WorldWideScience

Sample records for model including litter

  1. Extension Leads Model City Litter Fight

    Science.gov (United States)

    Magnuson, Doris

    1971-01-01

    A three-year war on litter is in effect in the Portland, Maine, area, as a result of the University of Maine's enlisting the county extension service to help the local Model Cities program clean up the inner city. Article details problems and progress in meeting the objectives. (PD)

  2. Analysis of litter size and average litter weight in pigs using a recursive model

    DEFF Research Database (Denmark)

    Varona, Luis; Sorensen, Daniel; Thompson, Robin

    2007-01-01

    An analysis of litter size and average piglet weight at birth in Landrace and Yorkshire using a standard two-trait mixed model (SMM) and a recursive mixed model (RMM) is presented. The RMM establishes a one-way link from litter size to average piglet weight. It is shown that there is a one......-to-one correspondence between the parameters of SMM and RMM and that they generate equivalent likelihoods. As parameterized in this work, the RMM tests for the presence of a recursive relationship between additive genetic values, permanent environmental effects, and specific environmental effects of litter size...

  3. Artificial neural networks for modeling time series of beach litter in the southern North Sea.

    Science.gov (United States)

    Schulz, Marcus; Matthies, Michael

    2014-07-01

    In European marine waters, existing monitoring programs of beach litter need to be improved concerning litter items used as indicators of pollution levels, efficiency, and effectiveness. In order to ease and focus future monitoring of beach litter on few important litter items, feed-forward neural networks consisting of three layers were developed to relate single litter items to general categories of marine litter. The neural networks developed were applied to seven beaches in the southern North Sea and modeled time series of five general categories of marine litter, such as litter from fishing, shipping, and tourism. Results of regression analyses show that general categories were predicted significantly moderately to well. Measured and modeled data were in the same order of magnitude, and minima and maxima overlapped well. Neural networks were found to be eligible tools to deliver reliable predictions of marine litter with low computational effort and little input of information. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. [Applicability analysis of spatially explicit model of leaf litter in evergreen broad-leaved forests].

    Science.gov (United States)

    Zhao, Qing-Qing; Liu, He-Ming; Jonard, Mathieu; Wang, Zhang-Hua; Wang, Xi-Hua

    2014-11-01

    The spatially explicit model of leaf litter can help to understand its dispersal process, which is very important to predict the distribution pattern of leaves on the surface of the earth. In this paper, the spatially explicit model of leaf litter was developed for 20 tree species using litter trap data from the mapped forest plot in an evergreen broad-leaved forest in Tiantong, Zhejiang Pro- vince, eastern China. Applicability of the model was analyzed. The model assumed an allometric equation between diameter at breast height (DBH) and leaf litter amount, and the leaf litter declined exponentially with the distance. Model parameters were estimated by the maximum likelihood method. Results showed that the predicted and measured leaf litter amounts were significantly correlated, but the prediction accuracies varied widely for the different tree species, averaging at 49.3% and ranging from 16.0% and 74.0%. Model qualities of tree species significantly correlated with the standard deviations of the leaf litter amount per trap, DBH of the tree species and the average leaf dry mass of tree species. There were several ways to improve the forecast precision of the model, such as installing the litterfall traps according to the distribution of the tree to cover the different classes of the DBH and distance apart from the parent trees, determining the optimal dispersal function of each tree species, and optimizing the existing dispersal function.

  5. Litter-Spinning Retarders

    Science.gov (United States)

    Wilson, John C.

    1995-01-01

    Aerodynamic plates stop litter from spinning during hoisting by helicopter. Features of proposed litter-spinning retarders include convenience of deployment and independence from ground restraint. Retarder plate(s) folded flat against bottom of litter during storage or while litter is loaded. Plate(s) held in storage position by latch that releases manually or automatically as litter is hoisted. Upon release, springs move plates into deployed position.

