vision requires robustness to a myriad of environmental factors that degrade stimuli. Foreground clutter can occlude objects of interest, and complex lighting and shadows can decrease the contrast of items. How does the brain recognize visual objects despite these low-quality inputs? On the basis of predictions from a model of object recognition that contains excitatory feedback, we hypothesized that recurrent processing would promote robust recognition when objects were degraded by strengthening bottom-up signals that were weakened because of occlusion and contrast reduction. To test this hypothesis, we used backward masking to interrupt the processing of partially occluded and contrast reduced images during a categorization experiment. As predicted by the model, we found significant interactions between the mask and occlusion and the mask and contrast, such that the recognition of heavily degraded stimuli was differentially impaired by masking. The model provided a close fit of these results in an isomorphic version of the experiment with identical stimuli. The model also provided an intuitive explanation of the interactions between the mask and degradations, indicating that masking interfered specifically with the extensive recurrent processing necessary to amplify and resolve highly degraded inputs, whereas less degraded inputs did not require much amplification and could be rapidly resolved, making them less susceptible to masking. Together, the results of the experiment and the accompanying model simulations illustrate the limits of feedforward vision and suggest that object recognition is better characterized as a highly interactive, dynamic process that depends on the coordination of multiple brain areas. PMID:22905822

  15. 40 CFR Table 2 to Subpart Ffff of... - Emission Limits and Work Practice Standards for Batch Process Vents

    Science.gov (United States)

    2010-07-01

    ... Standards for Batch Process Vents 2 Table 2 to Subpart FFFF of Part 63 Protection of Environment...—Emission Limits and Work Practice Standards for Batch Process Vents As required in § 63.2460, you must meet each emission limit and work practice standard in the following table that applies to your...

  16. 40 CFR Appendix A to Part 419 - Processes Included in the Determination of BAT Effluent Limitations for Total Chromium...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Processes Included in the Determination of BAT Effluent Limitations for Total Chromium, Hexavalent Chromium, and Phenolic Compounds (4AAP) A...—Processes Included in the Determination of BAT Effluent Limitations for Total Chromium, Hexavalent...

  17. Belowground responses to elevation in a changing cloud forest.

    Science.gov (United States)

    Looby, Caitlin I; Maltz, Mia R; Treseder, Kathleen K

    2016-04-01

    Few studies have investigated how soil fungal communities respond to elevation, especially within TMCF (tropical montane cloud forests). We used an elevation gradient in a TMCF in Costa Rica to determine how soil properties, processes, and community composition of fungi change in response to elevation and across seasons. As elevation increased, soil temperature and soil pH decreased, while soil moisture and soil C:N ratios increased with elevation. Responses of these properties varied seasonally. Fungal abundance increased with elevation during wet and dry seasons. Fungal community composition shifted in response to elevation, and to a lesser extent by season. These shifts were accompanied by varying responses of important fungal functional groups during the wet season and the relative abundance of certain fungal phyla. We suggest that elevation and the responses of certain fungal functional groups may be structuring fungal communities along this elevation gradient. TMCF are ecosystems that are rapidly changing due to climate change. Our study suggests that these changes may affect how fungal communities are structured. PMID:27066220

  18. Advanced remote sensing to quantify temperate peatland capacity for belowground carbon capture

    Science.gov (United States)

    Byrd, K. B.; Blanchard, S.; Schile, L. M.; Kolding, S.; Kelly, M.; Windham-Myers, L.; Miller, R.

    2011-12-01

    Temperate peatlands typically dominated by grasses and sedges generate among the greatest annual rates of net primary productivity (NPP, up to 4 kg C m-2) and soil carbon storage (up to 1 kg C m-2) for natural ecosystems. Belowground tissues represent 20-80% of total NPP, thus understanding the controls on belowground NPP (BNPP) in these wetland ecosystems is particularly important to quantifying peatland carbon balances. In addition, there is a growing need to quantify large-scale belowground C sequestration rates in wetlands to better understand marsh resilience to sea level rise and to help define eligibility for carbon offset credits. Since plant productivity influences wetland C budgets, combining field and remote sensing techniques for estimating above and belowground productivity of wetland vegetation over a large spatial extent will help to address these needs. We are working in a USGS long-term experimental wetland restoration site on drained peatland in the Sacramento-San Joaquin River Delta. Using the spatial variability in water depth and residence time across the 7 ha wetland, our goal is to develop practical methods to quantify and map BNPP of emergent marsh vegetation from remotely sensed estimates of aboveground plant characteristics and aboveground NPP. Field data collected on wetland plants hardstem bulrush (Schoenoplectus acutus) and cattail (Typha spp.) were coupled with reflectance data from a field spectrometer (range 350-2500 nm) every two to three weeks during the summer of 2011. We are analyzing reflectance data to develop hyperspectral indices that predict the biophysical characteristics of wetland vegetation - biomass, leaf area index (LAI), and the fraction of absorbed photosynthetically active radiation (fAPAR) - which may be used to infer belowground biomass and productivity. Soil cores and root in-growth bags were used to calculate root biomass and productivity rates. Existing allometric relationships were used to calculate

  19. Contrasting above- and belowground sensitivity of three Great Plains grasslands to altered rainfall regimes.

    Science.gov (United States)

    Wilcox, Kevin R; von Fischer, Joseph C; Muscha, Jennifer M; Petersen, Mark K; Knapp, Alan K

    2015-01-01

    Intensification of the global hydrological cycle with atmospheric warming is expected to increase interannual variation in precipitation amount and the frequency of extreme precipitation events. Although studies in grasslands have shown sensitivity of aboveground net primary productivity (ANPP) to both precipitation amount and event size, we lack equivalent knowledge for responses of belowground net primary productivity (BNPP) and NPP. We conducted a 2-year experiment in three US Great Plains grasslands--the C4-dominated shortgrass prairie (SGP; low ANPP) and tallgrass prairie (TGP; high ANPP), and the C3-dominated northern mixed grass prairie (NMP; intermediate ANPP)--to test three predictions: (i) both ANPP and BNPP responses to increased precipitation amount would vary inversely with mean annual precipitation (MAP) and site productivity; (ii) increased numbers of extreme rainfall events during high-rainfall years would affect high and low MAP sites differently; and (iii) responses belowground would mirror those aboveground. We increased growing season precipitation by as much as 50% by augmenting natural rainfall via (i) many (11-13) small or (ii) fewer (3-5) large watering events, with the latter coinciding with naturally occurring large storms. Both ANPP and BNPP increased with water addition in the two C4 grasslands, with greater ANPP sensitivity in TGP, but greater BNPP and NPP sensitivity in SGP. ANPP and BNPP did not respond to any rainfall manipulations in the C3 -dominated NMP. Consistent with previous studies, fewer larger (extreme) rainfall events increased ANPP relative to many small events in SGP, but event size had no effect in TGP. Neither system responded consistently above- and belowground to event size; consequently, total NPP was insensitive to event size. The diversity of responses observed in these three grassland types underscores the challenge of predicting responses relevant to C cycling to forecast changes in precipitation regimes even

  20. Ecohydrological optimization of pattern and processes in water-limited ecosystems

    Science.gov (United States)

    Caylor, K. K.; Scanlon, T. M.; Rodriguez-Iturbe, I.

    2006-12-01

    The coupled nature of hydrological and ecological dynamics is perhaps nowhere more evident than in water- limited ecosystems. Despite the close coupling that exists between dynamics of surface water and vegetation structure, the challenge of predicting vegetation response to changing climate in these environments is particularly daunting. A central challenge is defining the ecologically and hydrologically relevant processes that led to the formation of vegetation patterns in water-limited ecosystems. There remains a need to clarify the manner by which vegetation self-organizes across scales within semi-arid landscapes, and how regional, landscape, and individual-based patterns of vegetation interact with their accompanying climates and soils. Such clarification necessitates the development of conceptual models capable of interpreting and predicting spatial pattern formation in savannas (and similar dry woodland ecosystems) as well as metrics for assessing optimization or organization of patterns - from individual canopies to landscapes and beyond. This presentation focuses on the spatial aspects of interactions between plants, soils, and climates in two different water-limited systems. The first is a series of savanna sites spanning a large rainfall gradient within southern African, and the second is a semi-arid river basin organized around a drainage network in central New Mexico. We explore the drivers of ecohydrological spatial pattern formation at a hierarchy of scales that range from climate gradients spanning thousands of kilometers to that of individual tree canopies spanning only a few meters. In each case, we link the dynamics of soil moisture to patterns of vegetation in order to explore the general hypothesis that many semi-arid ecosystems tend to self-organize with respect to optimizing water use. Model results indicate that observed patterns are likely due to an optimization scheme that both maximizes water use while minimizing water stress.

  1. Apparatus and process to eliminate diffusional limitations in a membrane biological reactor by pressure cycling

    Science.gov (United States)

    Efthymiou, George S.; Shuler, Michael L.

    1989-08-29

    An improved multilayer continuous biological membrane reactor and a process to eliminate diffusional limitations in membrane reactors in achieved by causing a convective flux of nutrient to move into and out of an immobilized biocatalyst cell layer. In a pressure cycled mode, by increasing and decreasing the pressure in the respective layers, the differential pressure between the gaseous layer and the nutrient layer is alternately changed from positive to negative. The intermittent change in pressure differential accelerates the transfer of nutrient from the nutrient layers to the biocatalyst cell layer, the transfer of product from the cell layer to the nutrient layer and the transfer of byproduct gas from the cell layer to the gaseous layer. Such intermittent cycling substantially eliminates mass transfer gradients in diffusion inhibited systems and greatly increases product yield and throughput in both inhibited and noninhibited systems.

  2. Linking Above- and Belowground Dynamics in Tropical Urban Forests

    Science.gov (United States)

    Atkinson, E. E.; Marin-Spiotta, E.

    2013-12-01

    Secondary forests that emerge after a long history of agriculture can have altered plant community composition and relative abundances of different species. These forests can look and behave differently compared to pre-agricultural forests due changes in primary productivity, resource allocation, and phenology, which can significantly affect processes such as carbon accumulation and nutrient availability. Our research explores how alternative successional trajectories following intensive agricultural use affect linkages among the establishment of novel plant communities, soil nutrient availability and turnover, and soil microbial community composition and function. We hypothesize that different plant species composition due to differing land use legacies and successional trajectories would drive changes in soil microbial community structure and function, affecting soil C and N chemistry and turnover. We conducted this research in the subtropical dry forest life zone of St. Croix, U.S. Virgin Islands where island-wide abandonment of sugarcane resulted in a mosaic of sites in different stages of forest succession. We identified replicate sites with the following post-sugarcane trajectories: 1) natural forest regeneration, 2) low intensity pasture use, followed by reforestation with timber plantation, which are no longer being managed, 3) high intensity pasture use and recent natural forest regeneration, and 4) high intensity pasture use and current active grazing. During 2011-2013, we sampled soils seasonally (0-10 cm) and measured tree species composition. The successional trajectories showed distinct tree species composition. The first two trajectories yielded 40-year old mixed-species secondary forest, dominated by the dry forest tree species Melicoccus bijugatas, Guapira fragrans, Maniklara zapota, and Sideroxylon foetidissimum. The tree species Melicoccus bijugatas primarily drove differences between the first two trajectories (natural forest regeneration vs

  3. Territorial resources, limits and strategies of local development processes and agri-food productions of quality

    Directory of Open Access Journals (Sweden)

    Severino Romano

    2011-02-01

    Full Text Available The aim of this work is to analyse the role that typical products can play in the local development process. Territorial resources involved, limits and strategies for their enhancement are analysed; this analysis will permit both to define the results that have been achieved since nowadays in the local development process and to point out future themes for the research in the field of agricultural economics. The typicality of an agri-food product regards qualitative characteristics that derive from its tie with the territory, this tie becomes a relevant element for the differentiation of the typical product from the others. In this context, the typical product maintains all the specificities associated to its origin, involving also aspects related to the traditions and the culture of the territories, to the collective dimension and to the local knowledge. Consumers tent to look for good which are differentiated and to connect authenticity and local specificity of food with healthiness. Due to the strong socio-economic ties that typical products have with the territory, they play a crucial role in the economy of the local systems and can promote development in lagging areas.

  4. Optimization of cold rolling process parameters in order to increasing rolling speed limited by chatter vibrations

    Directory of Open Access Journals (Sweden)

    Ali Heidari

    2013-01-01

    Full Text Available Chatter has been recognized as major restriction for the increase in productivity of cold rolling processes, limiting the rolling speed for thin steel strips. It is shown that chatter has close relation with rolling conditions. So the main aim of this paper is to attain the optimum set points of rolling to achieve maximum rolling speed, preventing chatter to occur. Two combination methods were used for optimization. First method is done in four steps: providing a simulation program for chatter analysis, preparing data from simulation program based on central composite design of experiment, developing a statistical model to relate system tendency to chatter and rolling parameters by response surface methodology, and finally optimizing the process by genetic algorithm. Second method has analogous stages. But central composite design of experiment is replaced by Taguchi method and response surface methodology is replaced by neural network method. Also a study on the influence of the rolling parameters on system stability has been carried out. By using these combination methods, new set points were determined and significant improvement achieved in rolling speed.

  5. Vegetation drives belowground biogeochemical gradients and C accumulation in an ombrotrophic bog

    Science.gov (United States)

    Knorr, Klaus-Holger; Galka, Mariusz; Borken, Werner

    2016-04-01

    Peat decomposition and C accumulation is determined by hydrology and climate and by concomitant changes in vegetation and changes in the quality of carbon inputs. Especially changes from moss dominated to vascular plant dominated vegetation affect belowground biogeochemistry and decomposition, as Sphagnum mosses provide refractory, nutrient poor litter, while vascular plants produce more labile litter and may have aerenchymatic rooting systems. In-site variability in moisture and vegetation, e.g. hummock-hollow structures, lawns, and medium scale surface topography, could thus cause large differences in decomposition and C accumulation within a site. In order to understand within-site variability and to see how C accumulation, common decomposition indices, and major biogeochemical parameters in the pore waters are affected by site specific conditions and vegetation, we investigated a moisture-vegetation gradient along a 800 m transect in an oceanic, ombrotrophic bog in Southern Patagonia. Along the transect, conditions changed from wet, Sphagnum dominated (S. magellanicum), to intermediate drier and wetter with Sphagnum/shrubs mixtures, sedges and rushes to more wind exposed, dominated by cushion plants (mainly Astelia pumila). We hypothesized that under arenchymatic vascular plants, decomposition is enhanced and C accumulation is decreased. Vegetation development was elucidated by plant macrofossils and carbon accumulation was attributed to the respective vegetation. The transect demonstrated a high variability of depth records within the bog. At the two most contrasting sites, the uppermost 1 meter persistently dominated by either Sphagnum magellanicum or Astelia pumila had accumulated over 2400 or 4200 years, respectively. Accordingly, the peat under cushion plants was much more decomposed, with C/N ratios of 20-50 compared to C/N ratios of 40-80 under Sphagnum patches. Mixed sites in between had C/N ratios of 30-90, depending on plant community, and

  6. Plutonium Equivalent Inventory for Belowground Radioactive Waste at the Los Alamos National Laboratory Technical Area 54, Area G Disposal Facility - Fiscal Year 2011

    Energy Technology Data Exchange (ETDEWEB)

    French, Sean B. [Los Alamos National Laboratory; Shuman, Rob [WPS: WASTE PROJECTS AND SERVICES

    2012-04-18

    The Los Alamos National Laboratory (LANL) generates radioactive waste as a result of various activities. Many aspects of the management of this waste are conducted at Technical Area 54 (TA-54); Area G plays a key role in these management activities as the Laboratory's only disposal facility for low-level radioactive waste (LLW). Furthermore, Area G serves as a staging area for transuranic (TRU) waste that will be shipped to the Waste Isolation Pilot Plant for disposal. A portion of this TRU waste is retrievably stored in pits, trenches, and shafts. The radioactive waste disposed of or stored at Area G poses potential short- and long-term risks to workers at the disposal facility and to members of the public. These risks are directly proportional to the radionuclide inventories in the waste. The Area G performance assessment and composite analysis (LANL, 2008a) project long-term risks to members of the public; short-term risks to workers and members of the public, such as those posed by accidents, are addressed by the Area G Documented Safety Analysis (LANL, 2011a). The Documented Safety Analysis uses an inventory expressed in terms of plutonium-equivalent curies, referred to as the PE-Ci inventory, to estimate these risks. The Technical Safety Requirements for Technical Area 54, Area G (LANL, 2011b) establishes a belowground radioactive material limit that ensures the cumulative projected inventory authorized for the Area G site is not exceeded. The total belowground radioactive waste inventory limit established for Area G is 110,000 PE-Ci. The PE-Ci inventory is updated annually; this report presents the inventory prepared for 2011. The approach used to estimate the inventory is described in Section 2. The results of the analysis are presented in Section 3.

  7. Solar-thermal complex sample processing for nucleic acid based diagnostics in limited resource settings.

    Science.gov (United States)

    Gumus, Abdurrahman; Ahsan, Syed; Dogan, Belgin; Jiang, Li; Snodgrass, Ryan; Gardner, Andrea; Lu, Zhengda; Simpson, Kenneth; Erickson, David

    2016-05-01

    The use of point-of-care (POC) devices in limited resource settings where access to commonly used infrastructure, such as water and electricity, can be restricted represents simultaneously one of the best application fits for POC systems as well as one of the most challenging places to deploy them. Of the many challenges involved in these systems, the preparation and processing of complex samples like stool, vomit, and biopsies are particularly difficult due to the high number and varied nature of mechanical and chemical interferents present in the sample. Previously we have demonstrated the ability to use solar-thermal energy to perform PCR based nucleic acid amplifications. In this work demonstrate how the technique, using similar infrastructure, can also be used to perform solar-thermal based sample processing system for extracting and isolating Vibrio Cholerae nucleic acids from fecal samples. The use of opto-thermal energy enables the use of sunlight to drive thermal lysing reactions in large volumes without the need for external electrical power. Using the system demonstrate the ability to reach a 95°C threshold in less than 5 minutes and maintain a stable sample temperature of +/- 2°C following the ramp up. The system is demonstrated to provide linear results between 10(4) and 10(8) CFU/mL when the released nucleic acids were quantified via traditional means. Additionally, we couple the sample processing unit with our previously demonstrated solar-thermal PCR and tablet based detection system to demonstrate very low power sample-in-answer-out detection. PMID:27231636

  8. Solar-thermal complex sample processing for nucleic acid based diagnostics in limited resource settings

    Science.gov (United States)

    Gumus, Abdurrahman; Ahsan, Syed; Dogan, Belgin; Jiang, Li; Snodgrass, Ryan; Gardner, Andrea; Lu, Zhengda; Simpson, Kenneth; Erickson, David

    2016-01-01

    The use of point-of-care (POC) devices in limited resource settings where access to commonly used infrastructure, such as water and electricity, can be restricted represents simultaneously one of the best application fits for POC systems as well as one of the most challenging places to deploy them. Of the many challenges involved in these systems, the preparation and processing of complex samples like stool, vomit, and biopsies are particularly difficult due to the high number and varied nature of mechanical and chemical interferents present in the sample. Previously we have demonstrated the ability to use solar-thermal energy to perform PCR based nucleic acid amplifications. In this work demonstrate how the technique, using similar infrastructure, can also be used to perform solar-thermal based sample processing system for extracting and isolating Vibrio Cholerae nucleic acids from fecal samples. The use of opto-thermal energy enables the use of sunlight to drive thermal lysing reactions in large volumes without the need for external electrical power. Using the system demonstrate the ability to reach a 95°C threshold in less than 5 minutes and maintain a stable sample temperature of +/− 2°C following the ramp up. The system is demonstrated to provide linear results between 104 and 108 CFU/mL when the released nucleic acids were quantified via traditional means. Additionally, we couple the sample processing unit with our previously demonstrated solar-thermal PCR and tablet based detection system to demonstrate very low power sample-in-answer-out detection. PMID:27231636

  9. Attentional gain and processing capacity limits predict the propensity to neglect unexpected visual stimuli.

    Science.gov (United States)

    Papera, Massimiliano; Richards, Anne

    2016-05-01

    Exogenous allocation of attentional resources allows the visual system to encode and maintain representations of stimuli in visual working memory (VWM). However, limits in the processing capacity to allocate resources can prevent unexpected visual stimuli from gaining access to VWM and thereby to consciousness. Using a novel approach to create unbiased stimuli of increasing saliency, we investigated visual processing during a visual search task in individuals who show a high or low propensity to neglect unexpected stimuli. When propensity to inattention is high, ERP recordings show a diminished amplification concomitantly with a decrease in theta band power during the N1 latency, followed by a poor target enhancement during the N2 latency. Furthermore, a later modulation in the P3 latency was also found in individuals showing propensity to visual neglect, suggesting that more effort is required for conscious maintenance of visual information in VWM. Effects during early stages of processing (N80 and P1) were also observed suggesting that sensitivity to contrasts and medium-to-high spatial frequencies may be modulated by low-level saliency (albeit no statistical group differences were found). In accordance with the Global Workplace Model, our data indicate that a lack of resources in low-level processors and visual attention may be responsible for the failure to "ignite" a state of high-level activity spread across several brain areas that is necessary for stimuli to access awareness. These findings may aid in the development of diagnostic tests and intervention to detect/reduce inattention propensity to visual neglect of unexpected stimuli. PMID:26849023

  10. Interactive effects of elevated CO2 and nitrogen deposition on fatty acid molecular and isotope composition of above- and belowground tree biomass and forest soil fractions.

    Science.gov (United States)

    Griepentrog, Marco; Eglinton, Timothy I; Hagedorn, Frank; Schmidt, Michael W I; Wiesenberg, Guido L B

    2015-01-01

    Atmospheric carbon dioxide (CO2) and reactive nitrogen (N) concentrations have been increasing due to human activities and impact the global carbon (C) cycle by affecting plant photosynthesis and decomposition processes in soil. Large amounts of C are stored in plants and soils, but the mechanisms behind the stabilization of plant- and microbial-derived organic matter (OM) in soils are still under debate and it is not clear how N deposition affects soil OM dynamics. Here, we studied the effects of 4 years of elevated (13C-depleted) CO2 and N deposition in forest ecosystems established in open-top chambers on composition and turnover of fatty acids (FAs) in plants and soils. FAs served as biomarkers for plant- and microbial-derived OM in soil density fractions. We analyzed above- and belowground plant biomass of beech and spruce trees as well as soil density fractions for the total organic C and FA molecular and isotope (δ13C) composition. FAs did not accumulate relative to total organic C in fine mineral fractions, showing that FAs are not effectively stabilized by association with soil minerals. The δ13C values of FAs in plant biomass increased under high N deposition. However, the N effect was only apparent under elevated CO2 suggesting a N limitation of the system. In soil fractions, only isotope compositions of short-chain FAs (C16+18) were affected. Fractions of 'new' (experimental-derived) FAs were calculated using isotope depletion in elevated CO2 plots and decreased from free light to fine mineral fractions. 'New' FAs were higher in short-chain compared to long-chain FAs (C20-30), indicating a faster turnover of short-chain compared to long-chain FAs. Increased N deposition did not significantly affect the quantity of 'new' FAs in soil fractions, but showed a tendency of increased amounts of 'old' (pre-experimental) C suggesting that decomposition of 'old' C is retarded by high N inputs. PMID:24953725

  11. Performance of Statistical Control Charts with Bilateral Limits of Probability to Monitor Processes Weibull in Maintenance

    Directory of Open Access Journals (Sweden)

    Quintana Alicia Esther

    2015-01-01

    Full Text Available Manufacturing with optimal quality standards is underpinned to the high reliability of its equipment and systems, among other essential pillars. Maintenance Engineering is responsible for planning control and continuous improvement of its critical equipment by any approach, such as Six Sigma. This is nourished by numerous statistical tools highlighting, among them, statistical process control charts. While their first applications were in production, other designs have emerged to adapt to new needs as monitoring equipment and systems in the manufacturing environment. The time between failures usually fits an exponential or Weibull model. The t chart and adjusted t chart, with probabilistic control limits, are suitable alternatives to monitor the mean time between failures. Unfortunately, it is difficult to find publications of them applied to the models Weibull, very useful in contexts such as maintenance. In addition, literature limits the study of their performance to the analysis of the standard metric average run length, thus giving a partial view. The aim of this paper is to explore the performance of the t chart and adjusted t chart using three metrics, two unconventional. To do this, it incorporates the concept of lateral variability, in their forms left and right variability. Major precisions of the behavior of these charts allow to understand the conditions under which are suitable: if the main objective of monitoring lies in detecting deterioration, the t chart with adjustment is recommended. On the other hand, when the priority is to detect improvements, the t chart without adjustment is the best choice. However, the response speed of both charts is very variable from run to run.

  12. Above- and belowground biomass in relation to envi- ronmental factors in temperate grasslands, Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Above- and belowground biomasses of grasslands are important parameters for characterizing re- gional and global carbon cycles in grassland ecosystems. Compared with the relatively detailed in- formation for aboveground biomass (AGB), belowground biomass (BGB) is poorly reported at the re- gional scales. The present study, based on a total of 113 sampling sites in temperate grassland of the Inner Mongolia, investigated regional distribution patterns of AGB, BGB, vertical distribution of roots, and their relationships with environmental factors. AGB and BGB increased from the southwest to the northeast of the study region. The largest biomass occurred in meadow steppe, with mean AGB and BGB of 196.7 and 1385.2 g/m2, respectively; while the lowest biomass occurred in desert steppe, with an AGB of 56.6 g/m2 and a BGB of 301.0 g/m2. In addition, about 47% of root biomass was distributed in the top 10 cm soil. Further statistical analysis indicated that precipitation was the primary determinant factor in shaping these distribution patterns. Vertical distribution of roots was significantly affected by precipitation, while the effects of soil texture and grassland types were weak.

  13. The fungal endophyte Chaetomium globosum negatively affects both above- and belowground herbivores in cotton.

    Science.gov (United States)

    Zhou, Wenqing; Starr, James L; Krumm, Janice L; Sword, Gregory A

    2016-10-01

    Mutualistic plant-endophyte symbioses can benefit plants by increasing host fitness through reductions in herbivory. The fungus, Chaetomium globosum strain TAMU 520, was previously isolated as an endophyte from cotton (Gossypium hirsutum) and can be re-inoculated to systemically colonize cotton plants via seed treatment. We evaluated the potential impacts of the endophyte in cotton on plant parasitic nematodes belowground, along with piercing-sucking and chewing insects aboveground. Endophytic C. globosum inhibited root-knot nematode (Meloidogyne incognita) infection and reduced female reproduction belowground. To confirm the endophytic effect of C. globosum on root-knot nematode, a contact fungicide was applied to remove soil-borne and epiphytic C. globosum Consistent inhibition of nematode activity was observed post-fungicide treatment, with positive C. globosum colonization confirmed within plant tissues. Aboveground, endophytic C. globosum also negatively affected the fecundity of both cotton aphids (Aphis gossypii) and beet armyworms (Spodoptera exigua). Faster development rates and smaller head capsule of beet armyworm larvae were observed when fed Chaetomium-colonized plants. However, no larval weight difference was found between Chaetomium-colonized and control plants. No consistent effect on plant performance was found across experiments. Our findings illustrate how a single facultative fungal endophyte can increase plant systemic resistance against a range of invertebrate herbivores in a major crop. PMID:27451418

  14. Derivation of the Limits for Control Chart Using the Median Absolute Deviation for Monitoring Non-Normal Process

    Directory of Open Access Journals (Sweden)

    P. I. Azubuike

    2012-01-01

    Full Text Available Problem statement: The Shewhart and S control charts, in the literature, were combined to evaluate the stability of a process. These charts were based on the fundamental assumption of normality of the quality characteristics under investigation. Approach: In practice, the normality assumption was often violated by real life data, therefore, use of the Shewhart and S control charts on real life data might leads to misplacement of control limits. There were many alternatives in the literature to handle non-normality of quality characteristics. The Median Absolute Deviation (MAD claimed in the literature to be the best estimate when the data under consideration is non-normal. Thus in this study, we derived the control limits for the-control chart using the median absolute deviation for monitoring process stability when the quality characteristic under investigation was non-normal. Results: The derived control limits were compared with the control limits when the sample standard deviation was used as a measure of controlling the process variability using manufacturing process (real life data. Furthermore, a simulation study was carried out to evaluate the performance of the proposed MAD based control charts on both normal and non-normal process. Conclusion: The obtained results show that the derived control limit is an improvement on the control limit of the Shewhart and that the MAD control charts performed better for non-normal process than for normal process.

  15. Internationalization Process of Thai Office Furniture Company in India: A case study of Rockworth Public Company Limited

    OpenAIRE

    netwong, weeraya; trakarnthai, priyawat

    2010-01-01

    The purpose of this thesis is to study the internationalization process by investigate how Rockworth Public Company Limited manage internationalization in Indian market efficiently. Additionally, we aim to improve our understanding and knowledge in international business comprehensively.

  16. Demands, subjectivity and therapeutic process: construction and limitations of Therapeutic Accompaniment

    Directory of Open Access Journals (Sweden)

    Luís Felipe Ferro

    2014-12-01

    Full Text Available The Brazilian Psychiatric Reform movement proposed several changes in the field of mental health. Since then, guidelines have been redirecting actions to respond to different demands, associating social inclusion with clinical follow-up. In this context, Therapeutic Accompaniment (TA appears as an important device to compose interventions focused on the demands of individuals with mental disorders. Thus the present work aims to present reflections on the limitations and potentials of TA. This study was based on the practice of TA in the Occupational Therapy Traineeship in Mental Health of the Federal University of Parana - UFPR. Regarding the methodological framework, this paper is structured in a two-way approach: presentation of a case report and exploratory research using unstructured interviews focused on two subjects monitored by TA. Hermeneutic-dialectic analysis was used for data treatment. The results indicate that TA provides significant gains to the process of rehabilitation and construction of citizenship of individuals with mental disorders, enabling actions focused on the demands of the individual, family and community. Nevertheless, there is still the need for continuity of TA interventions, as well as some structural deadlocks that tend to decrease the power of this device.

  17. Processing of metals and dielectric materials with ps-laserpulses: results, strategies, limitations and needs

    Science.gov (United States)

    Neuenschwander, Beat; Bucher, Guido F.; Nussbaum, Christian; Joss, Benjamin; Muralt, Martin; Hunziker, Urs W.; Schuetz, Peter

    2010-02-01

    Ultra short (ps, fs) laser pulses are used, when high requirements concerning accuracy, surface roughness, heat affected zone etc. are demanded for surface structuring. Ps-laser systems that are suited to be operated in industrial environments are of great interest for many practical applications. Here results in the field of 3-d structuring (metals and transparent materials), induced processes and structuring of flexible solar cells will be presented. Beside the pulse duration, which is given by the laser system, the user has a wide variety of optimization parameters such as fluence, repetition rate and wavelength. Based on a simple model it will be shown, that there exist optimum laser parameters to achieve maximum volume ablation rates at a given average power. To take benefit of these optimum parameters and to prevent harmful effects like plasma shielding and surface melting, adapted structuring strategies, depending on the requirements, have to be used. Today's ultra short pulsed systems have average powers from a few W up to a few 10W at high repetition rates. The actual available beam guiding systems are limited and can often not fulfill the requirements needed for high throughput structuring with optimized parameters. Based on the achieved results, the needs for future beam guiding systems will be discussed.

  18. Tidal Influences on Belowground Methane Dynamics in a Mesohaline Coastal Marsh

    Science.gov (United States)

    Reid, M. C.; Tripathee, R.; Pal, D.; Schafer, K. V.; Jaffe, P. R.

    2012-12-01

    The influence of tidal hydrology on belowground distributions and atmospheric fluxes of methane (CH4) remain poorly understood. The greenhouse gas balance of coastal wetland systems is a topic of increasing importance due to mounting proposals for coastal wetland preservation and/or restoration for carbon sequestration purposes, so it is essential that the effects of tides on methane dynamics be more fully understood. Here we describe a set of porewater measurements intended to clarify the influence of tides on belowground CH4 dynamics and their consequent effects on atmospheric emissions. Monthly measurements were conducted for one year in a marsh with mixed Spartina alterniflora and Phragmites australis vegetation and in an adjacent intertidal mud flat. The site is located in the Hackensack Meadowlands in northern New Jersey and is mesohaline, with a range of salinities from 4 - 8 ppt. Measurements indicate major differences in the spatial and temporal dynamics of belowground CH4 between the low marsh and mud flat sediments, though both are characterized by very high dissolved CH4 concentrations of >1,000 μM in summer months. A particularly important distinction is that mud flat porewaters remain saturated with dissolved CH4 into early winter, while low marsh porewarers never reach CH4 saturation and rapidly fall off to negligible concentrations in the autumn months. We attribute this long-term CH4 storage to differences in low-tide water table depths between the mud flat and low marsh, as well as the ventilating effects of macrophytes in the low marsh. We hypothesize that CH4-enriched gas bubbles are produced in mud flat sediments in summer, and then slowly dissolve over the fall and early winter months to maintain near-saturation concentrations in porewater. Static flux chamber measurements conducted at the same site, and discussed in detail in a separate submission, confirm the importance of mud flat CH4 storage in contributing to significant CH4 emissions

  19. Quantifying above- and belowground biomass carbon loss with forest conversion in tropical lowlands of Sumatra (Indonesia).

    Science.gov (United States)

    Kotowska, Martyna M; Leuschner, Christoph; Triadiati, Triadiati; Meriem, Selis; Hertel, Dietrich

    2015-10-01

    Natural forests in South-East Asia have been extensively converted into other land-use systems in the past decades and still show high deforestation rates. Historically, lowland forests have been converted into rubber forests, but more recently, the dominant conversion is into oil palm plantations. While it is expected that the large-scale conversion has strong effects on the carbon cycle, detailed studies quantifying carbon pools and total net primary production (NPPtotal ) in above- and belowground tree biomass in land-use systems replacing rainforest (incl. oil palm plantations) are rare so far. We measured above- and belowground carbon pools in tree biomass together with NPPtotal in natural old-growth forests, 'jungle rubber' agroforests under natural tree cover, and rubber and oil palm monocultures in Sumatra. In total, 32 stands (eight plot replicates per land-use system) were studied in two different regions. Total tree biomass in the natural forest (mean: 384 Mg ha(-1) ) was more than two times higher than in jungle rubber stands (147 Mg ha(-1) ) and >four times higher than in monoculture rubber and oil palm plantations (78 and 50 Mg ha(-1) ). NPPtotal was higher in the natural forest (24 Mg ha(-1)  yr(-1) ) than in the rubber systems (20 and 15 Mg ha(-1)  yr(-1) ), but was highest in the oil palm system (33 Mg ha(-1)  yr(-1) ) due to very high fruit production (15-20 Mg ha(-1)  yr(-1) ). NPPtotal was dominated in all systems by aboveground production, but belowground productivity was significantly higher in the natural forest and jungle rubber than in plantations. We conclude that conversion of natural lowland forest into different agricultural systems leads to a strong reduction not only in the biomass carbon pool (up to 166 Mg C ha(-1) ) but also in carbon sequestration as carbon residence time (i.e. biomass-C:NPP-C) was 3-10 times higher in the natural forest than in rubber and oil palm plantations. PMID:25980371

  20. 48 CFR 2436.602-5 - Short selection processes for contracts not to exceed the small purchase limitation.

    Science.gov (United States)

    2010-10-01

    ... CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 2436.602-5 Short selection processes for contracts not to exceed the small purchase limitation. The short selection process described in... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true Short selection...

  1. Interactions between above- and belowground biota: importance for small-scale vegetation mosaics in a grassland ecosystem

    NARCIS (Netherlands)

    Blomqvist, M.M.; Olff, H.; Blaauw, M.B.; Bongers, T.; Van der Putten, W.H.

    2000-01-01

    Grasslands are often characterised by small-scale mosaics in plant community composition that contribute to their diversity. Although above- and belowground biota can both cause such mosaics, few studies have addressed their interacting effects. We studied multi-trophic interactions between abovegro

  2. Systemic above- and belowground cross talk: hormone-based responses triggered by Heterodera schachtii and shoot herbivores in Arabidopsis thaliana

    Czech Academy of Sciences Publication Activity Database

    Kammerhofer, N.; Egger, B.; Dobrev, Petre; Vaňková, Radomíra; Hofmann, J.; Schausberger, P.; Wieczorek, K.

    2015-01-01

    Roč. 66, č. 22 (2015), s. 7005-7017. ISSN 0022-0957 R&D Projects: GA MŠk LD14120 Institutional support: RVO:61389030 Keywords : Aboveground–belowground interactions * Frankliniella occidentalis * herbivores Subject RIV: EF - Botanics Impact factor: 5.526, year: 2014

  3. The P\\'olya sum process: Limit theorems for conditioned random fields

    OpenAIRE

    Rafler, Mathias

    2012-01-01

    In \\cite{hZ09}, Zessin constructed the so-called P\\'olya sum process via partial integration technique. This process shares some important properties with the Poisson process such as complete randomness and infinite divisibility. This work discusses H-sufficient statistics for the P\\'olya sum process as it was done for the Poisson process in \\cite{hZ76}.

  4. Belowground ectomycorrhizal fungal communities respond to liming in three southern Swedish coniferous forest stands

    DEFF Research Database (Denmark)

    Kjøller, Rasmus; Clemmensen, Karina

    2009-01-01

    In this study we report on changes in the belowground ectomycorrhizal fungal communities in southern Swedish coniferous forests as a consequence of liming with 3-7 ton limestone per hectare 16 years prior to the study. A total of 107 ectomycorrhizal fungi were identified from 969 independently...... sampled root tips by sequencing the internal transcribed spacer region of the ribosomal DNA. Forty, 59 and 51 species were identified in three pine and spruce forests. Within all sites only about 25% of the species overlapped between the limed and the reference areas. However, the most abundant species...... were often found in both limed and reference plots and 60-70% of the root tips at each site were colonised by species occurring in both limed and reference plots. Across all three sites, fungal species belonging to the genus Tylospora and the order Pezizales became significantly more frequent in limed...

  5. Grassland management affects belowground carbon allocation in mountain grasslands and its resistance and resilience to drought

    Science.gov (United States)

    Karlowsky, Stefan; Augusti, Angela; Ingrisch, Johannes; Hasibeder, Roland; Bahn, Michael; Gleixner, Gerd

    2015-04-01

    Future climate scenarios do not only forecast increased extreme events during summer, but also more frequent drought events in the early season. In mountain grasslands, different land uses may contribute to the response of the ecosystem to climate changes, like drought in May and June. In this study, we examined the drought response of two differently managed grasslands, 1) a more intensive used meadow and 2) a less intensive used abandoned area. Our aim was to highlight differences in both resistance and resilience of ecosystem functioning, based on carbon (C) belowground allocation as a key function in the plant-rhizosphere continuum. Therefore, we used an isotopic approach and in particular, we used 13C pulse labelling to track the fate of newly assimilated C from leaves, to roots and to soil, up to different microbial communities. We performed two 13C pulse labellings, the first during the acute phase of drought, when the water status of soil was drastically decreased compared to the control; and the second during the recovery phase, when the soil water status was restored to control level. We followed the kinetics of 13C incorporation in above- and below-ground bulk material as well as non-structural sugars, in general soil microbial biomass, in different soil microbial communities and in CO2 respired from roots, up to 5 days from each labelling. Preliminary results from the 13C analyses of bulk phytomass material and soil microbial biomass indicate, as expected, different kinetics of aboveground 13C incorporation and its belowground allocation. During the acute phase of drought, 13C incorporation shows a decrease compared to the control for both land uses, with generally higher reductions in meadow treatments. Root 13C tracer dynamics follow the leaf 13C enrichment with a delay. High label amounts are found in leaves directly after labelling, whereas in roots high 13C incorporation is found first after 24 hours, accompanied by a fast decrease of 13C label in

  6. Plant-Mediated Systemic Interactions Between Pathogens, Parasitic Nematodes, and Herbivores Above- and Belowground.

    Science.gov (United States)

    Biere, Arjen; Goverse, Aska

    2016-08-01

    Plants are important mediators of interactions between aboveground (AG) and belowground (BG) pathogens, arthropod herbivores, and nematodes (phytophages). We highlight recent progress in our understanding of within- and cross-compartment plant responses to these groups of phytophages in terms of altered resource dynamics and defense signaling and activation. We review studies documenting the outcome of cross-compartment interactions between these phytophage groups and show patterns of cross-compartment facilitation as well as cross-compartment induced resistance. Studies involving soilborne pathogens and foliar nematodes are scant. We further highlight the important role of defense signaling loops between shoots and roots to activate a full resistance complement. Moreover, manipulation of such loops by phytophages affects systemic interactions with other plant feeders. Finally, cross-compartment-induced changes in root defenses and root exudates extend systemic defense loops into the rhizosphere, enhancing or reducing recruitment of microbes that induce systemic resistance but also affecting interactions with root-feeding phytophages. PMID:27359367

  7. Above- and belowground fluxes of CH4 from boreal shrubs and Scots pine

    Science.gov (United States)

    Halmeenmäki, Elisa; Heinonsalo, Jussi; Santalahti, Minna; Putkinen, Anuliina; Fritze, Hannu; Pihlatie, Mari

    2016-04-01

    Boreal upland forests are considered as an important sink for the greenhouse gas methane (CH4) due to CH4 oxidizing microbes in the soil. However, recent evidence suggests that vegetation can act as a significant source of CH4. Also, preliminary measurements indicate occasional emissions of CH4 above the tree canopies of a boreal forest. Nevertheless, the sources and the mechanisms of the observed CH4 emissions are still mostly unknown. Furthermore, the majority of CH4 flux studies have been conducted with the soil chamber method, thus not considering the role of the vegetation itself. We conducted a laboratory experiment to study separately the above- and belowground CH4 fluxes of bilberry (Vaccinium myrtillus), lingonberry (Vaccinium vitis-idaea), heather (Calluna vulgaris), and Scots pine (Pinus sylvestris), which were grown in microcosms. The above- and belowground fluxes of the plants were measured separately, and these fluxes were compared to fluxes of microcosms containing only humus soil. In addition to the flux measurements, we analysed the CH4 producing archaea (methanogens) and the CH4 consuming bacteria (methanotrophs) with the qPCR method to discover whether these microbes contribute to the CH4 exchange from the plant material and the soil. The results of the flux measurements indicate that the humus soil with roots of lingonberry, heather, and Scots pine consume CH4 compared to bare humus soil. Simultaneously, the shoots of heather and Scots pine emit small amounts of CH4. We did not find detectable amounts of methanogens from any of the samples, suggesting the produced CH4 could be of non-microbial origin, or produced by very small population of methanogens. Based on the first preliminary results, methanotrophs were present in all the studied plant species, and especially in high amounts in the rooted soils, thus implying that the methanotrophs could be responsible of the CH4 uptake in the root-soil systems.

  8. Tuberculosis Epidemiology at the Country Scale: Self-Limiting Process and the HIV Effects

    Science.gov (United States)

    Krsulovic, Felipe Augusto Maurin; Lima, Mauricio

    2016-01-01

    Background The global spread of the human immunodeficiency virus (HIV) is the main hypothesis behind tuberculosis (TB) positive trends in the last decades, according to modeling studies and World Health Organization Reports (WHO). On one hand, TB (WHO) reports do not explicitly consider a modeling approach, but cover country and global TB trends. On the other hand, modeling studies usually do not cover the scale of WHO reports, because of the amount of parameters estimated to describe TB natural history. Here we combined these two principal sources of TB studies covering TB High Burden Countries (HBCs) dynamics. Our main goals were: (i) to detect the endogenous component of TB dynamics since 1974 for TB HBCs; and (ii) to explore the HIV exogenous effects on TB models`parameters. Methods and Findings We explored the relationship between the TB per capita population rate of change (RI) and the infectious class size following an endogenous/exogenous framework. RI can be affected by intra-population processes (i.e. competition, predation) and exogenous variables like HIV. We found that TB dynamics had always a strong endogenous component, represented by a negative correlation between TB population size and RI, which was captured by the discrete logistic model. Moreover, we explored the HIV exogenous effects on TB models`parameters. We found that overall the TB+HIV logistic model was more parsimonious than TB model alone, principally in the African region. Our results showed that HIV affected principally TB carrying capacity, as expected by the known HIV effects on TB natural-history. We also tested if DOTS (Directly Observed Treatment Short-Course Strategy), poverty levels and BCG (Bacillus Calmette-Guérin) coverage explained the models´ residuals variances, but they did not. Conclusions Since 1974, TB dynamics were categorized in distinct chronological domains, with different dynamics but nearly the same underlying mechanism: a negative relationship between RI and

  9. Solar-wind tritium limit and nuclear processes in the solar atmosphere

    Science.gov (United States)

    Fireman, E. L.; Damico, J.; Defelice, J.

    1975-01-01

    Tritium in Surveyor 3 material is measured, and the resulting H-3/H-1 ratio for the solar wind is applied in a solar flare-solar wind relation to investigate the mixing requirements for the solar atmosphere. The flare-wind relation is derived. None of the tritium can be attributed to solar-wind implantation. The upper limit for the H-3/He ratio in the solar wind is 4 times 10 to the minus tenth power and corresponds to a H-3/H-1 limit of 2 times 10 to the minus eleventh power. This limit imposes a requirement on the mixing rate in the solar atmosphere if the H-3 production rate in solar-surface nuclear reactions is greater than 160/sq cm per sec.

  10. Central limit approximations for Markov population processes with countably many types

    CERN Document Server

    Barbour, A D

    2012-01-01

    When modelling metapopulation dynamics, the influence of a single patch on the metapopulation depends on the number of individuals in the patch. Since there is usually no obvious natural upper limit on the number of individuals in a patch, this leads to systems in which there are countably infinitely many possible types of entity. Analogous considerations apply in the transmission of parasitic diseases. In this paper, we prove central limit theorems for quite general systems of this kind, together with bounds on the rate of convergence in an appropriately chosen weighted $\\ell_1$ norm.

  11. Fundamental limitations of non-thermal plasma processing for internal combustion engine NOx control

    International Nuclear Information System (INIS)

    This paper discusses the physics and chemistry of non-thermal plasma processing for post-combustion NOx control in internal combustion engines. A comparison of electron beam and electrical discharge processing is made regarding their power consumption, radical production, NOx removal mechanisms, and by product formation. Can non-thermal deNOx operate efficiently without additives or catalysts? How much electrical power does it cost to operate? What are the by-products of the process? This paper addresses these fundamental issues based on an analysis of the electron-molecule processes and chemical kinetics

  12. Information-Limited Parallel Processing in Difficult Heterogeneous Covert Visual Search

    Science.gov (United States)

    Dosher, Barbara Anne; Han, Songmei; Lu, Zhong-Lin

    2010-01-01

    Difficult visual search is often attributed to time-limited serial attention operations, although neural computations in the early visual system are parallel. Using probabilistic search models (Dosher, Han, & Lu, 2004) and a full time-course analysis of the dynamics of covert visual search, we distinguish unlimited capacity parallel versus serial…

  13. Use of Archimedes' Process for Approximating Circle Area as an Introduction to Limits

    Science.gov (United States)

    Ozgun-Koca, S. Asli

    2007-01-01

    This article offers an introductory activity for the limit concept with a geometrical and historical foundation. A connection among Geometry, Measurement and Calculus is highlighted with the help of technology. The geometrical drawing, measurement and graphing capabilities of both TI-89 and Geometer's Sketchpad make it possible for students to…

  14. Statistical analysis of the blast furnace process output parameter using arima control chart with proposed methodology of control limits setting

    OpenAIRE

    Noskievičová, Darja

    2009-01-01

    The paper deals with the statistical analysis of the selected parameter of the blast furnace process. It was proved that analyzed measurements have been autocorrelated. ARIMA control chart was selected for their analysis as a very useful statistical process control (SPC) method. At first the methodology for control limits setting in ARIMA control charts considering the time series outlier analysis as an integral part of the ARIMA model building was designed. Then this proposal was...

  15. Statistical analysis of the blast furnace process output parameter using arima control chart with proposed methodology of control limits setting

    OpenAIRE

    D. Noskievičová

    2009-01-01

    The paper deals with the statistical analysis of the selected parameter of the blast furnace process. It was proved that analyzed measurements have been autocorrelated. ARIMA control chart was selected for their analysis as a very useful statistical process control (SPC) method. At first the methodology for control limits setting in ARIMA control charts considering the time series outlier analysis as an integral part of the ARIMA model building was designed. Then this proposal was applied to ...

  16. Strategic environmental assessment and the limits to rationality in decision making processes

    DEFF Research Database (Denmark)

    Kørnøv, Lone

    The paper focueses on the subject of rationality in decision making processes and the implications for the integration of SEA.......The paper focueses on the subject of rationality in decision making processes and the implications for the integration of SEA....

  17. Advantages and limitations of 137Cs, 210Pb and 7Be methodologies for assessing erosion and sedimentation processes

    International Nuclear Information System (INIS)

    As demonstrated by around 4000 research papers published, fallout radionuclides 'FRN' (137Cs, 210Pb and 7Be) have been successfully used as soil redistribution tracers for measuring erosion and sedimentation processes. A table presents the advantages and limitations of each of the FRNs as soil redistribution tracers

  18. Processing bottlenecks in dual-task performance: structural limitation or strategic postponement?

    Science.gov (United States)

    Ruthruff, E.; Pashler, H. E.; Klaassen, A.

    2001-01-01

    Recent evidence indicates that a central bottleneck causes much of the slowing that occurs when two tasks are performed at the same time. This bottleneck might reflect a structural limitation inherent in the cognitive architecture. Alternatively, the bottleneck might reflect strategic (i.e., voluntary) postponement, induced by instructions to emphasize one task over the other. To distinguish structural limitations from strategic postponement, we examine a new paradigm in which subjects are told to place equal emphasis on both tasks and to emit both responses at about the same time. An experiment using this paradigm demonstrated patterns of interference that cannot easily be attributed to strategic postponement, preparation effects, or conflicts in response production. The data conform closely to the predictions of structural central bottleneck models.

  19. Review of cosmic background radiation spectrum measurements: limits on distortions, energy release, and cosmological processes

    International Nuclear Information System (INIS)

    This paper reviews the three major cosmic microwave background radiation (CMBR) spectrum measurement programs conducted and published since the last (XVII) IAU General Assembly. The results are consistent with a Planckian spectrum with temperature 2.72 +- 0.03 K spanning a wavelength range of 0.1 to 12 cm. Limits on possible distortions and implications are outlined. Ongoing and future measurements are discussed

  20. Towards microbiological quality assurance in radiation sterilization processing: a limiting case model

    International Nuclear Information System (INIS)

    A Limiting Case Model has been developed which describes the dependence on radiation dose of the proportion of items, in a population of items subjected to irradiation, which are contaminated by one or more organisms. This model is independent of the initial distribution of numbers of micro-organisms on items and represents a conservative approach to estimation of the proportions of non-sterile items in an irradiated population of items. (author)

  1. Moderate deviations and functional limits for random processes with stationary and independent increments

    Institute of Scientific and Technical Information of China (English)

    GAO; Fuqing

    2006-01-01

    We first give a functional moderate deviation principle for random processes with stationary and independent increments under the Ledoux's condition.Then we apply the result to laws of the iterated logarithm.

  2. Codigestion of manure and industrial organic waste at centralized biogas plants: process imbalances and limitations

    DEFF Research Database (Denmark)

    Bangsø Nielsen, Henrik; Angelidaki, Irini

    2008-01-01

    The present study focuses on process imbalances in Danish centralized biogas plants treating manure in combination with industrial waste. Collection of process data from various full-scale plants along with a number of interviews showed that imbalances occur frequently. High concentrations of...... conditions) and high fractions of industrial waste in the feedstock was also observed. The process imbalances and suboptimal conditions are mainly allowed to occur due to 1) inadequate knowledge about the waste composition, 2) inadequate knowledge about the waste degradation characteristics, 3) inadequate...... process surveillance, especially with regard to volatile fatty acids, and 4) insufficient pre-storage capacity causing inexpedient mixing and hindering exact dosing of the different waste products....

  3. Transient kinetics and rate limiting steps for the processive cellobiohydrolase Cel7A

    DEFF Research Database (Denmark)

    Cruys-Bagger, Nicolaj; Hirosuke, Tatsumi; Robin Ren, Guilin; Borch, Kim; Westh, Peter

    2013-01-01

    Cellobiohydrolases are exo-acting, processive enzymes, which effectively hydrolyze crystalline cellulose. They have attracted considerable interest due to their role in both in natural carbon cycling and industrial enzyme cocktails used for the deconstruction of cellulosic biomass, but many...

  4. Exploring the limits: A low-pressure, low-temperature Haber-Bosch process

    Science.gov (United States)

    Vojvodic, Aleksandra; Medford, Andrew James; Studt, Felix; Abild-Pedersen, Frank; Khan, Tuhin Suvra; Bligaard, T.; Nørskov, J. K.

    2014-04-01

    The Haber-Bosch process for ammonia synthesis has been suggested to be the most important invention of the 20th century, and called the ‘Bellwether reaction in heterogeneous catalysis’. We examine the catalyst requirements for a new low-pressure, low-temperature synthesis process. We show that the absence of such a process for conventional transition metal catalysts can be understood as a consequence of a scaling relation between the activation energy for N2 dissociation and N adsorption energy found at the surface of these materials. A better catalyst cannot obey this scaling relation. We define the ideal scaling relation characterizing the most active catalyst possible, and show that it is theoretically possible to have a low pressure, low-temperature Haber-Bosch process. The challenge is to find new classes of catalyst materials with properties approaching the ideal, and we discuss the possibility that transition metal compounds have such properties.

  5. Exploitation of a self-limiting process for reproducible formation of ultrathin Ni1-xPtx silicide films

    International Nuclear Information System (INIS)

    This letter reports on a process scheme to obtain highly reproducible Ni1-xPtx silicide films of 3-6 nm thickness formed on a Si(100) substrate. Such ultrathin silicide films are readily attained by sputter deposition of metal films, metal stripping in wet chemicals, and final silicidation by rapid thermal processing. This process sequence warrants an invariant amount of metal intermixed with Si in the substrate surface region independent of the initial metal thickness, thereby leading to a self-limiting formation of ultrathin silicide films. The crystallographic structure, thickness, uniformity, and morphological stability of the final silicide films depend sensitively on the initial Pt fraction.

  6. Nitrogen Addition Altered the Effect of Belowground C Allocation on Soil Respiration in a Subtropical Forest.

    Science.gov (United States)

    He, Tongxin; Wang, Qingkui; Wang, Silong; Zhang, Fangyue

    2016-01-01

    The availabilities of carbon (C) and nitrogen (N) in soil play an important role in soil carbon dioxide (CO2) emission. However, the variation in the soil respiration (Rs) and response of microbial community to the combined changes in belowground C and N inputs in forest ecosystems are not yet fully understood. Stem girdling and N addition were performed in this study to evaluate the effects of C supply and N availability on Rs and soil microbial community in a subtropical forest. The trees were girdled on 1 July 2012. Rs was monitored from July 2012 to November 2013, and soil microbial community composition was also examined by phospholipid fatty acids (PLFAs) 1 year after girdling. Results showed that Rs decreased by 40.5% with girdling alone, but N addition only did not change Rs. Interestingly, Rs decreased by 62.7% under the girdling with N addition treatment. The reducing effect of girdling and N addition on Rs differed between dormant and growing seasons. Girdling alone reduced Rs by 33.9% in the dormant season and 54.8% in the growing season compared with the control. By contrast, girdling with N addition decreased Rs by 59.5% in the dormant season and 65.4% in the growing season. Girdling and N addition significantly decreased the total and bacterial PLFAs. Moreover, the effect of N addition was greater than girdling. Both girdling and N addition treatments separated the microbial groups on the basis of the first principal component through principal component analysis compared with control. This indicated that girdling and N addition changed the soil microbial community composition. However, the effect of girdling with N addition treatment separated the microbial groups on the basis of the second principal component compared to N addition treatment, which suggested N addition altered the effect of girdling on soil microbial community composition. These results suggest that the increase in soil N availability by N deposition alters the effect of

  7. Above- and below-ground methane fluxes and methanotrophic activity in a landfill-cover soil

    International Nuclear Information System (INIS)

    Highlights: ► We quantify above- and below-ground CH4 fluxes in a landfill-cover soil. ► We link methanotrophic activity to estimates of CH4 loading from the waste body. ► Methane loading and emissions are highly variable in space and time. ► Eddy covariance measurements yield largest estimates of CH4 emissions. ► Potential methanotrophic activity is high at a location with substantial CH4 loading. - Abstract: Landfills are a major anthropogenic source of the greenhouse gas methane (CH4). However, much of the CH4 produced during the anaerobic degradation of organic waste is consumed by methanotrophic microorganisms during passage through the landfill-cover soil. On a section of a closed landfill near Liestal, Switzerland, we performed experiments to compare CH4 fluxes obtained by different methods at or above the cover-soil surface with below-ground fluxes, and to link methanotrophic activity to estimates of CH4 ingress (loading) from the waste body at selected locations. Fluxes of CH4 into or out of the cover soil were quantified by eddy-covariance and static flux-chamber measurements. In addition, CH4 concentrations at the soil surface were monitored using a field-portable FID detector. Near-surface CH4 fluxes and CH4 loading were estimated from soil–gas concentration profiles in conjunction with radon measurements, and gas push–pull tests (GPPTs) were performed to quantify rates of microbial CH4 oxidation. Eddy-covariance measurements yielded by far the largest and probably most representative estimates of overall CH4 emissions from the test section (daily mean up to ∼91,500 μmol m−2 d−1), whereas flux-chamber measurements and CH4 concentration profiles indicated that at the majority of locations the cover soil was a net sink for atmospheric CH4 (uptake up to −380 μmol m−2 d−1) during the experimental period. Methane concentration profiles also indicated strong variability in CH4 loading over short distances in the cover soil, while

  8. Differences in volatile profiles of turnip plants subjected to single and dual herbivory above- and belowground.

    Science.gov (United States)

    Pierre, Prisca S; Jansen, Jeroen J; Hordijk, Cornelis A; van Dam, Nicole M; Cortesero, Anne-Marie; Dugravot, Sébastien

    2011-04-01

    Plants attacked by herbivorous insects emit volatile organic compounds that are used by natural enemies to locate their host or prey. The composition of the blend is often complex and specific. It may vary qualitatively and quantitatively according to plant and herbivore species, thus providing specific information for carnivorous arthropods. Most studies have focused on simple interactions that involve one species per trophic level, and typically have investigated the aboveground parts of plants. These investigations need to be extended to more complex networks that involve multiple herbivory above- and belowground. A previous study examined whether the presence of the leaf herbivore Pieris brassicae on turnip plants (Brassica rapa subsp. rapa) influences the response of Trybliographa rapae, a specialist parasitoid of the root feeder Delia radicum. It showed that the parasitoid was not attracted by volatiles emitted by plants under simultaneous attack. Here, we analyzed differences in the herbivore induced plant volatile (HIPV) mixtures that emanate from such infested plants by using Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA). This multivariate model focuses on the differences between odor blends, and highlights the relative importance of each compound in an HIPV blend. Dual infestation resulted in several HIPVs that were present in both isolated infestation types. However, HIPVs collected from simultaneously infested plants were not the simple combination of volatiles from isolated forms of above- and belowground herbivory. Only a few specific compounds characterized the odor blend of each type of damaged plant. Indeed, some compounds were specifically induced by root herbivory (4-methyltridecane and salicylaldehyde) or shoot herbivory (methylsalicylate), whereas hexylacetate, a green leaf volatile, was specifically induced after dual herbivory. It remains to be determined whether or not these minor quantitative variations, within the

  9. Carbon allocation belowground in Pinus pinaster using stable carbon isotope pulse labeling technique

    Science.gov (United States)

    Dannoura, M.; Bosc, A.; Chipeaux, C.; Sartore, M.; Lambrot, C.; Trichet, P.; Bakker, M.; Loustau, D.; Epron, D.

    2010-12-01

    Carbon allocation belowground competes with aboveground growth and biomass production. In the other hand, it contributes to resource acquisition such as nutrient, water and carbon sequestration in soil. Thus, a better characterization of carbon flow from plant to soil and its residence time within each compartment is an important issue for understanding and modeling forest ecosystem carbon budget. 13C pulse labeling of whole crown was conducted at 4 seasons to study the fate of assimilated carbon by photosynthesis into the root on 12 year old Pinus pinaster planted in the INRA domain of Pierroton. Maritime pine is the most widely planted species in South-West Europe. Stem, root and soil CO2 effluxes and their isotope composition were measured continuously by tunable diode laser absorption spectroscopy with a trace gas analyzer (TGA 100A; Campbell Scientific) coupled to flow-through chambers. 13CO2 recovery and peak were observed in respiration of each compartment after labeling. It appeared sequentially from top of stem to bottom, and to coarse root. The maximum velocity of carbon transfer was calculated as the difference in time lag of recovery between two positions on the trunk or on the root. It ranged between 0.08-0.2 m h-1 in stem and between 0.04-0.12 m h-1 in coarse root. This velocity was higher in warmer season, and the difference between time lag of recovery and peak increased after first frost. Photosynthates arrived underground 1.5 to 5 days after labeling, at similar time in soil CO2 effluxes and coarse root respiration. 0.08-1.4 g of carbon was respired per tree during first 20 days following labeling. It presented 0.6 -10% of 13C used for labeling and it is strongly related to seasons. The isotope signal was detected in fine root organs and microbial biomass by periodical core sampling. The peak was observed 6 days after labeling in early summer while it was delayed more than 10 days in autumn and winter with less amount of carbon allocated

  10. High Energy Limit of the Two-Electron Photoionization Processes in the Helium-Like Systems

    International Nuclear Information System (INIS)

    We present the analysis of double photoionization and of ionization accompanied by excitation of the helium atom and helium-like ions. The high-energy limit corresponding to the ultrarelativistic energies transferred to the atom is considered. The cross-sections ratios are expressed through certain integral parameters of the wave function of the initial state. The calculations with the wave function obtained earlier by Correlation Function Hyperspherical Harmonic Method are carried out. The dependence of the relative role of the quasifree mechanism on the nuclear charge Z in ionization of the ground state and of the excited n's states is analyzed

  11. Large graph limit for an SIR process in random network with heterogeneous connectivity

    CERN Document Server

    Decreusefond, Laurent; Moyal, Pascal; Tran, Viet Chi

    2010-01-01

    We consider an SIR epidemic model propagating on a Configuration Model network, where the degree distribution of the vertices is given and where the edges are randomly matched. The evolution of the epidemic is summed up into three measure-valued equations that describe the degrees of the susceptible individuals and the number of edges from an infectious or removed individual to the set of susceptibles. These three degree distributions are sufficient to describe the course of the disease. The limit in large population is investigated. As a corollary, this provides a rigorous proof of the equations obtained by Volz (2008).

  12. Limitation of the EIA Process for the assessment of nuclear fuel waste disposal in Canada

    International Nuclear Information System (INIS)

    The Canadian environmental impact assessment process for the Nuclear Fuel Waste Management and Disposal Concept was completed in 1994. Almost four years later, in February 1998, the Review Panel released its report. The viewpoints of those who participated in the assessment process is archived in the thousands of pages of hearing testimony, meeting transcripts and written briefs. One of the most contentious issues raised, and one that continues to plague management in Canada, is the debate surrounding how the problem of NFW waste management should be defined. The purpose of this paper is to critically assess the problem frame of the Canadian NFW management disposal concept EIS. This will be accomplished through an analysis of stakeholder participation and views, and through an evaluation of the range and nature of the information considered legitimate or constrained in the Canadian process

  13. Limitation of the EIA Process for the assessment of nuclear fuel waste disposal in Canada

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, B.L.; Kuhn, R.G. [Guelph Univ., ON (Canada). Dept. of Geography

    1999-12-01

    The Canadian environmental impact assessment process for the Nuclear Fuel Waste Management and Disposal Concept was completed in 1994. Almost four years later, in February 1998, the Review Panel released its report. The viewpoints of those who participated in the assessment process is archived in the thousands of pages of hearing testimony, meeting transcripts and written briefs. One of the most contentious issues raised, and one that continues to plague management in Canada, is the debate surrounding how the problem of NFW waste management should be defined. The purpose of this paper is to critically assess the problem frame of the Canadian NFW management disposal concept EIS. This will be accomplished through an analysis of stakeholder participation and views, and through an evaluation of the range and nature of the information considered legitimate or constrained in the Canadian process.

  14. Stroop Dilution Revisited: Evidence for Domain-Specific, Limited-Capacity Processing

    Science.gov (United States)

    Roberts, Martha Anne; Besner, Derek

    2005-01-01

    Nine experiments show that in the context of Stroop dilution the extent to which flanking distractors are processed depends on the nature of the material at fixation. A Stroop effect is eliminated if a word or a nonword is colored and appears at fixation and the color word appears as a flanker. A Stroop effect is observed when the color carrier at…

  15. Am/Cm melter processing limitations evaluation for product loading extremes

    International Nuclear Information System (INIS)

    Six vitrification runs were conducted in the 5-inch Cylindrical Induction Melter (CIM5) to evaluate the system's ability to process potential product loading extremes that may be encountered during Am/Cm vitrification in the F-Canyon MPPF. This evaluation demonstrates the CIM5 system's ability to vitrify feed streams of the specified extremes

  16. Pre-processing SAR image stream to facilitate compression for transport on bandwidth-limited-link

    Science.gov (United States)

    Rush, Bobby G.; Riley, Robert

    2015-09-29

    Pre-processing is applied to a raw VideoSAR (or similar near-video rate) product to transform the image frame sequence into a product that resembles more closely the type of product for which conventional video codecs are designed, while sufficiently maintaining utility and visual quality of the product delivered by the codec.

  17. Ozone/electron beam process for water treatment: design, limitations and economic considerations

    International Nuclear Information System (INIS)

    Electron beam irradiation of water is the easiest way to generate OH free radicals but the efficiency of the irradiation process as advanced oxidation process (AOP) is deteriorated by reducing species formed simultaneously with the OH free radicals. Addition of ozone to the water before or during irradiation improves the efficiency essentially by converting the reducing species into OH free radicals and turning by that the irradiation process into a full AOP. The main reaction pathways of the primary species formed by the action of ionizing radiation on water in a natural groundwater with and without the presence of ozone are reviewed. Based on these data an explanation of both the dose rate effect and the ozone effect is attempted. New data is presented which illustrates the effect of alkalinity on the way in which ozone is introduced into the water, and the impact of both water matrix and chemical structure of the pollutants to the efficacy of the ozone/electron beam process. (author)

  18. Quantifying planetary limits of Earth system processes relevant to human activity using a thermodynamic view of the whole Earth system

    Science.gov (United States)

    Kleidon, Axel

    2014-05-01

    Food, water, and energy play, obviously, a central role in maintaining human activity. In this contribution, I derive estimates for the fundamental limits on the rates by which these resources are provided by Earth system processes and the levels at which these can be used sustainably. The key idea here is that these resources are, directly or indirectly, generated out of the energy associated with the absorption of sunlight, and that the energy conversions from sunlight to other forms ultimately limit the generation of these resources. In order to derive these conversion limits, we need to trace the links between the processes that generate food, water and energy to the absorption of sunlight. The resource "food" results from biomass production by photosynthesis, which requires light and a sufficient magnitude of gas exchange of carbon dioxide at the surface, which is maintained by atmospheric motion which in turn is generated out of differential radiative heating and cooling. The resource "water" is linked to hydrologic cycling, with its magnitude being linked to the latent heat flux of the surface energy balance and water vapor transport in the atmosphere which is also driven by differential radiative heating and cooling. The availability of (renewable) energy is directly related to the generation of different forms of energy of climate system processes, such as the kinetic energy of atmospheric motion, which, again, relates to radiative heating differences. I use thermodynamics and its limits as a basis to establish the planetary limits of these processes and use a simple model to derive first-order estimates. These estimates compare quite well with observations, suggesting that this thermodynamic view of the whole Earth system provides an objective, physical basis to define and quantify planetary boundaries as well as the factors that shape these boundaries.

  19. Impacts of Jatropha-based biodiesel production on above and below-ground carbon stocks: A case study from Mozambique

    International Nuclear Information System (INIS)

    The need to mitigate climate change makes production of liquid biofuels a high priority. Substituting fossil fuels by biodiesel produced from Jatropha curcas has gained widespread attention as Jatropha cultivation is claimed to offer green house gas emission reductions. Farmers respond worldwide to this increasing demand by converting forests into Jatropha, but whether Jatropha-based biodiesel offers carbon savings depends on the carbon emissions that occur when land use is changed to Jatropha. This paper provides an impact assessment of a small-scale Jatropha project in Cabo Delgado, Mozambique. The paper outlines the estimated impacts on above and below-ground carbon stocks when land use is changed to increase Jatropha production. The results show that expansion of Jatropha production will most likely lead to the conversion of miombo forest areas to Jatropha, which implies a reduction in above and below-ground carbon stocks. The carbon debts created by the land use change can be repaid by replacing fossil fuels with Jatropha-based biodiesel. A repayment time of almost two centuries is found with optimistic estimates of the carbon debt, while the use of pessimistic values results in a repayment time that approaches the millennium. - Highlights: ► Demands for biofuels make production of Jatropha-based biodiesel a priority. ► Farmers in Northern Mozambique are likely to convert un-logged miombo to Jatropha. ► Converting miombo to Jatropha creates reductions in above and below-ground carbon. ► It takes 187–966 years to repay emissions from above and below-ground carbon stocks.

  20. Influence of transplant size on the above- and below-ground performance of four contrasting field-grown lettuce cultivars

    OpenAIRE

    Kerbiriou, P.J.; Stomph, T.J.; Lammerts van Bueren, E.T.; Struik, P.C.

    2013-01-01

    Background and aims: Modern lettuce cultivars underperform under conditions of variable temporal and spatial resource availability, common in organic or low-input production systems. Information is scarce on the impact of below-ground traits on such resource acquisition and performance of field-grown lettuce; exploring genetic variation in such traits might contribute to strategies to select for robust cultivars, i.e., cultivars that perform well in the field, even under stress. Methods: To i...

  1. Effects of Manipulated Above- and Belowground Organic Matter Input on Soil Respiration in a Chinese Pine Plantation

    OpenAIRE

    Juan Fan; Jinsong Wang; Bo Zhao; Lianhai Wu; Chunyu Zhang; Xiuhai Zhao; Gadow, Klaus V.

    2015-01-01

    Alteration in the amount of soil organic matter input can have profound effect on carbon dynamics in forest soils. The objective of our research was to determine the response in soil respiration to above- and belowground organic matter manipulation in a Chinese pine (Pinus tabulaeformis) plantation. Five organic matter treatments were applied during a 2-year experiment: both litter removal and root trenching (LRRT), only litter removal (LR), control (CK), only root trenching (RT) and litter a...

  2. Belowground neighbor perception in Arabidopsis thaliana studied by transcriptome analysis: roots of Hieracium pilosella cause biotic stress

    OpenAIRE

    Schmid, Christoph; Bauer, Sibylle; Müller, Benedikt; Bartelheimer, Maik

    2013-01-01

    Root-root interactions are much more sophisticated than previously thought, yet the mechanisms of belowground neighbor perception remain largely obscure. Genome-wide transcriptome analyses allow detailed insight into plant reactions to environmental cues. A root interaction trial was set up to explore both morphological and whole genome transcriptional responses in roots of Arabidopsis thaliana in the presence or absence of an inferior competitor, Hieracium pilosella. Neighbor perception was ...

  3. Plasticity in above- and belowground resource acquisition traits in response to single and multiple environmental factors in three tree species

    OpenAIRE

    Freschet, Grégoire T; Bellingham, Peter J.; Lyver, Philip O'B.; Bonner, Karen I.; Wardle, David A.

    2013-01-01

    Functional trait plasticity is a major component of plant adjustment to environmental stresses. Here, we explore how multiple local environmental gradients in resources required by plants (light, water, and nutrients) and soil disturbance together influence the direction and amplitude of intraspecific changes in leaf and fine root traits that facilitate capture of these resources. We measured population-level analogous above- and belowground traits related to resource acquisition, i.e. “speci...

  4. Plasticity in above- and belowground resource acquisition traits in response to single and multiple environmental factors in three tree species.

    Science.gov (United States)

    Freschet, Grégoire T; Bellingham, Peter J; Lyver, Philip O'B; Bonner, Karen I; Wardle, David A

    2013-04-01

    Functional trait plasticity is a major component of plant adjustment to environmental stresses. Here, we explore how multiple local environmental gradients in resources required by plants (light, water, and nutrients) and soil disturbance together influence the direction and amplitude of intraspecific changes in leaf and fine root traits that facilitate capture of these resources. We measured population-level analogous above- and belowground traits related to resource acquisition, i.e. "specific leaf area"-"specific root length" (SLA-SRL), and leaf and root N, P, and dry matter content (DMC), on three dominant understory tree species with contrasting carbon and nutrient economics across 15 plots in a temperate forest influenced by burrowing seabirds. We observed similar responses of the three species to the same single environmental influences, but partially species-specific responses to combinations of influences. The strength of intraspecific above- and belowground trait responses appeared unrelated to species resource acquisition strategy. Finally, most analogous leaf and root traits (SLA vs. SRL, and leaf versus root P and DMC) were controlled by contrasting environmental influences. The decoupled responses of above- and belowground traits to these multiple environmental factors together with partially species-specific adjustments suggest complex responses of plant communities to environmental changes, and potentially contrasting feedbacks of plant traits with ecosystem properties. We demonstrate that despite the growing evidence for broadly consistent resource-acquisition strategies at the whole plant level among species, plants also show partially decoupled, finely tuned strategies between above- and belowground parts at the intraspecific level in response to their environment. This decoupling within species suggests a need for many species-centred ecological theories on how plants respond to their environments (e.g. competitive/stress-tolerant/ruderal and

  5. Release from belowground enemies and shifts in root traits as interrelated drivers of alien plant invasion success : a hypothesis

    OpenAIRE

    Dawson, W.

    2015-01-01

    Abstract Our understanding of the interrelated mechanisms driving plant invasions, such as the interplay between enemy release and resource‐acquisition traits, is biased by an aboveground perspective. To address this bias, I hypothesize that plant release from belowground enemies (especially fungal pathogens) will give invasive plant species a fitness advantage in the alien range, via shifts in root traits (e.g., increased specific root length and branching intensity) that increase resource u...

  6. Testing the Paradox of Enrichment along a Land Use Gradient in a Multitrophic Aboveground and Belowground Community

    OpenAIRE

    Meyer, K. M.; M. Vos; Mooij, W.M.; Hol, W.H.G.; Termorshuizen, A.J.; van der Putten, W.H.

    2012-01-01

    In the light of ongoing land use changes, it is important to understand how multitrophic communities perform at different land use intensities. The paradox of enrichment predicts that fertilization leads to destabilization and extinction of predatorprey systems. We tested this prediction for a land use intensity gradient from natural to highly fertilized agricultural ecosystems. We included multiple aboveground and belowground trophic levels and land use-dependent searching effici...

  7. Release from belowground enemies and shifts in root traits as interrelated drivers of alien plant invasion success: a hypothesis.

    Science.gov (United States)

    Dawson, Wayne

    2015-10-01

    Our understanding of the interrelated mechanisms driving plant invasions, such as the interplay between enemy release and resource-acquisition traits, is biased by an aboveground perspective. To address this bias, I hypothesize that plant release from belowground enemies (especially fungal pathogens) will give invasive plant species a fitness advantage in the alien range, via shifts in root traits (e.g., increased specific root length and branching intensity) that increase resource uptake and competitive ability compared to native species in the alien range, and compared to plants of the invader in its native range. Such root-trait changes could be ecological or evolutionary in nature. I explain how shifts in root traits could occur as a consequence of enemy release and contribute to invasion success of alien plants, and how they could be interrelated with other potential belowground drivers of invasion success (allelopathy, mutualist enhancement). Finally, I outline the approaches that could be taken to test whether belowground enemy release results in increased competitive ability and nutrient uptake by invasive alien plants, via changes in root traits in the alien range. PMID:26668717

  8. A hybrid model for mapping relative differences in belowground biomass and root: Shoot ratios using spectral reflectance, foliar N and plant biophysical data within coastal marsh

    Science.gov (United States)

    Jessica L. O'Connell; Byrd, Kristin B.; Maggi Kelly

    2015-01-01

    Broad-scale estimates of belowground biomass are needed to understand wetland resiliency and C and N cycling, but these estimates are difficult to obtain because root:shoot ratios vary considerably both within and between species. We used remotely-sensed estimates of two aboveground plant characteristics, aboveground biomass and % foliar N to explore biomass allocation in low diversity freshwater impounded peatlands (Sacramento-San Joaquin River Delta, CA, USA). We developed a hybrid modeling approach to relate remotely-sensed estimates of % foliar N (a surrogate for environmental N and plant available nutrients) and aboveground biomass to field-measured belowground biomass for species specific and mixed species models. We estimated up to 90% of variation in foliar N concentration using partial least squares (PLS) regression of full-spectrum field spectrometer reflectance data. Landsat 7 reflectance data explained up to 70% of % foliar N and 67% of aboveground biomass. Spectrally estimated foliar N or aboveground biomass had negative relationships with belowground biomass and root:shoot ratio in both Schoenoplectus acutus and Typha, consistent with a balanced growth model, which suggests plants only allocate growth belowground when additional nutrients are necessary to support shoot development. Hybrid models explained up to 76% of variation in belowground biomass and 86% of variation in root:shoot ratio. Our modeling approach provides a method for developing maps of spatial variation in wetland belowground biomass.

  9. Psychophysical Estimates of Frequency Discrimination: More than Just Limitations of Auditory Processing

    OpenAIRE

    Beate Sabisch; Benjamin Weiss; Barry, Johanna G.

    2013-01-01

    Efficient auditory processing is hypothesized to support language and literacy development. However, behavioral tasks used to assess this hypothesis need to be robust to non-auditory specific individual differences. This study compared frequency discrimination abilities in a heterogeneous sample of adults using two different psychoacoustic task designs, referred to here as: 2I_6A_X and 3I_2AFC designs. The role of individual differences in nonverbal IQ (NVIQ), socioeconomic status (SES) and m...

  10. Consolidating soil carbon turnover models by improved estimates of belowground carbon input

    Science.gov (United States)

    Taghizadeh-Toosi, Arezoo; Christensen, Bent T.; Glendining, Margaret; Olesen, Jørgen E.

    2016-01-01

    World soil carbon (C) stocks are third only to those in the ocean and earth crust, and represent twice the amount currently present in the atmosphere. Therefore, any small change in the amount of soil organic C (SOC) may affect carbon dioxide (CO2) concentrations in the atmosphere. Dynamic models of SOC help reveal the interaction among soil carbon systems, climate and land management, and they are also frequently used to help assess SOC dynamics. Those models often use allometric functions to calculate soil C inputs in which the amount of C in both above and below ground crop residues are assumed to be proportional to crop harvest yield. Here we argue that simulating changes in SOC stocks based on C input that are proportional to crop yield is not supported by data from long-term experiments with measured SOC changes. Rather, there is evidence that root C inputs are largely independent of crop yield, but crop specific. We discuss implications of applying fixed belowground C input regardless of crop yield on agricultural greenhouse gas mitigation and accounting. PMID:27580672

  11. Above- and Belowground Biomass Models for Trees in the Miombo Woodlands of Malawi

    Directory of Open Access Journals (Sweden)

    Daud J. Kachamba

    2016-02-01

    Full Text Available In this study we present general (multiple tree species from several sites above- and belowground biomass models for trees in the miombo woodlands of Malawi. Such models are currently lacking in the country. The modelling was based on 74 trees comprising 33 different species with diameters at breast height (dbh and total tree height (ht ranging from 5.3 to 2 cm and from 3.0 to 25.0 m, respectively. Trees were collected from four silvicultural zones covering a wide range of conditions. We tested different models including dbh, ht and wood specific gravity ( ρ as independent variables. We evaluated model performance using pseudo-R2, root mean square error (RMSE, a covariance matrix for the parameter estimates, mean prediction error (MPE and relative mean prediction error (MPE%. Computation of MPE% was based on leave-one-out cross-validation. Values of pseudo-R2 and MPE% ranged 0.82–0.97 and 0.9%–2.8%, respectively. Model performance indicated that the models can be used over a wide range of geographical and ecological conditions in Malawi.

  12. Plant species distribution along environmental gradient: do belowground interactions with fungi matter?

    Directory of Open Access Journals (Sweden)

    Loïc ePellissier

    2013-12-01

    Full Text Available The distribution of plants along environmental gradients is constrained by abiotic and biotic factors. Cumulative evidence attests of the impact of abiotic factors on plant distributions, but only few studies discuss the role of belowground communities. Soil fungi, in particular, are thought to play an important role in how plant species assemble locally into communities. We first review existing evidence, and then test the effect of the number of soil fungal operational taxonomic units (OTUs on plant species distributions using a recently collected dataset of plant and metagenomic information on soil fungi in the Western Swiss Alps. Using species distribution models, we investigated whether the distribution of individual plant species is correlated to the number of OTUs of two important soil fungal classes known to interact with plants: the Glomeromycetes, that are obligatory symbionts of plants, and the Agaricomycetes, that may be facultative plant symbionts, pathogens, or wood decayers. We show that including the fungal richness information in the models of plant species distributions improves predictive accuracy. Number of fungal OTUs is especially correlated to the distribution of high elevation plant species. We suggest that high elevation soil show greater variation in fungal assemblages that may in turn impact plant turnover among communities. We finally discuss how to move beyond correlative analyses, through the design of field experiments manipulating plant and fungal communities along environmental gradients.

  13. Consolidating soil carbon turnover models by improved estimates of belowground carbon input.

    Science.gov (United States)

    Taghizadeh-Toosi, Arezoo; Christensen, Bent T; Glendining, Margaret; Olesen, Jørgen E

    2016-01-01

    World soil carbon (C) stocks are third only to those in the ocean and earth crust, and represent twice the amount currently present in the atmosphere. Therefore, any small change in the amount of soil organic C (SOC) may affect carbon dioxide (CO2) concentrations in the atmosphere. Dynamic models of SOC help reveal the interaction among soil carbon systems, climate and land management, and they are also frequently used to help assess SOC dynamics. Those models often use allometric functions to calculate soil C inputs in which the amount of C in both above and below ground crop residues are assumed to be proportional to crop harvest yield. Here we argue that simulating changes in SOC stocks based on C input that are proportional to crop yield is not supported by data from long-term experiments with measured SOC changes. Rather, there is evidence that root C inputs are largely independent of crop yield, but crop specific. We discuss implications of applying fixed belowground C input regardless of crop yield on agricultural greenhouse gas mitigation and accounting. PMID:27580672

  14. Picturing Adoption of Below-Ground Biodiversity Technologies among Smallholder Farmers around Mabira Forest, Uganda

    Directory of Open Access Journals (Sweden)

    Isabirye, BE.

    2010-01-01

    Full Text Available Faced with a multitude of soil and water amendment technologies, farmers have the task of choosing the technologies to adopt for ensuring subsistence and income sustainability. In 2008, a study to characterize the farmers was conducted around Mabira Forest, to assess the adoption of soil technologies fostering Belowground Biodiversity (BGBD. Eighty-four households (38 participating and 46 non-participants from four villages were randomly selected and interviewed. Results showed that the adoption pattern was significantly driven by farm size, labor, household size, age and wealth status of the house. Also important were farm location, gender of household head, primary occupation, soil and water conservation technologies training, land tenure, and social capital. For the few current adopters, there was a perceived increase in labor demand but overall productivity was higher, partly resulting from increased crop productivity due to soil fertility enhancement and soil structure modification. It is therefore concluded that, around Mabira forest, BGBD technologies will be adopted by farming households with sufficient land, labor and social capital.

  15. Quantifying below-ground nitrogen of legumes: Optimizing procedures for 15N shoot-labelling

    International Nuclear Information System (INIS)

    Quantifying below-ground nitrogen (N) of legumes is fundamental to understanding their effects on soil mineral N fertility and on the N economies of following or companion crops in legume-based rotations. Methodologies based on 15N-labelling of whole plants with subsequent measurement of 15N in recovered plant parts and in the root-zone soil have proved promising. We report four glasshouse experiments with objectives to develop appropriate protocols for in situ 15N labelling of four pulses, faba bean (Vicia faba), chickpea (Cicer arietinum), mung bean (Vigna radiata) and pigeon pea (Cajanus cajan). Treatments included 15N-urea concentration, feeding technique, leaflet/petiole position, and frequency of feeding. Nitrogen-15-labelling via the leaf-flap was best for faba bean, mung and pigeon pea, whilst petiole feeding was best for chickpea, in all cases using 0.2-mL volumes of 0.5% urea (98 atom% 15N excess). The implications of uneven enrichment of the nodulated roots because of effects of the 15N-depleted nodules when calculating root-derived N in soil are discussed. (author)

  16. Nutrient limitation on ecosystem productivity and processes of mature and old-growth subtropical forests in China.

    Directory of Open Access Journals (Sweden)

    Enqing Hou

    Full Text Available Nitrogen (N is considered the dominant limiting nutrient in temperate regions, while phosphorus (P limitation frequently occurs in tropical regions, but in subtropical regions nutrient limitation is poorly understood. In this study, we investigated N and P contents and N:P ratios of foliage, forest floors, fine roots and mineral soils, and their relationships with community biomass, litterfall C, N and P productions, forest floor turnover rate, and microbial processes in eight mature and old-growth subtropical forests (stand age >80 yr at Dinghushan Biosphere Reserve, China. Average N:P ratios (mass based in foliage, litter (L layer and mixture of fermentation and humus (F/H layer, and fine roots were 28.3, 42.3, 32.0 and 32.7, respectively. These values are higher than the critical N:P ratios for P limitation proposed (16-20 for foliage, ca. 25 for forest floors. The markedly high N:P ratios were mainly attributed to the high N concentrations of these plant materials. Community biomass, litterfall C, N and P productions, forest floor turnover rate and microbial properties were more strongly related to measures of P than N and frequently negatively related to the N:P ratios, suggesting a significant role of P availability in determining ecosystem production and productivity and nutrient cycling at all the study sites except for one prescribed disturbed site where N availability may also be important. We propose that N enrichment is probably a significant driver of the potential P limitation in the study area. Low P parent material may also contribute to the potential P limitation. In general, our results provided strong evidence supporting a significant role for P availability, rather than N availability, in determining ecosystem primary productivity and ecosystem processes in subtropical forests of China.