  6. Does litter size variation affect models of terrestrial carnivore extinction risk and management?

    Directory of Open Access Journals (Sweden)

    Eleanor S Devenish-Nelson

    Full Text Available BACKGROUND: Individual variation in both survival and reproduction has the potential to influence extinction risk. Especially for rare or threatened species, reliable population models should adequately incorporate demographic uncertainty. Here, we focus on an important form of demographic stochasticity: variation in litter sizes. We use terrestrial carnivores as an example taxon, as they are frequently threatened or of economic importance. Since data on intraspecific litter size variation are often sparse, it is unclear what probability distribution should be used to describe the pattern of litter size variation for multiparous carnivores. METHODOLOGY/PRINCIPAL FINDINGS: We used litter size data on 32 terrestrial carnivore species to test the fit of 12 probability distributions. The influence of these distributions on quasi-extinction probabilities and the probability of successful disease control was then examined for three canid species - the island fox Urocyon littoralis, the red fox Vulpes vulpes, and the African wild dog Lycaon pictus. Best fitting probability distributions differed among the carnivores examined. However, the discretised normal distribution provided the best fit for the majority of species, because variation among litter-sizes was often small. Importantly, however, the outcomes of demographic models were generally robust to the distribution used. CONCLUSION/SIGNIFICANCE: These results provide reassurance for those using demographic modelling for the management of less studied carnivores in which litter size variation is estimated using data from species with similar reproductive attributes.

  7. Experimental evidence that the Ornstein-Uhlenbeck model best describes the evolution of leaf litter decomposability.

    Science.gov (United States)

    Pan, Xu; Cornelissen, Johannes H C; Zhao, Wei-Wei; Liu, Guo-Fang; Hu, Yu-Kun; Prinzing, Andreas; Dong, Ming; Cornwell, William K

    2014-09-01

    Leaf litter decomposability is an important effect trait for ecosystem functioning. However, it is unknown how this effect trait evolved through plant history as a leaf 'afterlife' integrator of the evolution of multiple underlying traits upon which adaptive selection must have acted. Did decomposability evolve in a Brownian fashion without any constraints? Was evolution rapid at first and then slowed? Or was there an underlying mean-reverting process that makes the evolution of extreme trait values unlikely? Here, we test the hypothesis that the evolution of decomposability has undergone certain mean-reverting forces due to strong constraints and trade-offs in the leaf traits that have afterlife effects on litter quality to decomposers. In order to test this, we examined the leaf litter decomposability and seven key leaf traits of 48 tree species in the temperate area of China and fitted them to three evolutionary models: Brownian motion model (BM), Early burst model (EB), and Ornstein-Uhlenbeck model (OU). The OU model, which does not allow unlimited trait divergence through time, was the best fit model for leaf litter decomposability and all seven leaf traits. These results support the hypothesis that neither decomposability nor the underlying traits has been able to diverge toward progressively extreme values through evolutionary time. These results have reinforced our understanding of the relationships between leaf litter decomposability and leaf traits in an evolutionary perspective and may be a helpful step toward reconstructing deep-time carbon cycling based on taxonomic composition with more confidence.

  8. Some Sensitivity Studies of Chemical Transport Simulated in Models of the Soil-Plant-Litter System

    Energy Technology Data Exchange (ETDEWEB)

    Begovich, C.L.

    2002-10-28

    Fifteen parameters in a set of five coupled models describing carbon, water, and chemical dynamics in the soil-plant-litter system were varied in a sensitivity analysis of model response. Results are presented for chemical distribution in the components of soil, plants, and litter along with selected responses of biomass, internal chemical transport (xylem and phloem pathways), and chemical uptake. Response and sensitivity coefficients are presented for up to 102 model outputs in an appendix. Two soil properties (chemical distribution coefficient and chemical solubility) and three plant properties (leaf chemical permeability, cuticle thickness, and root chemical conductivity) had the greatest influence on chemical transport in the soil-plant-litter system under the conditions examined. Pollutant gas uptake (SO{sub 2}) increased with change in plant properties that increased plant growth. Heavy metal dynamics in litter responded to plant properties (phloem resistance, respiration characteristics) which induced changes in the chemical cycling to the litter system. Some of the SO{sub 2} and heavy metal responses were not expected but became apparent through the modeling analysis.

  9. Some sensitivity studies of chemical transport simulated in models of the soil-plant-litter system

    Energy Technology Data Exchange (ETDEWEB)

    Begovich, C.L.; Luxmoore, R.J.