  17. Kappa Distribution in a Homogeneous Medium: Adiabatic Limit of a Super-diffusive Process?

    Science.gov (United States)

    Roth, I.

    2015-12-01

    The classical statistical theory predicts that an ergodic, weakly interacting system like charged particles in the presence of electromagnetic fields, performing Brownian motions (characterized by small range deviations in phase space and short-term microscopic memory), converges into the Gibbs-Boltzmann statistics. Observation of distributions with a kappa-power-law tails in homogeneous systems contradicts this prediction and necessitates a renewed analysis of the basic axioms of the diffusion process: characteristics of the transition probability density function (pdf) for a single interaction, with a possibility of non-Markovian process and non-local interaction. The non-local, Levy walk deviation is related to the non-extensive statistical framework. Particles bouncing along (solar) magnetic field with evolving pitch angles, phases and velocities, as they interact resonantly with waves, undergo energy changes at undetermined time intervals, satisfying these postulates. The dynamic evolution of a general continuous time random walk is determined by pdf of jumps and waiting times resulting in a fractional Fokker-Planck equation with non-integer derivatives whose solution is given by a Fox H-function. The resulting procedure involves the known, although not frequently used in physics fractional calculus, while the local, Markovian process recasts the evolution into the standard Fokker-Planck equation. Solution of the fractional Fokker-Planck equation with the help of Mellin transform and evaluation of its residues at the poles of its Gamma functions results in a slowly converging sum with power laws. It is suggested that these tails form the Kappa function. Gradual vs impulsive solar electron distributions serve as prototypes of this description.

  18. Minkowski space is locally the Noldus limit of Poisson process causets

    Science.gov (United States)

    Cristina, Jan

    2016-09-01

    A Poisson process {P}λ on {{{R}}}d with causal structure inherited from the the usual Minkowski metric on {{{R}}}d has a normalised discrete causal distance {D}λ (x,y) given by the height of the longest causal chain normalised by {λ }1/d{c}d. We prove that {P}λ restricted to a compact set Q converges in probability in the sense of Noldus (2004 Class. Quantum Grav. 21 839–50) to Q with the Minkowski metric.

  19. Investigation of Coupled Processes and Impact of High Temperature Limits in Argillite Rock

    International Nuclear Information System (INIS)

    The focus of research within the UFD Campaign is on repository-induced interactions that may affect the key safety characteristics of an argillaceous rock. These include thermal-hydrological-mechanical-chemical (THMC) process interactions that occur as a result of repository construction and waste emplacement. Some of the key questions addressed in this report include the development of fracturing in the excavation damaged zone (EDZ) and THMC effects on the near-field argillaceous rock and buffer minerals and petrophysical characteristics, particularly the impacts of induced temperature rise caused by waste heat.

  20. On control of loading process up to the limit load in Hencky plasticity

    Czech Academy of Sciences Publication Activity Database

    Sysala, Stanislav

    Agora : University of Jyväskylä, 2014 - (Neittaanmäki, P.; Repin, S.; Tuovien, T.), s. 84-87 ISBN 978-951-39-5621-9. ISSN 1456-4351. - (Reports of the Department of Mathematical Information Technology. Series A Collections. No. A 1/2014). [International Conference for Mathematical Modelling and Optimization in Mechanics. Jyväskylä (FI), 06.03.2014-07.03.2014] R&D Projects: GA MŠk ED1.1.00/02.0070 Institutional support: RVO:68145535 Keywords : Hencky plasticity * loading process * discretization * nonlinear models Subject RIV: BA - General Mathematics

  1. Investigation of Coupled Processes and Impact of High Temperature Limits in Argillite Rock

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Liange [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rutqvist, Jonny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kim, Kunhwi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Houseworth, Jim [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-07-01

    The focus of research within the UFD Campaign is on repository-induced interactions that may affect the key safety characteristics of an argillaceous rock. These include thermal-hydrological-mechanical-chemical (THMC) process interactions that occur as a result of repository construction and waste emplacement. Some of the key questions addressed in this report include the development of fracturing in the excavation damaged zone (EDZ) and THMC effects on the near-field argillaceous rock and buffer minerals and petrophysical characteristics, particularly the impacts of induced temperature rise caused by waste heat.

  2. Conversion of organic micropollutants with limited bromate formation during the Peroxone process in drinking water treatment

    OpenAIRE

    Knol, A.H.; Lekkerkerker-Teunissen, K.; C. J. Houtman; Scheideler, J.; Ried, A.; Van Dijk, J. C.

    2015-01-01

    Advanced oxidation with O3/H2O2 (peroxone) is conducted on pilot plant scale on pre-treated Meuse river water to investigate the conversion of organic micropollutants (OMPs) and the formation of bromate. Fourteen selected model compounds are dosed to the pre-treated river water on a regular basis to assess the efficiency of the peroxone process and to establish the influence of the water matrix. The height of the ozone dose is the main factor in the conversion of t...

  3. Quasi-Resonant Nonlinear Absorption for Optical Power Limiting: solgel-Processed Er(3+)-Doped Multicomponent Silica Glass.

    Science.gov (United States)

    Maciel, G S; Biswas, A; Friend, C S; Prasad, P N

    2000-05-20

    We demonstrate optical power limiting by what we believe to be a new mechanism of nonlinear absorption, which involves a quasi-resonant ground-state absorption that is either phonon assisted or assisted by the presence of defect sites (tail absorption). Such a mechanism provides high transmittance at low intensity yet optical limiting under cw conditions. The sample used was a novel solgel-processed Er(3+)-doped multicomponent silica glass. In this system the nonlinear absorption process is achieved because the resonant excited-state ((4)I(13/2) ? (4)S(3/2)) absorption cross section is larger than the quasi-resonant ground-state ((4)I(15/2) ? (4)I(9/2)) absorption cross section. PMID:18345156

  4. Possibilities and limitations of digital speckle pattern interferometry in the analysis of corrosion processes in metallic materials

    International Nuclear Information System (INIS)

    Digital speckle pattern interferometry (DSPI) has been applied to evaluate corrosion levels in the surface of a copper electrode while immersed in a 0.1M CuSO4 solution. The corrosion process has been induced by applying an electrical current between two such metallic Cu electrodes. The corrosion process can induce changes not only in the electrode surface but also in the solution refractive index. Different DSPI experimental setups have been proposed for evaluating both contributions and removing the refractive index contribution. Surface changes on the electrode as measured by DSPI have been compared with topography data obtained by confocal microscopy. Confocal microscopy data have shown that the corrosion process occurs at small scales. The possibilities and limitations of DSPI for measuring such non-uniform corrosion processes have been analyzed. (paper)

  5. Psychophysical Estimates of Frequency Discrimination: More than Just Limitations of Auditory Processing

    Directory of Open Access Journals (Sweden)

    Beate Sabisch

    2013-07-01

    Full Text Available Efficient auditory processing is hypothesized to support language and literacy development. However, behavioral tasks used to assess this hypothesis need to be robust to non-auditory specific individual differences. This study compared frequency discrimination abilities in a heterogeneous sample of adults using two different psychoacoustic task designs, referred to here as: 2I_6A_X and 3I_2AFC designs. The role of individual differences in nonverbal IQ (NVIQ, socioeconomic status (SES and musical experience in predicting frequency discrimination thresholds on each task were assessed using multiple regression analyses. The 2I_6A_X task was more cognitively demanding and hence more susceptible to differences specifically in SES and musical training. Performance on this task did not, however, relate to nonword repetition ability (a measure of language learning capacity. The 3I_2AFC task, by contrast, was only susceptible to musical training. Moreover, thresholds measured using it predicted some variance in nonword repetition performance. This design thus seems suitable for use in studies addressing questions regarding the role of auditory processing in supporting language and literacy development.

  6. Harmonisation of standards related to limiting chemical risk associated with work processes.

    Science.gov (United States)

    Bostan, Ionel

    2013-01-01

    The presented paper tackles the issue of risk factors specific to work processes that involve the presence of chemicals. The reason that supports the present approach is the fact that the risks most likely to affect health in the workplace have been lately associated with the exposure of workers engaged in industrial activities to aggressive chemical agents. In order to tackle this problem, we shall resort to the normative regulations that have been adjusted upon Romania's inclusion in the European Union. The harmonization and alignment of the national standards--applied to the work systems that make use of various chemical substances likely to affect the health of the human resource--to the European guidelines and regulations has brought about a significant improvement in workplace security practices. Consequently, the arguments and demonstrations in the presented study are based on elements of the European acquis and the Romanian regulations which are all related to the chemical risk factors generated by harmful chemicals, or the potentially accident-prone properties of the substances used in work processes. PMID:24069850

  7. Generalized renewal process for analysis of repairable systems with limited failure experience

    International Nuclear Information System (INIS)

    Repairable systems can be brought to one of possible states following a repair. These states are: 'as good as new', 'as bad as old', 'better than old but worse than new', 'better than new', and 'worse than old'. The probabilistic models traditionally used to estimate the expected number of failures account for the first two states, but they do not properly apply to the last three, which are more realistic in practice. In this paper, a robust solution to a probabilistic model that is applicable to all of the five after repair states, called generalized renewal process (GRP), is presented. This research demonstrates that the GRP offers a general approach to modeling repairable systems and discusses application of the classical maximum likelihood and Bayesian approaches to estimation of the GRP parameters. This paper also presents a review of the traditional approaches to the analysis of repairable systems as well as some applications of the GRP and shows that they are subsets of the GRP approach. It is shown that the proposed GRP solution accurately describes the failure data, even when a small amount of failure data is available. Recent emphasis in the use of performance-based analysis in operation and regulation of complex engineering systems (such as those in space and process industries) require use of sound models for predicting failures based on the past performance of the systems. The GRP solution in this paper is a promising and efficient approach for such performance-based applications

  8. Study of the $W^+ W^- \\gamma$ Process and Limits on Anomalous Quartic Gauge Boson Couplings at LEP

    CERN Document Server

    Achard, P; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, V P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Buijs, A; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo-Llatas, M; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J A; De Asmundis, R; Déglon, P L; Debreczeni, J; Degré, A; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Van Dierendonck, D N; Dionisi, C; Dittmar, Michael; Doria, A; Dova, M T; Duchesneau, D; Duinker, P; Echenard, B; Eline, A; El-Mamouni, H; Engler, A; Eppling, F J; Ewers, A; Extermann, Pierre; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisher, W; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Hu, Y; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Levchenko, P M; Li Chuan; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mans, J; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Ofierzynski, R A; Organtini, G; Palomares, C; Pandoulas, D; Paolucci, P; Paramatti, R; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pioppi, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Pothier, J; Prokofiev, D O; Prokofev, D; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Roth, S; Rosenbleck, C; Roux, B; Rubio, Juan Antonio; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S V; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Ulbricht, J; Valente, E; Van de Walle, R T; Veszpremi, V; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Violini, P; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wallraff, W; Wang, X L; Wang, Z M; Weber, M; Wienemann, P; Wilkens, H; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zilizi, G; Zimmermann, B; Zöller, M

    2002-01-01

    The process e+e- --> W+ W- \\gamma is studied using the data collected by the L3 detector at LEP. New results, corresponding to an integrated luminosity of 427.4 pb-1 at centre-of-mass energies from 192~GeV to 207~GeV, are presented. The W+W-\\gamma cross sections are measured to be in agreement with Standard Model expectations. No hints of anomalous quartic gauge boson couplings are observed. Limits at 95\\% confidence level are derived using also the process e+e- --> \

  9. Berry-Esseen's central limit theorem for non-causal linear processes in Hilbert space

    CERN Document Server

    Machkouri, Mohamed EL

    2010-01-01

    Let $H$ be a real separable Hilbert space and $(a_k)_{k\\in\\mathbb{Z}}$ a sequence of bounded linear operators from $H$ to $H$. We consider the linear process $X$ defined for any $k$ in $\\mathbb{Z}$ by $X_k=\\sum_{j\\in\\mathbb{Z}}a_j(\\varepsilon_{k-j})$ where $(\\varepsilon_k)_{k\\in\\mathbb{Z}}$ is a sequence of i.i.d. centered $H$-valued random variables. We investigate the rate of convergence in the CLT for $X$ and in particular we obtain the usual Berry-Esseen's bound provided that $\\sum_{j\\in\\mathbb{Z}}\\vert j\\vert\\|a_j\\|_{\\mathcal{L}(H)}<+\\infty$ and $\\varepsilon_0$ belongs to $L_H^{\\infty}$.

  10. Copper accumulation in vineyard soils: Rhizosphere processes and agronomic practices to limit its toxicity.

    Science.gov (United States)

    Brunetto, Gustavo; Bastos de Melo, George Wellington; Terzano, Roberto; Del Buono, Daniele; Astolfi, Stefania; Tomasi, Nicola; Pii, Youry; Mimmo, Tanja; Cesco, Stefano

    2016-11-01

    Viticulture represents an important agricultural practice in many countries worldwide. Yet, the continuous use of fungicides has caused copper (Cu) accumulation in soils, which represent a major environmental and toxicological concern. Despite being an important micronutrient, Cu can be a potential toxicant at high concentrations since it may cause morphological, anatomical and physiological changes in plants, decreasing both food productivity and quality. Rhizosphere processes can, however, actively control the uptake and translocation of Cu in plants. In particular, root exudates affecting the chemical, physical and biological characteristics of the rhizosphere, might reduce the availability of Cu in the soil and hence its absorption. In addition, this review will aim at discussing the advantages and disadvantages of agronomic practices, such as liming, the use of pesticides, the application of organic matter, biochar and coal fly ashes, the inoculation with bacteria and/or mycorrhizal fungi and the intercropping, in alleviating Cu toxicity symptoms. PMID:27513550

  11. Scaling Limit for the Space-Time Covariance of the Stationary Totally Asymmetric Simple Exclusion Process

    Science.gov (United States)

    Ferrari, Patrik L.; Spohn, Herbert

    2006-07-01

    The totally asymmetric simple exclusion process (TASEP) on the one-dimensional lattice with the Bernoulli ρ measure as initial conditions, 0GUE Tracy-Widom distribution. The family [InlineMediaObject not available: see fulltext.] of distribution functions have been obtained before by Baik and Rains in the context of the PNG model with boundary sources, which requires the asymptotics of a Riemann-Hilbert problem. In our work we arrive at [InlineMediaObject not available: see fulltext.] through the asymptotics of a Fredholm determinant. [InlineMediaObject not available: see fulltext.] is simply related to the scaling function for the space-time covariance of the stationary TASEP, equivalently to the asymptotic transition probability of a single second class particle.

  12. Conditional limit theorems for intermediately subcritical branching processes in random environment

    CERN Document Server

    Afanasyev, Valeriy; Kersting, Götz; Vatutin, Vladimir

    2011-01-01

    For a branching process in random environment it is assumed that the offspring distribution of the individuals varies in a random fashion, independently from one generation to the other. For the subcritical regime a kind of phase transition appears. In this paper we study the intermediately subcritical case, which constitutes the borderline within this phase transition. We study the asymptotic behavior of the survival probability. Next the size of the population and the shape of the random environment conditioned on non-extinction is examined. Finally we show that conditioned on non-extinction periods of small and large population sizes alternate. This kind of 'bottleneck' behavior appears under the annealed approach only in the intermediately subcritical case.

  13. Combination process of limited filamentous bulking and nitrogen removal via nitrite for enhancing nitrogen removal and reducing aeration requirements.

    Science.gov (United States)

    Guo, Jianhua; Peng, Yongzhen; Yang, Xiong; Gao, Chundi; Wang, Shuying

    2013-03-01

    Limited filamentous bulking (LFB) activated sludge process was proposed by Guo et al. (2010) to increase the removal of tiny suspended particulates in the clarifier and reduce aeration energy consumption. However, when the use of LFB process, ammonium removal efficiency would be compromised due to low dissolved oxygen (DO). In this study, the combination process of nitrogen removal via nitrite and LFB was achieved to enhance nitrogen removal and reduce aeration energy consumption by controlling low DO levels (0.5-1.0 mg L(-1)) in a lab-scale anoxic-oxic reactor (V=66 L) treating real domestic wastewater at room temperature. Above 85% of nitrite accumulation ratio was steadily maintained during continuous operation period. The combined process improved the total nitrogen (TN) removal by about 20% in comparison to the traditional process via the nitrate pathway, and also reduced the specific aeration energy consumption by 35%. COD, ammonium and TN removal efficiencies were up to 86%, 94% and 75%, respectively. The process proved effective in achieving a steady LFB state, whereby sludge volume index between 150 and 250 mL g(-1) was sustained for long-term operation. The microbial community structure was analyzed by fluorescence in situ hybridization, which indicated ammonia-oxidizing bacteria out-competed nitrite-oxidizing bacteria. Moreover, the filaments Type 0041 and Microthrix parvicella proliferated with limited abundance. The results indicated the combination process of LFB and nitrogen removal via nitrite under low DO was a feasible solution for saving energy and enhancing nitrogen removal when treating domestic wastewater. PMID:23305749

  14. LIMITED RUN PRODUCTION USING ALUMIDE® TOOLING FOR THE PLASTIC INJECTION MOULDING PROCESS#1

    Directory of Open Access Journals (Sweden)

    J. Combrinck

    2012-01-01

    Full Text Available

    ENGLISH ABSTRACT: Existing techniques for the production of conventional steel tooling for plastic injection moulding are expensive and time-consuming. As a result, many new products often do not advance beyond the prototype stage. This paper describes an investigation into the possibility of using laser sintered Alumide® (an aluminium-filled nylon material in a novel alternative process for producing hybrid rapid tooling tools. Initial experiments performed by researchers at the Central University of Technology have shown excellent results. An Alumide® tool can be manufactured in a shorter time and at a significantly lower cost than the same size direct metal laser sintered tool.

    AFRIKAANSE OPSOMMING: Bestaande tegnieke vir die vervaardiging van konvensionele staal gietstukke vir die plastiek spuit-giet proses is duur en tydrowend. Die gevolg hiervan is dat baie nuwe produkte nie verder as die prototipe stadium vorder nie. Hierdie artikel ondersoek die moontlikheid om laser gesinterde Alumide® (aluminium gevulde nylon materiaal in ’n nuwe benadering as ’n alternatiewe proses vir die vervaardiging van snel hibried-gietvorms te gebruik. Aanvanklike eksperimente uitgevoer deur navorsers aan die Sentrale Universiteit vir Tegnologie het uitstekende resultate gelewer. ’n Alumide® gietvorm kan vinniger en goedkoper vervaardig word as dieselfde grootte direk metaal gesinterde gietvorm.

  15. Silicon limitation on primary production and its destiny in Jiaozhou Bay, China. V: Silicon deficit process

    Science.gov (United States)

    Yang, Dongfang; Gao, Zhenhui; Wang, Peigang; Sun, Peiyan; Liu, Shuang

    2005-06-01

    Silicon is a necessary nutrient for diatoms, silicon uptake in diatom reproduction decreased seawater silicon content. This paper clarified the characteristics of silicon transferring in the sea, which plays an important role in phytoplankton growth, zooplankton graze and marine ecosystem. Analysis revealed that silicate is supplied by terrestrial sources, through plankton uptake, death, and eventually deposits to the sea bottom, and cannot diffuse upward. This is a general silicon deficit process. Many global marine waters showed the same silicon transfer route: land→silicon biogeochemical process→sea bottom. River flow brings abundant silicate into marine waters, silicate concentration in the waters decreased in the distance away from the river estuaries. In discussion of silicon characteristics and its transfer route, it was considred that the main factor controlling the mechanism of diatom and non-diatom red tides occurrence is silicon, and the changes in silicon source. Human activities, such as sea-route cutting by building embankment and dam, and silicon supplement by the sea, such as sandstorm, rainstorm and storm tide, have largely impaired the earth ecosystem and hugely threatened the human existence. It is suggested in this paper that man should resume the original face of the Si input into the sea to keep natural ecosystem in sustainable pattern.

  16. The processing of emotional stimuli during periods of limited attentional resources in schizophrenia.

    Science.gov (United States)

    Strauss, Gregory P; Catalano, Lauren T; Llerena, Katiah; Gold, James M

    2013-05-01

    When participants are asked to attend to two target stimuli in a rapid serial visual presentation sequence, the successful identification of the 1st target (T1) leads to transient impairment in reporting the 2nd target (T2)--this effect is known as the attentional blink (AB). In healthy individuals, this AB effect is either diminished or accentuated when emotional stimuli are presented in the T2 or T1 positions, respectively, suggesting that affective content influences bottom-up (i.e., exogenous) attention. In the current study, we conducted two separate experiments using the Emotional Attentional Blink paradigm where emotional words were presented in the T2 or T1 position to determine whether schizophrenia patients with high and low negative symptoms differ from controls in the extent to which emotional stimuli influence bottom-up attentional processes. Participants included 33 schizophrenia patients and 28 controls in Experiment 1 (T2 Task), and 30 schizophrenia patients and 24 controls in Experiment 2 (T1 Task). In both experiments, patients were divided into high (HI-NEG) and low (LOW-NEG) negative symptom subgroups using the Scale for the Assessment of Negative Symptoms. Results of Experiment 1 indicated that controls and LOW-NEG patients displayed the typical pattern of AB sparing at early lags for emotional relative to neutral words; however, HI-NEG patients showed no difference in T2 accuracy between emotional and neutral stimuli. Results of Experiment 2 indicated that controls and LOW-NEG patients displayed reduced T2 accuracy following unpleasant T1 stimuli, while HI-NEG patients showed no decrement in T2 accuracy after emotional T1s. Across both experiments, findings suggest that emotional stimuli have a bottom-up competitive advantage in LOW-NEG patients and controls; however, this bottom-up advantage is absent in HI-NEG patients. PMID:23421529

  17. PAHs in soils: Sorption versus degradation - elucidation of rate-limiting processes

    Science.gov (United States)

    Herklotz, Ilka; Gocht, Tilman; Grathwohl, Peter

    2010-05-01

    Polycyclic aromatic hydrocarbons (PAHs) belong to the class of persistent organic pollutants, and are of special interest due to their ubiquituous distribution in the environment at relatively high concentrations. Subsequent to their emmission into the environment through incomplete combustion processes of natural and anthropogenic sources (e.g. vulcano eruptions, forest fires, industry, traffic), PAHs can be transported over long distances. Following atmospheric deposition they accumulate in particular in top-soils and have been found to be stable over long periods of time (decades to centuries). Based on that this study targets on the elucidation of the long-term PAH-fate in top-soils by means of degradation experiments under well-controlled laboratory conditions with well mixed batch experiments at a water to solids ratio 10:1. From a rural site in the Black Forest Mountains, Germany, top-soil samples were taken, which contains approximately 7-8 mg Σ18 PAHs per kg soil. This soil was sieved through 2 mm to sort out stones, roots- and leaf-parts and homogenised afterwards. Within the first month of incubation a depletion of native PAHs were observed. However, an exhaustive sequential extraction using accelerated solvent extraction with 3 cycles of acteone and 4 cycles of toluene (100 bar pressure, 10 min static time, 100°C and 150°C respectively) revealed a reduced extractability of PAHs subsequent to incubation. In order to stimulate PAH degradation a second experiment with a higher water to solid ratio (1000:1) was carried out, and phenanthrene was spiked to the water phase of this set up. Results revealed a reduction of phenanthrene concentration more likely to be due to sorption rather than degradation. The set up was changed to aqueous soil solutions without soil in the batch and spiked again with phenanthrene. Degradation of phenanthrene occurred within 10 days in these batches. The experiments show that the microorganisms present in the Black Forest

  18. Above-belowground interactions govern the course and impact of biological invasions.

    Science.gov (United States)

    Vestergård, Mette; Rønn, Regin; Ekelund, Flemming

    2015-01-01

    Introduction of exotic organisms that subsequently become invasive is considered a serious threat to global biodiversity, and both scientists and nature-conservationists attempt to find explanations and means to meet this challenge. This requires a thorough analysis of the invasion phenomenon in an evolutionary and ecological context; in the case of invasive plants, we must have a major focus on above-belowground interactions. Thus, we discuss different theories that have been proposed to explain the course of invasions through interactions between plants and soil organisms. Further, a thorough analysis of invasion must include a temporal context. Invasions will typically include an initial acute phase, where the invader expands its territory and a later chronic phase where equilibrium is re-established. Many studies fail to make this distinction, which is unfortunate as it makes it impossible to thoroughly understand the invasion of focus. Thus, we claim that invasions fall into two broad categories. Some invasions irreversibly change pools and pathways of matter and energy in the invaded system; even if the abundance of the invader is reduced or it is completely removed, the system will not return to its former state. We use earthworm invasion in North America as a particular conspicuous example of invasive species that irreversibly change ecosystems. However, invasions may also be reversible, where the exotic organism dominates the system for a period, but in the longer term it either disappears, declines or its negative impact decreases. If the fundamental ecosystem structure and flows of energy and matter have not been changed, the system will return to a state not principally different from the original. PMID:25854693

  19. Study of the $e^+ e^- \\to Z \\gamma$ Process at LEP and Limits on Triple Neutral-Gauge-Boson Couplings

    CERN Document Server

    Achard, P; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, V P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo-Llatas, M; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J A; De Asmundis, R; Déglon, P L; Debreczeni, J; Degré, A; Dehmelt, K; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Dionisi, C; Dittmar, M; Doria, A; Dova, M T; Duchesneau, D; Duda, M; Echenard, B; Eline, A; El-Hage, A; El-Mamouni, H; Engler, A; Eppling, F J; Extermann, P; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, M; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, F; Fisher, P H; Fisher, W; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Hu, Y; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kräber, M H; Krämer, R W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Levtchenko, M; Levchenko, P M; Li, C; Likhoded, S; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, C; Mans, J; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Nisati, A; Novák, T; Nowak, H; Ofierzynski, R A; Organtini, G; Pal, I; Palomares, C; Paolucci, P; Paramatti, R; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pioppi, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Pothier, J; Prokofev, D; Prokofiev, D O; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosemann, C; Rosenbleck, C; Rosier-Lees, S; Roth, S; Rubio, J A; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Schäfer, C; Shchegelskii, V; Schopper, Herwig Franz; Schotanus, D J; Sciacca, C; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Son, D; Souga, C; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Ulbricht, J; Valente, E; Van de Walle, R T; Vásquez, R; Veszpremi, V; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wang, Q; Wang, X L; Wang, Z M; Weber, M; Wilkens, H; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zimmermann, B; Zöller, M

    2004-01-01

    The process e^+e^- --> Z gamma, where the Z boson decays into hadrons or neutrinos, is studied with data collected with the L3 detector at LEP at centre-of-mass energies from 189 GeV up to 209 GeV. The cross sections are measured and found to be in agreement with the Standard Model predictions. Limits on triple neutral-gauge-boson couplings, forbidden in the Standard Model at tree level, are derived. Limits on the energy scales at which the anomalous couplings could be manifest are set. They range from 0.3 TeV to 2.3 TeV depending on the new physics effect under consideration.

  20. Scaling Solution in the Large Population Limit of the General Asymmetric Stochastic Luria-Delbrück Evolution Process

    Science.gov (United States)

    Kessler, David A.; Levine, Herbert

    2015-02-01

    One of the most popular models for quantitatively understanding the emergence of drug resistance both in bacterial colonies and in malignant tumors was introduced long ago by Luria and Delbrück. Here, individual resistant mutants emerge randomly during the birth events of an exponentially growing sensitive population. A most interesting limit of this process occurs when the population size is large and mutation rates are low, but not necessarily small compared to . Here we provide a scaling solution valid in this limit, making contact with the theory of Levy -stable distributions, in particular one discussed long ago by Landau. One consequence of this association is that moments of the distribution are highly misleading as far as characterizing typical behavior. A key insight that enables our solution is that working in the fixed population size ensemble is not the same as working in a fixed time ensemble. Some of our results have been presented previously in abbreviated form [12].

  1. Extending the process limits of laser polymer welding with high-brilliance beam sources (recent status and prospects of POLYBRIGHT)

    Science.gov (United States)

    Olowinsky, A.; Boglea, A.

    2011-03-01

    Plastics play an important role in almost every facet of our lives and constitute a wide variety of products, from everyday products such as food and beverage packaging, over furniture and building materials to high tech products in the automotive, electronics, aerospace, white goods, medical and other sectors [1]. The objective of PolyBright, the European Research project on laser polymer welding, is to provide high speed and flexible laser manufacturing technology and expand the limits of current plastic part assembly. New laser polymer joining processes for optimized thermal management in combination with adapted wavelengths will provide higher quality, high processing speed up to 1 m/s and robust manufacturing processes at lower costs. Key innovations of the PolyBright project are fibre lasers with high powers up to 500 W, high speed scanning and flexible beam manipulation systems for simultaneous welding and high-resolution welding, such as dynamic masks and multi kHz scanning heads. With this initial step, PolyBright will break new paths in processing of advanced plastic products overcoming the quality and speed limitations of conventional plastic part assembly. Completely new concepts for high speed processing, flexibility and quality need to be established in combination with high brilliance lasers and related equipment. PolyBright will thus open new markets for laser systems with a short term potential of over several 100 laser installations per year and a future much larger market share in the still growing plastic market. PolyBright will hence establish a comprehensive and sustainable development activity on new high brilliance lasers that will strengthen the laser system industry.

  2. Patterns of above-and belowground biomass allocation in China’s grasslands:Evidence from individual-level observations

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Above-and belowground biomass allocation not only influences growth of individual plants,but also influences vegetation structures and functions,and consequently impacts soil carbon input as well as terrestrial ecosystem carbon cycling.However,due to sampling difficulties,a considerable amount of uncertainty remains about the root:shoot ratio(R/S),a key parameter for models of terrestrial ecosystem carbon cycling.We investigated biomass allocation patterns across a broad spatial scale.We collected data on individual plant biomass and systematically sampled along a transect across the temperate grasslands in Inner Mongolia as well as in the alpine grasslands on the Tibetan Plateau.Our results indicated that the median of R/S for herbaceous species was 0.78 in China’s grasslands as a whole.R/S was significantly higher in temperate grasslands than in alpine grasslands(0.84 vs.0.65).The slope of the allometric relationship between above-and belowground biomass was steeper for temperate grasslands than for alpine.Our results did not support the hypothesis that aboveground biomass scales isometrically with belowground biomass.The R/S in China’s grasslands was not significantly correlated with mean annual temperature(MAT) or mean annual precipitation(MAP).Moreover,comparisons of our results with previous findings indicated a large difference between R/S data from individual plants and communities.This might be mainly caused by the underestimation of R/S at the individual level as a result of an inevitable loss of fine roots and the overestimation of R/S in community-level surveys due to grazing and difficulties in identifying dead roots.Our findings suggest that root biomass in grasslands tended to have been overestimated in previous reports of R/S.

  3. Aboveground and belowground responses to nutrient additions and herbivore exclusion in Arctic tundra ecosystems in northern Alaska

    Science.gov (United States)

    Moore, J. C.; Gough, L.; Simpson, R.; Johnson, D. R.

    2011-12-01

    The Arctic has experienced significant increased regional warming over the past 30 years. Warming generally increases tundra soil nutrient availability by creating a more favorable environment for plant growth, decomposition and nutrient mineralization. Aboveground there has been a "greening" of the Arctic with increased net primary productivity (NPP), and an increase in woody vegetation. Concurrent with the changes aboveground has been an increase in root growth at lower depths and a loss of soil organic C (40 -100 g C m-2 yr-1). Given that arctic soils contain 14% of the global soil C pool, understanding the mechanisms behind shifts of this magnitude that are changing arctic soils from a net sink to a net source of atmospheric C is critical. We took an integrated multi-trophic level approach to examine how altering soil nutrients and mammalian herbivore activity affects vegetation, soil fauna, and microbial communities as well as soil physical characteristics in moist acidic (MAT) and dry heath (DH) tundra. Our work was conducted at the Arctic LTER site in northern Alaska. We sampled the nutrient (controls and annual N+P additions) and herbivore (controls and exclosures) manipulations established in 1996 after 10 years of treatment. Models that incorporated the biomass estimates from the field were used to characterize the trophic structure of the belowground food web and to estimate carbon flux among soil organisms and C-mineralization rates. Both MAT and DH exhibited significant increases in NPP and root growth and changes in vegetation structure with transitions from a mixed community to deciduous shrubs in MAT and from lichens to grasses and shrubs in DH, with nutrient additions and herbivore exclosures. Belowground responses to the treatments were dependent on ecosystem type, but exposed alterations in trophic structure that included changes in microbial biomass, the establishment of microbivorous enchytreaids, increases in root-feeding nematodes, and

  4. Seasonal variations of belowground carbon transfer assessed by in situ 13CO2 pulse labelling of trees

    Directory of Open Access Journals (Sweden)

    L. Barthes

    2011-05-01

    Full Text Available Soil CO2 efflux is the main source of CO2 from forest ecosystems and it is tightly coupled to the transfer of recent photosynthetic assimilates belowground and their metabolism in roots, mycorrhiza and rhizosphere microorganisms feeding on root-derived exudates. The objective of our study was to assess patterns of belowground carbon allocation among tree species and along seasons. Pure 13CO2 pulse labelling of the entire crown of three different tree species (beech, oak and pine was carried out at distinct phenological stages. Excess 13C in soil CO2 efflux was tracked using tuneable diode laser absorption spectrometry to determine time lags between the start of the labelling and the appearance of 13C in soil CO2 efflux and the amount of 13C allocated to soil CO2 efflux. Isotope composition (δ13C of CO2 respired by fine roots and soil microbes was measured at several occasions after labelling, together with δ13C of bulk root tissue and microbial carbon. Time lags ranged from 0.5 to 1.3 days in beech and oak and were longer in pine (1.6–2.7 days during the active growing season, more than 4 days during the resting season, and the transfer of C to the microbial biomass was as fast as to the fine roots. The amount of 13C allocated to soil CO2 efflux was estimated from a compartment model. It varied between 1 and 21 % of the amount of 13CO2 taken up by the crown, depending on the species and the season. While rainfall exclusion that moderately decreased soil water content did not affect the pattern of carbon allocation to soil CO2 efflux in beech, seasonal patterns of carbon allocation belowground differed markedly between species, with pronounced seasonal variations in pine and beech. In beech, it may reflect competition with the strength of other sinks (aboveground growth in late spring and storage in late summer that were not observed in oak. We report a fast transfer of recent photosynthates to the mycorhizosphere and we conclude that the

  5. The relative importance of above- versus belowground competition for tree growth during early succession of a tropical moist forest

    DEFF Research Database (Denmark)

    Breugel, Michiel van; van Breugel, Paulo; Jansen, Patrick A.;

    2012-01-01

    Competition between neighboring plants plays a major role in the population dynamics of tree species in the early phases of humid tropical forest succession. We evaluated the relative importance of above-versus below-ground competition during the first years of old-field succession on soil with low...... Trichospermum mexicanum, two pioneer species that dominate the secondary forests in the study region, varied with the abundance and size of neighboring trees in 1-2 year old secondary vegetation. We found that local neighborhood basal area varied 10-fold (3 to 30 cm(2) m(-2)) and explained most of the variation...

  6. The Impact of Different Physical Processes on the Statistics of Lyman-limit and Damped Lyman-alpha Absorbers

    CERN Document Server

    Altay, Gabriel; Schaye, Joop; Booth, C M; Vecchia, Claudio Dalla

    2013-01-01

    We compute the z = 3 neutral hydrogen column density distribution function f(NHI) for 19 simulations drawn from the OWLS project using a post-processing correction for self-shielding calculated with full radiative transfer of the ionising background radiation. We investigate how different physical processes and parameters affect the abundance of Lyman-limit systems (LLSs) and damped Lyman-alpha absorbers (DLAs) including: i) metal-line cooling; ii) the efficiency of feedback from SNe and AGN; iii) the effective equation of state for the ISM; iv) cosmological parameters; v) the assumed star formation law and; vi) the timing of hydrogen reionization . We find that the normalisation and slope, D = d log10 f /d log10 NHI, of f(NHI) in the LLS regime are robust to changes in these physical processes. Among physically plausible models, f(NHI) varies by less than 0.2 dex and D varies by less than 0.18 for LLSs. This is primarily due to the fact that these uncertain physical processes mostly affect star-forming gas w...

  7. Parameter estimation and long-term process simulation of a biogas reactor operated under trace elements limitation

    International Nuclear Information System (INIS)

    Highlights: • Estimation of ADM1 parameter uncertainty by nonlinear, correlated parameter analysis. • Unbounded confidence regions were obtained for single hydrolysis rate constants. • ADM1 carbohydrates were divided into a slowly and readily degradable part. • Bioavailability of trace metals explained discrepancies between modeled and measured data. - Abstract: The Anaerobic Digestion Model No. 1 (ADM1) was modified to describe the long-term process stability of a two-stage agricultural biogas system operated for 494 days with a mono-substrate. The ADM1 model fraction for carbohydrates was divided into a slowly and readily degradable part. Significant different hydrolysis rate constants were found for proteins and single fractions of carbohydrates in batch experiments. Degradation of starch, xylan (hemicellulose), cellulose and zein (protein) were modeled with first order hydrolysis rate coefficients of 1.20 d−1, 0.70 d−1, 0.18 d−1 and 0.30 d−1, respectively. While the hydrolysis rate coefficients found in batch experiments could be used for predicting continuous process data, the statistically calculated confidence regions (nonlinear parameter estimation) showed that the upper limits were unbounded. Single discrepancies between measured and modeled process data of the two-stage pilot system could be explained by the lack of bioavailability of trace elements. Addition of iron, as Fe(III)Cl3, allowed stable process conditions for an organic loading rate (OLR) up to 2.5 gVS L−1 d−1. Additional supplement of trace elements was necessary for process operation at OLRs above 2.5 gVS L−1 d−1

  8. Belowground neighbor perception in Arabidopsis thaliana studied by transcriptome analysis: roots of Hieracium pilosella cause biotic stress.

    Science.gov (United States)

    Schmid, Christoph; Bauer, Sibylle; Müller, Benedikt; Bartelheimer, Maik

    2013-01-01

    Root-root interactions are much more sophisticated than previously thought, yet the mechanisms of belowground neighbor perception remain largely obscure. Genome-wide transcriptome analyses allow detailed insight into plant reactions to environmental cues. A root interaction trial was set up to explore both morphological and whole genome transcriptional responses in roots of Arabidopsis thaliana in the presence or absence of an inferior competitor, Hieracium pilosella. Neighbor perception was indicated by Arabidopsis roots predominantly growing away from the neighbor (segregation), while solitary plants placed more roots toward the middle of the pot. Total biomass remained unaffected. Database comparisons in transcriptome analysis revealed considerable similarity between Arabidopsis root reactions to neighbors and reactions to pathogens. Detailed analyses of the functional category "biotic stress" using MapMan tools found the sub-category "pathogenesis-related proteins" highly significantly induced. A comparison to a study on intraspecific competition brought forward a core of genes consistently involved in reactions to neighbor roots. We conclude that beyond resource depletion roots perceive neighboring roots or their associated microorganisms by a relatively uniform mechanism that involves the strong induction of pathogenesis-related proteins. In an ecological context the findings reveal that belowground neighbor detection may occur independently of resource depletion, allowing for a time advantage for the root to prepare for potential interactions. PMID:23967000

  9. Nitrogen mediates above-ground effects of ozone but not below-ground effects in a rhizomatous sedge

    Energy Technology Data Exchange (ETDEWEB)

    Jones, M.L.M., E-mail: lj@ceh.ac.u [Centre for Ecology and Hydrology (CEH), Environment Centre Wales, Deiniol Road, Bangor, LL57 2UW Wales (United Kingdom); Hodges, G. [AMEC, Earth and Environmental UK Ltd, Unit 1, Trinity Place, Thames St, Weybridge, Surrey KT13 8JB (United Kingdom); Mills, G. [Centre for Ecology and Hydrology (CEH), Environment Centre Wales, Deiniol Road, Bangor, LL57 2UW Wales (United Kingdom)

    2010-02-15

    Ozone and atmospheric nitrogen are co-occurring pollutants with adverse effects on natural grassland vegetation. Plants of the rhizomatous sedge Carex arenaria were exposed to four ozone regimes representing increasing background concentrations (background-peak): 10-30, 35-55, 60-80 and 85-105 ppb ozone at two nitrogen levels: 12 and 100 kg N ha{sup -1} yr{sup -1}. Ozone increased the number and proportion of senesced leaves, but not overall leaf number. There was a clear nitrogen x ozone interaction with high nitrogen reducing proportional senescence in each treatment and increasing the ozone dose (AOT40) at which enhanced senescence occurred. Ozone reduced total biomass due to significant effects on root biomass. There were no interactive effects on shoot:root ratio. Rhizome tissue N content was increased by both nitrogen and ozone. Results suggest that nitrogen mediates above-ground impacts of ozone but not impacts on below-ground resource translocation. This may lead to complex interactive effects between the two pollutants on natural vegetation. - Nitrogen alters threshold of ozone-induced senescence, but not below-ground resource allocation.

  10. Materials and process limitations for thermoplastic composite materials for wind turbine blades - preform of prepregs and commingled yarns

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakaran, R.T.D.

    2011-07-01

    Wind turbine blades are produced based on the current thermoset resin technology, but thermoplastics can offer better potential to become the future blade materials. One of the most important goals when designing larger blade systems is to keep the blade weight under control. Thermoplastic materials offer weight saving similar to thermosets, apart from many other benefits like design flexibility, durability, cost, weight saving, and performance advantageous to the wind industry. In the current research study a detailed discussion on material and process limitations such as thermoplastic prepreg tapes and commingled yams are presented in terms of their properties and available forms in the current markets. A critical review of thermoplastics discussed in the context of turbine blades applications. (Author)

  11. Silicon limitation on primary production and its destiny in Jiaozhou Bay, China Ⅵ: The ecological variation process of the phytoplankton

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The combination effect of light, water temperature and nutrients on phytoplankton growth in Jiaozhou Bay is studied in this paper. The order of importance of the influence on phytoplankton growth is determined as nutrients, water temperature, and light. The influence of these factors unveiled the mechanism of the influence, and revealed the variation process of the nutrients limiting phytoplankton primary production, and of the water temperature influencing the phytoplankton reproduction capacity, and hence influencing the structure of phytoplankton assemblage. Temporal and spatial quantification shows different stages of the influence by water temperature and nutrients on the phytoplankton growth. Moreover, the authors expatiated the ideal state of the phytoplankton growth and the reason of red tide occurrence. People should consider in their activity the input of nutrient Si first, and then the variation of water temperature, advocating sustainable development manner.

  12. Beyond roots alone: Novel methodologies for analyzing complex soil and minirhizotron imagery using image processing and GIS tools

    Science.gov (United States)

    Silva, Justina A.

    Quantifying belowground dynamics is critical to our understanding of plant and ecosystem function and belowground carbon cycling, yet currently available tools for complex belowground image analyses are insufficient. We introduce novel techniques combining digital image processing tools and geographic information systems (GIS) analysis to permit semi-automated analysis of complex root and soil dynamics. We illustrate methodologies with imagery from microcosms, minirhizotrons, and a rhizotron, in upland and peatland soils. We provide guidelines for correct image capture, a method that automatically stitches together numerous minirhizotron images into one seamless image, and image analysis using image segmentation and classification in SPRING or change analysis in ArcMap. These methods facilitate spatial and temporal root and soil interaction studies, providing a framework to expand a more comprehensive understanding of belowground dynamics.

  13. Multivariate detection limits of on-line NIR model for extraction process of chlorogenic acid from Lonicera japonica.

    Science.gov (United States)

    Wu, Zhisheng; Sui, Chenglin; Xu, Bing; Ai, Lu; Ma, Qun; Shi, Xinyuan; Qiao, Yanjiang

    2013-04-15

    A methodology is proposed to estimate the multivariate detection limits (MDL) of on-line near-infrared (NIR) model in Chinese Herbal Medicines (CHM) system. In this paper, Lonicera japonica was used as an example, and its extraction process was monitored by on-line NIR spectroscopy. Spectra of on-line NIR could be collected by two fiber optic probes designed to transmit NIR radiation by a 2mm-flange. High performance liquid chromatography (HPLC) was used as a reference method to determine the content of chlorogenic acid in the extract solution. Multivariate calibration models were carried out including partial least squares regression (PLS) and interval partial least-squares (iPLS). The result showed improvement of model performance: compared with PLS model, the root mean square errors of prediction (RMSEP) of iPLS model decreased from 0.111mg to 0.068mg, and the R(2) parameter increased from 0.9434 to 0.9801. Furthermore, MDL values were determined by a multivariate method using the type of errors and concentration ranges. The MDL of iPLS model was about 14ppm, which confirmed that on-line NIR spectroscopy had the ability to detect trace amounts of chlorogenic acid in L. japonica. As a result, the application of on-line NIR spectroscopy for monitoring extraction process in CHM could be very encouraging and reliable. PMID:23376723

  14. Soil respiration in Tibetan alpine grasslands: belowground biomass and soil moisture, but not soil temperature, best explain the large-scale patterns.

    Directory of Open Access Journals (Sweden)

    Yan Geng

    Full Text Available The Tibetan Plateau is an essential area to study the potential feedback effects of soils to climate change due to the rapid rise in its air temperature in the past several decades and the large amounts of soil organic carbon (SOC stocks, particularly in the permafrost. Yet it is one of the most under-investigated regions in soil respiration (Rs studies. Here, Rs rates were measured at 42 sites in alpine grasslands (including alpine steppes and meadows along a transect across the Tibetan Plateau during the peak growing season of 2006 and 2007 in order to test whether: (1 belowground biomass (BGB is most closely related to spatial variation in Rs due to high root biomass density, and (2 soil temperature significantly influences spatial pattern of Rs owing to metabolic limitation from the low temperature in cold, high-altitude ecosystems. The average daily mean Rs of the alpine grasslands at peak growing season was 3.92 µmol CO(2 m(-2 s(-1, ranging from 0.39 to 12.88 µmol CO(2 m(-2 s(-1, with average daily mean Rs of 2.01 and 5.49 µmol CO(2 m(-2 s(-1 for steppes and meadows, respectively. By regression tree analysis, BGB, aboveground biomass (AGB, SOC, soil moisture (SM, and vegetation type were selected out of 15 variables examined, as the factors influencing large-scale variation in Rs. With a structural equation modelling approach, we found only BGB and SM had direct effects on Rs, while other factors indirectly affecting Rs through BGB or SM. Most (80% of the variation in Rs could be attributed to the difference in BGB among sites. BGB and SM together accounted for the majority (82% of spatial patterns of Rs. Our results only support the first hypothesis, suggesting that models incorporating BGB and SM can improve Rs estimation at regional scale.

  15. Soil respiration in Tibetan alpine grasslands: belowground biomass and soil moisture, but not soil temperature, best explain the large-scale patterns.

    Science.gov (United States)

    Geng, Yan; Wang, Yonghui; Yang, Kuo; Wang, Shaopeng; Zeng, Hui; Baumann, Frank; Kuehn, Peter; Scholten, Thomas; He, Jin-Sheng

    2012-01-01

    The Tibetan Plateau is an essential area to study the potential feedback effects of soils to climate change due to the rapid rise in its air temperature in the past several decades and the large amounts of soil organic carbon (SOC) stocks, particularly in the permafrost. Yet it is one of the most under-investigated regions in soil respiration (Rs) studies. Here, Rs rates were measured at 42 sites in alpine grasslands (including alpine steppes and meadows) along a transect across the Tibetan Plateau during the peak growing season of 2006 and 2007 in order to test whether: (1) belowground biomass (BGB) is most closely related to spatial variation in Rs due to high root biomass density, and (2) soil temperature significantly influences spatial pattern of Rs owing to metabolic limitation from the low temperature in cold, high-altitude ecosystems. The average daily mean Rs of the alpine grasslands at peak growing season was 3.92 µmol CO(2) m(-2) s(-1), ranging from 0.39 to 12.88 µmol CO(2) m(-2) s(-1), with average daily mean Rs of 2.01 and 5.49 µmol CO(2) m(-2) s(-1) for steppes and meadows, respectively. By regression tree analysis, BGB, aboveground biomass (AGB), SOC, soil moisture (SM), and vegetation type were selected out of 15 variables examined, as the factors influencing large-scale variation in Rs. With a structural equation modelling approach, we found only BGB and SM had direct effects on Rs, while other factors indirectly affecting Rs through BGB or SM. Most (80%) of the variation in Rs could be attributed to the difference in BGB among sites. BGB and SM together accounted for the majority (82%) of spatial patterns of Rs. Our results only support the first hypothesis, suggesting that models incorporating BGB and SM can improve Rs estimation at regional scale. PMID:22509373

  16. Beyond the futility argument: the fair process approach and time-limited trials for managing dialysis conflict.

    Science.gov (United States)

    Rinehart, Ann

    2013-11-01

    Futility is an ancient concept arising from Greek mythology that was resurrected for its medical application in the 1980s with the proliferation of many lifesaving technologies, including dialysis and renal transplantation. By that time, the domineering medical paternalism that characterized the pre-1960s physician-patient relationship morphed into assertive patient autonomy, and some patients began to claim the right to demand aggressive, high-technology interventions, despite physician disapproval. To counter this power struggle, the establishment of a precise definition of futility offered hope for a futility policy that would allow physicians to justify withholding or withdrawing treatment, despite patient and family objections. This article reviews the various attempts made to define medical futility and describes their limited applicability to dialysis. When futility concerns arise, physicians should recognize the opportunity to address conflict, using best practice communication skills. Physicians would also benefit from understanding the ethical principles of respect for patient autonomy, beneficence, nonmaleficence, justice, and professional integrity that underlie medical decision-making. Also reviewed is the use of a fair process approach or time-limited trial when conflict resolution cannot be achieved. These topics are addressed in the Renal Physician Association's clinical practice guideline Shared Decision-Making in the Appropriate Initiation and Withdrawal from Dialysis, with which nephrologists should be well versed. A case presentation of intractable calciphylaxis in a new dialysis patient illustrates the pitfalls of physicians not fully appreciating the ethics of medical decision-making and failing to use effective conflict management approaches in the clinical practice guideline. PMID:23868900

  17. Application of Computer-Aided Tomography (CT) Technology to Visually Compare Belowground Components of Salt Marshes in Jamaica Bay and Long Island, New York

    Science.gov (United States)

    Using CT imaging, we found that rapidly deteriorating marshes in Jamaica Bay had significantly less belowground mass and abundance of coarse roots and rhizomes at depth (< 10 cm) compared to more stable areas in the Jamaica Bay Estuary. In addition, the rhizome diameters and pea...

  18. Impacts of an invasive non-native annual weed, Impatiens glandulifera, on above- and below-ground invertebrate communities in the United Kingdom.

    Science.gov (United States)

    Tanner, Robert A; Varia, Sonal; Eschen, René; Wood, Suzy; Murphy, Sean T; Gange, Alan C

    2013-01-01

    Vegetation community composition and the above- and below-ground invertebrate communities are linked intrinsically, though few studies have assessed the impact of non-native plants on both these parts of the community together. We evaluated the differences in the above- (foliage- and ground-dwelling) and below-ground invertebrate communities in nine uninvaded plots and nine plots invaded by the annual invasive species Impatiens glandulifera, in the UK during 2007 and 2008. Over 139,000 invertebrates were identified into distinct taxa and categorised into functional feeding groups. The impact of I. glandulifera on the vegetation and invertebrate community composition was evaluated using multivariate statistics including principal response curves (PRC) and redundancy analysis (RDA). In the foliage-dwelling community, all functional feeding groups were less abundant in the invaded plots, and the species richness of Coleoptera and Heteroptera was significantly reduced. In the ground-dwelling community, herbivores, detritivores, and predators were all significantly less abundant in the invaded plots. In contrast, these functional groups in the below-ground community appeared to be largely unaffected, and even positively associated with the presence of I. glandulifera. Although the cover of I. glandulifera decreased in the invaded plots in the second year of the study, only the below-ground invertebrate community showed a significant response. These results indicate that the above- and below-ground invertebrate communities respond differently to the presence of I. glandulifera, and these community shifts can potentially lead to a habitat less biologically diverse than surrounding native communities; which could have negative impacts on higher trophic levels and ecosystem functioning. PMID:23840648

  19. Impacts of an invasive non-native annual weed, Impatiens glandulifera, on above- and below-ground invertebrate communities in the United Kingdom.

    Directory of Open Access Journals (Sweden)

    Robert A Tanner

    Full Text Available Vegetation community composition and the above- and below-ground invertebrate communities are linked intrinsically, though few studies have assessed the impact of non-native plants on both these parts of the community together. We evaluated the differences in the above- (foliage- and ground-dwelling and below-ground invertebrate communities in nine uninvaded plots and nine plots invaded by the annual invasive species Impatiens glandulifera, in the UK during 2007 and 2008. Over 139,000 invertebrates were identified into distinct taxa and categorised into functional feeding groups. The impact of I. glandulifera on the vegetation and invertebrate community composition was evaluated using multivariate statistics including principal response curves (PRC and redundancy analysis (RDA. In the foliage-dwelling community, all functional feeding groups were less abundant in the invaded plots, and the species richness of Coleoptera and Heteroptera was significantly reduced. In the ground-dwelling community, herbivores, detritivores, and predators were all significantly less abundant in the invaded plots. In contrast, these functional groups in the below-ground community appeared to be largely unaffected, and even positively associated with the presence of I. glandulifera. Although the cover of I. glandulifera decreased in the invaded plots in the second year of the study, only the below-ground invertebrate community showed a significant response. These results indicate that the above- and below-ground invertebrate communities respond differently to the presence of I. glandulifera, and these community shifts can potentially lead to a habitat less biologically diverse than surrounding native communities; which could have negative impacts on higher trophic levels and ecosystem functioning.

  20. Seasonal variations of belowground carbon transfer assessed by in situ 13CO2 pulse labelling of trees

    Directory of Open Access Journals (Sweden)

    P. Priault

    2011-02-01

    Full Text Available Soil CO2 efflux is the main source of CO2 from forest ecosystems and it is tightly coupled to the transfer of recent photosynthetic assimilates belowground and their metabolism in roots, mycorrhiza and rhizosphere microorganisms feeding on root-derived exudates. The objectives of our study were to assess patterns of belowground carbon allocation among tree species and along seasons. Pure 13CO2 pulse labelling of the entire crown of three different tree species (beech, oak and pine was carried out at distinct phenological stages. Excess 13C in soil CO2 efflux was tracked using tunable diode laser absorption spectrometry to determine time lags between the start of the labelling and the appearance of 13C in soil CO2 efflux and the amount of 13C allocated to soil CO2 efflux. Isotope composition (δ13C of CO2 respired by fine roots and soil microbes was measured at several occasions after labelling, together with δ13C of bulk root tissue and microbial carbon. Time lags ranged from 0.5 to 1.3 days in beech and oak and were longer in pine (1.6–2.7 days during the active growing season, more than 4 days during the resting season, and the transfer of C to the microbial biomass was as fast as to the fine roots. The amount of 13C allocated to soil CO2 efflux was estimated from a compartment model. Seasonal patterns of carbon allocation to soil CO2 efflux differed markedly between species, with pronounced seasonal variations in pine and beech. In beech, it may reflect competition with other sinks (aboveground growth in late spring and storage in late summer that were not observed in oak.

  1. Linking soil moisture with chemical quality of soil organic matter to evaluate belowground carbon storage in savannas

    Science.gov (United States)

    Mladenov, N.; Okin, G. S.; O'Donnell, F. C.; D'Odorico, P.; Meyer, T.; Dintwe, K.; Caylor, K. K.; Kim, S.; Ringrose, S.

    2010-12-01

    Belowground carbon storage is a function of soil organic carbon content and soil respiration, and both of these factors are profoundly influenced by soil moisture. Soil organic matter (SOM) comprises a broad pool, including labile plant residues, microbial biomass and more biologically recalcitrant humic substances. Water extractable organic carbon (WEOC) represents the active fraction of SOM that becomes available for decomposition during wetting, and the chemical quality of WEOC provides information about its biodegradability. Under conditions of decreasing soil moisture, both the SOC pool and soil respiration are expected to decrease, but depending on the rates of both the net effect on soil carbon storage is unclear. Therefore, in the semiarid savanna ecosystem, the influence of WEOC chemical quality on SOM mineralization and soil respiration may be extremely important. In this study, we address this notion by comparing SOC content, C:N ratios, and SOM quality at two savanna sites in the Kalahari Desert, Botswana with contrasting soil moisture content. We present new results showing higher SOC content and more humified SOC in the wetter savanna site. Evidence from UV-vis absorbance and fluorescence spectroscopy also suggests that at the drier site, there is great contrast with respect to the degree of humification in soils beneath and between canopy than at the wetter site. The WEOC at both sites also contains a substantial amount of amino acid-like fluorescence (Fig. 1) that may be derived from microbial biomass. Our SOM characterization at these two sites is being applied in SOC dynamics model validation. We will also discuss the implications of our findings for belowground C sequestration in light of projected climate change for the region. Fig 1. Representative fluorescence excitation emission matrices from WEOC under A. mellifera canopy (top) and bare ground (bottom) at the dry savanna site.

  2. Design and performance of combined infrared canopy and belowground warming in the B4WarmED (Boreal Forest Warming at an Ecotone in Danger) experiment.

    Science.gov (United States)

    Rich, Roy L; Stefanski, Artur; Montgomery, Rebecca A; Hobbie, Sarah E; Kimball, Bruce A; Reich, Peter B

    2015-06-01

    Conducting manipulative climate change experiments in complex vegetation is challenging, given considerable temporal and spatial heterogeneity. One specific challenge involves warming of both plants and soils to depth. We describe the design and performance of an open-air warming experiment called Boreal Forest Warming at an Ecotone in Danger (B4WarmED) that addresses the potential for projected climate warming to alter tree function, species composition, and ecosystem processes at the boreal-temperate ecotone. The experiment includes two forested sites in northern Minnesota, USA, with plots in both open (recently clear-cut) and closed canopy habitats, where seedlings of 11 tree species were planted into native ground vegetation. Treatments include three target levels of plant canopy and soil warming (ambient, +1.7°C, +3.4°C). Warming was achieved by independent feedback control of voltage input to aboveground infrared heaters and belowground buried resistance heating cables in each of 72-7.0 m(2) plots. The treatments emulated patterns of observed diurnal, seasonal, and annual temperatures but with superimposed warming. For the 2009 to 2011 field seasons, we achieved temperature elevations near our targets with growing season overall mean differences (∆Tbelow ) of +1.84°C and +3.66°C at 10 cm soil depth and (∆T(above) ) of +1.82°C and +3.45°C for the plant canopies. We also achieved measured soil warming to at least 1 m depth. Aboveground treatment stability and control were better during nighttime than daytime and in closed vs. open canopy sites in part due to calmer conditions. Heating efficacy in open canopy areas was reduced with increasing canopy complexity and size. Results of this study suggest the warming approach is scalable: it should work well in small-statured vegetation such as grasslands, desert, agricultural crops, and tree saplings (<5 m tall). PMID:25640748

  3. Linkages Between Biotic and Abiotic Belowground Processes in a Mojave Desert Ecosystem: Responses to Experimental Nitrogen and Water Additions

    Science.gov (United States)

    Verburg, P. S.; Marion, G. M.; Young, A. C.; Glanzmann, I.; Stevenson, B.; Arnone, J. A.; Nowak, R. S.

    2007-05-01

    Fine roots play a critical role in nutrient acquisition and water uptake. Yet it is unclear how fine roots in arid environments respond to increased nitrogen deposition and rainfall, two important global change factors in arid lands in the southwestern United States. In addition it is unclear how changes in root activity may impact soil CO2 concentrations, an important parameter affecting carbonate dynamics. We measured fine root length density (RLD) and soil CO2 concentrations for two years in experimentally manipulated plots in a Mojave Desert ecosystem. The study was conducted at the Mojave Global Change Facility located at the Nevada Test Site 60 miles northwest of Las Vegas. The treatments included: 1) three 25 mm water additions during the summer, 2) one nitrogen addition in the fall equivalent to 40 kg per hectare per year, 3) a combined water and nitrogen addition and, 4) untreated controls. Root data were collected using minirhizotron imaging approximately every 90 days underneath shrubs and intershrub areas. Soil CO2 concentrations were collected at the same sampling times and locations at 10, 40 and 90 cm depth using gas wells. The RLD showed clear seasonal patterns with the fastest increase in RLD occurring between February and April. During the winter the increase in RLD was higher underneath shrubs than in intershrub areas but during the summer months increases in RLD were similar under shrubs and in intershrub areas. Water additions slightly increased root mortality during the summer but this increase in mortality was not large enough to cause consistent differences in RLD between control and irrigated plots. Nitrogen addition had no effect on root dynamics in any of the plots. In contrast to RLD, irrigation consistently increased soil CO2 concentrations at all depths during the summer even when roots were not actively growing anymore. We speculate that the increased mortality under irrigation causes increased heterotrophic respiration which may explain increases soil CO2 concentrations during the summer. These higher soil CO2 concentrations may result in increased carbonate dissolution especially in combination with increased soil moisture. Preliminary simulations using the CALGYP model indicate however that this increased dissolution will not result in changes in ecosystem C budgets since carbonates are likely to precipitate again deeper in the soil.

  4. Short- and longterm impacts of Acacia longifolia invasion on belowground processes of a Mediterranean coastal dune ecosystem

    DEFF Research Database (Denmark)

    Marchante, Elizabete; Kjøller, Annelise; Struwe, Sten; Freitas, Helena

    2008-01-01

    Many coastal dune ecosystems in Portugal are invaded by the leguminous tree Acacia longifolia (Andrews) Willd. This exotic species was first introduced over one hundred years ago in an effort to mitigate dune erosion and loss of coastal landscapes. However, since then A. longifolia has spread to...

  5. Self-limiting adsorption of SiCl2H2 and its application to the layer-by-layer photochemical process

    International Nuclear Information System (INIS)

    Adsorption of SiCl2H2 on the Ge(100) clean surface is investigated by X-ray photoelectron spectroscopy and thermal desorption spectrum measurement. It is concluded that the adsorption is self-limiting at temperatures below 350degC, and that the surface is reactivated by synchrotron radiation. The sequential processes of self-limiting adsorption of SiCl2H2 and synchrotron radiation are promising for development of Si atomic layer epitaxy. (author)

  6. The Limitations of International Law Expertise : War Amongst Peacemakers: The Juba Peace Process as Battleground for International Lawyer's Biases (name of panel)

    OpenAIRE

    Wrange, Pål

    2013-01-01

    This paper reflects on the limitations of international law expertise, using examples from the Juba peace process on the civil war in Uganda. In peace negotiations (like in all situations), the international law expert must acknowledge the limitations of international law. International law is one-dimensional, and cannot take all relevant factors into account. Further, in any given situation, there will be some regimes and some rules of international law that are more effective than others, b...

  7. Below-ground biomass production and allometric relationships of eucalyptus coppice plantation in the central highlands of Madagascar

    International Nuclear Information System (INIS)

    Short rotations of Eucalyptus plantations under coppice regime are extensively managed for wood production in Madagascar. Nevertheless, little is known about their biomass production and partitioning and their potential in terms of carbon sequestration. If above-ground biomass (AGB) can be estimated based on established allometric relations, below-ground (BGB) estimates are much less common. The aim of this work was to develop allometric equations to estimate biomass of these plantations, mainly for the root components. Data from 9 Eucalyptus robusta stands (47–87 years of plantation age, 3–5 years of coppice-shoot age) were collected and analyzed. Biomass of 3 sampled trees per stand was determined destructively. Dry weight of AGB components (leaves, branches and stems) were estimated as a function of basal area of all shoots per stump and dry weight for BGB components (mainly stump, coarse root (CR) and medium root (MR)) were estimated as a function of stump circumference. Biomass was then computed using allometric equations from stand inventory data. Stand biomass ranged from 102 to 130 Mg ha−1 with more than 77% contained in the BGB components. The highest dry weight was allocated in the stump and in the CR (51% and 42% respectively) for BGB parts and in the stem (69%) for AGB part. Allometric relationships developed herein could be applied to other Eucalyptus plantations which present similar stand density and growing conditions; anyhow, more is needed to be investigated in understanding biomass production and partitioning over time for this kind of forest ecosystem. -- Highlights: ► We studied the potential of old eucalyptus coppices in Madagascar to mitigate global warming. ► Biomass measurement, mainly for below-ground BGB (stump, coarse-medium-and fine roots) was provided. ► BGB allometry relationships for short rotation forestry under coppice were established. ► BGB were found to be important with their 102-130MgC ha-1 (<77% of the C in the

  8. Allometry and partitioning of above- and below-ground biomass in farmed eucalyptus species dominant in Western Kenyan agricultural landscapes

    International Nuclear Information System (INIS)

    Farmers in developing countries are one of the world's largest and most efficient producers of sequestered carbon. However, measuring, monitoring and verifying how much carbon trees in smallholder farms are removing from the atmosphere has remained a great challenge in developing nations. Devising a reliable way for measuring carbon associated with trees in agricultural landscapes is essential for helping smallholder farmers benefit from emerging carbon markets. This study aimed to develop biomass equations specific to dominant eucalyptus species found in agricultural landscapes in Western Kenya. Allometric relationships were developed by regressing diameter at breast height (DBH) alone or DBH in combination with height, wood density or crown area against the biomass of 48 trees destructively sampled from a 100 km2 site. DBH alone was a significant predictor variable and estimated aboveground biomass (AGB) with over 95% accuracy. The stems, branches and leaves formed up to 74, 22 and 4% of AGB, respectively, while belowground biomass (BGB) of the harvested trees accounted for 21% of the total tree biomass, yielding an overall root-to-shoot ratio (RS) of 0.27, which varied across tree size. Total tree biomass held in live Eucalyptus trees was estimated to be 24.4 ± 0.01 Mg ha−1, equivalent to 11.7 ± 0.01 Mg of carbon per hectare. The equations presented provide useful tools for estimating tree carbon stocks of Eucalyptus in agricultural landscapes for bio-energy and carbon accounting. These equations can be applied to Eucalyptus in most agricultural systems with similar agro-ecological settings where tree growth parameters would fall within ranges comparable to the sampled population. -- Highlights: ► Equation with DBH alone estimated aboveground biomass with about 95% accuracy. ► Local generic equations overestimated above- and below-ground biomass by 10 and 48%. ► Height, wood density and crown area data did not improve model accuracy. ► Stems, roots

  9. Nitrogen Addition and Warming Independently Influence the Belowground Micro-Food Web in a Temperate Steppe

    NARCIS (Netherlands)

    Li, Q.; Bai, H.; Liang, W.; Xia, J.; Wan, S.; Putten, van der W.H.

    2013-01-01

    Climate warming and atmospheric nitrogen (N) deposition are known to influence ecosystem structure and functioning. However, our understanding of the interactive effect of these global changes on ecosystem functioning is relatively limited, especially when it concerns the responses of soils and soil

  10. Effects of Savanna trees on soil nutrient limitation and carbon-sequestration potential in dry season

    Science.gov (United States)

    Becker, Joscha; Gütlein, Adrian; Sierra Cornejo, Natalia; Kiese, Ralf; Hertel, Dietrich; Kuzyakov, Yakov

    2016-04-01

    Semi-arid savannah ecosystems are under strong pressure from climate and land-use changes, especially around populous areas like Mt. Kilimanjaro region. Savannah vegetation consists of grassland with isolated trees and is therefore characterized by high spatial variation of canopy cover and aboveground biomass. Both are major regulators for soil ecological parameters and soil-atmospheric trace gas exchange (CO2, N2O, CH4), especially in water limited environments. The spatial distribution of these parameters and the connection between above and belowground processes are important to understand and predict ecosystem changes and estimate its vulnerability. Our objective was to determine spatial trends and changes of soil parameters and trace-gas fluxes and relate their variability to the vegetation structure. We chose three trees from each of the two most dominant species (Acacia nilotica and Balanites aegyptiaca). For each tree, we selected transects with total nine sampling points under and outside the crown. At each sampling point we measured soil and plant biomass carbon (C) and nitrogen (N) content, δ13C, microbial biomass C and N, soil respiration, available nutrients, pH, cation exchange capacity (CEC) as well as belowground biomass, soil temperature and soil water content. Contents and stocks of C and N fractions, Ca2+, K+ and total CEC decreased up to 50% outside the crown. This was unaffected by the tree species, tree size or other tree characteristics. Water content was below the permanent wilting point and independent from tree cover. In all cases tree litter inputs had far a closer C:N ratio than C4-grass litter. Microbial C:N ratio and CO2 efflux was about 30% higher in open area and strongly dependent on mineral N availability. This indicates N limitation and low microbial C use efficiency in soil under open area. We conclude that the spatial structure of aboveground biomass in savanna ecosystems leads to a spatial redistribution of nutrient

  11. Forming Limit Diagrams of Zircaloy-4 and Zirlo Sheets for Stamping Process of Spacer Grids of Nuclear Fuel Rod

    Science.gov (United States)

    Seo, Yunmi; Hyun, Hong Chul; Lee, Hyungyil; Kim, Naksoo

    2011-08-01

    We investigated the theoretical forming limit models for Zircaloy-4 and Zirlo used for spacer grid of nuclear fuel rods. Tensile tests were performed to obtain stress-strain curves and anisotropic coefficients, such as r-values. The experimental forming limit diagrams (FLD) for two materials were obtained by dome stretching tests following the specification of NUMISHEET 96. Theoretical FLD depends on forming limit model and yield criterion. To obtain the right hand side of FLD, we applied the forming limit models (Swift's diffuse necking, Marciniak-Kuczynski damage defect, Storen-Rice's vertex theory) to Zircaloy-4 and Zirlo sheets. Hill's local necking theory was adopted for the left side of FLD. To consider the anisotropy of sheets, the yield criteria of Hill (1948) and Hosford (1979) were applied. Comparing the predicted curves with the experimental data, we found that the FLD for Zircaloy-4 can be described by the Swift model with the Hill 48 yield criterion, while the FLD for Zirlo can be explained by the Storen-Rice model and the Hosford yield criterion (a = 8).

  12. Jiangrun Copper Limited Company Set its Eyes on the Leading Position of Copper Processing Industry in China

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>Jiangrun Copper Limited Company’s total investment volume for projects of stranded copper wire with high strength and high conductivity as well as high-performance copper and copper alloy wire are 500 million yuan and 360 million yuan, respectively. The company plans to introduce 85 units (sets) of high-end

  13. Availability and Temporal Heterogeneity of Water Supply Affect the Vertical Distribution and Mortality of a Belowground Herbivore and Consequently Plant Growth

    OpenAIRE

    Tsunoda, Tomonori; Kachi, Naoki; Suzuki, Jun-Ichirou

    2014-01-01

    We examined how the volume and temporal heterogeneity of water supply changed the vertical distribution and mortality of a belowground herbivore, and consequently affected plant biomass. Plantago lanceolata (Plantaginaceae) seedlings were grown at one per pot under different combinations of water volume (large or small volume) and heterogeneity (homogeneous water conditions, watered every day; heterogeneous conditions, watered every 4 days) in the presence or absence of a larva of the belowgr...

  14. Availability and temporal heterogeneity of water supply affect the vertical distribution and mortality of a belowground herbivore and consequently plant growth.

    Directory of Open Access Journals (Sweden)

    Tomonori Tsunoda

    Full Text Available We examined how the volume and temporal heterogeneity of water supply changed the vertical distribution and mortality of a belowground herbivore, and consequently affected plant biomass. Plantago lanceolata (Plantaginaceae seedlings were grown at one per pot under different combinations of water volume (large or small volume and heterogeneity (homogeneous water conditions, watered every day; heterogeneous conditions, watered every 4 days in the presence or absence of a larva of the belowground herbivorous insect, Anomala cuprea (Coleoptera: Scarabaeidae. The larva was confined in different vertical distributions to top feeding zone (top treatment, middle feeding zone (middle treatment, or bottom feeding zone (bottom treatment; alternatively no larva was introduced (control treatment or larval movement was not confined (free treatment. Three-way interaction between water volume, heterogeneity, and the herbivore significantly affected plant biomass. With a large water volume, plant biomass was lower in free treatment than in control treatment regardless of heterogeneity. Plant biomass in free treatment was as low as in top treatment. With a small water volume and in free treatment, plant biomass was low (similar to that under top treatment under homogeneous water conditions but high under heterogeneous ones (similar to that under middle or bottom treatment. Therefore, there was little effect of belowground herbivory on plant growth under heterogeneous water conditions. In other watering regimes, herbivores would be distributed in the shallow soil and reduced root biomass. Herbivore mortality was high with homogeneous application of a large volume or heterogeneous application of a small water volume. Under the large water volume, plant biomass was high in pots in which the herbivore had died. Thus, the combinations of water volume and heterogeneity affected plant growth via the change of a belowground herbivore.

  15. Tracing hidden herbivores: Time-resolved non-invasive analysis of belowground volatiles by proton-transfer-reaction mass spectrometry (PTR-MS)

    OpenAIRE

    Danner, H.; Samudrala, D.; Cristescu, S M; Van Dam, N.M.

    2012-01-01

    Root herbivores are notoriously difficult to study, as they feed hidden in the soil. However, root herbivores may be traced by analyzing specific volatile organic compounds (VOCs) that are produced by damaged roots. These VOCs not only support parasitoids in the localization of their host, but also may help scientists study belowground plant-herbivore interactions. Herbivore-induced VOCs are usually analyzed by gas-chromatography mass spectrometry (GC-MS), but with this off-line method, the g...

  16. Epiphyte-cover on seagrass (Zostera marina L. leaves impedes plant performance and radial O2 loss from the below-ground tissue

    Directory of Open Access Journals (Sweden)

    Kasper Elgetti Brodersen

    2015-08-01

    Full Text Available The O2 budget of seagrasses is a complex interaction between several sources and sinks, which is strongly regulated by light availability and mass transfer over the diffusive boundary layer (DBL surrounding the plant. Epiphyte growth on leaves may thus strongly affect the O2 availability of the seagrass plant and its capability to aerate its rhizosphere as a defence against plant toxins.We used electrochemical and fiber-optic microsensors to quantify the O2 flux, DBL and light microclimate around leaves with and without filamentous algal epiphytes. We also quantified the below-ground radial O2 loss from roots (~1 mm from the root-apex to elucidate how this below-ground oxic microzone was affected by the presence of epiphytes.Epiphyte-cover on seagrass leaves (~21% areal cover resulted in reduced light quality and quantity for photosynthesis, thus leading to reduced plant fitness. A ~4 times thicker diffusive boundary layer around leaves with epiphyte-cover impeded gas (and nutrient exchange with the surrounding water-column and thus the amount of O2 passively diffusing into the leaves in darkness. During light exposure of the leaves, radial oxygen loss from the below-ground tissue was ~2 times higher from plants without epiphyte-cover. In contrast, no O2 was detectable at the surface of the root-cap tissue of plants with epiphyte-cover during darkness, leaving the plants more susceptible to sulphide intrusion.Epiphyte growth on seagrass leaves thus negatively affects the light climate and O2 uptake in darkness, hampering the plants performance and thereby reducing the oxidation capability of its below-ground tissue.

  17. Below-ground carbon allocation in mature beech and spruce trees following long-term, experimentally enhanced O3 exposure in Southern Germany

    International Nuclear Information System (INIS)

    Canopies of adult European beech (Fagus sylvatica) and Norway spruce (Picea abies) were labeled with CO2 depleted in 13C to evaluate carbon allocation belowground. One-half the trees were exposed to elevated O3 for 6 yrs prior to and during the experiment. Soil-gas sampling wells were placed at 8 and 15 cm and soil CO2 was sampled during labeling in mid-late August, 2006. In beech, δ13CO2 at both depths decreased approximately 50 h after labeling, reflecting rapid translocation of fixed C to roots and release through respiration. In spruce, label was detected in fine-root tissue, but there was no evidence of label in δ13CO2. The results show that C fixed in the canopy rapidly reaches respiratory pools in beech roots, and suggest that spruce may allocate very little of recently-fixed carbon into root respiration during late summer. A change in carbon allocation belowground due to long-term O3 exposure was not observed. - Below-ground carbon allocation in mature beech and spruce exposed to ozone.

  18. Belowground carbon pools and dynamics in China's warm temperate and sub-tropical deciduous forests

    Directory of Open Access Journals (Sweden)

    C. W. Xiao

    2009-07-01

    Full Text Available We report the first estimates of pools and dynamics of microbes, roots, plant litter and soil organic carbon (SOC in three dominant types of China's vast deciduous forest area: Betula platyphylla, Quercus liaotungensis, and Quercus aliena varacuteserrata. Organic matter degradation rates overshadowed litter inputs as the main determinant of the soil carbon stocks. Across the three forests, rates of litter decomposition were also indicative for turnover rates of SOC. Litter and SOC decay was faster in the sub-tropical than in the warm-temperate forests. Among the latter, SOC turnover was highest in the forest producing the higher-quality litter. Microbial biomass was, as expected, correlated with SOC content. Microbial activity, in contrast, was highest at the sub-tropical forest, despite the lower SOC availability, lower fraction of labile SOC, and lower soil microbial biomass. These results may contribute to increased understanding of controls over belowground carbon cycling in deciduous forests.

  19. Effects of elevated pO3 on carbon cycle between above and belowground organs of trees

    Institute of Scientific and Technical Information of China (English)

    LIU Xi-ping; Rennenberg Heinz; Matyssek Rainer

    2006-01-01

    Translocation of carbohydrate from leaves to roots via phloem and reallocation from roots to leaves via xylem regulate the allocation of carbon (C) between above and belowground organs of trees. To quantitatively analyze effects of elevated ozone concentrations pO3 on the internal cycle of C, juvenile beech and spruce were grown in phytotrons and exposed to ambient and elevated pO3 (i.e. twice-ambient O3 levels, restricted to < 150 ppb) for two growing seasons. The translocation of C in the phloem and xylem was quantitatively studied by investigating the phloem/xylem-loading of sugars, the differentiation of stem conductive tissue and the hourly water flow through the stem. Results in the present study shown, elevated pO3 significantly decreased C translocation from shoot to roots in beech by reducing both sugar concentration in the phloem and conductive phloem area. Elevated pO3 also significantly decreased C reallocation from the roots to the shoot in beech by reducing both of sugar concentration in the xylem and transpiration rate. The adverse effects of elevated pO3 on C translocation in the phloem and xylem, however, were small in spruce.Contrasting to beech, spruce is less sensitive to elevated pO3, regarding to phloem differentiation and sugar concentrations in the phloem and xylem.

  20. Sensitivity analysis of maximum doses for a below-ground vault low-level radioactive waste disposal facility

    International Nuclear Information System (INIS)

    This paper reports on a radionuclide migration analysis performed for a hypothetical below-ground vault radioactive waste disposal facility as part of a prototype license application. The facility design incorporated different concrete vault designs for the Class A and Class B/C wastes. The facility was located in a humid environment with relatively permeable soil. Doses were calculated for an individual using well water at the site boundary. Parameters of interest for the sensitivity study were the quantity of water percolating through the cover, the permeability of the native soil, and the subsurface concentrations of chemical affecting concrete degradation. Variation of the water percolation rate to simulate failure of the cover system resulted in peak doses which were a factor of 2.7 larger than for the base case. A factor of ten variation in the natural soil permeability also resulted in a factor of 2.7 increase in the maximum dose. Variations in the subsurface concentration of sulfate ion had little effect on the magnitude of the groundwater doses, but affected the longevity of the concrete structures. Having different failure times for the Class A and Class B/C disposal vaults was shown to be beneficial

  1. Limits, discovery and cut optimization for a Poisson process with uncertainty in background and signal efficiency: TRolke 2.0

    OpenAIRE

    Lundberg, J.; Conrad, J.; Rolke, W.; Lopez, A

    2009-01-01

    A C++ class was written for the calculation of frequentist confidence intervals using the profile likelihood method. Seven combinations of Binomial, Gaussian, Poissonian and Binomial uncertainties are implemented. The package provides routines for the calculation of upper and lower limits, sensitivity and related properties. It also supports hypothesis tests which take uncertainties into account. It can be used in compiled C++ code, in Python or interactively via the ROOT analysis framework.

  2. Optimization of Gas Metal Arc Welding (GMAW) Process for Maximum Ballistic Limit in MIL A46100 Steel Welded All-Metal Armor

    Science.gov (United States)

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

    2015-01-01

    Our recently developed multi-physics computational model for the conventional gas metal arc welding (GMAW) joining process has been upgraded with respect to its predictive capabilities regarding the process optimization for the attainment of maximum ballistic limit within the weld. The original model consists of six modules, each dedicated to handling a specific aspect of the GMAW process, i.e., (a) electro-dynamics of the welding gun; (b) radiation-/convection-controlled heat transfer from the electric arc to the workpiece and mass transfer from the filler metal consumable electrode to the weld; (c) prediction of the temporal evolution and the spatial distribution of thermal and mechanical fields within the weld region during the GMAW joining process; (d) the resulting temporal evolution and spatial distribution of the material microstructure throughout the weld region; (e) spatial distribution of the as-welded material mechanical properties; and (f) spatial distribution of the material ballistic limit. In the present work, the model is upgraded through the introduction of the seventh module in recognition of the fact that identification of the optimum GMAW process parameters relative to the attainment of the maximum ballistic limit within the weld region entails the use of advanced optimization and statistical sensitivity analysis methods and tools. The upgraded GMAW process model is next applied to the case of butt welding of MIL A46100 (a prototypical high-hardness armor-grade martensitic steel) workpieces using filler metal electrodes made of the same material. The predictions of the upgraded GMAW process model pertaining to the spatial distribution of the material microstructure and ballistic limit-controlling mechanical properties within the MIL A46100 butt weld are found to be consistent with general expectations and prior observations.

  3. 40 CFR Table 1 to Subpart Hhhhh of... - Emission Limits and Work Practice Standards for Process Vessels

    Science.gov (United States)

    2010-07-01

    ... to a condenser that reduces the outlet gas temperature to: process vessel contains HAP... emissions through a closed-vent system to a condenser that reduces the outlet gas temperature to: combustion control device to control organic...

  4. Analysis and treatment of industrial wastewater through chemical coagulation-adsorption process-A case study of Clariant Pakistan limited

    Science.gov (United States)

    Ali Shah, Syed Farman; Shah, Abdul Karim; Mehdi, Ahmad; Memon, Aziza Aftab; Harijan, Khanji; Ali, Zeenat M.

    2012-05-01

    Textile dye manufacture processes are known as the most polluting chemical processes of industrial sectors of the world. Colored wastewaters along with many polluting agents are troublesome. They are heavily polluted with dyes, textile auxiliaries and chemicals. Current study applies a coupled technology for wastewater treatment. Combined coagulation-adsorption process was utilized for treatment of complex nature effluents of dyes, binder emulsion, pigments and textile chemicals plants at Clariant Pakistan. Cost effective coagulant and adsorbent was selected by using waste material from a power generation unit of Water and Power Development Authority (WAPDA), Pakistan. The treated effluent could be reused. Alum+ Activated Carbon, Ferrous sulfate+ Activated Carbon, Ferric chloride + Activated Carbon. Almost complete decolourization was achieved along with reduction in COD up to 65%. Pre and post treatment, TDS, COD, Turbidity and suspended solids were improved.

  5. Mesophilic co-digestion of dairy manure and lipid rich solid slaughterhouse wastes: process efficiency, limitations and floating granules formation.

    Science.gov (United States)

    Pitk, Peep; Palatsi, Jordi; Kaparaju, Prasad; Fernández, Belén; Vilu, Raivo

    2014-08-01

    Lipid and protein rich solid slaughterhouse wastes are attractive co-substrates to increase volumetric biogas production in co-digestion with dairy manure. Addition of decanter sludge (DS), containing 42.2% of lipids and 35.8% of proteins (total solids basis), up to 5% of feed mixture resulted in a stable process without any indication of long chain fatty acids (LCFA) or free ammonia (NH3) inhibition and in 3.5-fold increase of volumetric biogas production. Contrary, only lipids addition as technical fat (TF) at over 2% of feed mixture resulted in formation of floating granules (FG) and process efficiency decrease. Formed FG had low biodegradability and its organic part was composed of lipids and calcium salts of LCFAs. Anaerobic digestion process intentionally directed to FG formation, could be a viable option for mitigation and control of lipids overload and derived LCFA inhibition. PMID:24907576

  6. Materials processing strategies for colloidal quantum dot solar cells: advances, present-day limitations, and pathways to improvement

    KAUST Repository

    Carey, Graham H.

    2013-05-13

    Colloidal quantum dot photovoltaic devices have improved from initial, sub-1% solar power conversion efficiency to current record performance of over 7%. Rapid advances in materials processing and device physics have driven this impressive performance progress. The highest-efficiency approaches rely on a fabrication process that starts with nanocrystals in solution, initially capped with long organic molecules. This solution is deposited and the resultant film is treated using a solution containing a second, shorter capping ligand, leading to a cross-linked, non-redispersible, and dense layer. This procedure is repeated, leading to the widely employed layer-by-layer solid-state ligand exchange. We will review the properties and features of this process, and will also discuss innovative pathways to creating even higher-performing films and photovoltaic devices.