    1979-09-01

    Fifteen parameters in a set of five coupled models describing carbon, water, and chemical dynamics in the soil-plant-litter system were varied in a sensitivity analysis of model response. Results are presented for chemical distribution in the components of soil, plants, and litter along with selected responses of biomass, internal chemical transport (xylem and phloem pathways), and chemical uptake. Response and sensitivity coefficients are presented for up to 102 model outputs in an appendix. Two soil properties (chemical distribution coefficient and chemical solubility) and three plant properties (leaf chemical permeability, cuticle thickness, and root chemical conductivity) had the greatest influence on chemical transport in the soil-plant-litter system under the conditions examined. Pollutant gas uptake (SO/sub 2/) increased with change in plant properties that increased plant growth. Heavy metal dynamics in litter responded to plant properties (phloem resistance, respiration characteristics) which induced changes in the chemical cycling to the litter system. Some of the SO/sub 2/ and heavy metal responses were not expected but became apparent through the modeling analysis.

  10. Including Magnetostriction in Micromagnetic Models

    Science.gov (United States)

    Conbhuí, Pádraig Ó.; Williams, Wyn; Fabian, Karl; Nagy, Lesleis

    2016-04-01

    The magnetic anomalies that identify crustal spreading are predominantly recorded by basalts formed at the mid-ocean ridges, whose magnetic signals are dominated by iron-titanium-oxides (Fe3-xTixO4), so called "titanomagnetites", of which the Fe2.4Ti0.6O4 (TM60) phase is the most common. With sufficient quantities of titanium present, these minerals exhibit strong magnetostriction. To date, models of these grains in the pseudo-single domain (PSD) range have failed to accurately account for this effect. In particular, a popular analytic treatment provided by Kittel (1949) for describing the magnetostrictive energy as an effective increase of the anisotropy constant can produce unphysical strains for non-uniform magnetizations. I will present a rigorous approach based on work by Brown (1966) and by Kroner (1958) for including magnetostriction in micromagnetic codes which is suitable for modelling hysteresis loops and finding remanent states in the PSD regime. Preliminary results suggest the more rigorously defined micromagnetic models exhibit higher coercivities and extended single domain ranges when compared to more simplistic approaches.

  11. Linking an Integrative Behavior Model to Elements of Environmental Campaigns: An Analysis of Face-to-Face Communication and Posters against Littering

    Directory of Open Access Journals (Sweden)

    Ralph Hansmann

    2015-05-01

    Full Text Available Diverse elements of anti-littering campaigns may be effective at addressing different causes of littering. Therefore, a complementary approach combining various elements is needed to ensure the behavioral effectiveness of corresponding campaigns. The present study investigates personal, problem-centered face-to-face conversations compared to three different types of anti-littering posters (witty, authoritarian, environmentally oriented. In total, N = 147 persons participated in the questionnaire-based survey. Pictures of the three anti-littering posters were presented to all respondents, but only 82 of them additionally took part in problem-centered face-to-face conversations. Participants of the latter condition liked the conversations significantly more and judged them more effective for reducing littering than each of the three posters. Intentions for future behavior also improved more in the condition with face-to-face communications than in the reference condition in which only the anti-littering posters were presented. Regarding the posters, it was found that the witty and the environmentally-oriented poster were liked more and judged to be more effective by the respondents than the authoritarian poster. Findings are discussed in relation to the design of campaigns, which combine elements with reference to an integrative behavior model covering a broad range of factors, including processes of justifications, habit formation and reactance.

  12. Litter Species Composition and Topographic Effects on Fuels and Modeled Fire Behavior in an Oak-Hickory Forest in the Eastern USA.

    Science.gov (United States)

    Dickinson, Matthew B; Hutchinson, Todd F; Dietenberger, Mark; Matt, Frederick; Peters, Matthew P

    2016-01-01

    Mesophytic species (esp. Acer rubrum) are increasingly replacing oaks (Quercus spp.) in fire-suppressed, deciduous oak-hickory forests of the eastern US. A pivotal hypothesis is that fuel beds derived from mesophytic litter are less likely than beds derived from oak litter to carry a fire and, if they do, are more likely to burn at lower intensities. Species effects, however, are confounded by topographic gradients that affect overstory composition and fuel bed decomposition. To examine the separate and combined effects of litter species composition and topography on surface fuel beds, we conducted a common garden experiment in oak-hickory forests of the Ohio Hills. Each common garden included beds composed of mostly oak and mostly maple litter, representative of oak- and maple-dominated stands, respectively, and a mixture of the two. Beds were replenished each fall for four years. Common gardens (N = 16) were established at four topographic positions (ridges, benches on south- and northeast-facing slopes, and stream terraces) at each of four sites. Litter source and topographic position had largely independent effects on fuel beds and modeled fire dynamics after four years of development. Loading (kg m-2) of the upper litter layer (L), the layer that primarily supports flaming spread, was least in more mesic landscape positions and for maple beds, implying greater decomposition rates for those situations. Bulk density in the L layer (kg m-3) was least for oak beds which, along with higher loading, would promote fire spread and fireline intensity. Loading and bulk density of the combined fermentation and humic (FH) layers were least on stream terrace positions but were not related to species. Litter- and FH-layer moistures during a 5-day dry-down period after a rain event were affected by time and topographic effects while litter source effects were not evident. Characteristics of flaming combustion determined with a cone calorimeter pointed to greater fireline