  7. Limitations of the removal of cyanide from coking wastewater by ozonation and by the hydrogen peroxide-ozone process.

    Science.gov (United States)

    Pueyo, N; Miguel, N; Ovelleiro, J L; Ormad, M P

    2016-01-01

    The purpose of this study is to compare the efficiency of ozonation and the hydrogen peroxide-ozone process for the removal of cyanide from coking wastewater. The most efficient oxidation process is combined with coagulation-flocculation-decantation and lime-soda ash softening pretreatments. The oxidation in aqueous solution and industrial wastewater (at pH 9.5-12.3) by O3 was carried out using a range of concentration of consumed O3 from 10 to 290 mg/L. A molar ratio of H2O2/O3 from 0.1 to 5.2 with different concentrations of O3 constants was used for the H2O2-O3 process. The maximum cyanide removal obtained in coking wastewater was 90% using a mass ratio of O3/CN(-) of 9.5. Using lower concentrations of O3, cyanide is not removed and can even be generated due to the presence of other cyanide precursor organic micropollutants in the industrial matrix. The concentration of O3 is reduced to half for the same cyanide removal efficiency if the pretreatments are applied to reduce the carbonate and bicarbonate ions. The cyanide removal efficiency in coking wastewater is not improved if the O3 is combined with the H2O2. However, the preliminary cyanide removal treatment in aqueous solution showed an increase in the cyanide removal efficiency for the H2O2-O3 process. PMID:27438254

  8. Limits on Gravitino Production and New Processes with Large Missing Transverse Energy in $p\\overline{p}$ Collisions at $\\sqrt{s}$=1.8 TeV

    CERN Document Server

    Affolder, T; Akopian, A M; Albrow, Michael G; Amaral, P; Amendolia, S R; Amidei, D; Anikeev, K; Antos, J; Apollinari, G; Arisawa, T; Asakawa, T; Ashmanskas, W J; Atac, Muzaffer; Azfar, F; Azzi-Bacchetta, P; Bacchetta, N; Bailey, M W; Bailey, S; De Barbaro, P; Barbaro-Galtieri, A; Barnes, Virgil E; Barnett, B A; Barone, M; Bauer, G; Bedeschi, F; Belforte, S; Bellettini, Giorgio; Bellinger, J; Benjamin, D; Bensinger, J; Beretvas, A; Bergé, J P; Berryhill, J W; Bevensee, B; Bhatti, A A; Binkley, M; Bisello, D; Blair, R E; Blocker, C A; Bloom, K; Blumenfeld, B; Blusk, S R; Bocci, A; Bodek, Arie; Bokhari, W; Bölla, G; Bonushkin, Yu; Bortoletto, Daniela; Boudreau, J; Brandl, A; van den Brink, S C; Bromberg, C; Brozovic, M; Bruner, N L; Buckley-Geer, E; Budagov, Yu A; Budd, H S; Burkett, K; Busetto, G; Byon-Wagner, A; Byrum, K L; Campbell, M; Carithers, W C; Carlson, J; Carlsmith, D; Cassada, J A; Castro, A; Cauz, D; Cerri, A; Chan, A W; Chang, P S; Chang, P T; Chapman, J; Chen, C; Chen, Y C; Cheng, T; Chertok, M; Chiarelli, G; Chirikov-Zorin, I E; Chlachidze, G; Chlebana, F S; Christofek, L S; Chu, M L; Cihangir, S; Ciobanu, C I; Clark, A G; Connolly, A; Conway, J; Cooper, J; Cordelli, M; Cranshaw, J; Cronin-Hennessy, D; Cropp, R; Culbertson, R J; Dagenhart, D; De Jongh, F; Dell'Agnello, S; Dell'Orso, Mauro; Demina, R; Demortier, L; Deninno, M M; Derwent, P F; Devlin, T; Dittmann, J R; Donati, S; Done, J; Dorigo, T; Eddy, N; Einsweiler, Kevin F; Elias, J E; Engels, E; Erdmann, W; Errede, D; Errede, S; Fan, Q; Feild, R G; Ferretti, C; Field, R D; Fiori, I; Flaugher, B L; Foster, G W; Franklin, M; Freeman, J; Friedman, J; Fukui, Y; Galeotti, S; Gallinaro, M; Gao, T; García-Sciveres, M; Garfinkel, A F; Gatti, P; Gay, C; Geer, S; Gerdes, D W; Giannetti, P; Giromini, P; Glagolev, V; Gold, M; Goldstein, J; Gordon, A; Goshaw, A T; Gotra, Yu; Goulianos, K; Green, C; Groer, L S; Grosso-Pilcher, C; Günther, M; Guillian, G; Guimarães da Costa, J; Guo, R S; Haber, C; Hafen, E S; Hahn, S R; Hall, C; Handa, T; Handler, R; Hao, W; Happacher, F; Hara, K; Hardman, A D; Harris, R M; Hartmann, F; Hatakeyama, K; Hauser, J; Heinrich, J; Heiss, A; Herndon, M; Hinrichsen, B; Hoffman, K D; Holck, C; Hollebeek, R J; Holloway, L E; Hughes, R; Huston, J; Huth, J E; Ikeda, H; Incandela, J R; Introzzi, G; Iwai, J; Iwata, Y; James, E; Jensen, H; Jones, M; Joshi, U; Kambara, H; Kamon, T; Kaneko, T; Karr, K M; Kasha, H; Kato, Y; Keaffaber, T A; Kelley, K; Kelly, M; Kennedy, R D; Kephart, R D; Khazins, D M; Kikuchi, T; Kirk, M; Kim, B J; Kim, H S; Kim, M J; Kim, S H; Kim, Y K; Kirsch, L; Klimenko, S; Koehn, P; Köngeter, A; Kondo, K; Konigsberg, J; Kordas, K; Korn, A J; Korytov, A V; Kovács, E; Kroll, J; Kruse, M; Kuhlmann, S E; Kurino, K; Kuwabara, T; Laasanen, A T; Lai, N; Lami, S; Lammel, S; Lamoureux, J I; Lancaster, M; Latino, G; LeCompte, T J; Lee, A M; Leone, S; Lewis, J D; Lindgren, M; Liss, T M; Liu, J B; Liu, Y C; Lockyer, N; Loken, J G; Loreti, M; Lucchesi, D; Lukens, P; Lusin, S; Lyons, L; Lys, J; Madrak, R; Maeshima, K; Maksimovic, P; Malferrari, L; Mangano, Michelangelo L; Mariotti, M; Martignon, G; Martin, A; Matthews, J A J; Mayer, J; Mazzanti, P; McFarland, K S; McIntyre, P; McKigney, E A; Menguzzato, M; Menzione, A; Mesropian, C; Miao, T; Miller, R; Miller, J S; Minato, H; Miscetti, S; Mishina, M; Mitselmakher, G; Moggi, N; Moore, E; Moore, R; Morita, Y; Mukherjee, A; Müller, T; Munar, A; Murat, P; Murgia, S; Musy, M; Nachtman, J; Nahn, S; Nakada, H; Nakaya, T; Nakano, I; Nelson, C; Neuberger, D; Newman-Holmes, C; Ngan, C Y P; Nicolaidi, P; Niu, H; Nodulman, L; Nomerotski, A; Oh, S H; Ohmoto, T; Ohsugi, T; Oishi, R; Okusawa, T; Olsen, J; Pagliarone, C; Palmonari, F; Paoletti, R; Papadimitriou, V; Pappas, S P; Partos, D S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pescara, L; Phillips, T J; Piacentino, G; Pitts, K T; Plunkett, R K; Pompos, A; Pondrom, L; Pope, G; Popovic, M; Prokoshin, F; Proudfoot, J; Ptohos, F; Punzi, G; Ragan, K; Rakitine, A; Reher, D; Reichold, A; Riegler, W; Ribon, A; Rimondi, F; Ristori, L; Robertson, W J; Robinson, A; Rodrigo, T; Rolli, S; Rosenson, L; Roser, R M; Rossin, R; Sakumoto, W K; Saltzberg, D; Sansoni, A; Santi, L; Sato, H; Savard, P; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Scodellaro, L; Scott, A; Scribano, A; Segler, S L; Seidel, S; Seiya, Y; Semenov, A A; Semeria, F; Shah, T; Shapiro, M D; Shepard, P F; Shibayama, T; Shimojima, M; Shochet, M J; Siegrist, J L; Signorelli, G; Sill, A F; Sinervo, P K; Singh, P; Slaughter, A J; Sliwa, K; Smith, C; Snider, F D; Solodsky, A; Spalding, J; Speer, T; Sphicas, Paris; Spinella, F; Spiropulu, M; Spiegel, L; Steele, J; Stefanini, A; Strologas, J; Strumia, F; Stuart, D; Sumorok, K; Suzuki, T; Takano, T; Takashima, R; Takikawa, K; Tamburello, P D; Tanaka, M; Tannenbaum, B; Taylor, W; Tecchio, M; Teng, P K; Terashi, K; Tether, S; Theriot, D; Thurman-Keup, R M; Tipton, P; Tkaczyk, S M; Tollefson, K; Tollestrup, Alvin V; Toyoda, H; Trischuk, W; De Trocóniz, J F; Tseng, J; Turini, N; Ukegawa, F; Vaiciulis, T; Valls, J; Vejcik, S; Velev, G V; Vidal, R; Vilar, R; Volobuev, I P; Vucinic, D; Wagner, R G; Wagner, R L; Wahl, J; Wallace, N B; Walsh, A M; Wang, C; Wang, C H; Wang, M J; Watanabe, T; Waters, D; Watts, T; Webb, R; Wenzel, H; Wester, W C; Wicklund, A B; Wicklund, E; Williams, H H; Wilson, P; Winer, B L; Winn, D; Wolbers, S; Wolinski, D; Wolinski, J; Wolinski, S; Worm, S; Wu, X; Wyss, J; Yagil, A; Yao, W; Yeh, G P; Yeh, P; Yoh, J K; Yosef, C; Yoshida, T; Yu, I; Yu, S; Zanetti, A; Zetti, F; Zucchelli, S

    2000-01-01

    Events collected by the Collider Detector at Fermilab (CDF) with an energetic jet plus large missing transverse energy can be used to search for physics beyond the Standard Model. We see no deviations from the expected background and set upper limits on the production of new processes. We consider in addition the production of light gravitinos within the framework of the Gauge Mediated Supersymmetry Breaking models and set a limit at 95onfidence level on the breaking scale sqrt(F) >= 217 GeV, which excludes gravitino masses smaller than 1.1x10^-5 eV/c^2.

  9. Harmonisation of licensing processes for decommissioning. Options and limitations; Genehmigungsverfahren fuer die Stilllegung der deutschen Kernkraftwerke. Konvoi oder Kakophonie?

    Energy Technology Data Exchange (ETDEWEB)

    Raetzke, Christian

    2016-03-15

    The shutdown of eight reactors in Germany in the wake of Fukushima 2011 and the scheduled phase-out of the remaining units in several steps ending 2022 has obviously triggered a wave of applications for decommissioning and dismantling licences. It would seem natural to strive for a harmonised handling of these processes, analogous to the 'convoi' concept which was successfully employed for licensing and construction of the three most recent German NPPs in the 1980s. However, a comparative analysis shows that the motivation of all players is much different from that of earlier times and that harmonisation of licensing processes for dismantling is not as crucial for operators, authorities and technical support organisations as it was for construction.

  10. Porthole Extrusion Process Design for Magnesium-Alloy Bumper Back Beam by Using FE Analysis and Extrusion Limit Diagram

    OpenAIRE

    Lee, Sung-Yun; Ko, Dae-Cheol; Lee, Sang-Kon; Lee, In-Kyu; Joeng, Myeong-Sik; Kim, Da Hye; Cho, Yong-Jae

    2014-01-01

    In recent years, several studies with focus on developing state-of-the-art manufacturing technologies have been conducted to produce light vehicles by employing parts made of light materials such as aluminum and magnesium. Of such materials, magnesium has been found to pose numerous issues, because it cannot be deformed (plastic deformation) easily at low temperatures. Furthermore, oxidation on the surface of manganese occurs at high temperatures. This study analyzes the extrusion process for...

  11. The process of recovery from alcohol addiction – from the limitations and fetters to a better quality of life

    OpenAIRE

    Ewa Włodarczyk

    2014-01-01

    In analyzing the broadness of Polish literature on alcoholic addiction one can conclude that the process of getting out of alcoholic addiction is fragmentarily studied and described. This article presents one of the views shared by many therapists of addiction (in Poland and abroad), which recognizes the problems of alcoholism as a disease and contains considerations around the issue of coping with them, with reference to exactly this model of understanding them. Although this perception assu...

  12. Plant diversity and overyielding: insights from belowground facilitation of intercropping in agriculture.

    Science.gov (United States)

    Li, Long; Tilman, David; Lambers, Hans; Zhang, Fu-Suo

    2014-07-01

    Despite increasing evidence that plant diversity in experimental systems may enhance ecosystem productivity, the mechanisms causing this overyielding remain debated. Here, we review studies of overyielding observed in agricultural intercropping systems, and show that a potentially important mechanism underlying such facilitation is the ability of some crop species to chemically mobilize otherwise-unavailable forms of one or more limiting soil nutrients such as phosphorus (P) and micronutrients (iron (Fe), zinc (Zn) and manganese (Mn)). Phosphorus-mobilizing crop species improve P nutrition for themselves and neighboring non-P-mobilizing species by releasing acid phosphatases, protons and/or carboxylates into the rhizosphere which increases the concentration of soluble inorganic P in soil. Similarly, on calcareous soils with a very low availability of Fe and Zn, Fe- and Zn-mobilizing species, such as graminaceous monocotyledonous and cluster-rooted species, benefit themselves, and also reduce Fe or Zn deficiency in neighboring species, by releasing chelating substances. Based on this review, we hypothesize that mobilization-based facilitative interactions may be an unsuspected, but potentially important mechanism enhancing productivity in both natural ecosystems and biodiversity experiments. We discuss cases in which nutrient mobilization might be occurring in natural ecosystems, and suggest that the nutrient mobilization hypothesis merits formal testing in natural ecosystems. PMID:25013876

  13. Nitrogen addition and warming independently influence the belowground micro-food web in a temperate steppe.

    Directory of Open Access Journals (Sweden)

    Qi Li

    Full Text Available Climate warming and atmospheric nitrogen (N deposition are known to influence ecosystem structure and functioning. However, our understanding of the interactive effect of these global changes on ecosystem functioning is relatively limited, especially when it concerns the responses of soils and soil organisms. We conducted a field experiment to study the interactive effects of warming and N addition on soil food web. The experiment was established in 2006 in a temperate steppe in northern China. After three to four years (2009-2010, we found that N addition positively affected microbial biomass and negatively influenced trophic group and ecological indices of soil nematodes. However, the warming effects were less obvious, only fungal PLFA showed a decreasing trend under warming. Interestingly, the influence of N addition did not depend on warming. Structural equation modeling analysis suggested that the direct pathway between N addition and soil food web components were more important than the indirect connections through alterations in soil abiotic characters or plant growth. Nitrogen enrichment also affected the soil nematode community indirectly through changes in soil pH and PLFA. We conclude that experimental warming influenced soil food web components of the temperate steppe less than N addition, and there was little influence of warming on N addition effects under these experimental conditions.

  14. The sky is the limit? 20 years of small-format aerial photography taken from UAS for monitoring geomorphological processes

    Science.gov (United States)

    Marzolff, Irene

    2014-05-01

    One hundred years after the first publication on aerial photography taken from unmanned aerial platforms (Arthur Batut 1890), small-format aerial photography (SFAP) became a distinct niche within remote sensing during the 1990s. Geographers, plant biologists, archaeologists and other researchers with geospatial interests re-discovered the usefulness of unmanned platforms for taking high-resolution, low-altitude photographs that could then be digitized and analysed with geographical information systems, (softcopy) photogrammetry and image processing techniques originally developed for digital satellite imagery. Even before the ubiquity of digital consumer-grade cameras and 3D analysis software accessible to the photogrammetric layperson, do-it-yourself remote sensing using kites, blimps, drones and micro air vehicles literally enabled the questing researcher to get their own pictures of the world. As a flexible, cost-effective method, SFAP offered images with high spatial and temporal resolutions that could be ideally adapted to the scales of landscapes, forms and distribution patterns to be monitored. During the last five years, this development has been significantly accelerated by the rapid technological advancements of GPS navigation, autopiloting and revolutionary softcopy-photogrammetry techniques. State-of-the-art unmanned aerial systems (UAS) now allow automatic flight planning, autopilot-controlled aerial surveys, ground control-free direct georeferencing and DEM plus orthophoto generation with centimeter accuracy, all within the space of one day. The ease of use of current UAS and processing software for the generation of high-resolution topographic datasets and spectacular visualizations is tempting and has spurred the number of publications on these issues - but which advancements in our knowledge and understanding of geomorphological processes have we seen and can we expect in the future? This presentation traces the development of the last two decades

  15. A Correction to the Hydrodynamic Limit of Boundary Driven Weakly Asymmetric Exclusion Processes in a Quasi-Static Time Scale

    Science.gov (United States)

    Chavez, E.; Landim, C.

    2016-06-01

    We consider a one-dimensional, weakly asymmetric, boundary driven exclusion process on the interval [0,N]\\cap {Z} in the quasi-static time scale N^2 ɛ ^{-1}_N, where 1≪ ɛ ^{-1}_N ≪ N^{1/4}. We assume that the external field and the chemical potentials, which fix the density at the boundaries, evolve smoothly in the macroscopic time scale. We derive an equation which describes the evolution of the density up to the order ɛ _N.

  16. Involving private persons and corporations in the planning process according to paragraph 9b German nuclear law - practicability and limits

    International Nuclear Information System (INIS)

    The 4th Amendment to the German Nuclear Law has procured the legal base for the disposal of radioactive waste in the German Federal Republic. The Nuclear Law states that the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig is responsible for the disposal of radioactive waste. The PTB can be assisted in its responsibilities by persons and institutions of private character. Involving private persons and corporations in the licensing process figures a legal problem, and there has been a seminar in the PTB discussing such problems. The present contribution gives a brief summary of the opinions stated by the various legal experts taking part in this seminar. (orig./HP)

  17. Belowground Ecology of Scarabs Feeding on Grass Roots: Current Knowledge and Future Directions for Management in Australasia.

    Science.gov (United States)

    Frew, Adam; Barnett, Kirk; Nielsen, Uffe N; Riegler, Markus; Johnson, Scott N

    2016-01-01

    Many scarab beetles spend the majority of their lives belowground as larvae, feeding on grass roots. Many of these larvae are significant pests, causing damage to crops and grasslands. Damage by larvae of the greyback cane beetle (Dermolepida albohirtum), for example, can cause financial losses of up to AU$40 million annually to the Australian sugarcane industry. We review the ecology of some scarab larvae in Australasia, focusing on three subfamilies; Dynastinae, Rutelinae, and Melolonthinae, containing key pest species. Although considerable research on the control of some scarab pests has been carried out in Australasia, for some species, the basic biology and ecology remains largely unexplored. We synthesize what is known about these scarab larvae and outline key knowledge gaps to highlight future research directions with a view to improve pest management. We do this by presenting an overview of the scarab larval host plants and feeding behavior; the impacts of abiotic (temperature, moisture, and fertilization) and biotic (pathogens, natural enemies, and microbial symbionts) factors on scarab larvae and conclude with how abiotic and biotic factors can be applied in agriculture for improved pest management, suggesting future research directions. Several host plant microbial symbionts, such as arbuscular mycorrhizal fungi and endophytes, can improve plant tolerance to scarabs and reduce larval performance, which have shown promise for use in pest management. In addition to this, several microbial scarab pathogens have been isolated for commercial use in pest management with particularly promising results. The entomopathogenic fungus Metarhizium anisopliae caused a 50% reduction in cane beetle larvae while natural enemies such as entomopathogenic nematodes have also shown potential as a biocontrol. Key abiotic factors, such as soil water, play an important role in affecting both scarab larvae and these control agents and should therefore feature in future multi

  18. Aboveground and Belowground Herbivores Synergistically Induce Volatile Organic Sulfur Compound Emissions from Shoots but Not from Roots.

    Science.gov (United States)

    Danner, Holger; Brown, Phil; Cator, Eric A; Harren, Frans J M; van Dam, Nicole M; Cristescu, Simona M

    2015-07-01

    Studies on aboveground (AG) plant organs have shown that volatile organic compound (VOC) emissions differ between simultaneous attack by herbivores and single herbivore attack. There is growing evidence that interactive effects of simultaneous herbivory also occur across the root-shoot interface. In our study, Brassica rapa roots were infested with root fly larvae (Delia radicum) and the shoots infested with Pieris brassicae, either singly or simultaneously, to study these root-shoot interactions. As an analytical platform, we used Proton Transfer Reaction Mass Spectrometry (PTR-MS) to investigate VOCs over a 3 day time period. Our set-up allowed us to monitor root and shoot emissions concurrently on the same plant. Focus was placed on the sulfur-containing compounds; methanethiol, dimethylsulfide (DMS), and dimethyldisulfide (DMDS), because these compounds previously have been shown to be biologically active in the interactions of Brassica plants, herbivores, parasitoids, and predators, yet have received relatively little attention. The shoots of plants simultaneously infested with AG and belowground (BG) herbivores emitted higher levels of sulfur-containing compounds than plants with a single herbivore species present. In contrast, the emission of sulfur VOCs from the plant roots increased as a consequence of root herbivory, independent of the presence of an AG herbivore. The onset of root emissions was more rapid after damage than the onset of shoot emissions. The shoots of double infested plants also emitted higher levels of methanol. Thus, interactive effects of root and shoot herbivores exhibit more strongly in the VOC emissions from the shoots than from the roots, implying the involvement of specific signaling interactions. PMID:26195194

  19. Effects of manipulated above- and belowground organic matter input on soil respiration in a Chinese pine plantation.

    Directory of Open Access Journals (Sweden)

    Juan Fan

    Full Text Available Alteration in the amount of soil organic matter input can have profound effect on carbon dynamics in forest soils. The objective of our research was to determine the response in soil respiration to above- and belowground organic matter manipulation in a Chinese pine (Pinus tabulaeformis plantation. Five organic matter treatments were applied during a 2-year experiment: both litter removal and root trenching (LRRT, only litter removal (LR, control (CK, only root trenching (RT and litter addition (LA. We found that either aboveground litter removal or root trenching decreased soil respiration. On average, soil respiration rate was significantly decreased in the LRRT treatment, by about 38.93% ± 2.01% compared to the control. Soil respiration rate in the LR treatment was 30.65% ± 1.87% and in the RT treatment 17.65% ± 1.95% lower than in the control. Litter addition significantly increased soil respiration rate by about 25.82% ± 2.44% compared to the control. Soil temperature and soil moisture were the main factors affecting seasonal variation in soil respiration. Up to the 59.7% to 82.9% seasonal variation in soil respiration is explained by integrating soil temperature and soil moisture within each of the various organic matter treatments. The temperature sensitivity parameter, Q10, was higher in the RT (2.72 and LA (3.19 treatments relative to the control (2.51, but lower in the LRRT (1.52 and LR treatments (1.36. Our data suggest that manipulation of soil organic matter input can not only alter soil CO2 efflux, but also have profound effect on the temperature sensitivity of organic carbon decomposition in a temperate pine forest.

  20. Belowground Ecology of Scarabs Feeding on Grass Roots: Current Knowledge and Future Directions for Management in Australasia

    Science.gov (United States)

    Frew, Adam; Barnett, Kirk; Nielsen, Uffe N.; Riegler, Markus; Johnson, Scott N.

    2016-01-01

    Many scarab beetles spend the majority of their lives belowground as larvae, feeding on grass roots. Many of these larvae are significant pests, causing damage to crops and grasslands. Damage by larvae of the greyback cane beetle (Dermolepida albohirtum), for example, can cause financial losses of up to AU$40 million annually to the Australian sugarcane industry. We review the ecology of some scarab larvae in Australasia, focusing on three subfamilies; Dynastinae, Rutelinae, and Melolonthinae, containing key pest species. Although considerable research on the control of some scarab pests has been carried out in Australasia, for some species, the basic biology and ecology remains largely unexplored. We synthesize what is known about these scarab larvae and outline key knowledge gaps to highlight future research directions with a view to improve pest management. We do this by presenting an overview of the scarab larval host plants and feeding behavior; the impacts of abiotic (temperature, moisture, and fertilization) and biotic (pathogens, natural enemies, and microbial symbionts) factors on scarab larvae and conclude with how abiotic and biotic factors can be applied in agriculture for improved pest management, suggesting future research directions. Several host plant microbial symbionts, such as arbuscular mycorrhizal fungi and endophytes, can improve plant tolerance to scarabs and reduce larval performance, which have shown promise for use in pest management. In addition to this, several microbial scarab pathogens have been isolated for commercial use in pest management with particularly promising results. The entomopathogenic fungus Metarhizium anisopliae caused a 50% reduction in cane beetle larvae while natural enemies such as entomopathogenic nematodes have also shown potential as a biocontrol. Key abiotic factors, such as soil water, play an important role in affecting both scarab larvae and these control agents and should therefore feature in future multi

  1. Aboveground and belowground biomass allocation in native Prosopis caldenia Burkart secondaries woodlands in the semi-arid Argentinean pampas

    International Nuclear Information System (INIS)

    The woodlands in the south-west of the Argentinean pampas are dominated by Prosopis Caldenia Burkart (calden). The current deforestation rate of this woodlands is 0.82% per year. Different compensation initiatives have begun that recognize the role of forests as environmental service providers. The financial incentives they offer make it necessary to quantify the amount of carbon stored in the forest biomass. A model for estimating calden biomass was developed. Thirty-eight trees were selected, felled and divided into sections. An equation system was fitted using joint generalized regression to ensure the additivity property. A weighted regression was used to avoid heteroscedasticity. In these woodlands fire is the main disturbance and it can modify tree allometry, due this all models included the area of the base of the stem and tree height as independent variables since it indirectly collects this variability. Total biomass and the stem fraction had the highest R2Adj. values (0.75), while branches with a diameter less than 7 cm had the lowest (0.58). Tree biomass was also analyzed by partitioning into the basic fractions of stem, crown, roots, and the root/shoot ratio. Biomass allocation was greatest in the crown fraction and the mean root/shoot ratio was 0.58. The carbon stock of the caldenales considering only calden tree biomass is 20.2 Mg ha−1. While the overall carbon balance of the region is negative (deforestation and biomass burning, the remnant forested area has increased their calden density and in an indirect way his carbon sequestration capacity could also be increased. - Highlights: • A model for estimating aboveground and belowground Prosopis caldenia biomass was developed. • Biomass allocation into the tree and the root/shoot ratio were analyzed. • The equation systems presented had made it possible to more accurately estimate the biomass stored in calden woodlands

  2. Effects of manipulated above- and belowground organic matter input on soil respiration in a Chinese pine plantation.

    Science.gov (United States)

    Fan, Juan; Wang, Jinsong; Zhao, Bo; Wu, Lianhai; Zhang, Chunyu; Zhao, Xiuhai; Gadow, Klaus V

    2015-01-01

    Alteration in the amount of soil organic matter input can have profound effect on carbon dynamics in forest soils. The objective of our research was to determine the response in soil respiration to above- and belowground organic matter manipulation in a Chinese pine (Pinus tabulaeformis) plantation. Five organic matter treatments were applied during a 2-year experiment: both litter removal and root trenching (LRRT), only litter removal (LR), control (CK), only root trenching (RT) and litter addition (LA). We found that either aboveground litter removal or root trenching decreased soil respiration. On average, soil respiration rate was significantly decreased in the LRRT treatment, by about 38.93% ± 2.01% compared to the control. Soil respiration rate in the LR treatment was 30.65% ± 1.87% and in the RT treatment 17.65% ± 1.95% lower than in the control. Litter addition significantly increased soil respiration rate by about 25.82% ± 2.44% compared to the control. Soil temperature and soil moisture were the main factors affecting seasonal variation in soil respiration. Up to the 59.7% to 82.9% seasonal variation in soil respiration is explained by integrating soil temperature and soil moisture within each of the various organic matter treatments. The temperature sensitivity parameter, Q10, was higher in the RT (2.72) and LA (3.19) treatments relative to the control (2.51), but lower in the LRRT (1.52) and LR treatments (1.36). Our data suggest that manipulation of soil organic matter input can not only alter soil CO2 efflux, but also have profound effect on the temperature sensitivity of organic carbon decomposition in a temperate pine forest. PMID:25970791

  3. Participation of Electron Transfer Process in Rate-Limiting Step of Aromatic Hydroxylation Reactions by Compound I Models of Heme Enzymes.

    Science.gov (United States)

    Asaka, Maaya; Fujii, Hiroshi

    2016-07-01

    Hydroxylation reactions of aromatic rings are key reactions in various biological and chemical processes. In spite of their significance, no consensus mechanism has been established. Here we performed Marcus plot analysis for aromatic hydroxylation reactions with oxoiron(IV) porphyrin π-cation radical complexes (compound I). Although many recent studies support the mechanism involving direct electrophilic attack of compound I, the slopes of the Marcus plots indicate a significant contribution of an electron transfer process in the rate-limiting step, leading us to propose a new reaction mechanism in which the electron transfer process between an aromatic compound and compound I is in equilibrium in a solvent cage and coupled with the subsequent bond formation process. PMID:27327623

  4. Carbon input belowground is the major C flux contributing to leaf litter mass loss

    DEFF Research Database (Denmark)

    Rubino, Mauro; Dungait; Evershed; Bertolini; De Angelis; D'Onofrio; Lagomarsino; Lubritto; Merola; Terrasi; Cotrufo

    2010-01-01

    Partitioning of the quantities of C lost by leaf litter through decomposition into (i) CO2 efflux to the atmosphere and (ii) C input to soil organic matter (SOM) is essential in order to develop a deeper understanding of the litter-soil biogeochemical continuum. However, this is a challenging task...... due to the occurrence of many different processes contributing to litter biomass loss. With the aim of quantifying different fluxes of C lost by leaf litter decomposition, a field experiment was performed at a short rotation coppice poplar plantation in central Italy. Populus nigra leaf litter......, enriched in 13C (d13C +160‰) was placed within collars to decompose in direct contact with the soil (d13C -26‰) for 11 months. CO2 efflux from within the collars and its isotopic composition were determined at monthly intervals. After 11 months, remaining litter and soil profiles (0–20 cm) were sampled and...

  5. Limits and failures in hydrology: examples and lessons learned from three decades of process oriented hydrological modelling

    Science.gov (United States)

    Bronstert, Axel

    2016-04-01

    In hydrological sciences there have been rather many attempts to develop new mathematical analysis and modelling tools. Some (or even many?) of them failed or were at least only partially successful. Unfortunately, such nun-successful attempts are hardly reported on, because our common academic recognition is based on reports about success only. With all due respect to successful attempts, the scientific community could benefit a lot from reports of unsuccessful attempts or unexpected results. Therefore, in this contribution, the author presents examples of modelling failures from his own experiences during the last three decades. Emphasis is given on results obtained from process-oriented hydrological models, where the "right answer" was obtained "for the wrong reasons". Such example comprise, for instance, modelling infiltration experiments at the plot scale, modelling runoff generation from hillslope scale and in experimental catchments and modelling runoff from glaciated catchments It is explained how the "wrong reasons" could be identified and what was learned from such failures. It is argued that failures, which causes can be identified by the modeller or anybody else, could significantly contribute to a progress in hydrological system understanding or - at least - to the identification of research needs. Identification of causes of failure may even contribute more to scientific progress then brute force modelling of parameter sensitivity and uncertainty.

  6. Silicon limitation on primary production and its destiny in Jiaozhou Bay,China V: Silicon deficit process

    Institute of Scientific and Technical Information of China (English)

    YANG Dongfang; GAO Zhenhui; WANG Peigang; SUN Peiyan; LIU Shuang

    2005-01-01

    Silicon is a necessary nutrient for diatoms, silicon uptake in diatom reproduction decreased seawater silicon content. This paper clarified the characteristics of silicon transferring in the sea, which plays an important role in phytoplankton growth, zooplankton graze and marine ecosystem. Analysis revealed that silicate is supplied by terrestrial sources, through plankton uptake, death, and eventually deposits to the sea bottom, and cannot diffuse upward. This is a general silicon deficit process. Many global marine waters showed the same silicon transfer route: land→silicon biogeochemical process→sea bottom. River flow brings abundant silicate into marine waters, silicate concentration in the waters decreased in the distance away from the river estuaries. In discussion of silicon characteristics and its transfer route, it was considered that the main factor controlling the mechanism of diatom and non-diatom red tides occurrence is silicon, and the changes in silicon source. Human activities, such as sea-route cutting by building embankment and dam, and silicon supplement by the sea, such as sandstorm, rainstorm and storm tide, have largely impaired the earth ecosystem and hugely threatened the human existence. It is suggested in this paper that man should resume the original face of the Si input into the sea to keep natural ecosystem in sustainable pattern.

  7. Effects of elevated temperature and CO2 on aboveground-belowground systems: a case study with plants, their mutualistic bacteria and root / shoot herbivores

    Directory of Open Access Journals (Sweden)

    James Michael William Ryalls

    2013-11-01

    Full Text Available Interactions between above- and belowground herbivores have been prominent in the field of aboveground-belowground ecology from the outset, although little is known about how climate change affects these organisms when they share the same plant. Additionally, the interactive effects of multiple factors associated with climate change such as elevated temperature (eT and elevated atmospheric carbon dioxide (eCO2 are untested. We investigated how eT and eCO2 affected larval development of the lucerne weevil (Sitona discoideus and colonisation by the pea aphid (Acyrthosiphon pisum, on three cultivars of a common host plant, lucerne (Medicago sativa. Sitona discoideus larvae feed on root nodules housing N2-fixing rhizobial bacteria, allowing us to test the effects of eT and eCO2 on three trophic levels. Moreover, we assessed the influence of these factors on plant growth. eT increased plant growth rate initially (6, 8 and 10 weeks after sowing, with cultivar ‘Sequel’ achieving the greatest height. Inoculation with aphids, however, reduced plant growth at week 14. eT severely reduced root nodulation by 43%, whereas eCO2 promoted nodulation by 56%, but only at ambient temperatures. Weevil presence increased net root biomass and nodulation, by 31 and 45%, respectively, showing an overcompensatory plant growth response. Effects of eT and eCO2 on root nodulation were mirrored by weevil larval development; eT and eCO2 reduced and increased larval development, respectively. Contrary to expectations, aphid colonisation was unaffected by eT or eCO2, but there was a near-significant 10% reduction in colonisation rates on plants with weevils present belowground. The contrasting effects of eT and eCO2 on weevils potentially occurred through changes in root nodulation patterns.

  8. Interactive effects of belowground organic matter input, increased precipitation and clipping on soil carbon and nitrogen mineralization in a temperate steppe

    Directory of Open Access Journals (Sweden)

    L. N. Ma

    2013-06-01

    Full Text Available Soil organic matter (SOM inputs, increased precipitation and clipping (reducing belowground photosynthates allocation are predicted to affect soil C and N cycling in temperate grassland ecosystems. However, the interactive effects between SOM inputs (or increased precipitation and clipping on soil C and N mineralization in temperate steppes are still poorly understood. A field manipulation experiment was conducted to quantify the effects of SOM inputs, increased precipitation, clipping and their interactions on soil C and N mineralization in a temperate steppe of northeastern China from 2010 to 2011. The results showed that SOM inputs significantly increased soil C mineralization rate (CMR and net N mineralization rate (NMR. Increased precipitation-induced enhancement of soil CMR essentially ceased after the first year, stimulation of soil NMR and NNR continued into the second year. However, clipping only marginally decreased soil CMR and NMR during the two years. There were significant synergistic interactions between SOM inputs (or increased precipitation and clipping on soil CMR and NMR, as SOM inputs (or increased precipitation showed greater effects on soil CMR and NMR under clipped plots than under unclipped plots, which could be explained by the relative shifts in soil microbial community structure because of bacterial biomass increases, and by the relative decreases in arbuscular mycorrhizal fungi biomass due to the reduction of belowground photosynthates allocation. These results highlight the importance of plants in mediating the responses of soil C and N mineralization to potentially increased SOM and precipitation by controlling belowground photosynthates allocation in the temperate steppe. Thus, the findings have important implications for improving prediction of C and N sequestration potential and its feedbacks to climate change in temperate steppe ecosystems.

  9. Sorption-desorption processes of radioisotopes with solid materials from liquid releases and atmosphere deposits. The distribution coefficient (Ksub(d)), its uses, limitations, and practical applications

    International Nuclear Information System (INIS)

    The various sorption-desorption processes of radionuclides with environmental materials are presented. The parameters governing the distribution coefficient are reviewed in the light of various examples. The factors affecting equilibria between the different phases are: reaction time, concentration of the solid phase, water quality, salinity, competition between ions, concentration of radioisotopes or stable isotopes, pH of the mobile phase, particle diameter, chemical form of the radioisotopes, nature of the solid phase, temperature. The effects of the biological parameters on the distribution coefficient are discussed. Biological processes affect the main chemical transformations: mineralization, insolubilization, oxidation-reduction, complexation, ... The importance of these processes is demonstrated by a number of examples in various media. Finally, the practical use of Ksub(d) in the assessment of the environmental impact of radioactive releases is developed, with special emphasis on the limits of its use in siting studies and its essential interest in specifying pathways and capacity of a river system

  10. Impact of long-term wetting on belowground respiration and methanogenesis in Luther Bog, Ontario

    Science.gov (United States)

    Goebel, Marie; Blodau, Christian

    2016-04-01

    Peatlands play a major role in the global carbon cycle. They store one-third of total world soil carbon, sequester carbon dioxide (CO2) and release CO2 and methane (CH4). Climate and land-use change are predicted to cause either wetter winters and wetter summers or wetter winters and drier summers in the area where northern peatlands are located. Feedback on processes in the peat is poorly understood on the time scale of decades. In this study, we investigated impacts of long-term wetting and long-term fluctuating water table on potential CO2 and CH4 production rates and organic matter quality of the fractions bulk peat, pore water and leachate. Bulk peat potential CO2 production rates of 2.38 to 25.55 μmol g‑1 d‑1 (aerobic) and 1.53 to 7.33 μmol g‑1 d‑1 (anaerobic) decreased with depth along with a decrease in organic matter quality. Potential CH4 production rates (0.002 to 2.60 μmol g‑1 d‑1) increased with anaerobic conditions and a lack of electron acceptors rather than being dependent on the availability of labile organic matter. This pattern was less evident in solute fraction samples where labile compounds in top layers were probably either too labile to be detected or water movement obscured differences between depths. Bulk peat potential anaerobic CO2 and CH4 production increased through long-term wetting. As wetting did not change organic matter quality or aerobic production rates, increased anaerobic production rates likely originate from microorganisms adapted to anaerobic conditions. All indicators of organic matter quality, FTIR ratios, SUVA254, E2:E3, HIX, FI and PARAFAC, provided similar results. Other than expected, wetting did not result in higher organic matter quality in bulk peat and leachate. Drier conditions in summer led to reduced organic matter quality. In pore water, long-term wetter conditions resulted in a higher organic matter quality. Slow-down of decomposition due to anaerobic conditions is unlikely, as this was not the

  11. Belowground ecology of scarabs feeding on grass roots: current knowledge and future directions for management in Australasia

    Directory of Open Access Journals (Sweden)

    Adam eFrew

    2016-03-01

    Full Text Available Many scarab beetles spend the majority of their lives belowground as larvae, feeding on grass roots. Many of these larvae are significant pests, causing damage to crops and grasslands. Damage by larvae of the greyback cane beetle (Dermolepida albohirtum, for example, can cause financial losses of up to AU$40 million annually to the Australian sugarcane industry. We review the ecology of some scarab larvae in Australasia, focusing on three subfamilies; Dynastinae, Rutelinae and Melolonthinae, containing key pest species. Although considerable research on the control of some scarab pests has been carried out in Australasia, for some species, the basic biology and ecology remains largely unexplored. We synthesize what is known about these scarab larvae and outline key knowledge gaps to highlights future research directions with a view to improve pest management. We do this by presenting an overview of the scarab larval host plants and feeding behavior; the impacts of abiotic (temperature, moisture and fertilization and biotic (pathogens, natural enemies and microbial symbionts factors on scarab larvae and conclude with how abiotic and biotic factors can be applied in agriculture for improved pest management, suggesting future research directions.Several host plant microbial symbionts, such as arbuscular mycorrhizal fungi and endophytes, can improve plant tolerance to scarabs and reduce larval performance, which have shown promise for use in pest management. In addition to this, several microbial scarab pathogens have been isolated for commercial use in pest management with particularly promising results. The entomopathogenic fungus Metarhizium anisopliae caused a 50% reduction in cane beetle larvae while natural enemies such as entomopathogenic nematodes have also shown potential as a biocontrol. Continued research should focus on filling the gaps in the knowledge of the basic ecology and feeding behavior of scarab larval species within Australasia

  12. Inappropriate Use of the Quasi-Reversible Electrode Kinetic Model in Simulation-Experiment Comparisons of Voltammetric Processes That Approach the Reversible Limit

    KAUST Repository

    Simonov, Alexandr N.

    2014-08-19

    Many electrode processes that approach the "reversible" (infinitely fast) limit under voltammetric conditions have been inappropriately analyzed by comparison of experimental data and theory derived from the "quasi-reversible" model. Simulations based on "reversible" and "quasi-reversible" models have been fitted to an extensive series of a.c. voltammetric experiments undertaken at macrodisk glassy carbon (GC) electrodes for oxidation of ferrocene (Fc0/+) in CH3CN (0.10 M (n-Bu)4NPF6) and reduction of [Ru(NH 3)6]3+ and [Fe(CN)6]3- in 1 M KCl aqueous electrolyte. The confidence with which parameters such as standard formal potential (E0), heterogeneous electron transfer rate constant at E0 (k0), charge transfer coefficient (α), uncompensated resistance (Ru), and double layer capacitance (CDL) can be reported using the "quasi- reversible" model has been assessed using bootstrapping and parameter sweep (contour plot) techniques. Underparameterization, such as that which occurs when modeling CDL with a potential independent value, results in a less than optimal level of experiment-theory agreement. Overparameterization may improve the agreement but easily results in generation of physically meaningful but incorrect values of the recovered parameters, as is the case with the very fast Fc0/+ and [Ru(NH3)6]3+/2+ processes. In summary, for fast electrode kinetics approaching the "reversible" limit, it is recommended that the "reversible" model be used for theory-experiment comparisons with only E0, R u, and CDL being quantified and a lower limit of k 0 being reported; e.g., k0 ≥ 9 cm s-1 for the Fc0/+ process. © 2014 American Chemical Society.

  13. Can ectomycorrhizal symbiosis and belowground plant traits be used as ecological tools to mitigate erosion on degraded slopes in the ultramafic soils of New Caledonia?

    Science.gov (United States)

    Demenois, Julien; Carriconde, Fabian; Rey, Freddy; Stokes, Alexia

    2015-04-01

    New Caledonia is an archipelago in the South West Pacific located just above the Tropic of Capricorn. The main island is bisected by a continuous mountain chain whose highest peaks reach more than 1 600 m. With mean annual rainfall above 2 000 mm in the South of the main island, frequent downpours and steep slopes, its soils are prone to water erosion. Deforestation, fires and mining activity are the main drivers of water erosion. Stakes are high to mitigate the phenomenon: extraction of nickel from ultramafic substrates (one third of the whole territory) is the main economic activity; New Caledonia is considered as a biodiversity hotspot. Restoration ecology is seen as a key approach for tackling such environmental challenges. Soil microorganisms could play significant roles in biological processes such as plant nutrition and plant resistance to abiotic and biotic stresses. Microorganisms could increase soil aggregate stability and thus mitigate soil erodibility. Plant roots increase soil cohesion through exudation and decomposition processes. To date, few studies have collected data on the soil aggregate stability of steep slopes affected by erosion and, to our knowledge, interactions between ectomycorrhizas (ECM), roots and erodibility of ultramafic soils have never been considered. The objective of our study is to assess the influence of ECM symbiosis and plant root traits on the erodibility of ultramafic soils of New Caledonia and answer the following questions: 1/ What is the influence of plant root traits of vegetal communities and ECM fungal diversity on soil erodibility? 2/ What are the belowground plant traits of some mycorrhized endemic species used in ecological restoration? 3/ What is the influence of plant root traits and ECM fungal inoculation on soil erodibility? At the scale of plant communities, five types of vegetation have been chosen in the South of the main island: degraded ligno-herbaceous shrubland, ligno-herbaceous shrubland, degraded humid

  14. 设计阶段的限额设计应用研究%The Design Process of Investment Control Based on Design Limits

    Institute of Scientific and Technical Information of China (English)

    张文杰; 张哲奇; 李洪砚

    2014-01-01

    In the investment control, construction units pay more attention to the construction aspects and less to the design aspects, which will lead to inefficient use of funds and show the "three excesses" phenomenon. This paper discusses an effective method for investment control at the design stage: using the limits design in the design process to control the design investment in the plan investment degree of construction project, achieve the investment limits not exceeded, and reach the purpose of investment control. Finally the paper reflects the features of limits design.%建设单位在投资控制中过度重视施工环节而轻视设计环节,将导致资金的利用效率低下,出现“三超”现象。本文探讨了在设计阶段实现投资控制的一条有效方法:在设计过程中使用限额设计的方法,将设计投资控制在建设项目的计划投资内,实现投资限额不被突破,达到投资控制的目的。最后针对限额设计的特点,表明了一些思考。

  15. Modeling Complex Time Limits

    Directory of Open Access Journals (Sweden)

    Oleg Svatos

    2013-01-01

    Full Text Available In this paper we analyze complexity of time limits we can find especially in regulated processes of public administration. First we review the most popular process modeling languages. There is defined an example scenario based on the current Czech legislature which is then captured in discussed process modeling languages. Analysis shows that the contemporary process modeling languages support capturing of the time limit only partially. This causes troubles to analysts and unnecessary complexity of the models. Upon unsatisfying results of the contemporary process modeling languages we analyze the complexity of the time limits in greater detail and outline lifecycles of a time limit using the multiple dynamic generalizations pattern. As an alternative to the popular process modeling languages there is presented PSD process modeling language, which supports the defined lifecycles of a time limit natively and therefore allows keeping the models simple and easy to understand.

  16. Process of care and preliminary outcome in limited-stage small-cell lung cancer: results of the 1995-1997 patterns of care study in Japan

    International Nuclear Information System (INIS)

    Purpose: To evaluate the practice process using the national average (Na); to compare differences in the process of care by age group; and to provide a preliminary outcome data for limited-stage small-cell lung cancer in Japan. Methods and Materials: The Patterns of Care Study conducted a nationwide survey of the care process for Stage I-III small-cell lung cancer in Japan. Patients were divided into three age groups: <65 years (younger group, n = 73); between 65 and 74 years (intermediate group, n = 81); and ≥75 years (elderly group, n = 20). Results: The NA for the total dose was 49.0 Gy, and for use of photon energy ≥6 MV, chemotherapy, and prophylactic cranial irradiation was 77.3%, 93.2%, and 1.69%, respectively. Age stratification had no impact on the variables of radiotherapy (RT) such as total dose and field size. Only 37% of patients received chemotherapy and thoracic RT concurrently. The proportion of patients who received chemotherapy and RT concurrently was 44%, 27%, and 25% of the younger, intermediate, and elderly groups, respectively (p = 0.029). Etoposide and cisplatin were less frequently used in the elderly group (≥75 years old). Overall survival at 3 years for the entire group was 26%. The 3-year survival rate was 30% in the younger group, 28% in the intermediate group, and 9% in the elderly group. Variables found to have a significant impact on survival by multivariate analysis were the use of chemotherapy (p = 0.030), age (p 0.032), and T stage (p = 0.042). Conclusion: Calculated NAs showed that the results of clinical study had favorably penetrated into the practice process in Japan. The results demonstrated that patient age significantly influenced the process of chemotherapy such as the use of etoposide and cisplatin for limited-stage small-cell lung cancer in Japan. More concurrent chemotherapy and thoracic RT and the application of prophylactic cranial irradiation for complete responders need to be investigated in the future

  17. The Limit Properties of the Bisexual Branching Process with Two Kinds of Immigration%双移民两性分支过程的极限性质

    Institute of Scientific and Technical Information of China (English)

    刘宣

    2015-01-01

    考虑同时带个体移民和配对单元移民的两性分支过程,称为双移民两性分支过程。本文首先介绍这种两性分支过程模型,然后讨论过程的状态性质,在一定的条件下得到过程的正常返性,最后研究第n代每个配对单元平均增长率的极限行为并利用马氏链的相关结论给出过程的极限性质。%In this paper,we consider a bisexual branching process with individual immigration and unit immigration called two types of immigration.First we introduce this bisexual Galton-Watson branching processes, then discuss the properties of its state space and ob-tained positive recurrent in some conditions.Finally thelimit behaviour of the mean growth rate per mating unit is studied and the limit properties for the process is investigated by using relevant conclusions of Markovchain.

  18. Direct measurement of acylenzyme hydrolysis demonstrates rate-limiting deacylation in cleavage of physiological sequences by the processing protease Kex2.

    Science.gov (United States)

    Rockwell, N C; Fuller, R S

    2001-03-27

    Saccharomyces cerevisiae Kex2 protease is the prototype for the family of eukaryotic proprotein convertases that includes furin, PC1/3, and PC2. These enzymes belong to the subtilase superfamily of serine proteases and are distinguished from degradative subtilisins by structural features and by their much more stringent substrate specificity. Pre-steady-state studies have shown that both Kex2 and furin exhibit an initial burst of 7-amino-4-methylcoumarin release in cleavage of peptidyl methylcoumarinamide substrates that are based on physiological cleavage sites. Thus, in cleavage of such substrates, formation of the acylenzyme intermediate is fast relative to some later step (deacylation or N-terminal product release). This behavior is significant, because Kex2 also exhibits burst kinetics in cleavage of peptide bonds. k(cat) for cleavage of a tetrapeptidyl methylcoumarinamide substrate based on the physiological yeast substrate pro-alpha-factor exhibits a weak solvent isotope effect, but neither this isotope effect nor temperature dependence studies with this substrate conclusively identify the rate-limiting step for Kex2 cleavage of this substrate. We therefore developed an assay to measure deacylation directly by pulse-chase incorporation of H(2)(18)O in a rapid-quenched-flow mixer followed by mass spectrometric quantitation. The results given by this assay rule out rate-limiting product release for cleavage of this substrate by Kex2. These experiments demonstrate that cleavage of the acylenzyme ester bond, as opposed to either the initial attack on the amide bond or product release, is rate-limiting for the action of Kex2 at physiological sequences. This work demonstrates a fundamental difference in the catalytic strategy of proprotein processing enzymes and degradative subtilisins. PMID:11297433

  19. Evidence that acidification-induced declines in plant diversity and productivity are mediated by changes in below-ground communities and soil properties in a semi-arid steppe

    Science.gov (United States)

    Chen, Dima; Lan, Zhichun; Bai, Xue; Grace, James B.; Bai, Yongfei

    2013-01-01

    Anthropogenic acid deposition–induced soil acidification is one of the major threats to biodiversity, ecosystem functioning and services. Few studies, however, have explored in detail how above-ground changes in plant species richness and productivity resulting from soil acidification are mediated by effects on below-ground biota and soil properties.

  20. Assessment of Current Process Modeling Approaches to Determine Their Limitations, Applicability and Developments Needed for Long-Fiber Thermoplastic Injection Molded Composites

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ba Nghiep; Holbery, Jim; Smith, Mark T.; Kunc, Vlastimil; Norris, Robert E.; Phelps, Jay; Tucker III, Charles L.

    2006-11-30

    This report describes the status of the current process modeling approaches to predict the behavior and flow of fiber-filled thermoplastics under injection molding conditions. Previously, models have been developed to simulate the injection molding of short-fiber thermoplastics, and an as-formed composite part or component can then be predicted that contains a microstructure resulting from the constituents’ material properties and characteristics as well as the processing parameters. Our objective is to assess these models in order to determine their capabilities and limitations, and the developments needed for long-fiber injection-molded thermoplastics (LFTs). First, the concentration regimes are summarized to facilitate the understanding of different types of fiber-fiber interaction that can occur for a given fiber volume fraction. After the formulation of the fiber suspension flow problem and the simplification leading to the Hele-Shaw approach, the interaction mechanisms are discussed. Next, the establishment of the rheological constitutive equation is presented that reflects the coupled flow/orientation nature. The decoupled flow/orientation approach is also discussed which constitutes a good simplification for many applications involving flows in thin cavities. Finally, before outlining the necessary developments for LFTs, some applications of the current orientation model and the so-called modified Folgar-Tucker model are illustrated through the fiber orientation predictions for selected LFT samples.

  1. Recommendations to the NRC for review criteria for alternative methods of low-level radioactive waste disposal: Task 2a, Below-ground vaults

    International Nuclear Information System (INIS)

    The US Army Engineer Waterways Experiment Station (WES) and the US Army Engineer Division, Huntsville (HNDED) have developed general design criteria and specific design review criteria for the below-ground vault (BGV) alternative method of low-level radioactive waste (LLW) disposal. A BGV is a reinforced concrete vault (floor, walls, and roof) placed underground below the frost line, and above the water table, surrounded by filter blanket and drainage zones and covered with a low permeability earth layer and top soil with vegetation. Eight major review criteria categories have been developed ranging from the loads imposed on the BGV structure through material quality and durability considerations. Specific design review criteria have been developed in detail for seven of the eight major categories. 59 refs., 14 figs., 2 tabs

  2. On limit and limit setting.

    Science.gov (United States)

    Gorney, J E

    1994-01-01

    This article investigates the role of limit and limit setting within the psychoanalytic situation. Limit is understood to be a boundary between self and others, established as an interactional dimension of experience. Disorders of limit are here understood within the context of Winnicott's conception of the "anti-social tendency." Limit setting is proposed as a necessary and authentic response to the patient's acting out via holding and empathic responsiveness, viewed here as a form of boundary delineation. It is proposed that the patient attempts to repair his or her boundary problem through a seeking of secure limits within the analyst. The setting of secure and appropriate limits must arise from a working through of the analyst's own countertransference response to the patient. It is critical that this response be evoked by, and arise from, the immediate therapeutic interaction so that the patient can experience limit setting as simultaneously personal and authentic. PMID:7972580

  3. Determination of a limit on the branching ratio of the rare process b → s γ with the L3 detector at LEP

    International Nuclear Information System (INIS)

    This work is dedicated to the determination of a limit on the branching ratio of the rare process b -> Sγ, from Z -> bb-bar events collected at LEP with the L3 detector during collisions at √S ∼ MZ, MZ ± 2 GeV. The rare decay of the b quark, b -> sγ, is forbidden at tree level and occurs, in the Standard Model, through one loop diagram (called penguin diagram) which makes it sensitive to contributions of new particles such as charged Higgs bosons or supersymmetric particles. The theoretical branching ratio is given in Standard Model by Br(b->Sγ) (2.55 ± 0.58) x 10-4. The aim of this study was to observe, in the inclusive mode, a possible excess of the rate of the b -> sγ transition, compare to the expected value. The selection of b hadrons from Z hadronic decays is achieved by the use of both an algorithm based on a multidimensional analysis of the event shape and an algorithm based on the impact parameter of the tracks. The energetic photon is selected by using a π0/γ discriminator based on the transverse shape of its electromagnetic shower. The s-jet reconstruction is achieved by the use of an iterative method with search of the minimum invariant mass. It allows the determination of the b hadron rest frame, which picks near 2.5 GeV, is used in a new method of signal events simulation. No excess of event is observed in the data after the analysis of 1.5 million of Z decays. The limit obtained, when the systematic errors are included, is: Br(b -> sγ) ≤9.2 x 104 at 90% confidence level. This result is consistent with the Standard Model expectation. (author)

  4. Quench limits

    International Nuclear Information System (INIS)

    With thirteen beam induced quenches and numerous Machine Development tests, the current knowledge of LHC magnets quench limits still contains a lot of unknowns. Various approaches to determine the quench limits are reviewed and results of the tests are presented. Attempt to reconstruct a coherent picture emerging from these results is taken. The available methods of computation of the quench levels are presented together with dedicated particle shower simulations which are necessary to understand the tests. The future experiments, needed to reach better understanding of quench limits as well as limits for the machine operation are investigated. The possible strategies to set BLM (Beam Loss Monitor) thresholds are discussed. (author)

  5. Universal Limits on Computation

    CERN Document Server

    Krauss, L M

    2004-01-01

    The physical limits to computation have been under active scrutiny over the past decade or two, as theoretical investigations of the possible impact of quantum mechanical processes on computing have begun to make contact with realizable experimental configurations. We demonstrate here that the observed acceleration of the Universe can produce a universal limit on the total amount of information that can be stored and processed in the future, putting an ultimate limit on future technology for any civilization, including a time-limit on Moore's Law. The limits we derive are stringent, and include the possibilities that the computing performed is either distributed or local. A careful consideration of the effect of horizons on information processing is necessary for this analysis, which suggests that the total amount of information that can be processed by any observer is significantly less than the Hawking-Beckenstein entropy associated with the existence of an event horizon in an accelerating universe.

  6. Nitridation of organo-silicate glass: A self-limiting process for PVD Ta1+xN/Ta barrier formation

    International Nuclear Information System (INIS)

    Interfacial reactions of sputter-deposited Ta with a low dielectric constant Si-O-C-H material (SiCOH), and with surface-nitrided SiCOH (N-SiCOH) were investigated using X-ray photoelectron spectroscopy (XPS). The studies were carried out in a system containing a processing chamber attached to an XPS analysis chamber so that sample transport between deposition and analysis environments occurred under ultrahigh vacuum (UHV) conditions. Ta sputter deposition on unmodified SiCOH yielded an interfacial phase ∼3 nm thick composed of Ta oxide/carbide (Ta-O-C), which is known to interact only weakly with Cu. Bombardment of the vicinal SiCOH surface by 500 eV Ar+ in the presence of NH3 resulted in carbon depletion and the self-limiting nitridation of the surface, with N attachment primarily at Si sites. Subsequent Ta sputter deposition yielded reduced Ta oxide and carbide formation, and formation of a Ta-rich nitride layer of 10 A average thickness. Subsequent deposition resulted in metallic Ta formation.

  7. Three-dimensional spectrum mapping of bright emission centers: Investigating the brightness-limiting process in Eu-doped GaN red light emitting diodes

    International Nuclear Information System (INIS)

    A pulse-driven emission-spectroscopy mapping technique is used to investigate the bright emission centers in Eu-doped GaN (GaN:Eu) red light emitting diodes (LED). The LEDs are operated in pulse-driven mode, and the emission spectra are acquired for a range of pulse frequencies. This ensemble of emission spectral data yields a three-dimensional mapping that allows the origin of emission lines to be identified by visual inspection. The identification was achieved even for a weak 5D0 → 7F3 transition in conventional photoluminescence measurements. A peculiar split is observed in the 5D0 → 7F3 transition for the bright emission center referred to as OMVPE 8. Despite the unique transition at this emission center, the emission efficiencies for the 5D0 → 7F3 and 5D0 → 7F2 transitions were identical. This finding indicates that the excitation of the emission centers, rather than the radiative transitions, is the limiting process that determines the GaN:Eu red LED brightness

  8. Limited Neutrality

    DEFF Research Database (Denmark)

    Nielsen, Morten Ebbe Juul

    2006-01-01

    Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."......Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."...

  9. Dose limits

    International Nuclear Information System (INIS)

    The dose limit is defined to be the level of harmfulness which must not be exceeded, so that an activity can be exercised in a regular manner without running a risk unacceptable to man and the society. The paper examines the effects of radiation categorised into stochastic and non-stochastic. Dose limits for workers and the public are discussed

  10. Limiting Skepticism

    DEFF Research Database (Denmark)

    Hendricks, Vincent Fella; Symons, John

    2011-01-01

    Skeptics argue that the acquisition of knowledge is impossible given the standing possibility of error. We present the limiting convergence strategy for responding to skepticism and discuss the relationship between conceivable error and an agent’s knowledge in the limit. We argue that the skeptic...... must demonstrate that agents are operating with a bad method or are in an epistemically cursed world. Such demonstration involves a significant step beyond conceivability and commits the skeptic to potentially convergent inquiry...

  11. Limit analysis via creep

    International Nuclear Information System (INIS)

    In this paper it is presented a variational method for the limit analysis of an ideal plastic solid. This method has been denominated as Modified Secundary Creep and enables to find the collapse loads through a minimization of a functional and a limit process. Given an ideal plastic material it is shown how to determinate the associated secundary creep constitutive equation. Finally, as an application, it is found the limit load in an pressurized von Mises rigid plastic sphere. (Author)

  12. Patterns in root traits of woody species hosting arbuscular and ectomycorrhizas: implications for the evolution of belowground strategies

    Science.gov (United States)

    Despite large variation in root traits among species, we have limited understanding of how traits are related to diverse soil resource acquisition strategies. We examined root trait variation among 33 species co-existing in Northeastern US forests that form the two most common mutualisms with mycorr...

  13. The release of dipicolinic acid--the rate-limiting step of Bacillus endospore inactivation during the high pressure thermal sterilization process.

    Science.gov (United States)

    Reineke, Kai; Schlumbach, Karl; Baier, Daniel; Mathys, Alexander; Knorr, Dietrich

    2013-03-01

    High pressure combined with elevated temperatures can produce low acid, commercially sterile and shelf-stable foods. Depending on the temperature and pressure levels applied, bacterial endospores pass through different pathways, which can lead to a pressure-induced germination or inactivation. Regardless of the pathway, Bacillus endospores first release pyridine-2,6-dicarboxylic acid (DPA), which contributes to the low amount of free water in the spore core and is consequently responsible for the spore's high resistance against wet and dry heat. This is therefore the rate-limiting step in the high pressure sterilization process. To evaluate the impact of a broad pressure, temperature and time domain on the DPA release, Bacillus subtilis spores were pressure treated between 0.1 and 900 MPa at between 30 and 80 °C under isothermal isobaric conditions during dwell time. DPA quantification was assessed using HPLC, and samples were taken both immediately and 2 h after the pressure treatment. To obtain a release kinetic for some pressure-temperature conditions, samples were collected between 1s and 60 min after decompression. A multiresponse kinetic model was then used to derive a model covering all kinetic data. The isorate lines modeled for the DPA release in the chosen pressure-temperature landscape enabled the determination of three distinct zones. (I) For pressures temperatures >50 °C, a 90% DPA release was achievable in less than 5 min and no difference in the amount of DPA was found immediately 2 h after pressurization. This may indicate irreversible damage to the inner spore membrane or membrane proteins. (II) Above 600 MPa the synergism between pressure and temperature diminished, and the treatment temperature alone dominated DPA release. (III) Pressures temperatures <50 °C resulted in a retarded release of DPA, with strong increased differences in the amount of DPA released after 2 h, which implies a pressure-induced physiological like germination with

  14. Geophysical Processes - PRE-WISCONSIN_GLACIAL_LIMIT_IN: Southern extent of glaciation in Indiana (Indiana Geological Survey, 1:500,000, Line Shapefile)

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — PRE-WISCONSIN_GLACIAL_LIMIT_IN.shp is a line shapefile that shows the extent of glaciation in Indiana as delineated by mapped glacial deposits of various types and...

  15. Limits on the Dipole Moments of the $\\tau$-Lepton via the Process $e^{+}e^{-}\\to \\tau^+ \\tau^- \\gamma in a Left-Right Symmetric Model

    CERN Document Server

    Gutiérrez-Rodríguez, A; Noriega, L N Luis

    2004-01-01

    Limits on the anomalous magnetic moment and the electric dipole moment of the $\\tau$ lepton are calculated through the reaction $e^{+}e^{-}\\to \\tau^+ \\tau^- \\gamma$ at the $Z_1$-pole and in the framework of a left-right symmetric model. The results are based on the recent data reported by the L3 Collaboration at CERN LEP. Due to the stringent limit of the model mixing angle $\\phi$, the effect of this angle on the dipole moments is quite small.

  16. Exploring the 'divergence' problem using a simple process-based model of tree growth

    Science.gov (United States)

    Li, Guangqi; Harrison, Sandy P.; Prentice, I. Colin

    2016-04-01

    There has been an apparent change in the sensitivity of tree rings to temperature in northern extratropical regions since the 1980s - a phenomenon often referred to as the divergence problem. Several potential explanations have been suggested to explain the decoupling between ring width (or density) and temperature, including exceedance of limiting temperature thresholds with global warming, changes in light availability with global dimming, the increasing importance of soil or atmospheric drought as a limitation to tree growth, or the CO2 'fertilization effect'. Here we use a simple, process-based tree-growth and carbon allocation model to explore these hypotheses. While changes in light availability and drought contribute to explain the declining influence of temperature on tree growth, the most important factor is changes in carbon allocation to roots and mycorrhizae in response to increasing [CO2] and the demand for increased nutrients to support photosynthesis. The magnitude of the increase in below-ground allocation, and hence the relative importance of this mechanism versus climate in controlling tree radial growth, appears to be influenced by nutrient and water availability. The potential importance of changes in carbon allocation challenges the use of statistical models for climate reconstructions from tree rings during intervals when [CO2] was different from historical values.

  17. Assessing the Significance of Above- and Belowground Carbon Allocation of Fast- and Slow-Growing Families of Loblolly Pine - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Topa, M. A.; Weinstein, D. A.; Retzlaff, W. A.

    2001-03-01

    During this project we experimentally evaluated the below-ground biomass and carbon allocation and partitioning of four different fast- and slow-growing families of loblolly pine located in Scotland County, NC, in an effort to increase the long-term performance of the crop. The trees were subjected to optimal nutrition and control since planting in 1993. Destructive harvests in 1998 and 2000 were used for whole?plant biomass estimates and to identify possible family differences in carbon acquisition (photosynthesis) and water use efficiency. At regular intervals throughout each year we sampled tissues for carbohydrate analyses to assess differences in whole-tree carbon storage. Mini rhizotron observation tubes were installed to monitor root system production and turnover. Stable isotope analysis was used to examine possible functional differences in water and nutrient acquisition of root systems between the various families. A genetic dissection of root ontogenic and architectural traits, including biomass partitioning, was conducted using molecular markers to better understand the functional implications of these traits on resource acquisition and whole-plant carbon allocation.

  18. Seasonal Belowground Ecosystem and Eco-enzymatic Responses to Soil pH and Phosphorus Availability in Temperate Hardwood Forests

    Science.gov (United States)

    Smemo, K. A.; Deforest, J. L.; Petersen, S. L.; Burke, D.; Hewins, C.; Kluber, L. A.; Kyker, S. R.

    2013-12-01

    Atmospheric acid deposition can increase phosphorus (P) limitation in temperate hardwood forests by increasing N availability, and therefore P demand, and/or by decreasing pH and occluding inorganic P. However, only recently have studies demonstrated that P limitation can occur in temperate forests and very little is known about the temporal aspects of P dynamics in acidic forest soils and how seasonal shifts in nutrient availability and demand influence microbial investment in extracellular enzymes. The objectives of this study were to investigate how P availability and soil pH influence seasonal patterns of nutrient cycling and soil microbial activity in hardwood forests that experience chronic acid deposition. We experimentally manipulated soil pH, P, or both for three years and examined soil treatment responses in fall, winter, spring, early summer, and late summer. We found that site (glaciated versus unglaciated) and treatment had the most significant influence on nutrient pools and cycling. In general, nutrient pools were higher in glaciated soils than unglaciated for measured nutrients, including total C and N (2-3 times higher), extractable inorganic nitrogen, and readily available P. Treatment had no impact on total C and N pools in either region, but did affect other measured nutrients such as ammonium, which was greatest in the elevated pH treatment for both sites. As expected, readily available P pools were highest in the elevated P treatments (3 fold increase in both sites), but raising pH decreased available P pools in the glaciated site. Raising soil pH increased both net N mineralization rates and net P mineralization rates, regardless of site. Nitrification responses were complex, but we observed an overall significant nitrification increase under elevated pH, particularly in the growing season. Extracellular enzyme activity showed more seasonal patterns than site and treatment effects, exhibiting significant growing season activity reductions for

  19. Apports et limites du traitement de texte dans une tâche de rédaction en L2 Benefits and limits of word processing in a writing task in L2

    Directory of Open Access Journals (Sweden)

    Michèle Catroux

    2012-03-01

    Full Text Available L’expérimentation décrite dans cet article a été conduite auprès de jeunes apprenants d’anglais afin de déterminer les effets de l’utilisation du traitement de texte sur la conduite d’une tâche collaborative de production écrite. L’objet de cette recherche était d’analyser les stades de planification, mise en mots et révision opérés par les élèves. Les verbalisations pendant le travail, les phases rédactionnelles et les performances du groupe travaillant avec le traitement de texte ont été comparées à celles du groupe travaillant sur support papier. L’analyse des variations a permis d’estimer le degré de la surcharge cognitive liée à la manipulation de l’ordinateur et les apports du traitement de texte.The experiment described in the article has been carried out with young learners of English so as to determine the effects of word processing on a collaborative writing task. The purpose of this research was to analyse the stages of planning, translating and reviewing implemented by the learners. The verbalizations during their work, the writing phases and the performance of the group working with a word-processor have been compared to those of the group working with pen and paper. The analysis of the variations made it possible to estimate the degree of cognitive overload in relation to the use of the computer and the benefits of word processing.

  20. Limits on the dipole moments of the $\\tau$-lepton via the process $e^{+}e^{-} \\to \\tau^{+}\\tau^{-}\\gamma$ in a left-right symmetric model

    CERN Document Server

    Gutiérrez-Rodríguez, A; Noriega, Luis; 10.1142/S0217732304014689

    2004-01-01

    Limits on the anomalous magnetic moment and the electric dipole moment of the tau lepton are calculated through the reaction e/sup + /e/sup -/ to tau /sup +/ tau /sup -/ gamma at the Z/sub 1/-pole and in the framework of a left-right symmetric model. The results are based on the recent data reported by the L3 collaboration at CERN LEP. Due to the stringent limit of the model mixing angle phi , the effect of this angle on the dipole moments is quite small.

  1. Process limitations of a whole-cell P450 catalyzed reaction using a CYP153A-CPR fusion construct expressed in Escherichia coli

    DEFF Research Database (Denmark)

    Lundemo, M. T.; Notonier, S.; Striedner, G.;

    2016-01-01

    Cytochrome P450s are interesting biocatalysts due to their ability to hydroxylate non-activated hydrocarbons in a selective manner. However, to date only a few P450-catalyzed processes have been implemented in industry due to the difficulty of developing economically feasible processes. In this s...

  2. Impact of Privatization : "Managing the Process of Privatization and its impacts on Performance and Development: A case Study of Pakistan Telecommunication Limited"

    OpenAIRE

    Haroon-Ur-Rashid, Haroon; Shah, Muhammad-Anwar-Jamal; Ullah, Hussain; Ahmed, Sheraz

    2009-01-01

    Objective: The purpose of the thesis is to evaluate the impacts of privatization on Growth, profitability and employment of Pakistan Telecommunication Limited, So that the organization may be able to get the fruitful impacts of this globally recognized phenomenon. In such a situation where privatization is still a matter of suspicion, it will make some positive contribution. Methods: In our dissertation we have followed the Qualitative method, while our main sources of information are reports...

  3. "I have surly passed a limit, it is simply too much" : women's and men's experiences of stress and wellbeing when living within a process of housework resignation

    OpenAIRE

    Harryson, Lisa; Aléx, Lena; Hammarström, Anne

    2016-01-01

    BACKGROUND: Gender inequality within paid and unpaid work exposes women and men to different environments and responsibilities. These gender patterns shape living conditions for women and men, either negatively or positively, by affecting the prospect of good health. Most public health studies of gender and housework are quantitative, and knowledge about the relationship between housework experiences and health for women and men is limited. The aim of this study was to explore the housework e...

  4. Towards microbiological quality assurance in radiation sterilization processing: the limiting case model applied to a microbial population having a distribution of radiation responses

    International Nuclear Information System (INIS)

    A limiting case model, developed earlier to provide a conservative estimate of the proportion of non-sterile items (P) in an irradiated population of items contaminated with micro-organisms of a single type, has been extended to include items having organisms of different types. Estimates of P are compared with exact values derived on purely theoretical grounds and with values obtained by computer simulation of microbiological inactivation on items. (author)

  5. C allocation among fine roots, above-, and belowground wood in a deciduous forest and its implication to ecosystem C cycling: a modelling analysis

    Directory of Open Access Journals (Sweden)

    M. Campioli

    2008-09-01

    Full Text Available Knowledge about allocation of carbohydrates among tree organs with different life times and decomposition rates is crucial in determining the residence time of carbon (C in forests and the overall ecosystem C cycling rate. A new model (named CAF able to simulate C allocation among fine roots, above-, and belowground wood in deciduous forests was developed and integrated into the net ecosystem exchange model FORUG.

    CAF draws on growth rules and source-sink relationships. Maintenance and growth of the modelled sinks i.e. fine roots, coarse roots, stems, and branches, are controlled by phenology, environment, and by the reserve of non-structural carbohydrates. CAF was parameterized for 2-y and tested against 6-y observations from a beech (Fagus sylvatica L. stand in North-East France, experiencing summer droughts of different intensities.

    The model reproduced well (i the C fluxes allocated annually to assimilation, respiration and biomass production, and (ii the interannual pattern of wood biomass accumulation. Seasonality of C reserve and wood growth was captured, but some discrepancies were detected at the onset of the growing season.

    The allocation pattern differed among years, although the overall net primary production decreased only in case of severe drought. During a year with severe drought, the fraction of C allocated to production of fast-decomposing C pools (e.g. fine roots, C reserve increased by +13% than years without drought, whereas the same fraction increased on average by +18% in case of low to moderate drought. Carbon invested in biomass during a year with summer drought has therefore a shorter residence time in the ecosystem than the C stored during a year without summer drought.

  6. Modeling the Seasonality of Carbon, Evapotranspiration and Heat Processes for Cold Climate Conditions

    OpenAIRE

    Wu, Sihong

    2010-01-01

    The productivity of agricultural and forest ecosystems in regions at higher latitudes is to a large extent governed by low temperature and moisture conditions. Environmental conditions are acting both above- and below-ground and regulating carbon fluxes and evapotranspiration. However, the understanding of various feedbacks between vegetation and environmental conditions is still unclear. In this thesis, two studies were conducted to understand the physical and biological processes. In the fi...

  7. Algorithm оf Computer Model Realization оf High-Frequency Processes in Switchgears Containing Non-Linear Over-Voltage Limiters

    Directory of Open Access Journals (Sweden)

    Ye. V. Dmitriev

    2014-06-01

    Full Text Available Analysis of the Over-Voltage Limiter (OVL influence on electromagnetic high-frequency over-voltages at commutations with isolators of unloaded sections of wires and possibility of application of a frequency-dependent resistor in case of necessity to facilitate OVL operation conditions is provided in the paper.It is shown that it is necessary to take into account characteristics of OVL by IEEE circuit and its modifications at computer modeling of high-frequency over-voltages.

  8. Dose limits for astronauts

    Science.gov (United States)

    Sinclair, W. K.

    2000-01-01

    Radiation exposures to individuals in space can greatly exceed natural radiation exposure on Earth and possibly normal occupational radiation exposures as well. Consequently, procedures limiting exposures would be necessary. Limitations were proposed by the Radiobiological Advisory Panel of the National Academy of Sciences/National Research Council in 1970. This panel recommended short-term limits to avoid deterministic effects and a single career limit (of 4 Sv) based on a doubling of the cancer risk in men aged 35 to 55. Later, when risk estimates for cancer had increased and were recognized to be age and sex dependent, the NCRP, in Report No. 98 in 1989, recommended a range of career limits based on age and sex from 1 to 4 Sv. NCRP is again in the process of revising recommendations for astronaut exposure, partly because risk estimates have increased further and partly to recognize trends in limiting radiation exposure occupationally on the ground. The result of these considerations is likely to be similar short-term limits for deterministic effects but modified career limits.

  9. Spin observables in the three-body break-up process near the quasi-free limit in deuteron–deuteron scattering

    International Nuclear Information System (INIS)

    We have studied spin observables in the three-body break-up reaction in deuteron–deuteron scattering in the phase-space regime that corresponds to the quasi-free deuteron–proton scattering process with the neutron as spectator. The data are compared to measurements of the elastic deuteron–proton scattering process and state-of-the-art Faddeev calculations. The results for iT11 and T22 for the quasi-free scattering data agree very well with previously published elastic-scattering data. A significant discrepancy is found for T20, which could point to a break-down of the quasi-free assumption

  10. Application for approval of derived authorized limits for the release of the 190-C trenches and 105-C process water tunnels at the Hanford Site: Volume 2 - source term development

    International Nuclear Information System (INIS)

    As part of environmental restoration activities at the Hanford Site, Bechtel Hanford, Inc. is conducting a series of evaluations to determine appropriate release conditions for specific facilities following the completion of decontamination and decommissioning projects. The release conditions, with respect to the residual volumetric radioactive contamination, are termed authorized limits. This report presents the summary of the supporting information and the final application for approval of derived authorized limits for the release of the 190-C trenches and the 105-C process water tunnels. This document contains two volumes; this volume (Vol. 2) contains the radiological characterization data, spreadsheet analyses, and radiological source terms

  11. A FIRE-ACE/SHEBA Case Study of Mixed-Phase Arctic Boundary Layer Clouds: Entrainment Rate Limitations on Rapid Primary Ice Nucleation Processes

    Science.gov (United States)

    Fridlin, Ann; vanDiedenhoven, Bastiaan; Ackerman, Andrew S.; Avramov, Alexander; Mrowiec, Agnieszka; Morrison, Hugh; Zuidema, Paquita; Shupe, Matthew D.

    2012-01-01

    Observations of long-lived mixed-phase Arctic boundary layer clouds on 7 May 1998 during the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE)Arctic Cloud Experiment (ACE)Surface Heat Budget of the Arctic Ocean (SHEBA) campaign provide a unique opportunity to test understanding of cloud ice formation. Under the microphysically simple conditions observed (apparently negligible ice aggregation, sublimation, and multiplication), the only expected source of new ice crystals is activation of heterogeneous ice nuclei (IN) and the only sink is sedimentation. Large-eddy simulations with size-resolved microphysics are initialized with IN number concentration N(sub IN) measured above cloud top, but details of IN activation behavior are unknown. If activated rapidly (in deposition, condensation, or immersion modes), as commonly assumed, IN are depleted from the well-mixed boundary layer within minutes. Quasi-equilibrium ice number concentration N(sub i) is then limited to a small fraction of overlying N(sub IN) that is determined by the cloud-top entrainment rate w(sub e) divided by the number-weighted ice fall speed at the surface v(sub f). Because w(sub c) 10 cm/s, N(sub i)/N(sub IN)<< 1. Such conditions may be common for this cloud type, which has implications for modeling IN diagnostically, interpreting measurements, and quantifying sensitivity to increasing N(sub IN) (when w(sub e)/v(sub f)< 1, entrainment rate limitations serve to buffer cloud system response). To reproduce observed ice crystal size distributions and cloud radar reflectivities with rapidly consumed IN in this case, the measured above-cloud N(sub IN) must be multiplied by approximately 30. However, results are sensitive to assumed ice crystal properties not constrained by measurements. In addition, simulations do not reproduce the pronounced mesoscale heterogeneity in radar reflectivity that is observed.

  12. In vivo photosystem I reduction in thermophilic and mesophilic cyanobacteria: The thermal resistance of the process is limited by factors other than the unfolding of the partners

    International Nuclear Information System (INIS)

    Photosystem I reduction by plastocyanin and cytochrome c 6 in cyanobacteria has been extensively studied in vitro, but much less information is provided on this process inside the cell. Here, we report an analysis of the electron transfer from both plastocyanin and cytochrome c 6 to photosystem I in intact cells of several cyanobacterial species, including a comparative study of the temperature effect in mesophilic and thermophilic organisms. Our data show that cytochrome c 6 reduces photosystem I by following a reaction mechanism involving complex formation, whereas the copper-protein follows a simpler collisional mechanism. These results contrast with previous kinetic studies in vitro. The effect of temperature on photosystem I reduction leads us to conclude that the thermal resistance of this process is determined by factors other than the proper stability of the protein partners

  13. Does the Internet ‘absorb’ human subjectivity and sociality? The limitations of two current dynamic process models to answer this question

    OpenAIRE

    Vass, J.

    2012-01-01

    Some recent social theories have argued that human activities are immersed in 'flows' rather than social structures as traditionally conceived. Flows may both facilitate social order in complex globalised life or threaten it. The Internet and its associated technologies have been seen as (1) part of the mechanism that produces flow characteristics in communication processes, and (2) a threat to human subjectivity and sociality when viewed as a mechanism of flow. This paper reviews the social ...

  14. Limit experiments of GARCH

    CERN Document Server

    Buchmann, Boris; 10.3150/10-BEJ328

    2012-01-01

    GARCH is one of the most prominent nonlinear time series models, both widely applied and thoroughly studied. Recently, it has been shown that the COGARCH model (which was introduced a few years ago by Kl\\"{u}ppelberg, Lindner and Maller) and Nelson's diffusion limit are the only functional continuous-time limits of GARCH in distribution. In contrast to Nelson's diffusion limit, COGARCH reproduces most of the stylized facts of financial time series. Since it has been proven that Nelson's diffusion is not asymptotically equivalent to GARCH in deficiency, in the present paper, we investigate the relation between GARCH and COGARCH in Le Cam's framework of statistical equivalence. We show that GARCH converges generically to COGARCH, even in deficiency, provided that the volatility processes are observed. Hence, from a theoretical point of view, COGARCH can indeed be considered as a continuous-time equivalent to GARCH. Otherwise, when the observations are incomplete, GARCH still has a limiting experiment, which we ...

  15. Evaluation of carbon stocks in above- and below-ground biomass in Central Africa: case study of Lesio-louna tropical rainforest of Congo

    Science.gov (United States)

    Liu, X.; Ekoungoulou, R.; Loumeto, J. J.; Ifo, S. A.; Bocko, Y. E.; Koula, F. E.

    2014-07-01

    The study was aimed to estimate the carbon stocks of above- and below-ground biomass in Lesio-louna forest of Congo. The methodology of allometric equations was used to measure the carbon stocks of Lesio-louna natural forest. We are based precisely on the model II which is also called non-destructive method or indirect method of measuring carbon stocks. While there has been use of parameters such as the DBH and wood density. The research was done with 22 circular plots each 1256 m2. In the 22 plots studied, 19 plots are in the gallery forest and three plots in the secondary forest. Also, 22 circular plots were distributed in 5 sites studies of Lesio-louna forest, including: Inkou forest island, Iboubikro, Ngoyili, Blue lake and Ngambali. So, there are two forest types (secondary forest and gallery forest) in this forest ecosystem. In the 5 sites studied, we made measurements on a total of 347 trees with 197 trees for the class of 10-30 cm diameter, 131 trees for the class of 30-60 cm diameter and 19 trees in the diameter class > 60 cm. The results show that in the whole forest, average carbon stock for the 22 plots of the study was 168.601 t C ha-1 for AGB, or 81% and 39.551 t C ha-1 for BGB, or 19%. The total carbon stocks in all the biomass was 3395.365 t C for AGB, which is 3.395365 × 10-6 Gt C and 909.689934 t C for BGB, which was 9.09689934 × 10-7 Gt C. In this forest, the carbon stock was more important in AGB compared to BGB with respectively 3395.365 t C against 909.689934 t C. Plot10 (AGB = 363.899 t C ha-1 and BGB = 85.516 t C ha-1) was the most dominant in terms of carbon quantification in Lesio-louna.

  16. Evaluation of carbon stocks in above- and below-ground biomass in Central Africa: case study of Lesio-louna tropical rainforest of Congo

    Directory of Open Access Journals (Sweden)

    X. Liu

    2014-07-01

    Full Text Available The study was aimed to estimate the carbon stocks of above- and below-ground biomass in Lesio-louna forest of Congo. The methodology of allometric equations was used to measure the carbon stocks of Lesio-louna natural forest. We are based precisely on the model II which is also called non-destructive method or indirect method of measuring carbon stocks. While there has been use of parameters such as the DBH and wood density. The research was done with 22 circular plots each 1256 m2. In the 22 plots studied, 19 plots are in the gallery forest and three plots in the secondary forest. Also, 22 circular plots were distributed in 5 sites studies of Lesio-louna forest, including: Inkou forest island, Iboubikro, Ngoyili, Blue lake and Ngambali. So, there are two forest types (secondary forest and gallery forest in this forest ecosystem. In the 5 sites studied, we made measurements on a total of 347 trees with 197 trees for the class of 10–30 cm diameter, 131 trees for the class of 30–60 cm diameter and 19 trees in the diameter class > 60 cm. The results show that in the whole forest, average carbon stock for the 22 plots of the study was 168.601 t C ha−1 for AGB, or 81% and 39.551 t C ha−1 for BGB, or 19%. The total carbon stocks in all the biomass was 3395.365 t C for AGB, which is 3.395365 × 10–6 Gt C and 909.689934 t C for BGB, which was 9.09689934 × 10–7 Gt C. In this forest, the carbon stock was more important in AGB compared to BGB with respectively 3395.365 t C against 909.689934 t C. Plot10 (AGB = 363.899 t C ha−1 and BGB = 85.516 t C ha−1 was the most dominant in terms of carbon quantification in Lesio-louna.

  17. Diversity and spatial structure of belowground plant-fungal symbiosis in a mixed subtropical forest of ectomycorrhizal and arbuscular mycorrhizal plants.