  13. Comparison of models used for national agricultural ammonia emission inventories in Europe: Litter-based manure systems

    Science.gov (United States)

    Reidy, B.; Webb, J.; Misselbrook, T. H.; Menzi, H.; Luesink, H. H.; Hutchings, N. J.; Eurich-Menden, B.; Döhler, H.; Dämmgen, U.

    Six N-flow models, used to calculate national ammonia (NH 3) emissions from agriculture in different European countries, were compared using standard data sets. Scenarios for litter-based systems were run separately for beef cattle and for broilers, with three different levels of model standardisation: (a) standardized inputs to all models (FF scenario); (b) standard N excretion, but national values for emission factors (EFs) (FN scenario); (c) national values for N excretion and EFs (NN scenario). Results of the FF scenario for beef cattle produced very similar estimates of total losses of total ammoniacal-N (TAN) (±6% of the mean total), but large differences in NH 3 emissions (±24% of the mean). These differences arose from the different approaches to TAN immobilization in litter, other N losses and mineralization in the models. As a result of those differences estimates of TAN available at spreading differed by a factor of almost 3. Results of the FF scenario for broilers produced a range of estimates of total changes in TAN (±9% of the mean total), and larger differences in the estimate of NH 3 emissions (±17% of the mean). The different approaches among the models to TAN immobilization, other N losses and mineralization, produced estimates of TAN available at spreading which differed by a factor of almost 1.7. The differences in estimates of NH 3 emissions decreased as estimates of immobilization and other N losses increased. Since immobilization and denitrification depend also on the C:N ratio in manure, there would be advantages to include C flows in mass-flow models. This would also provide an integrated model for the estimation of emissions of methane, non-methane VOCs and carbon dioxide. Estimation of these would also enable an estimate of mass loss, calculation of the N and TAN concentrations in litter-based manures and further validation of model outputs.

  14. Modeling the growth and death kinetics of Salmonella in poultry litter as a function of pH and water activity.

    Science.gov (United States)

    Payne, J B; Osborne, J A; Jenkins, P K; Sheldon, B W

    2007-01-01

    Contaminated poultry litter, serving as a reservoir for Salmonella, can be linked to both food safety concerns when contaminated birds enter processing plants and environmental concerns when used as a fertilizer. Predictive modeling allows for the estimation of microbial growth or inactivation as a function of controlling environmental growth factors. A study was conducted to observe the combined effects of pH and water activity (A(w)) at a constant temperature on Salmonella populations in used turkey litter to predict microbial response over time. Litter, first pH-adjusted and then inoculated with a 3-strain Salmonella serovar cocktail to an initial concentration of approximately 10(7) cfu/g, was placed into individual sealed plastic containers with saturated salt solutions for controlling A(w). A balanced design including 3 A(w) values (0.84, 0.91, 0.96), 3 pH values (4, 7, 9), and a constant temperature of 30 degrees C was used, with litter samples periodically removed and analyzed for Salmonella populations, pH, and A(w). At each combination of environmental factors, the Churchill or exponential inactivation mathematical models were used to describe the growth and death of Salmonella over time. Salmonella populations exhibited growth (approximately 2 log) with little decline up to 42 d in litter environments of pH 7 and 9 and a A(w) of 0.96. As litter A(w) and pH levels were reduced, populations declined, with the most drastic reductions (approximately 5 log in 9 h) occurring in low-pH (4) and low-A(w) (0.84) environments. Generalized models for bacterial growth and death under grouped pH environments were successfully developed to predict Salmonella behavior in litter over time. These findings suggest that the best management practices and litter treatments that lower litter A(w) to growth and decline of Salmonella populations as a function of pH and A(w) has potential application for use in the development of effective pathogen control strategies at the farm

  15. Challenges of including nitrogen effects on decomposition in earth system models

    Science.gov (United States)

    Hobbie, S. E.