    Directory of Open Access Journals (Sweden)

    Hirokazu Toju

    Full Text Available Plant-mycorrhizal fungal interactions are ubiquitous in forest ecosystems. While ectomycorrhizal plants and their fungi generally dominate temperate forests, arbuscular mycorrhizal symbiosis is common in the tropics. In subtropical regions, however, ectomycorrhizal and arbuscular mycorrhizal plants co-occur at comparable abundances in single forests, presumably generating complex community structures of root-associated fungi. To reveal root-associated fungal community structure in a mixed forest of ectomycorrhizal and arbuscular mycorrhizal plants, we conducted a massively-parallel pyrosequencing analysis, targeting fungi in the roots of 36 plant species that co-occur in a subtropical forest. In total, 580 fungal operational taxonomic units were detected, of which 132 and 58 were probably ectomycorrhizal and arbuscular mycorrhizal, respectively. As expected, the composition of fungal symbionts differed between fagaceous (ectomycorrhizal and non-fagaceous (possibly arbuscular mycorrhizal plants. However, non-fagaceous plants were associated with not only arbuscular mycorrhizal fungi but also several clades of ectomycorrhizal (e.g., Russula and root-endophytic ascomycete fungi. Many of the ectomycorrhizal and root-endophytic fungi were detected from both fagaceous and non-fagaceous plants in the community. Interestingly, ectomycorrhizal and arbuscular mycorrhizal fungi were concurrently detected from tiny root fragments of non-fagaceous plants. The plant-fungal associations in the forest were spatially structured, and non-fagaceous plant roots hosted ectomycorrhizal fungi more often in the proximity of ectomycorrhizal plant roots. Overall, this study suggests that belowground plant-fungal symbiosis in subtropical forests is complex in that it includes "non-typical" plant-fungal combinations (e.g., ectomycorrhizal fungi on possibly arbuscular mycorrhizal plants that do not fall within the conventional classification of mycorrhizal symbioses, and in

  18. Effects of aboveground and belowground competition between grass and tree on elm seedlings growth in Horqin Sandy Land%地上竞争与地下竞争对科尔沁沙地榆树幼苗生长的影响

    Institute of Scientific and Technical Information of China (English)

    唐毅; 蒋德明; 陈卓; 押田敏雄

    2011-01-01

    榆树疏林草原对科尔沁沙地植被恢复和景观保护有着重要意义.本文采用双因素两水平控制试验,从幼苗生物量、地下/地上生物量、茎高、根茎比、叶片数等方面,研究了草-树地上、地下竞争对科尔沁沙地榆树幼苗生长的影响.结果表明:对于1年生榆树幼苗,单株平均生物量表现为无竞争>地上竞争>全竞争>地下竞争;地下/地上生物量表现为地下竞争>全竞争>无竞争>地上竞争;幼苗高度表现为地上竞争>无竞争>全竞争>地下竞争;根茎比表现为地下竞争>全竞争>无竞争>地上竞争;叶片数表现为地上竞争>无竞争>地下竞争>全竞争.地下竞争对1年生榆树幼苗生长影响显著,而地上竞争对榆树幼苗生长无显著影响.地上竞争与地下竞争对2年生榆树幼苗生长的影响均不显著.科尔沁沙地草本植物对榆树幼苗生长的影响主要通过地下竞争的方式实现,但地下竞争并没有改变榆树幼苗的资源分配方式.随榆树幼苗龄级的增长,草本植物竞争作用的影响逐渐减弱.%Elm sparse woodland steppe plays an important role in vegetation restoration and landscape protection in Horqin Sandy Land. In this paper, a two-factor and two-level field experiment was conducted to explore the effects of aboveground and belowground competition between grass and tree on the growth of elm seedlings in the Sandy Land. Five aspects were considered, I. E. , seedling biomass, belowground biomass/aboveground biomass, stem height, ratio of root to stem, and leaf number. For the one-year-old elm seedlings, their biomass showed a trend of no competition > aboveground competition > full competition > belowground competition, belowground biomass / aboveground biomass showed a trend of belowground competition > full competition > no competition > aboveground competition, stem height showed a trend of aboveground competition > no competition

  19. Microstructure, optical and optoelectrical properties of mesoporous nc-TiO2 films by hydrolysis-limited sol-gel process with different inhibitors

    International Nuclear Information System (INIS)

    Mesoporous nanocrystalline titania (nc-TiO2) films were synthesized by sol-gel route using poly (alkylene oxide) block copolymer as template and tetrabutyl orthotitanate as titanium source. Influence of acetylacetone (AcAc), glacial acetic acid, HCl and AcAc-HCl as inhibitors on hydrolysis/condensation reaction was investigated. The mesopore structure, crystalline phase and optical characteristics were analyzed by N2 adsorption, X-ray diffraction, transmission electron microscopy and UV-VIS-NIR spectrum. Photoaction measurements were performed on dye-sensitized solar cells (DSSCs) using the mesoporous nc-TiO2 as photoanodes. The results show that the formed films are anatase phase and mesoporous structure. Different restraining mechanisms of these inhibitors to hydrolysis/condensation process lead to different mesoporous structure whose specific surface area (SBET) varies from 34 to 176 m2/g, and crystal size is from 5.6 to 38.2 nm. The mesoporous photoanode with high SBET and large crystalline grains may be responsible for increasing conversion efficiency of the DSSCs.

  20. Application for approval of derived authorized limits for the release of the 190-C trenches and 105-C process water tunnels at the Hanford Site: Volume 2 - Source term development

    International Nuclear Information System (INIS)

    As part of environmental restoration activities at the Hanford Site, Bechtel Hanford, Inc. (BHI) is conducting a series of evaluations to determine appropriate release conditions for specific facilities following the completion of decontamination and decommissioning (D and D) projects. The release conditions, with respect to the residual volumetric radioactive contamination, are termed authorized limits. This two volume report provides the necessary evaluations for the 290-C trenches and 105-C process water tunnels, and is intended to serve as the technical basis for a request for approval of authorized limits of residual radioactive contamination levels associated with these facilities. Volume 2 contains the Source Term Determination. This volume contains the radiological characterization data, spreadsheet analyses, and results of efforts to determine the radiological source terms. The source terms characterize the radionuclides and activity concentration levels for the facilities, and serves as input to the various radiation exposure pathways and scenarios used to estimate the individual radiation doses that could result from release of these facilities. Based on the results of these evaluations, it is determined that the application of the proposed authorized limits for the 190-C trenches and the 105-C process water tunnels represents a safe and cost-effective approach to their final disposition

  1. A review of belowground interspecific interactions and allelopathy in silvopasture systems%林草复合系统地下部分种间互作关系与化感作用研究进展

    Institute of Scientific and Technical Information of China (English)

    秦树高; 吴斌; 张宇清

    2011-01-01

    Silvopasture (forest-pasture complex), a sustainable land-use/management strategy, has been widely practised and increasingly researched worldwide against a background of global population explosion, exorbitant resource consumption and deterioration of eco-environments. In silvopasture systems, interspecific interaction relationships is one of the most important research foci. It directly relates to the results of this land-use/management strategy and research has progressively shown that the belowground interspecific interactions, and allelopathy play a more important role than aboveground interspecific interactions in system stability. This paper reviews and summarizes existing research on belowground interspecific interactions and allelopathy in silvopasture systems, and offers some suggestions for design and management of systems, for optimizing system structures and resource utility patterns, thereby reducing interspecific negative effects, and resulting in maximal comprehensive harvesting benefits. It is suggested that future research on belowground interspecific interactions and allelopathy, in silvopasture systems, focus on: the association among allelopathy, belowground and aboveground interspecific interactions, the water & nutrition coupling utilization effect of woody plants and herbage, the separate mechanisms of woody and herbaceous roots centralized layers, finding and collating appropriate hydraulic life trees in systems, the response of belowground interspecific interaction between woody plants and herbage to global climate change, researching allelopathy for optimization of systems species structure and in ecological management of silvopasture systems.%林草复合系统作为一种具有可持续发展特点的土地利用方式,已在全球范围内得到了广泛的应用和研究,其经营的成败通常是由各生物组分之间的相互作用关系所决定.目前,林草复合系统的经营者比较重视对系统地上部分种间互

  2. The distribution of naturally occurring radionuclides from ores processing to the environment - a case study of milling and treatment of ores for gold in Golden Star Resources of Bogoso Prestea Limited

    International Nuclear Information System (INIS)

    This research work was geared towards studying the distribution of naturally occurring radionuclides from the processing stages of oxide and sulphide ores for gold to the critical environment of the Golden Star Resources of Bogoso Prestea Limited in the Western region of Ghana. The study was carried out by measuring the natural radionuclide contents of raw feed ore and pulp samples from physical and chemical processing stages of oxide and sulphide ore treatment plants; tailings; de-silted sediments of a run-off from the tailings dam vicinity through a critical community and; soils and drinking water from the critical community. Also, as part of a comprehensive approach, the geochemical compositions were measured to determine any possible influence on the radionuclide distributions. Amongst the radionuclide decay chains, 238U-series were the dominant throughout all the measurements. However, the concentrations are lower than the world permissible limits. The indicative doses associated with the activity concentration distributions in the processed feed ores at various processing stages ranged from 2 to 70 μSv/y in the oxide plant and from 2 to 108 μSv/y for the sulphide plant. If effective dose of ≤ 10 μSv/y recommended by IAEA for exemption from regulatory control is applied, the processing of ores in the plants must be regulated. However, the estimated annual effective dose received by the workers from any of these stages of operation did not exceed the range of 1-2 mSv recommended by the ICRP-75 (10 μSv/y ≤ Effective dose ≤ 1-2 mSv/y) for the exemption of a practice. This range is far lower than the annual occupational dose limit of 20 mSv/y recommended by IAEA for artificial radioactive sources. Imposing the IAEA recommendation of effective dose of ? 10 μSv/y for exemption from regulatory control of practices could result in many mining and other NORMs industries being regulated without any net benefit in terms of risk reduction. Conversely, Sn, As

  3. Physical limits on self-replication processes

    CERN Document Server

    Alicki, R

    2005-01-01

    Using few very general axioms which should be satisfied by any reasonable theory consistent with general physical principles and some more recent results concerning "broadcasting" of quantum states we show that: a) only classical information can self-replicate perfectly, b) "parent" and "offspring" must be strongly correlated, c) "separation of species" is possible only in a non-homogeneous environment. To illustrate the existence of theoretical schemes which possess both classical and quantum features, we present a model based on the classical probability but with overlapping pure states and "entangled states" for composite systems.

  4. Hydrodynamic Limit For An Active Exclusion Process

    OpenAIRE

    Clément, Erignoux

    2016-01-01

    Collective dynamics can be observed among many animal species, and have given rise in the last decades to an active and interdisciplinary field of study. Such behaviors are often modeled by active matter, in which each individual is self-driven and tends to update its velocity depending on the one of its neighbors. In a classical model introduced by Vicsek \\and al., as well as in numerous related active matter models, a phase transition between chaotic behavior at high temperature and global ...

  5. Wrinkling limit prediction of rotary-draw bending process for thin-walled rectangular aluminum alloy tube%铝合金薄壁矩形管绕弯成形起皱极限的预测

    Institute of Scientific and Technical Information of China (English)

    刘郁丽; 李佳佳; 赵刚要; 杨合

    2011-01-01

    Wrinkling is one of main forming defects of the rotary-draw bending process for thin-walled rectangular aluminium alloy tube, which severely restricts the improvement of the forming quality and forming limit. Therefore, a regression prediction model of the wrinkling wave height is built based on finite element(FE) simulation combined with orthogonal regression analysis, and its reliability is validated by experiments. Then the analytical model of forming limit without the occurrence of wrinkling is derived. The laws of the core number, the clearance between mandrel and tube and the clearance between wiper die and tube affecting wrinkling limit are obtained, and the wrinkling limit diagram for the rotary-draw process of thin-walled rectangular tube is obtained. This research provides basis and guidance for improving forming quality of the rotary-draw bending process for the rectangular tubes in production.%失稳起皱是铝合金薄壁矩形波导管绕弯成形过程中的主要缺陷之一,严重制约着薄壁矩形管绕弯成形极限的提高.笔者采用有限元数值模拟结合正交回归分析的方法,建立了薄壁矩形管绕弯成形起皱波纹度回归预测模型,并通过实验验证了该模型的可靠性;在此基础上推导出了基于失稳起皱成形极限的解析模型.研究获得了芯头个数、防皱块与管坯间隙及芯模与管坯间隙对起皱极限的影响规律,并获得了铝合金薄壁矩形管绕弯成形起皱极限图.该研究为提高实际生产中薄壁矩形管绕弯成形质量提供了依据和指导.

  6. Physical limits to biochemical signaling

    CERN Document Server

    Bialek, W

    2003-01-01

    Many crucial biological processes operate with surprisingly small numbers of molecules, and there is renewed interest in analyzing the impact of noise associated with these small numbers. Twenty--five years ago, Berg and Purcell showed that bacterial chemotaxis, where a single celled organism must respond to small changes in concentration of chemicals outside the cell, is limited directly by molecule counting noise, and that aspects of the bacteria's behavioral and computational strategies must be chosen to minimize the effects of this noise. Here we revisit and generalize their arguments to estimate the physical limits to signaling processes within the cell, and argue that recent experiments are consistent with performance approaching these limits.

  7. Limites do cuidado: representações e processos inconscientes sobre a população na porta de entrada de um hospital de emergência Health care limits: representations and unconscious processes related to the population at the hospital emergency entrance

    Directory of Open Access Journals (Sweden)

    Marilene de Castilho Sá

    2008-06-01

    Full Text Available Este artigo apresenta parte dos resultados de uma investigação voltada para a análise dos limites e possibilidades que os processos intersubjetivos e inconscientes presentes nos serviços de saúde estabelecem para o exercício da solidariedade, para a cooperação e para a produção do cuidado com a vida. Elegeu-se como estudo de caso um hospital público de emergência, situado no Município do Rio de Janeiro, Brasil. A Psicossociologia francesa, de inspiração clínica psicanalítica, a teoria psicanalítica sobre os processos intersubjetivos e grupais e a Psicodinâmica do Trabalho são os referenciais centrais que orientaram o desenho da investigação e a análise do material empírico. As representações psíquicas e os processos inconscientes relativos à população e suas demandas, produzidos pelos trabalhadores de saúde do hospital estudado, foram analisados, discutindo-se suas conseqüências sobre a produção do cuidado. Algumas imagens se destacaram, como a "carência", utilizada como uma categoria encobridora da diversidade da demanda, num processo inconsciente de múltiplas reduções: da negação do sofrimento social à negação da condição de humanidade dos pacientes.This article presents some results from a study aimed at analyzing the limits and possibilities defined by inter-subjective and unconscious processes of solidarity, cooperation, and life care production in health services. A public hospital with an emergency department in the city of Rio de Janeiro, Brazil, was selected as a case study. The French school of psychosociology, oriented by the psychoanalytical clinical approach, the psychoanalytical theory on inter-subjective and group processes, and work psychodynamics provided the basis for the study's methodological strategies and analysis of the results. The study analyzed health professionals' psychological representations and unconscious processes related to emergency department users and their

  8. 45 CFR 5.35 - Time limits.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Time limits. 5.35 Section 5.35 Public Welfare... Denial of Records § 5.35 Time limits. (a) General. FOIA sets certain time limits for us to decide whether... time limits, but if it appears that processing your request may take longer than we would wish, we...

  9. The Limits of Vertical Accretion in Sediment-Poor Microtidal Estuaries

    Science.gov (United States)

    Morris, J. T.

    2015-12-01

    A meta-analysis of sediment bulk density and loss-on-ignition (LOI) data from marshes in thirteen estuaries on the U.S. Pacific, Gulf, and East Coasts consisting of over 2400 samples shows that dry bulk density can be predicted very well as a function of LOI (r2=0.8) using a conservative mixing model. The estimated bulk densities of pure organic and mineral matter were 0.08 and 1.9 g/cm3, respectively, as determined by a best fit of the mixing model. The composite bulk density and LOI of a mixture are best explained as the result of a conservative mix of these two end members. These bulk densities are useful in establishing limits on the vertical accretion in tidal wetlands. For example, if we assume a maximum belowground production of 2.5 kg/m2 and that 10% of this is preserved, then the maximum vertical accretion from this amount of belowground production is 3 mm/yr (0.1 x 2500 g m-2 y-1 × m2/1000 cm2 ÷ 0.08 g/cm3 = 0.3 cm/y). For a sediment-poor estuary with a suspended inorganic sediment concentration in flood water of 20 mg/L, flooding a marsh surface twice daily to an average depth of 12.5 cm, the vertical accretion rate would be no greater than about 1 mm/yr. This assumes that the surface captures 100% of the sediment load. The maximum vertical accretion is the sum of the two components, and in a sediment-poor, microtidal estuary (typical of many on the Gulf Coast) this should be no more than about 4 mm/y.

  10. HOME Income Limits

    Data.gov (United States)

    Department of Housing and Urban Development — HOME Income Limits are calculated using the same methodology that HUD uses for calculating the income limits for the Section 8 program. These limits are based on...

  11. Interfacial dynamics in transport-limited dissolution

    OpenAIRE

    Bazant, Martin Z.

    2006-01-01

    Various model problems of ``transport-limited dissolution'' in two dimensions are analyzed using time-dependent conformal maps. For diffusion-limited dissolution (reverse Laplacian growth), several exact solutions are discussed for the smoothing of corrugated surfaces, including the continuous analogs of ``internal diffusion-limited aggregation'' and ``diffusion-limited erosion''. A class of non-Laplacian, transport-limited dissolution processes are also considered, which raise the general qu...

  12. Limits to biofuels

    Science.gov (United States)

    Johansson, S.

    2013-06-01

    Biofuel production is dependent upon agriculture and forestry systems, and the expectations of future biofuel potential are high. A study of the global food production and biofuel production from edible crops implies that biofuel produced from edible parts of crops lead to a global deficit of food. This is rather well known, which is why there is a strong urge to develop biofuel systems that make use of residues or products from forest to eliminate competition with food production. However, biofuel from agro-residues still depend upon the crop production system, and there are many parameters to deal with in order to investigate the sustainability of biofuel production. There is a theoretical limit to how much biofuel can be achieved globally from agro-residues and this amounts to approximately one third of todays' use of fossil fuels in the transport sector. In reality this theoretical potential may be eliminated by the energy use in the biomass-conversion technologies and production systems, depending on what type of assessment method is used. By surveying existing studies on biofuel conversion the theoretical limit of biofuels from 2010 years' agricultural production was found to be either non-existent due to energy consumption in the conversion process, or up to 2-6000TWh (biogas from residues and waste and ethanol from woody biomass) in the more optimistic cases.

  13. Limits to biofuels

    Directory of Open Access Journals (Sweden)

    Johansson S.

    2013-06-01

    Full Text Available Biofuel production is dependent upon agriculture and forestry systems, and the expectations of future biofuel potential are high. A study of the global food production and biofuel production from edible crops implies that biofuel produced from edible parts of crops lead to a global deficit of food. This is rather well known, which is why there is a strong urge to develop biofuel systems that make use of residues or products from forest to eliminate competition with food production. However, biofuel from agro-residues still depend upon the crop production system, and there are many parameters to deal with in order to investigate the sustainability of biofuel production. There is a theoretical limit to how much biofuel can be achieved globally from agro-residues and this amounts to approximately one third of todays’ use of fossil fuels in the transport sector. In reality this theoretical potential may be eliminated by the energy use in the biomass-conversion technologies and production systems, depending on what type of assessment method is used. By surveying existing studies on biofuel conversion the theoretical limit of biofuels from 2010 years’ agricultural production was found to be either non-existent due to energy consumption in the conversion process, or up to 2–6000TWh (biogas from residues and waste and ethanol from woody biomass in the more optimistic cases.

  14. The variable effects of soil nitrogen availability and insect herbivory on aboveground and belowground plant biomass in an old-field ecosystem

    DEFF Research Database (Denmark)

    Blue, Jarrod D.; Souza, Lara; Classen, Aimée T.;

    2011-01-01

    N may not be limiting primary production in this ecosystem. Insects reduced the aboveground biomass of subdominant plant species and decreased coarse root production. We found no statistical interactions between N availability and insect herbivory for any response variable. Overall, the results of 6...

  15. Passive immitance limiters

    OpenAIRE

    Filinyuk N. A.; Lischinskaya L. B.; Chekhmestruk R. Yu.

    2015-01-01

    The paper presents quadripole R, L, C immittance limiters, in which output immittance to the certain value depends on the input immittance. A classification of immittance limiters is given. Basic parameters are considered: low and high levels of output immittance limiters; low and high values of input immittance, corresponding to low and high levels of limitation, accordingly; range of possible values of output immittance; steepness of immittance limiters; time of wearing-out (or delay); high...

  16. 棘突间有限植骨融合治疗腰椎间盘突出症%Limited bone grafting surgery between spinous processes for lumbar disc herniation

    Institute of Scientific and Technical Information of China (English)

    宋超; 刘祖德; 钟贵彬; 李新锋; 劳立峰

    2013-01-01

    Objective To investigate the effect and feasibility of the surgery with limited bone grafting surgery between spinous processes for lumbar disc herniation. Methods 11 posterior decompressive laminectomy and allogenic bone grafting surgery between spinous processes were used to treat for patients suffering backleg pain because of lumbar disc herniation. The fusion rate of implanted bone and JOA score were analyzed. Results All patients were followed up for 12 ~ 18 ( 15 ± 1. 22 ) months without wound infection, dura tear, nerve root injury and other complications. The preoperative JOA score was ( 8. 56 ± 1. 45 ), the 3rd postoperative day JOA score was ( 12. 94 ± 1. 55 ), the score was( 13. 15 ±1.21 ) 12 months after operation. Compared with the preoperative JOA score, the difference had statistical significance(P <0. 05 ). The JOA score improvement rates were over 50% . The allograft bones were found absorbed partly or entirely through CT scanning and did not reach the bone fusion. Conclusions It is difficult to achieve bone fusion between the limited allograft bone and spinous processes. Further research need to be done such as the choice of materials,the way to fix etc.%目的 探讨棘突间有限植骨融合治疗腰椎间盘突出症的疗效及可行性.方法 采用后路椎板开窗减压+棘突间同种异体骨有限植入术治疗11例腰椎间盘突出症导致的腰腿痛患者.对植骨融合率、JOA评分进行临床分析.结果 患者均获随访,时间12~18(15±1.22)个月.无切口感染、硬膜囊撕裂、神经根损伤等并发症.术前JOA评分为(8.56±1.45)分,术后3 d为(12.94±1.55)分、12个月为(13.15±1.21)分,与术前比较差异有统计学意义(P<0.05).JOA评分改善率均>50%.CT扫描证实棘突间植骨均不同程度被吸收,均未达到骨性融合.结论 单纯在棘突间植入有限的同种异体骨很难达到骨性融合,在材料选择和固定方式等方面须做进一步研究.

  17. Statistical limitations on molecular evolution.

    Science.gov (United States)

    Perlovsky, Leonid I

    2002-06-01

    Complexity of functions evolving in an evolution process are expected to be limited by the time length of an evolution process among other factors. This paper outlines a general method of deriving function-complexity limitations based on mathematical statistics and independent from details of a biological or genetic mechanism of the evolution of the function. Limitations on the emergence of life are derived, these limitations indicate a possibility of a very fast evolution and are consistent with "RNA world" hypothesis. The discussed method is general and can be used to characterize evolution of more specific biological organism functions and relate functions to genetic structures. The derived general limitations indicate that a co-evolution of multiple functions and species could be a slow process, whereas an evolution of a specific function might proceed very fast, so that no trace of intermediate forms (species) is preserved in fossil records of phenotype or DNA structure; this is consistent with a picture of "punctuated equilibrium". PMID:12023805

  18. 32 CFR 806.22 - Time limits.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Time limits. 806.22 Section 806.22 National... INFORMATION ACT PROGRAM § 806.22 Time limits. Any FOIA appeals received after the 60-day time limit are not processed, unless the requester provides adequate justification for failing to comply with the time...

  19. 40 CFR 1501.8 - Time limits.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Time limits. 1501.8 Section 1501.8 Protection of Environment COUNCIL ON ENVIRONMENTAL QUALITY NEPA AND AGENCY PLANNING § 1501.8 Time limits. Although the Council has decided that prescribed universal time limits for the entire NEPA process are...

  20. Alternative methods for dispoal of low-level radioactive wastes. Task 1. Description of methods and assessment of criteria. [Alternative methods are belowground vaults, aboveground vaults; earth mounded concrete bunkers, mined cavities, augered holes

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, R.D.; Miller, W.O.; Warriner, J.B.; Malone, P.G.; McAneny, C.C.

    1984-04-01

    The study reported herein contains the results of Task 1 of a four-task study entitled Criteria for Evaluating Engineered Facilities. The overall objective of this study is to ensure that the criteria needed to evaluate five alternative low-level radioactive waste (LLW) disposal methods are available to the Nuclear Regulatory Commission (NRC) and the Agreement States. The alternative methods considered are belowground vaults, aboveground vaults, earth mounded concrete bunkers, mined cavities, and augered holes. Each of these alternatives is either being used by other countries for low-level radioactive waste (LLW) disposal or is being considered by other countries or US agencies. In this report the performance requirements are listed, each alternative is described, the experience gained with its use is discussed, and the performance capabilities of each method are addressed. Next, the existing 10 CFR Part 61 Subpart D criteria with respect to paragraphs 61.50 through 61.53, pertaining to site suitability, design, operations and closure, and monitoring are assessed for applicability to evaluation of each alternative. Preliminary conclusions and recommendations are offered on each method's suitability as an LLW disposal alternative, the applicability of the criteria, and the need for supplemental or modified criteria.

  1. Limits to adaptation

    Science.gov (United States)

    Dow, Kirstin; Berkhout, Frans; Preston, Benjamin L.; Klein, Richard J. T.; Midgley, Guy; Shaw, M. Rebecca

    2013-04-01

    An actor-centered, risk-based approach to defining limits to social adaptation provides a useful analytic framing for identifying and anticipating these limits and informing debates over society's responses to climate change.

  2. Interval graph limits

    CERN Document Server

    Diaconis, Persi; Janson, Svante

    2011-01-01

    We work out the graph limit theory for dense interval graphs. The theory developed departs from the usual description of a graph limit as a symmetric function $W(x,y)$ on the unit square, with $x$ and $y$ uniform on the interval $(0,1)$. Instead, we fix a $W$ and change the underlying distribution of the coordinates $x$ and $y$. We find choices such that our limits are continuous. Connections to random interval graphs are given, including some examples. We also show a continuity result for the chromatic number and clique number of interval graphs. Some results on uniqueness of the limit description are given for general graph limits.

  3. Passive immitance limiters

    Directory of Open Access Journals (Sweden)

    Filinyuk N. A.

    2015-06-01

    Full Text Available The paper presents quadripole R, L, C immittance limiters, in which output immittance to the certain value depends on the input immittance. A classification of immittance limiters is given. Basic parameters are considered: low and high levels of output immittance limiters; low and high values of input immittance, corresponding to low and high levels of limitation, accordingly; range of possible values of output immittance; steepness of immittance limiters; time of wearing-out (or delay; high and low cutoff frequencies; central working frequency; frequency band; relative range of working frequencies; non-linearity coefficient. The authors have designed passive R-, L-, C-limiters with possibility of limitation from above and from below. The influence of the input parasitic immittances on the immittance transfer characteristic is evaluated. In most cases parasite immittance does not influence the considered devices, including R-limiters «from above» with the input quality factor of QR(Linp=0,1…0,2 and L-limiters «from above» with high-quality input circuits with QL(Rinp>2. The analysis also shows that high-qualitiy circuits with QN(RinpN>3 should be used in C-limiters with input parasitic immittances, while at parasitic immittance of the limiting element low-quality circuits with QN(RiN>0,2 should be selected.

  4. Summary of Dissolved Concentration Limits

    Energy Technology Data Exchange (ETDEWEB)

    Yueting Chen

    2001-06-11

    According to the Technical Work Plan titled Technical Work Plan for Waste Form Degradation Process Model Report for SR (CRWMS M&O 2000a), the purpose of this study is to perform abstractions on solubility limits of radioactive elements based on the process-level information and thermodynamic databases provided by Natural Environment Program Operations (NEPO) and Waste Package Operations (WPO). The scope of this analysis is to produce solubility limits as functions, distributions, or constants for all transported radioactive elements identified by the Performance Assessment Operations (PAO) radioisotope screening. Results from an expert elicitation for solubility limits of most radioactive elements were used in the previous Total System Performance Assessments (TSPAs). However, the elicitation conducted in 1993 does not meet the criteria set forth by the U.S. Nuclear Regulatory Commission (NRC) due to lack of documentation and traceability (Kotra et al. 1996, Section 3). Therefore, at the Waste Form Abstraction Workshop held on February 2-4, 1999, at Albuquerque, New Mexico, the Yucca Mountain Site Characterization Project (YMP) decided to develop geochemical models to study solubility for the proposed Monitored Geologic Repository. WPO/NEPO is to develop process-level solubility models, including review and compilation of relevant thermodynamic data. PAO's responsibility is to perform abstractions based on the process models and chemical conditions and to produce solubility distributions or response surfaces applicable to the proposed repository. The results of this analysis and conceptual model will feed the performance assessment for Total System Performance Assessment--Site Recommendation (TSPA-SR) and Total System Performance Assessment--License Application (TSPA-LA), and to the Waste Form Degradation Process Model Report section on concentration limits.

  5. Limits on the Dipole Moments of the $\\tau$-Lepton via the Process $e^{+}e^{-}\\to \\tau^+ \\tau^- \\gamma$ in a Left-Right Symmetric Model in a Left-Right Symmetric Model

    CERN Document Server

    Gutiérrez-Rodríguez, A; Noriega, L N Luis

    2004-01-01

    Limits on the anomalous magnetic moment and the electric dipole moment of the $\\tau$ lepton are calculated through the reaction $e^{+}e^{-}\\to \\tau^+ \\tau^- \\gamma$ at the $Z_1$-pole and in the framework of a left-right symmetric model. The results are based on the recent data reported by the L3 Collaboration at CERN LEP. Due to the stringent limit of the model mixing angle $\\phi$, the effect of this angle on the dipole moments is quite small.

  6. The JET belt limiter

    International Nuclear Information System (INIS)

    A limiter with an effective area in contact with the plasma of about 16 m2 is presently being manufactured for installation in 1987. This belt limiter consists of two toroidal rings located above and below the equatorial plane of the vacuum vessel. Each of the two rings comprises a structure with water cooling pipes and fins welded to the pipes. The limiter material in contact with the plasma (graphite or beryllium) is inserted between fins in the form of tiles. The belt limiter is designed to handle up to 40 MW of total power at flux densities of 3 - 5 MW/m2 for 10 s and to permit rapid exchange of different limiter materials. The design and manufacture of the belt limiter and the results of thermomechanical analysis for different edge properties, power levels and shot repetition rates, are reported. (author)

  7. The jet belt limiter

    International Nuclear Information System (INIS)

    A limiter with an effective area in contact with the plasma of about 16 m/sup 2/ is presently being manufactured for installation in 1987. This belt limiter consists of two toroidal rings located above and below the equatorial plane of the vacuum vessel. Each of the two rings comprises a structure with water cooling pipes and fins welded to the pipes. The limiter material in contact with the plasma (graphite or beryllium) is inserted between fins in the form of tiles. The belt limiter is designed to handle up to 40 MW of total power at flux densities of 3 - 5 MW/m/sup 2/ for 10 s and to permit rapid exchange of different limiter materials. This paper describes the design and manufacture of the belt limiter and the results of thermomechanical analysis for different edge properties, power levels and shot repetition rates

  8. Limit loads in nozzles

    International Nuclear Information System (INIS)

    The static method for the evaluation of the limit loads of a perfectly elasto-plastic structure is presented. Using the static theorem of Limit Analysis and the Finite Element Method, a lower bound for the colapso load can be obtained through a linear programming problem. This formulation if then applied to symmetrically loaded shells of revolution and some numerical results of limit loads in nozzles are also presented. (Author)

  9. Reactor limit control system

    International Nuclear Information System (INIS)

    The very extensive use of limitations in the operational field between protection system and closed-loop controls is an important feature of German understanding of operational safety. The design of limitations is based on very large activities in the computational field but mostly on the high level of the plant-wide own commissioning experience of a turnkey contractor. Limitations combine intelligence features of closed-loop controls with the high availability of protection systems. (orig.)

  10. Friction Generated Limit Cycles

    OpenAIRE

    Ohlsson, Henrik; Åström, Karl Johan

    2001-01-01

    This paper treats limit cycles caused by friction. The goal has been to explain phenomena that have been observed experimentally in mechatronic systems. Experiments have shown that oscillations of qualitatively different types can be obtained simply by changing controller specifications. Stiction is important in some cases but not in others. Necessary conditions for limit cycle are given for the case where stiction is important. Conditions for local stability of the limit cycles are also pres...

  11. Numerical Limit Analysis:

    DEFF Research Database (Denmark)

    Damkilde, Lars

    2007-01-01

    Limit State analysis has a long history and many prominent researchers have contributed. The theoretical foundation is based on the upper- and lower-bound theorems which give a very comprehensive and elegant formulation on complicated physical problems. In the pre-computer age Limit State analysis...

  12. Limits to Inclusion

    Science.gov (United States)

    Hansen, Janne Hedegaard

    2012-01-01

    In this article, I will argue that a theoretical identification of the limit to inclusion is needed in the conceptual identification of inclusion. On the one hand, inclusion is formulated as a vision that is, in principle, limitless. On the other hand, there seems to be an agreement that inclusion has a limit in the pedagogical practice. However,…

  13. Tokamak pump limiters

    International Nuclear Information System (INIS)

    Recent experiments with a scoop limiter without active internal pumping have been carried out in the PDX tokamak with up to 6MW of auxiliary neutral beam heating. Experiments have also been done with a rotating head pump limiter in the PLT tokamak in conjunction with RF plasma heating. Extensive experiments have been done in the ISX-B tokamak and first experiments have been completed with the ALT-I limiter in TEXTOR. The pump limiter modules in these latter two machines have internal getter pumping. Experiments in ISX-B are with ohmic and auxiliary neutral beam heating. The results in ISX-B and TEXTOR show that active density control and particle removal is achieved with pump limiters. In ISX-B, the boundary layer (or scape-off layer) plasma partially screens the core plasma from gas injection. In both ISX-B and TEXTOR, the pressure internal to the module scales linearly with plasma density but in ISX-B, with neutral beam injection, a nonlinear increase is observed at the highest densities studied. Plasma plugging is the suspected cause. Results from PDX suggest that a region may exist in which core plasma energy confinement improves using a pump limiter during neutral beam injection. Asymmetric radial profiles and an increased edge electron temperature are observed in discharges with improved confinement. The injection of small amounts of neon into ISX-B has more clearly shown an improved electron core energy confinement during neutral beam injection. While carried out with a regular limiter, this Z-mode of operation is ideal for use with pump limiters and should be a way to achieve energy confinement times similar to values for H-mode tokamak plasmas. The implication of all these results for the design of a reactor pump limiter is described

  14. Interval Graph Limits

    OpenAIRE

    Diaconis, Persi; Holmes, Susan; Janson, Svante

    2012-01-01

    We work out the graph limit theory for dense interval graphs. The theory developed departs from the usual description of a graph limit as a symmetric function $W(x,y)$ on the unit square, with $x$ and $y$ uniform on the interval $(0,1)$. Instead, we fix a $W$ and change the underlying distribution of the coordinates $x$ and $y$. We find choices such that our limits are continuous. Connections to random interval graphs are given, including some examples. We also show a continuity result for th...

  15. HUD Program Income Limits

    Data.gov (United States)

    Department of Housing and Urban Development — Income limits used to determine the income eligibility of applicants for assistance under three programs authorized by the National Housing Act. These programs are...

  16. Limited Income and Resources

    Data.gov (United States)

    U.S. Department of Health & Human Services — Information for those with limited income and resources (those who may qualify for or already have the Low Income Subsidy to lower their prescription drug coverage...

  17. Limited Denial of Participation

    Data.gov (United States)

    Department of Housing and Urban Development — A Limited Denial of Participation (LDP) is an action taken by a HUD Field Office or the Deputy Assistant Secretary for Single Family (DASSF) or Multifamily (DASMF)...

  18. SIS - Annual Catch Limit

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Annual Catch Limit (ACL) dataset within the Species Information System (SIS) contains information and data related to management reference points and catch data.

  19. HOME Rent Limits

    Data.gov (United States)

    Department of Housing and Urban Development — In accordance with 24 CFR Part 92.252, HUD provides maximum HOME rent limits. The maximum HOME rents are the lesser of: The fair market rent for existing housing...

  20. Coagulation with limited aggregations

    CERN Document Server

    Bertoin, Jean

    2012-01-01

    Smoluchowski's coagulation equations can be used as elementary mathematical models for the formation of polymers. We review here some recent contributions on a variation of this model in which the number of aggregations for each atom is a priori limited. Macroscopic results in the deterministic setting can be explained at the microscopic level by considering a version of stochastic coalescence with limited aggregations, which can be related to the so-called random configuration model of random graph theory.

  1. Limits for Life

    Science.gov (United States)

    Marion, Giles M.; Kargel, Jeffrey S.

    The current mantra of astrobiology is “Follow the Water.” Where there is water, there may be life. The FREZCHEM model can determine the presence or absence of water down to the eutectic temperature, below which only solid phases are thermodynamically stable. Salinity, the desiccation potential, and acidity are other potentially life-limiting factors that are calculated by FREZCHEM. In Chapter 4, we discuss potential life-limiting factors such as temperature, salinity, acidity, desiccation, radiation, pressure, and time.

  2. Limited Liability Company

    OpenAIRE

    Jarolímková, Vendula

    2010-01-01

    Limited liability company is today the most common legal form of business entities. This is mainly due to its simple establishment together with a low capital requirements. Preconditions of a foundation of a limited liability company require an establishment of the company, optaining a business license, a pay off of capital to the extent specified by the founding documents and laws, the acting on behalf of the company before its birth, and filling for incorporation into the trade register. Th...

  3. 47 CFR 10.430 - Character limit.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Character limit. 10.430 Section 10.430 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMERCIAL MOBILE ALERT SYSTEM Alert Message Requirements § 10.430 Character limit. A CMAS Alert Message processed by a Participating CMS Provider must...

  4. Engineering Options Assessment Report. Nitrate Salt Waste Stream Processing

    International Nuclear Information System (INIS)

    This report examines and assesses the available systems and facilities considered for carrying out remediation activities on remediated nitrate salt (RNS) and unremediated nitrate salt (UNS) waste containers at Los Alamos National Laboratory (LANL). The assessment includes a review of the waste streams consisting of 60 RNS, 29 above-ground UNS, and 79 candidate below-ground UNS containers that may need remediation. The waste stream characteristics were examined along with the proposed treatment options identified in the Options Assessment Report . Two primary approaches were identified in the five candidate treatment options discussed in the Options Assessment Report: zeolite blending and cementation. Systems that could be used at LANL were examined for housing processing operations to remediate the RNS and UNS containers and for their viability to provide repackaging support for remaining LANL legacy waste.

  5. Engineering Options Assessment Report. Nitrate Salt Waste Stream Processing

    Energy Technology Data Exchange (ETDEWEB)

    Anast, Kurt Roy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-13

    This report examines and assesses the available systems and facilities considered for carrying out remediation activities on remediated nitrate salt (RNS) and unremediated nitrate salt (UNS) waste containers at Los Alamos National Laboratory (LANL). The assessment includes a review of the waste streams consisting of 60 RNS, 29 above-ground UNS, and 79 candidate below-ground UNS containers that may need remediation. The waste stream characteristics were examined along with the proposed treatment options identified in the Options Assessment Report . Two primary approaches were identified in the five candidate treatment options discussed in the Options Assessment Report: zeolite blending and cementation. Systems that could be used at LANL were examined for housing processing operations to remediate the RNS and UNS containers and for their viability to provide repackaging support for remaining LANL legacy waste.

  6. Engineering Options Assessment Report: Nitrate Salt Waste Stream Processing

    Energy Technology Data Exchange (ETDEWEB)

    Anast, Kurt Roy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-18

    This report examines and assesses the available systems and facilities considered for carrying out remediation activities on remediated nitrate salt (RNS) and unremediated nitrate salt (UNS) waste containers at Los Alamos National Laboratory (LANL). The assessment includes a review of the waste streams consisting of 60 RNS, 29 aboveground UNS, and 79 candidate belowground UNS containers that may need remediation. The waste stream characteristics were examined along with the proposed treatment options identified in the Options Assessment Report . Two primary approaches were identified in the five candidate treatment options discussed in the Options Assessment Report: zeolite blending and cementation. Systems that could be used at LANL were examined for housing processing operations to remediate the RNS and UNS containers and for their viability to provide repackaging support for remaining LANL legacy waste.

  7. Trace elements in NaWaRo biogas plants for balancing substrate limited deficiency symptoms and stabilizing the fermentation process; Spurenelemente in NawaRo-Biogasanlagen zum Ausgleich substratbedingter Mangelerscheinungen und zur Stabilisierung des Gaerprozesses

    Energy Technology Data Exchange (ETDEWEB)

    Oechsner, Hans; Lemmer, Andreas [Hohenheim Univ., Stuttgart (Germany). Landesanstalt fuer Agrartechnik und Bioenergie; Preissler, Daniel

    2011-07-01

    The authors of the contribution under consideration report on trace elements in renewable resource biogas plants in order to compensate for substrate induced deficiency symptoms and to stabilize the fermentation process. The analysis of biological connections in biogas processes showed, that an optimal supply of the microorganisms with trace elements is essential for the course of the four stages of decomposition of the biogas process. Trace elements significantly are involved in the structure of coenzymes or cofactors, reduce the sulfide toxicity and stimulate the growth of methanogens. If the individual items are missing, the biogas process can be disrupted. This can result in a cut-off of the fermenter and in a stopping of the biogas production.

  8. The quantum geometric limit

    CERN Document Server

    Lloyd, Seth

    2012-01-01

    This letter analyzes the limits that quantum mechanics imposes on the accuracy to which spacetime geometry can be measured. By applying the fundamental physical bounds to measurement accuracy to ensembles of clocks and signals moving in curved spacetime -- e.g., the global positioning system -- I derive a covariant version of the quantum geometric limit: the total number of ticks of clocks and clicks of detectors that can be contained in a four volume of spacetime of radius r and temporal extent t is less than or equal to rt/\\pi x_P t_P, where x_P, t_P are the Planck length and time. The quantum geometric limit bounds the number of events or `ops' that can take place in a four-volume of spacetime: each event is associated with a Planck-scale area. Conversely, I show that if each quantum event is associated with such an area, then Einstein's equations must hold. The quantum geometric limit is consistent with and complementary to the holographic bound which limits the number of bits that can exist within a spat...

  9. Fundamental Limits of Cooperation

    CERN Document Server

    Lozano, Angel; Andrews, Jeffrey G

    2012-01-01

    Cooperation is viewed as a key ingredient for interference management in wireless systems. This paper shows that cooperation has fundamental limitations. The main result is that even full cooperation between transmitters cannot in general change an interference-limited network to a noise-limited network. The key idea is that there exists a spectral efficiency upper bound that is independent of the transmit power. First, a spectral efficiency upper bound is established for systems that rely on pilot-assisted channel estimation; in this framework, cooperation is shown to be possible only within clusters of limited size, which are subject to out-of-cluster interference whose power scales with that of the in-cluster signals. Second, an upper bound is also shown to exist when cooperation is through noncoherent communication; thus, the spectral efficiency limitation is not a by-product of the reliance on pilot-assisted channel estimation. Consequently, existing literature that routinely assumes the high-power spect...

  10. Quantum Diffusion-Limited Aggregation

    CERN Document Server

    Johnson, David B

    2011-01-01

    Though classical random walks have been studied for many years, research concerning their quantum analogues, quantum random walks, has only come about recently. Numerous simulations of both types of walks have been run and analyzed, and are generally well-understood. Research pertaining to one of the more important properties of classical random walks, namely, their ability to build fractal structures in diffusion-limited aggregation, has been particularly noteworthy. However, only now has research begun in this area in regards to quantum random motion. The study of random walks and the structures they build has various applications in materials science. Since all processes are quantum in nature, it is important to consider the quantum variant of diffusion-limited aggregation. Recognizing that Schr\\"odinger equation and a classical random walk are both diffusion equations, it is possible to connect and compare them. Using similar parameters for both equations, we ran various simulations aggregating particles....