    2011-12-01

    Despite the importance of litter decomposition for ecosystem fertility and carbon balance, key uncertainties remain about how this fundamental process is affected by nitrogen (N) availability. Nevertheless, resolving such uncertainties is critical for mechanistic inclusion of such processes in earth system models, towards predicting the ecosystem consequences of increased anthropogenic reactive N. Towards that end, we have conducted a series of experiments examining nitrogen effects on litter decomposition. We found that both substrate N and externally supplied N (regardless of form) accelerated the initial decomposition rate. Faster initial decomposition rates were linked to the higher activity of carbohydrate-degrading enzymes associated with externally supplied N and the greater relative abundances of Gram negative and Gram positive bacteria associated with green leaves and externally supplied organic N (assessed using phospholipid fatty acid analysis, PLFA). By contrast, later in decomposition, externally supplied N slowed decomposition, increasing the fraction of slowly decomposing litter and reducing lignin-degrading enzyme activity and relative abundances of Gram negative and Gram positive bacteria. Our results suggest that elevated atmospheric N deposition may have contrasting effects on the dynamics of different soil carbon pools, decreasing mean residence times of active fractions comprising very fresh litter, while increasing those of more slowly decomposing fractions including more processed litter. Incorporating these contrasting effects of N on decomposition processes into models is complicated by lingering uncertainties about how these effects generalize across ecosystems and substrates.

  16. Cross-biome transplants of plant litter show decomposition models extend to a broader climatic range but lose predictability at the decadal time scale

    Science.gov (United States)

    William S. Currie; Mark E. Harmon; Ingrid C. Burke; Stephen C. Hart; William J. Parton; Whendee L. Silver

    2009-01-01

    We analyzed results from 10-year long field incubations of foliar and fine root litter from the Long-term lntersite Decomposition Experiment Team (LIDET) study. We tested whether a variety of climate and litter quality variables could be used to develop regression models of decomposition parameters across wide ranges in litter quality and climate and whether these...

  17. Genetic variation in litter size and kit survival of mink (Neovison vison)

    DEFF Research Database (Denmark)

    Hansen, B K; Su, G; Berg, P

    2010-01-01

    The aims of this study are to estimate variance components of litter size and kit survival rate and estimate genetic correlations of litter size and kit survival rate with dam's juvenile body weight and pregnancy length. Variance components for litter size and kit survival were analysed using an AI......-REML approach, based on data from 1940 litters of the black colour type mink from 1996 to 2001. The models included (i) additive genetic effect of dam; (ii) dam and sire genetic effects; (iii) additive genetic effect of dam in relation to litter size and dam and sire genetic effects in relation to survival rate......; (iv) additive genetic effect of dam to estimate the correlations of litter size or kit survival with dam juvenile body weight and pregnancy length on yearling dams (1357 litters). The dam heritabilities were of litter size (0.02-0.08) and survival rate (0.05-0.10). The permanent effects of dam were...

  18. A new conceptual model for the fate of lignin in decomposing plant litter

    NARCIS (Netherlands)

    Klotzbücher, T.; Kaiser, K.; Guggenberger, G.; Gatzek, C.; Kalbitz, K.

    2011-01-01

    Lignin is a main component of plant litter. Its degradation is thought to be critical for litter decomposition rates and the build-up of soil organic matter. We studied the relationships between lignin degradation and the production of dissolved organic carbon (DOC) and of CO2 during litter decompos

  19. Environmentally friendly animal litter

    Science.gov (United States)

    Chett, Boxley; McKelvie, Jessica

    2013-08-20

    A method of making an animal litter that includes geopolymerized ash, wherein, the animal litter is made from a quantity of a pozzolanic ash mixed with a sufficient quantity of water and an alkaline activator to initiate a geopolymerization reaction that forms geopolymerized ash. After the geopolymerized ash is formed, it is dried, broken into particulates, and sieved to a desired size. These geopolymerized ash particulates are used to make a non-clumping or clumping animal litter. Odor control may be accomplished with the addition of a urease inhibitor, pH buffer, an odor eliminating agent, and/or fragrance.

  20. Emissions modeling of fluidised bed co-combustion of poultry litter and peat

    Energy Technology Data Exchange (ETDEWEB)

    Henihan, A.M.; Leahy, J.J.; Kelleher, B.P. [University of Limerick (Ireland). Dept. of Chemical and Environmental Science; Leahy, M.J. [University of Limerick (Ireland). Dept. of Physics; Cummins, E. [University College, Dublin (Ireland). Dept. of Agricultural and Food Engineering

    2003-05-01

    Gaseous emissions from the fluidised bed co-combustion of 50% w/w chicken litter and peat were monitored and recorded. Emission data were used to create a dispersion model for a proposed site on a poultry farm in Ireland. Variables within the combustion unit influenced both combustion and emission levels of pollutants such as SO{sub 2} and NO{sub x}, CO. Concentrations of atmospheric pollutants decreased with use of the correct ratio between fluidising and secondary air. Dispersion modelling of combustion at a proposed poultry unit predicted that ground level concentrations for the set of emissions data would be below the limits and guidelines set by air quality standards. (author)

  1. Evaluating litter decomposition in earth system models with long-term litterbag experiments: an example using the Community Land Model version 4 (CLM4).

    Science.gov (United States)

    Bonan, Gordon B; Hartman, Melannie D; Parton, William J; Wieder, William R

    2013-03-01

    Decomposition is a large term in the global carbon budget, but models of the earth system that simulate carbon cycle-climate feedbacks are largely untested with respect to litter decomposition. We tested the litter decomposition parameterization of the community land model version 4 (CLM4), the terrestrial component of the community earth system model, with data from the long-term intersite decomposition experiment team (LIDET). The LIDET dataset is a 10-year study of litter decomposition at multiple sites across North America and Central America. We performed 10-year litter decomposition simulations comparable with LIDET for 9 litter types and 20 sites in tundra, grassland, and boreal, conifer, deciduous, and tropical forest biomes using the LIDET-provided climatic decomposition index to constrain temperature and moisture effects on decomposition. We performed additional simulations with DAYCENT, a version of the CENTURY model, to ask how well an established ecosystem model matches the observations. The results show large discrepancy between the laboratory microcosm studies used to parameterize the CLM4 litter decomposition and the LIDET field study. Simulated carbon loss is more rapid than the observations across all sites, and nitrogen immobilization is biased high. Closer agreement with the observations requires much lower decomposition rates, obtained with the assumption that soil mineral nitrogen severely limits decomposition. DAYCENT better replicates the observations, for both carbon mass remaining and nitrogen, independent of nitrogen limitation. CLM4 has low soil carbon in global earth system simulations. These results suggest that this bias arises, in part, from too rapid litter decomposition. More broadly, the terrestrial biogeochemistry of earth system models must be critically tested with observations, and the consequences of particular model choices must be documented. Long-term litter decomposition experiments such as LIDET provide a real

  2. DEVELOPMENT OF WATER CIRCULATION MODEL INCLUDING IRRIGATION

    Science.gov (United States)

    Kotsuki, Shunji; Tanaka, Kenji; Kojiri, Toshiharu; Hamaguchi, Toshio

    It is well known that since agricultural water withdrawal has much affect on water circulation system, accurate analysis of river discharge or water balance are difficult with less regard for it. In this study, water circulation model composed of land surface model and distributed runoff model is proposed at 10km 10km resolution. In this model, irrigation water, which is estimated with land surface model, is introduced to river discharge analysis. The model is applied to the Chao Phraya River in Thailand, and reproduced seasonal water balance. Additionally, the discharge on dry season simulated with the model is improved as a result of including irrigation. Since the model, which is basically developed from global data sets, simulated seasonal change of river discharge, it can be suggested that our model has university to other river basins.

  3. Marine debris in central California: quantifying type and abundance of beach litter in Monterey Bay, CA.

    Science.gov (United States)

    Rosevelt, C; Los Huertos, M; Garza, C; Nevins, H M

    2013-06-15

    Monitoring beach litter is essential for reducing ecological threats towards humans and wildlife. In Monterey Bay, CA information on seasonal and spatial patterns is understudied. Central California's coastal managers require reliable information on debris abundance, distribution, and type, to support policy aimed at reducing litter. We developed a survey method that allowed for trained citizen scientists to quantify the types and abundance of beach litter. Sampling occurred from July 2009-June 2010. Litter abundance ranged from 0.03 to 17.1 items m(-2). Using a mixed model approach, we found season and location have the greatest effect on litter abundance. Styrofoam, the most numerically abundant item, made up 41% of the total amount of litter. Unexpected items included fertilizer pellets. The results of this study provide a baseline on the types and abundance of litter on the central coast and have directly supported policy banning Styrofoam take out containers from local municipalities.