  11. Containing Internal Diffusion Limited Aggregation

    CERN Document Server

    Duminil-Copin, Hugo; Yadin, Ariel; Yehudayoff, Amir

    2011-01-01

    Internal Diffusion Limited Aggregation (IDLA) is a model that describes the growth of a random aggregate of particles from the inside out. Shellef proved that IDLA processes on supercritical percolation clusters of integer-lattices fill Euclidean balls, with high probability. In this article, we complete the picture and prove a limit-shape theorem for IDLA on such percolation clusters, by providing the corresponding upper bound. The technique to prove upper bounds is new and robust: it only requires the existence of a "good" lower bound. Specifically, this way of proving upper bounds on IDLA clusters is more suitable for random environments than previous ways, since it does not harness harmonic measure estimates.

  12. Force Limit System

    Science.gov (United States)

    Pawlik, Ralph; Krause, David; Bremenour, Frank

    2011-01-01

    The Force Limit System (FLS) was developed to protect test specimens from inadvertent overload. The load limit value is fully adjustable by the operator and works independently of the test system control as a mechanical (non-electrical) device. When a test specimen is loaded via an electromechanical or hydraulic test system, a chance of an overload condition exists. An overload applied to a specimen could result in irreparable damage to the specimen and/or fixturing. The FLS restricts the maximum load that an actuator can apply to a test specimen. When testing limited-run test articles or using very expensive fixtures, the use of such a device is highly recommended. Test setups typically use electronic peak protection, which can be the source of overload due to malfunctioning components or the inability to react quickly enough to load spikes. The FLS works independently of the electronic overload protection.

  13. Quantum-Limited Spectroscopy

    CERN Document Server

    Truong, Gar-Wing; May, Eric F; Stace, Thomas M; Luiten, Andre N

    2015-01-01

    Spectroscopy has an illustrious history delivering serendipitous discoveries and providing a stringent testbed for new physical predictions, including applications from trace materials detection, to understanding the atmospheres of stars and planets, and even constraining cosmological models. Reaching fundamental-noise limits permits optimal extraction of spectroscopic information from an absorption measurement. Here we demonstrate a quantum-limited spectrometer that delivers high-precision measurements of the absorption lineshape. These measurements yield a ten-fold improvement in the accuracy of the excited-state (6P$_{1/2}$) hyperfine splitting in Cs, and reveals a breakdown in the well-known Voigt spectral profile. We develop a theoretical model that accounts for this breakdown, explaining the observations to within the shot-noise limit. Our model enables us to infer the thermal velocity-dispersion of the Cs vapour with an uncertainty of 35ppm within an hour. This allows us to determine a value for Boltzm...

  14. Limits on nonlinear electrodynamics

    Science.gov (United States)

    Fouché, M.; Battesti, R.; Rizzo, C.

    2016-05-01

    In this paper we set a framework in which experiments whose goal is to test QED predictions can be used in a more general way to test nonlinear electrodynamics (NLED) which contains low-energy QED as a special case. We review some of these experiments and we establish limits on the different free parameters by generalizing QED predictions in the framework of NLED. We finally discuss the implications of these limits on bound systems and isolated charged particles for which QED has been widely and successfully tested.

  15. Inhomogeneous diffusion-limited aggregation

    Science.gov (United States)

    Selinger, Robin Blumberg; Nittmann, Johann; Stanley, H. E.

    1989-01-01

    It is demonstrated here that inhomogeneous diffusion-limited aggregation (DLA) model can be used to simulate viscous fingering in a medium with inhomogeneous permeability and homogeneous porosity. The medium consists of a pipe-pore square-lattice network in which all pores have equal volume and the pipes have negligible volume. It is shown that fluctuations in a DLA-based growth process may be tuned by noise reduction, and that fluctuations in the velocity of the moving interface are multiplicative in form.

  16. Food irradiation, profits and limitations

    International Nuclear Information System (INIS)

    The utility of the irradiation to overcome diverse problems of lost nutritious, it has been demonstrated in multiple investigation works, that its have confirmed the value and the inoculation of the irradiated foods. The quantity of energy applied to each food, is in function of the wanted effect. In this document a guide with respect to the practical application and the utility of the irradiation process in different foods, as well as the suggested dose average is shown. Among the limitations of the use of this technology, its are the costs and not being able to apply it to some fresh foods. (Author)

  17. Impact of nitrogen deposition on forest and lake food webs in nitrogen-limited environments.

    Science.gov (United States)

    Meunier, Cédric L; Gundale, Michael J; Sánchez, Irene S; Liess, Antonia

    2016-01-01

    Increased reactive nitrogen (Nr ) deposition has raised the amount of N available to organisms and has greatly altered the transfer of energy through food webs, with major consequences for trophic dynamics. The aim of this review was to: (i) clarify the direct and indirect effects of Nr deposition on forest and lake food webs in N-limited biomes, (ii) compare and contrast how aquatic and terrestrial systems respond to increased Nr deposition, and (iii) identify how the nutrient pathways within and between ecosystems change in response to Nr deposition. We present that Nr deposition releases primary producers from N limitation in both forest and lake ecosystems and raises plants' N content which in turn benefits herbivores with high N requirements. Such trophic effects are coupled with a general decrease in biodiversity caused by different N-use efficiencies; slow-growing species with low rates of N turnover are replaced by fast-growing species with high rates of N turnover. In contrast, Nr deposition diminishes below-ground production in forests, due to a range of mechanisms that reduce microbial biomass, and decreases lake benthic productivity by switching herbivore growth from N to phosphorus (P) limitation, and by intensifying P limitation of benthic fish. The flow of nutrients between ecosystems is expected to change with increasing Nr deposition. Due to higher litter production and more intense precipitation, more terrestrial matter will enter lakes. This will benefit bacteria and will in turn boost the microbial food web. Additionally, Nr deposition promotes emergent insects, which subsidize the terrestrial food web as prey for insectivores or by dying and decomposing on land. So far, most studies have examined Nr -deposition effects on the food web base, whereas our review highlights that changes at the base of food webs substantially impact higher trophic levels and therefore food web structure and functioning. PMID:25953197

  18. Limitation of Auditors' Liability

    DEFF Research Database (Denmark)

    Werlauff, Erik; Foged-Ladefoged, Lise Kolding

    2014-01-01

    The article examines the question of whether rules on the limitation of auditors’ liability within the perspective of EU law are needed, and if so, which rules can provide an appropriate balance between the potential injured party’s interests and those of the auditing sector, including with respect...

  19. The Limits of Laughter.

    Science.gov (United States)

    Mindess, Harvey

    1983-01-01

    Three incidents which elucidate the limits of laughter are described. Most persons enjoy humor as comic relief, but when humor strikes a blow at something they hold dear, they find it very hard to laugh. People are upset by an irreverent attitude toward things they hold in esteem. (RM)

  20. Occupational dose equivalent limits

    International Nuclear Information System (INIS)

    This paper considers methods of limiting individual radiation risks by recognizing the variation of risk with age at exposure, taking into account both somatic and genetic risks and proposes a simple formula for controlling individual cumulative exposure and hence risk. (Author)

  1. Limitations on blanket performance

    International Nuclear Information System (INIS)

    The limitations on the performance of breeding blankets in a fusion power plant are evaluated. The breeding blankets will be key components of a plant and their limitations with regard to power density, thermal efficiency and lifetime could determine to a large degree the attractiveness of a power plant. The performance of two rather well known blanket concepts under development in the frame of the European Blanket Programme is assessed and their limitations are compared with more advanced (and more speculative) concepts. An important issue is the question of which material (structure, breeder, multiplier, coatings) will limit the performance and what improvement would be possible with a 'better' structural material. This evaluation is based on the premise that the performance of the power plant will be limited by the blankets (including first wall) and not by other components, e.g. divertors, or the plasma itself. However, the justness of this premise remains to be seen. It is shown that the different blanket concepts cover a large range of allowable power densities and achievable thermal efficiencies, and it is concluded that there is a high incentive to go for better performance in spite of possibly higher blanket cost. However, such high performance blankets are usually based on materials and technologies not yet developed and there is a rather high risk that the development could fail. Therefore, it is explained that a part of the development effort should be devoted to concepts where the materials and technologies are more or less in hand in order to ensure that blankets for a DEMO reactor can be developed and tested in a given time frame. (orig.)

  2. Belowground carbon trade among tall forest trees

    Science.gov (United States)

    Klein, Tamir; Siegwolf, Rolf; Koerner, Christian

    2016-04-01

    Just imagine one tree could hand over large quantities of carbon to another tree. How would that change our thinking about carbon relations of forests, the single biggest biological C reservoir on earth? If such a tree-to-tree C shuttle would exist, it required a demand-supply gradient and a pipeline. Here we show that exactly this unthinkable does occur in overlapping root spheres of tall trees in a mixed temperate forest. Using canopy scale stable carbon isotope labelling applied from a construction crane, we demonstrate that carbon assimilated by spruce is traded over to neighbouring beech, larch, and pine in amounts so large that fine roots almost equilibrate the carbon source signature. The isotope mixing ratio indicated that the interspecific transfer accounted for 40% of the fine root carbon, which is ca. 280 kg ha-1 a-1. This is the first forest scale evidence of a large flux of carbon among mature trees from evolutionary distant taxa. Carbon transfer most likely occurred through common ectomycorrhiza networks, which also exhibited the labelled carbon signal. These observations indicate that while competition for resources (e.g. light, water, nutrients) is often considered the dominant tree-tree interaction in a forest, trees actually interact in more complex pathways including a massive carbon exchange.

  3. Mathematical methods for hydrodynamic limits

    CERN Document Server

    Masi, Anna

    1991-01-01

    Entropy inequalities, correlation functions, couplings between stochastic processes are powerful techniques which have been extensively used to give arigorous foundation to the theory of complex, many component systems and to its many applications in a variety of fields as physics, biology, population dynamics, economics, ... The purpose of the book is to make theseand other mathematical methods accessible to readers with a limited background in probability and physics by examining in detail a few models where the techniques emerge clearly, while extra difficulties arekept to a minimum. Lanford's method and its extension to the hierarchy of equations for the truncated correlation functions, the v-functions, are presented and applied to prove the validity of macroscopic equations forstochastic particle systems which are perturbations of the independent and of the symmetric simple exclusion processes. Entropy inequalities are discussed in the frame of the Guo-Papanicolaou-Varadhan technique and of theKipnis-Oll...

  4. Proposition Algebra with Projective Limits

    CERN Document Server

    Bergstra, J A

    2008-01-01

    Sequential logic deviates from propositional logic by taking into account that atomic propositions yield different Boolean values at different times during the sequential evaluation of a single proposition. Reactive valuations capture this dynamics of a proposition's environment. This logic is phrased as an equationally specified algebra rather than in the form of proof rules. It is strictly more general than Boolean algebra to the extent that the classical connectives fail to be expressively complete in the sequential case. The proposition algebra PRA is developed in a fashion similar to the process algebra ACP and the program algebra PGA via an algebraic specification which has a meaningful initial algebra for which a range of courser congruences are considered important as well. In addition infinite objects (that is propositions, processes and programs respectively) are preferably dealt with by means of an inverse limit construction which allows the transfer of knowledge concerning finite objects to facts ...

  5. Regulating the introduction of new chemicals under section 5 of TSCA: improving the efficiency of the process and reducing potential injury in the workplace through the use of operational MSDS and exposure limits.

    Science.gov (United States)

    Rosenthal, I; Jayjock, M A; Keener, R L; Plamondon, J E

    1991-10-01

    The Toxic Substances Control Act (TSCA) authorizes the EPA to take appropriate actions to ensure that new and existing chemicals do not pose "unreasonable risk" to health or the environment. Section 2(b)(3) of the Act directs the Agency to accomplish this objective in a manner that does "not impede unduly or create unnecessary economic barriers to technological innovation." In recent years, critics have felt that the EPA has failed to achieve these primary goals of TSCA. This paper considers some of the reasons for this criticism and advocates an alternate approach of exposure limits and operationally sufficient controls to assist in achieving these goals. An illustration of how this alternate approach might work under practical conditions is presented, using as an example a new chemical substance from the class of acrylate monomers. These concepts and risk assessments provide data for a better design of future studies according to good laboratory practice and quality assurance. PMID:1669965

  6. The need to promote behaviour change at the cultural level: one factor explaining the limited impact of the MEMA kwa Vijana adolescent sexual health intervention in rural Tanzania. A process evaluation

    Directory of Open Access Journals (Sweden)

    Wight Daniel

    2012-09-01

    Full Text Available Abstract Background Few of the many behavioral sexual health interventions in Africa have been rigorously evaluated. Where biological outcomes have been measured, improvements have rarely been found. One of the most rigorous trials was of the multi-component MEMA kwa Vijana adolescent sexual health programme, which showed improvements in knowledge and reported attitudes and behaviour, but none in biological outcomes. This paper attempts to explain these outcomes by reviewing the process evaluation findings, particularly in terms of contextual factors. Methods A large-scale, primarily qualitative process evaluation based mainly on participant observation identified the principal contextual barriers and facilitators of behavioural change. Results The contextual barriers involved four interrelated socio-structural factors: culture (i.e. shared practices and systems of belief, economic circumstances, social status, and gender. At an individual level they appeared to operate through the constructs of the theories underlying MEMA kwa Vijana - Social Cognitive Theory and the Theory of Reasoned Action – but the intervention was unable to substantially modify these individual-level constructs, apart from knowledge. Conclusion The process evaluation suggests that one important reason for this failure is that the intervention did not operate sufficiently at a structural level, particularly in regard to culture. Recently most structural interventions have focused on gender or/and economics. Complementing these with a cultural approach could address the belief systems that justify and perpetuate gender and economic inequalities, as well as other barriers to behaviour change.

  7. Auctions with Limited Commitment

    OpenAIRE

    Qingmin Liu; Konrad Mierendorff; Xianwen Shi

    2013-01-01

    We study auction design in the standard symmetric independent private values environment, where the seller lacks the commitment power to withhold an unsold object off the market. The seller has a single object and can conduct an infinite sequence of standard auctions with reserve prices to maximize her expected profit. In each period, the seller can commit to a reserve price for the current period but cannot commit to future reserve prices. We analyze the problem with limited commitment throu...

  8. Persuasion and Limited Communication

    OpenAIRE

    Itai Sher

    2008-01-01

    This paper studies optimal persuasion. A speaker must decide which arguments to present and a listener which arguments to accept. Communication is limited in that the arguments available to the speaker depend on her information. Optimality is assessed from the listener's perspective assuming that the listener can commit to a persuasion rule. I show that this seemingly simple scenario--introduced by Glazer and Rubinstein (2006)--is computationally intractable (formally, NP-hard). However under...

  9. Photovoltaic energy cost limit

    International Nuclear Information System (INIS)

    Referring to a photovoltaic system for grid connected applications, a parametric expression of kWh cost is derived. The limit of kWh cost is carried out extrapolating the values of cost components to their lowest figure. The reliability of the forecast is checked by disaggregating kWh cost in direct and indirect costs and by discussing the possible cost reduction of each component

  10. Limiting Similarity Revisited

    OpenAIRE

    Szabo, P; Meszena, G.

    2005-01-01

    We reinvestigate the validity of the limiting similarity principle via numerical simulations of the Lotka-Volterra model. A Gaussian competition kernel is employed to describe decreasing competition with increasing difference in a one-dimensional phenotype variable. The simulations are initiated by a large number of species, evenly distributed along the phenotype axis. Exceptionally, the Gaussian carrying capacity supports coexistence of all species, initially present. In case of any other, d...

  11. TFTR movable limiter installation

    International Nuclear Information System (INIS)

    The TFTR movable limiter is a poloidal limiter consisting of graphite tiles mounted on three blades with hinge connections supported by three independent actuators. The installed configuration is shown. The blades and actuators underwent mechanical, electrical and vacuum tests at the fabricator and at PPL prior to assembly with the TFTR vacuum vessel. During the preparation phase the installation crew removed the bus bar segments and air ducts that interfered with assembly and installed the support steel and the support table for the blade fixture. The actuators were assembled with the extension tubes and motor drives. The lower vertical actuator was rolled into the basement on carts, then pulled into position by a cable through the vacuum vessel. The upper vertical actuator was installed next by lowering into position from above. The three blades (with most of the graphite tiles installed), the cover plate, the horizontal actuator and water and instrumentation feed-throughs were mounted on an air cushion installation fixture, which was then lowered onto the support table. The assembly was floated into position with hand adjustment to engage the roller assemblies with the limiter bridges and the guide pins into the vacuum vessel. The cover plate was then bolted onto the vacuum vessel and the remaining graphite tiles are installed. The whole assembly underwent final adjustment and calibration after installation in the vacuum vessel

  12. 7 CFR 1400.204 - Limited partnerships, limited liability partnerships, limited liability companies, corporations...

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Limited partnerships, limited liability partnerships, limited liability companies, corporations, and other similar legal entities. 1400.204 Section 1400.204... entities. (a) A limited partnership, limited liability partnership, limited liability company,......

  13. Elevated carbon dioxide increases soil nitrogen and phosphorus availability in a phosphorus-limited Eucalyptus woodland.

    Science.gov (United States)

    Hasegawa, Shun; Macdonald, Catriona A; Power, Sally A

    2016-04-01

    Free-air CO2 enrichment (FACE) experiments have demonstrated increased plant productivity in response to elevated (e)CO2, with the magnitude of responses related to soil nutrient status. Whilst understanding nutrient constraints on productivity responses to eCO2 is crucial for predicting carbon uptake and storage, very little is known about how eCO2 affects nutrient cycling in phosphorus (P)-limited ecosystems. Our study investigates eCO2 effects on soil N and P dynamics at the EucFACE experiment in Western Sydney over an 18-month period. Three ambient and three eCO2 (+150 ppm) FACE rings were installed in a P-limited, mature Cumberland Plain Eucalyptus woodland. Levels of plant accessible nutrients, evaluated using ion exchange resins, were increased under eCO2, compared to ambient, for nitrate (+93%), ammonium (+12%) and phosphate (+54%). There was a strong seasonality to responses, particularly for phosphate, resulting in a relatively greater stimulation in available P, compared to N, under eCO2 in spring and summer. eCO2 was also associated with faster nutrient turnover rates in the first six months of the experiment, with higher N (+175%) and P (+211%) mineralization rates compared to ambient rings, although this difference did not persist. Seasonally dependant effects of eCO2 were seen for concentrations of dissolved organic carbon in soil solution (+31%), and there was also a reduction in bulk soil pH (-0.18 units) observed under eCO2. These results demonstrate that CO2 fertilization increases nutrient availability - particularly for phosphate - in P-limited soils, likely via increased plant belowground investment in labile carbon and associated enhancement of microbial turnover of organic matter and mobilization of chemically bound P. Early evidence suggests that there is the potential for the observed increases in P availability to support increased ecosystem C-accumulation under future predicted CO2 concentrations. PMID:26546164

  14. Orind Refractories Limited

    Institute of Scientific and Technical Information of China (English)

    Mr R. Mishra; Group Manging Director

    2005-01-01

    @@ "Sight can be acquired, Vision cannot". Orind Refractories Limited (ORIND), China was formed with this rare vision. At a time when the world was testing the tepid waters of China; Mr. Ravin Jhunjhunwala, Chairman of ORIND and the management of ORIND India had looked over the Great Wall to begin a journey of success. Incorported on 18th August 1994 with an initial investment of USD 5 million, ORL caters to the ever-demanding needs of the steel industry and beyond. Incidentally ORIND was the first wholly owned India company to set up base in China. Pesently, ORIND China has a 616 strong work force including 23 expatriates.

  15. (Limiting the greenhouse effect)

    Energy Technology Data Exchange (ETDEWEB)

    Rayner, S.

    1991-01-07

    Traveler attended the Dahlem Research Conference organized by the Freien Universitat, Berlin. The subject of the conference was Limiting the Greenhouse Effect: Options for Controlling Atmospheric CO{sub 2} Accumulation. Like all Dahlem workshops, this was a meeting of scientific experts, although the disciplines represented were broader than usual, ranging across anthropology, economics, international relations, forestry, engineering, and atmospheric chemistry. Participation by scientists from developing countries was limited. The conference was divided into four multidisciplinary working groups. Traveler acted as moderator for Group 3 which examined the question What knowledge is required to tackle the principal social and institutional barriers to reducing CO{sub 2} emissions'' The working rapporteur was Jesse Ausubel of Rockefeller University. Other working groups examined the economic costs, benefits, and technical feasibility of options to reduce emissions per unit of energy service; the options for reducing energy use per unit of GNP; and the significant of linkage between strategies to reduce CO{sub 2} emissions and other goals. Draft reports of the working groups are appended. Overall, the conference identified a number of important research needs in all four areas. It may prove particularly important in bringing the social and institutional research needs relevant to climate change closer to the forefront of the scientific and policy communities than hitherto.

  16. Smoothness of limit functors

    Indian Academy of Sciences (India)

    Benedictus Margaux

    2015-05-01

    Let be a scheme. Assume that we are given an action of the one dimensional split torus $\\mathbb{G}_{m,S}$ on a smooth affine -scheme $\\mathfrak{X}$. We consider the limit (also called attractor) subfunctor $\\mathfrak{X}_{}$ consisting of points whose orbit under the given action `admits a limit at 0’. We show that $\\mathfrak{X}_{}$ is representable by a smooth closed subscheme of $\\mathfrak{X}$. This result generalizes a theorem of Conrad et al. (Pseudo-reductive groups (2010) Cambridge Univ. Press) where the case when $\\mathfrak{X}$ is an affine smooth group and $\\mathbb{G}_{m,S}$ acts as a group automorphisms of $\\mathfrak{X}$ is considered. It also occurs as a special case of a recent result by Drinfeld on the action of $\\mathbb{G}_{m,S}$ on algebraic spaces (Proposition 1.4.20 of Drinfeld V, On algebraic spaces with an action of $\\mathfrak{G}_{m}$, preprint 2013) in case is of finite type over a field.

  17. Sensitivity Limitations for Multivariable Linear Filtering

    Directory of Open Access Journals (Sweden)

    Steven R. Weller

    2007-01-01

    Full Text Available This paper examines fundamental limitations in performance which apply to linear filtering problems associated with multivariable systems having as many inputs as outputs. The results of this paper quantify unavoidable limitations in the sensitivity of state estimates to process and measurement disturbances, as represented by the maximum singular values of the relevant transfer matrices. These limitations result from interpolation constraints imposed by open right half-plane poles and zeros in the transfer matrices linking process noise and output noise with state estimates. Using the Poisson integral inequality, this paper shows how sensitivity limitations and tradeoffs in multivariable filtering problems are intimately related to the directionality properties of the open right half-plane poles and zeros in these transfer matrices.

  18. FY 1999 cold demonstration of the Multi-Point Injection (MPI) process for stabilizing contaminated sludge in buried horizontal tanks with limited access at the Oak Ridge National Laboratory

    International Nuclear Information System (INIS)

    A major problem faced by the U.S. Department of Energy is the remediation of buried tank waste. Exhumation of the sludge is currently the preferred remediation method. However, exhumation does not typically remove all the contaminated material from the tank. The best management practices for in-tank treatment of wastes require an integrated approach to develop appropriate treatment agents that can be safely delivered and uniformly mixed with the sludge. Ground Environmental Services, Inc., has developed and demonstrated a remotely controlled, high-velocity, jet-delivery system, which is termed Multi-Point-Injection (MPItrademark). This robust jet-delivery system has been used to create homogeneous monoliths containing shallow-buried miscellaneous waste in trenches [fiscal year (FY) 1995] and surrogate sludge in a cylindrical test tank (FY 1998). During the FY 1998 demonstration, the MPI process was able to successfully form a 32-ton uniform monolith in about 8 min. Analytical data indicated that 10 tons of a zeolite-type physical surrogate were uniformly mixed within the 40-inch-thick monolith without lifting the MPI jetting tools off the tank floor. Over 1,000 lb of cohesive surrogates, with consistencies of Gunite and Associated Tanks (GAATs) TH-4 and Hanford tank sludges, were easily mixed into the monolith without exceeding a core temperature of 100 F during curing

  19. Speed Limits for Entanglement

    CERN Document Server

    Hartman, Thomas

    2015-01-01

    We show that in any relativistic system, entanglement entropy obeys a speed limit set by the entanglement in thermal equilibrium. The bound is derived from inequalities on relative entropy with respect to a thermal reference state. Thus the thermal state constrains far-from-equilibrium entanglement dynamics whether or not the system actually equilibrates, in a manner reminiscent of fluctuation theorems in classical statistical mechanics. A similar shape-dependent bound constrains the full nonlinear time evolution, supporting a simple physical picture for entanglement propagation that has previously been motivated by holographic calculations in conformal field theory. We discuss general quantum field theories in any spacetime dimension, but also derive some results of independent interest for thermal relative entropy in 1+1d CFT.

  20. The Limits to Relevance

    Science.gov (United States)

    Averill, M.; Briggle, A.

    2006-12-01

    Science policy and knowledge production lately have taken a pragmatic turn. Funding agencies increasingly are requiring scientists to explain the relevance of their work to society. This stems in part from mounting critiques of the "linear model" of knowledge production in which scientists operating according to their own interests or disciplinary standards are presumed to automatically produce knowledge that is of relevance outside of their narrow communities. Many contend that funded scientific research should be linked more directly to societal goals, which implies a shift in the kind of research that will be funded. While both authors support the concept of useful science, we question the exact meaning of "relevance" and the wisdom of allowing it to control research agendas. We hope to contribute to the conversation by thinking more critically about the meaning and limits of the term "relevance" and the trade-offs implicit in a narrow utilitarian approach. The paper will consider which interests tend to be privileged by an emphasis on relevance and address issues such as whose goals ought to be pursued and why, and who gets to decide. We will consider how relevance, narrowly construed, may actually limit the ultimate utility of scientific research. The paper also will reflect on the worthiness of research goals themselves and their relationship to a broader view of what it means to be human and to live in society. Just as there is more to being human than the pragmatic demands of daily life, there is more at issue with knowledge production than finding the most efficient ways to satisfy consumer preferences or fix near-term policy problems. We will conclude by calling for a balanced approach to funding research that addresses society's most pressing needs but also supports innovative research with less immediately apparent application.

  1. Kyphoplasty: Chances and limits

    Directory of Open Access Journals (Sweden)

    Mueller Christian

    2005-01-01

    Full Text Available Kyphoplasty provides a minimal-invasive surgical technique for the cement augmentation of vertebral bodies following osteoprotic compression fractures or malignant processes. Kyphoplasty has been developed as an advancement of vertebroplasty. Both procedures feature high-success rates in terms of reliable and lasting reduction of pain. Advantages of kyphoplasty over vertebroplasty are to be seen in the possibility of deformity correction as well as in a decreased risk of cement leakage, which represents the most important source for clinical complications. Long-term experiences with the effect of cementing vertebral bodies are sparse. Thus indications and possibilities have to be judged realistically. Conditions, which have to be considered before performing kyphoplasty or vertebroplasty include age of the patient, age of the fracture, degree of deformation and additional degenerative changes of the spine. This article summarizes the present research and literature as well as indications and contraindications and is thought to provide guidelines for the aforementioned decision-making processes.

  2. Limitations in forensic odontology

    OpenAIRE

    B. KAVITHA; A Einstein; Sivapathasundharam, B.; T R Saraswathi

    2009-01-01

    The concept of using dental evidence in forensic investigation has kindled so much interest in the recent past that forensic odontology is even suggested as the single positive identification method to solve certain forensic cases. In this process, the shortcomings in forensic odontology though few are overlooked. These discrepancies associated with various methods are to be weighed cautiously to make forensic odontology a more accurate, reliable, and reproducible investigatory science. In th...

  3. Collider limits on leptophilic interactions

    International Nuclear Information System (INIS)

    In order to observe leptophilic interactions at the LHC we must require at least four leptons, which may be in particular neutrinos, in the final state. If they are mediated by a resonance in the di-leptonic channel, this must be of spin 1 to be produced through a renormalizable coupling. We study the LHC reach for such a vector boson allowing for arbitrary couplings, what in practice means for arbitrary couplings to muons because lepton flavor violating couplings are constrained by rare processes, couplings to electrons by LEP and LHC is not sensitive to final states involving taus in this case. This makes the ILC complementary as it will provide the best limits on Z' couplings to tau leptons. A prominent example is the case of the anomaly-free Z' coupling to the muon minus tau lepton number Lμ-Lτ. If no departure from the Standard Model is observed at the LHC, the most stringent bounds on this vector boson are provided from events with only three charged leptons plus missing energy. Masses of the order of 1 TeV can be probed at the high-luminosity phase of the LHC for Z' couplings of order one. Generic four-lepton operators parametrizing leptophilic interactions can be also restricted using three and four (or two at the ILC) charged lepton samples, but the corresponding limits are marginal, if meaningful, because the resonant behavior appears to be essential for the signal to be significant.

  4. LIMITED LIABILITY DALAM LIMITED LIABILITY PADA KONSTRUKSI PERUSAHAAN KELOMPOK PIRAMIDA

    Directory of Open Access Journals (Sweden)

    Ms. Sulistiowati

    2011-06-01

    Full Text Available Applicability of limited liability in corporate groups with pyramid construction creates a legal loophole in the form of a limited liability within a limited liability. To prevent moral hazard, it is necessary to stipulate new law that limits the number of levels in a corporate group. Berlakunya limited liability pada perusahaan kelompok dengan konstruksi piramida menciptakan celah hukum berupa limited liability dalam limited liability. Untuk mencegah munculnya moral hazard dari pemegang akhir atau induk perbuatan, perlu dilakukan terobosan hukum pembatasan jumlah lapisan anak perusahaan dalam konstruksi perusahaan kelompok.

  5. Bioenergy: Potentials and limitations

    Science.gov (United States)

    Schulze, E.-D.; Canadell, J. G.

    2015-08-01

    In this lecture we explain 1) the biochemical basis for photosynthesis and plant production and 2) the future demands on biomass for human use. Summing all physiological processes, the efficiency of converting solar energy into biomass is plant production will be available for bioenergy. We estimate this fraction to be between 3 and 8% of the global energy demand by 2050. The contribution of bioenergy is at the higher end in tropical regions and in the less industrialized parts of the world, but may even be < 3% in industrialized nations.

  6. One-dimensional long-range diffusion-limited aggregation III -- The limit aggregate

    CERN Document Server

    Amir, Gideon

    2009-01-01

    In this paper we study the structure of the limit aggregate (the union of all finite-time aggregates) of the one-dimensional long range diffusion limited aggregation process defined in [arXiv:0910.4416] . We show (under some regularity conditions) that for walks with finite third moment the limit aggregate has renewal structure and positive density, while for walks with finite variance the renewal structure no longer exists and the limit aggregate has 0 density. We define a tree structure on the aggregates and show some results on the degrees and number of ends of these random trees.

  7. Capsulorhexis: Its safe limits

    Directory of Open Access Journals (Sweden)

    Vasavada Abhay

    1995-01-01

    Full Text Available We undertook this study to determine the safe limits of capsulorhexis during nucleus expression in 40 eyes of patients undergoing extracapsular cataract extraction (ECCE with a posterior chamber intraocular lens (PC IOL implantation and in 30 cadaver eyes. In group I (patient eyes, capsulorhexis of 4.5 to 7.5 mm was performed and the nucleus was expressed by hydrodissection. The nuclei measured 4.5 to 9.0 mm. One relaxing incision at 12 o′clock position had to be placed in 9 patients. In group II (cadaver eyes, continuous curvilinear capsulotomies of 4.0, 4.5, 5.0, 5.5, 6.0 and 6.5 mm were made in 5 eyes each. No relaxing incisions were placed. In both the groups, nuclei of all sizes could be safely delivered through intact capsulotomies measuring 5.5 mm or more. In two patient eyes, posterior capsule rupture occurred with rhexis measuring 4.5 and 5.0 mm, respectively. In the cadaver eyes, intracapsular extraction occurred in 4 eyes with rhexis measuring 5.0 mm or less. We conclude that a rhexis less than 5.5 mm is not safe for nucleus delivery during ECCE.

  8. GCFR core cladding temperature limits

    International Nuclear Information System (INIS)

    This paper reviews the phenomena that affect selection of the GCFR cladding faulted temperature limit. The limiting effects are determined to be clad melting, strength and oxidation rate. The selected temperature limit is 13000C (23700F). The limits for normal, upset and emergency events are also breifly reviewed, and some changes under consideration are discussed

  9. The limits of deterrence

    International Nuclear Information System (INIS)

    The objective of this contribution is to propose a better insight of the validity of the theory of deterrence, and of related doctrines in more complex and more various situations than in the past: emergence of powers like China and India, of new nuclear States like North Korea and Pakistan, of countries planning to acquire nuclear weapons like Iran, and possibility of a new wave of nuclear proliferation in Middle-East and north-eastern Asia. It also aims at providing arguments in the debates on the struggle against nuclear proliferation and on the future of deterrence. The author first presents and comments the principles of deterrence, and illustrates them by more or less recent historical situations (Iran during the war with Iraq, USA after Pearl Harbour, Arab-Israeli wars, Iraq, and so on). He notably outlines that the notion of deterrence is present in Islamic culture, and that Iran has well integrated it in its defence strategy. Examples of statements and behaviours of other Arab leaders are discussed. The author also briefly indicates how the deterrence strategy is present in the official doctrines of Russia, India, Pakistan, and North Korea. In a second part, based on various examples, the author analyses the practical limitations of deterrence by distinguishing the psychological dimension (bounded rationality, political leaders suffering from various psychological problems, importance of the ideological and spiritual dimension, values prevailing on interests, the case of Iran), and the strategic dimension (good understanding of the enemy, sensitivity of the threat of massive damages, existence of a single decision centre and of an efficient communication). The author finally proposes seven recommendations for better deterrence efficiency

  10. Limits to Tidal Power

    Science.gov (United States)

    Garrett, C.

    2008-12-01

    Ocean tides have been proposed as a source of renewable energy, though the maximum available power may be shown to be only a fraction of the present dissipation rate of 3.5 TW, which is small compared with global insolation (nearly 105 TW), wind dissipation (103 TW), and even human power usage of 15 TW. Nonetheless, tidal power could be a useful contributor in some locations. Traditional use of tidal power, involving the trapping of water behind a barrage at high tide, can produce an average power proportional to the area of the headpond and the square of the tidal range; the power density is approximately 6 W per square meter for a tidal range of 10 m. Capital costs and fears of environmental damage have put barrage schemes in disfavor, with interest turning to the exploitation of strong tidal currents, using turbines in a manner similar to wind turbines. There is a limit to the available power, however, as adding turbines reduces the flow, ultimately reducing the power. For sinusoidal forcing of flow in a channel connecting two large open basins, the maximum available power may be shown to be given approximately by 0.2ρ g a Q_max, where ρ is the water density, g gravity, a the amplitude of the tidal sea level difference along the channel, and Q_max is the maximum volume flux in the natural state. The same formula applies if the channel is the entrance to a semi-enclosed basin, with a now the amplitude of the external tide. A flow reduction of approximately 40% is typically associated with the maximum power extraction. The power would be reduced if only smaller environmental changes are acceptable, and reduced further by drag on supporting structures, dissipation in turbine wakes, and internal inefficiencies. It can be suggested that the best use of strong, cold, tidal currents is to provide cooling water for nuclear reactors.

  11. Process automation

    International Nuclear Information System (INIS)

    Process automation technology has been pursued in the chemical processing industries and to a very limited extent in nuclear fuel reprocessing. Its effective use has been restricted in the past by the lack of diverse and reliable process instrumentation and the unavailability of sophisticated software designed for process control. The Integrated Equipment Test (IET) facility was developed by the Consolidated Fuel Reprocessing Program (CFRP) in part to demonstrate new concepts for control of advanced nuclear fuel reprocessing plants. A demonstration of fuel reprocessing equipment automation using advanced instrumentation and a modern, microprocessor-based control system is nearing completion in the facility. This facility provides for the synergistic testing of all chemical process features of a prototypical fuel reprocessing plant that can be attained with unirradiated uranium-bearing feed materials. The unique equipment and mission of the IET facility make it an ideal test bed for automation studies. This effort will provide for the demonstration of the plant automation concept and for the development of techniques for similar applications in a full-scale plant. A set of preliminary recommendations for implementing process automation has been compiled. Some of these concepts are not generally recognized or accepted. The automation work now under way in the IET facility should be useful to others in helping avoid costly mistakes because of the underutilization or misapplication of process automation. 6 figs

  12. Limitations in dual-task performance

    OpenAIRE

    Pannebakker, Merel Mathilde

    2009-01-01

    In this thesis, the effect of information-processing overload on working-memory dependent information processing was examined using dual-task paradigms. The experiments described strengthen the importance of a functional explanation for dual-task limitations. First, it showed evidence for a unified coding medium (as put forward in the theory of event coding; Hommel, Müsseler, Aschersleben, & Prinz, 2001) in which features, operations and responses are available and can influence each other. A...

  13. Pricing when customers have limited attention

    OpenAIRE

    Boyacı, Tamer; Akçay, Yalçın

    2016-01-01

    We study the optimal pricing problem of a firm facing customers with limited attention and capability to process information about the value (quality) of the offered products. We model customer choice based on the theory of rational inattention in the economics literature, which enables us to capture not only the impact of true qualities and prices, but also the intricate effects of customer's prior beliefs and cost of information acquisition and processing. We formulate the firm's price opti...

  14. Fundamental limitations for quantum and nano thermodynamics

    CERN Document Server

    Horodecki, Michał

    2011-01-01

    The relationship between thermodynamics and statistical physics is valid in the thermodynamic limit -- when the number of particles involved becomes very large. Here we study thermodynamics in the opposite regime -- at both the nano scale, and when quantum effects become important. Applying results from quantum information theory we construct a theory of thermodynamics in these extreme limits. In the quantum regime, we find that the standard free energy no longer determines the amount of work which can be extracted from a resource, nor which state transitions can occur spontaneously. We derive a criteria for thermodynamical state transitions, and find two free energies: one which determines the amount of work which can be extracted from a small system in contact with a heat bath, and the other which quantifies the reverse process. They imply that generically, there are additional constraints which govern spontaneous thermodynamical processes. We find that there are fundamental limitations on work extraction f...

  15. Diffusion limited growth in laminar flows

    NARCIS (Netherlands)

    R.M.H. Merks; A.G. Hoekstra; J.A. Kaandorp; P.M.A. Sloot

    2003-01-01

    In the diffusion-limited aggregation (DLA) model, pioneered by Witten and Sander (Phys. Rev. Lett.47, 1400 (1981)), diffusing particles irreversibly attach to a growing cluster which is initiated with a single solid seed. This process generates clusters with a branched morphology. Advectiondiffusion

  16. Limiting Spectral Distribution of Sample Autocovariance Matrices

    CERN Document Server

    Basak, Anirban; Sen, Sanchayan

    2011-01-01

    The empirical spectral distribution (ESD) of the sample variance covariance matrix of i.i.d. observations under suitable moment conditions converges almost surely as the dimension tends to infinity. The limiting spectral distribution (LSD) is universal and is known in closed form with support [0, 4]. In this article we show that the ESD of the sample autocovariance matrix converges as the dimension increases, when the time series is a linear process with reasonable restriction on the coefficients. This limit does not depend on the distribution of the underlying driving i.i.d. sequence but in contrast to the sample variance covariance matrix, its support is unbounded. The limit moments are certain functions of the autocovariances. This limit is inconsistent in the sense that it does not coincide with the spectral distribution of the theoretical autocovariance matrix. However, if we consider a suitably tapered version of the autocovariance matrix, then its LSD also exists and is consistent. We also discuss the ...

  17. FED pumped limiter configuration issues

    International Nuclear Information System (INIS)

    Impurity control in the Fusion Engineering Device (FED) is provided by a toroidal belt pumped limiter. Limiter design issues addressed in this paper are (1) poloidal location of the limiter belt, (2) shape of the limiter surface facing the plasma, and (3) whether the belt is pumped from one or both sides. The criteria used for evaluation of limiter configuration features were sensitivity to plasma-edge conditions and ease of maintenance and fabrication. The evaluation resulted in the selection of a baseline FED limiter that is located at the bottom of the device and has a flat surface with a single leading edge

  18. Collider limits on leptophilic interactions

    Energy Technology Data Exchange (ETDEWEB)

    Aguila, Francisco del; Yamamoto, Yasuhiro [Granada Univ. (Spain). CAFPE; Granada Univ. (Spain). Dept. de Fisica Teorica y del Cosmos; Chala, Mikael [Granada Univ. (Spain). CAFPE; Granada Univ. (Spain). Dept. de Fisica Teorica y del Cosmos; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Santiago, Jose [Granada Univ. (Spain). CAFPE; Granada Univ. (Spain). Dept. de Fisica Teorica y del Cosmos; European Organization for Nuclear Research (CERN), Geneva (Switzerland)

    2014-11-15

    In order to observe leptophilic interactions at the LHC we must require at least four leptons, which may be in particular neutrinos, in the final state. If they are mediated by a resonance in the di-leptonic channel, this must be of spin 1 to be produced through a renormalizable coupling. We study the LHC reach for such a vector boson allowing for arbitrary couplings, what in practice means for arbitrary couplings to muons because lepton flavor violating couplings are constrained by rare processes, couplings to electrons by LEP and LHC is not sensitive to final states involving taus in this case. This makes the ILC complementary as it will provide the best limits on Z' couplings to tau leptons. A prominent example is the case of the anomaly-free Z' coupling to the muon minus tau lepton number L{sub μ}-L{sub τ}. If no departure from the Standard Model is observed at the LHC, the most stringent bounds on this vector boson are provided from events with only three charged leptons plus missing energy. Masses of the order of 1 TeV can be probed at the high-luminosity phase of the LHC for Z' couplings of order one. Generic four-lepton operators parametrizing leptophilic interactions can be also restricted using three and four (or two at the ILC) charged lepton samples, but the corresponding limits are marginal, if meaningful, because the resonant behavior appears to be essential for the signal to be significant.

  19. 7 CFR 932.23a - Limited use.

    Science.gov (United States)

    2010-01-01

    ... U.S. Standards for Grades of Canned Ripe Olives (7 CFR part 52) or subsequent amendments thereto... 7 Agriculture 8 2010-01-01 2010-01-01 false Limited use. 932.23a Section 932.23a Agriculture... Regulating Handling Definitions § 932.23a Limited use. Limited use means the use of processed olives in...

  20. Limit theorems for extremes with random sample size

    OpenAIRE

    Silvestrov, Dmitrii S.; Teugels, Jozef L.

    1998-01-01

    This paper is devoted to the investigation of limit theorems for extremes with random sample size under general dependence-independence conditions for samples and random sample size indexes. Limit theorems of weak convergence type are obtained as well as functional limit theorems for extremal processes with random sample size indexes.