  4. Adequacy assessment of mathematical models in the dynamics of litter decomposition in a tropical forest Mosaic Atlantic, in southeastern Brazil

    Directory of Open Access Journals (Sweden)

    FP. Nunes

    Full Text Available The study of litter decomposition and nutrient cycling is essential to know native forests structure and functioning. Mathematical models can help to understand the local and temporal litter fall variations and their environmental variables relationships. The objective of this study was test the adequacy of mathematical models for leaf litter decomposition in the Atlantic Forest in southeastern Brazil. We study four native forest sites in Parque Estadual do Rio Doce, a Biosphere Reserve of the Atlantic, which were installed 200 bags of litter decomposing with 20×20 cm nylon screen of 2 mm, with 10 grams of litter. Monthly from 09/2007 to 04/2009, 10 litterbags were removed for determination of the mass loss. We compared 3 nonlinear models: 1 – Olson Exponential Model (1963, which considers the constant K, 2 – Model proposed by Fountain and Schowalter (2004, 3 – Model proposed by Coelho and Borges (2005, which considers the variable K through QMR, SQR, SQTC, DMA and Test F. The Fountain and Schowalter (2004 model was inappropriate for this study by overestimating decomposition rate. The decay curve analysis showed that the model with the variable K was more appropriate, although the values of QMR and DMA revealed no significant difference (p> 0.05 between the models. The analysis showed a better adjustment of DMA using K variable, reinforced by the values of the adjustment coefficient (R2. However, convergence problems were observed in this model for estimate study areas outliers, which did not occur with K constant model. This problem can be related to the non-linear fit of mass/time values to K variable generated. The model with K constant shown to be adequate to describe curve decomposition for separately areas and best adjustability without convergence problems. The results demonstrated the adequacy of Olson model to estimate tropical forest litter decomposition. Although use of reduced number of parameters equaling the steps of the

  5. Arsenic Metabolites, Including N-Acetyl-4-hydroxy-m-arsanilic Acid, in Chicken Litter from a Roxarsone-Feeding Study Involving 1600 Chickens.

    Science.gov (United States)

    Yang, Zonglin; Peng, Hanyong; Lu, Xiufen; Liu, Qingqing; Huang, Rongfu; Hu, Bin; Kachanoski, Gary; Zuidhof, Martin J; Le, X Chris

    2016-07-01

    The poultry industry has used organoarsenicals, such as 3-nitro-4-hydroxyphenylarsonic acid (Roxarsone, ROX), to prevent disease and to promote growth. Although previous studies have analyzed arsenic species in chicken litter after composting or after application to agricultural lands, it is not clear what arsenic species were excreted by chickens before biotransformation of arsenic species during composting. We describe here the identification and quantitation of arsenic species in chicken litter repeatedly collected on days 14, 24, 28, 30, and 35 of a Roxarsone-feeding study involving 1600 chickens of two strains. High performance liquid chromatography separation with simultaneous detection by both inductively coupled plasma mass spectrometry and electrospray ionization tandem mass spectrometry provided complementary information necessary for the identification and quantitation of arsenic species. A new metabolite, N-acetyl-4-hydroxy-m-arsanilic acid (N-AHAA), was identified, and it accounted for 3-12% of total arsenic. Speciation analyses of litter samples collected from ROX-fed chickens on days 14, 24, 28, 30, and 35 showed the presence of N-AHAA, 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA), inorganic arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MMA(V)), dimethylarsinic acid (DMA(V)), and ROX. 3-AHPAA accounted for 3-19% of the total arsenic. Inorganic arsenicals (the sum of As(III) and As(V)) comprised 2-6% (mean 3.5%) of total arsenic. Our results on the detection of inorganic arsenicals, methylarsenicals, 3-AHPAA, and N-AHAA in the chicken litter support recent findings that ROX is actually metabolized by the chicken or its gut microbiome. The presence of the toxic metabolites in chicken litter is environmentally relevant as chicken litter is commonly used as fertilizer.

  6. Litter decomposition patterns in a semiarid Mediterranean ecosystem

    Science.gov (United States)

    María, Almagro; Jorge, López; María, Martínez-Mena

    2010-05-01

    Accumulation of soil carbon is mainly controlled by the balance between litter production and litter decomposition. While aboveground litter decomposition in mesic systems is thought to be controlled by climate, litter quality, and soil faunal interactions (Aerts, 1997), it is becoming increasingly evident that factors other than water availability, including photodegradation, physical fragmentation of litter, and soil movement may play central roles in determining rates of carbon and nutrient turnover in arid and semiarid ecosystems (Whitford et al., 2002; Austin and Vivanco, 2006; Throop and Archer, 2007). Decomposition and its controls were studied using the litter-bag method by exposing two different litter types (Pinus halepensis Mill. and Rosmarinus officinalis Linn.) for a 20 month period in two Mediterranean ecosystems of the eastern Iberian Peninsula: 1) a ~ 150-yr-old forest stand, and 2) an abandoned agricultural field. Both sites are covered by a typical Mediterranean shrubland (Rosmarinus officinalis, Quercus coccifera, and Juniperus oxycedrus) with scattered Aleppo pines (Pinus halepensis). A single exponential decay model (Olson, 1963) fit the data well (R2 values ranging from 0.46 to 0.82). Litter types differed in their decomposition dynamics despite of similar initial content of C and N, and C:N ratios. Rosemary litter decomposed more rapidly than Aleppo pine litter across sites (R2 = 0.742; F= 132.18; Pofficinalis litter decay rates were 1.2 fold-higher in forest than in abandoned field site. Soil temperature or water availability could not explain the differences in decomposition rates between sites throughout the study period. Instead, there was a strong relationship across collection dates between decay rates and litterbag ash content, a conservative indicator of soil accumulation (Throop and Archer, 2007). Moreover, ash content was strongly correlated with the total duration of rainfall events across collection dates for both pine (R2= 0

  7. Models of bovine babesiosis including juvenile cattle.

    Science.gov (United States)

    Saad-Roy, C M; Shuai, Zhisheng; van den Driessche, P

    2015-03-01

    Bovine Babesiosis in cattle is caused by the transmission of protozoa of Babesia spp. by ticks as vectors. Juvenile cattle (Babesiosis, rarely show symptoms, and acquire immunity upon recovery. Susceptibility to the disease varies between breeds of cattle. Models of the dynamics of Bovine Babesiosis transmitted by the cattle tick that include these factors are formulated as systems of ordinary differential equations. Basic reproduction numbers are calculated, and it is proved that if these numbers are below the threshold value of one, then Bovine Babesiosis dies out. However, above the threshold number of one, the disease may approach an endemic state. In this case, control measures are suggested by determining target reproduction numbers. The percentage of a particular population (for example, the adult bovine population) needed to be controlled to eradicate the disease is evaluated numerically using Columbia data from the literature.

  8. Improving Genetic Evaluation of Litter Size Using a Single-step Model

    DEFF Research Database (Denmark)

    Guo, Xiangyu; Christensen, Ole Fredslund; Ostersen, Tage

    A recently developed single-step method allows genetic evaluation based on information from phenotypes, pedigree and markers simultaneously. This paper compared reliabilities of predicted breeding values obtained from single-step method and the traditional pedigree-based method for two litter size...... traits, total number of piglets born (TNB), and litter size at five days after birth (Ls 5) in Danish Landrace and Yorkshire pigs. The results showed that the single-step method combining phenotypic and genotypic information provided more accurate predictions than the pedigree-based method, not only...

  9. Climate and litter quality differently modulate the effects of soil fauna on litter decomposition across biomes.

    Science.gov (United States)

    García-Palacios, Pablo; Maestre, Fernando T; Kattge, Jens; Wall, Diana H

    2013-08-01

    Climate and litter quality have been identified as major drivers of litter decomposition at large spatial scales. However, the role played by soil fauna remains largely unknown, despite its importance for litter fragmentation and microbial activity. We synthesised litterbag studies to quantify the effect sizes of soil fauna on litter decomposition rates at the global and biome scales, and to assess how climate, litter quality and soil fauna interact to determine such rates. Soil fauna consistently enhanced litter decomposition at both global and biome scales (average increment ~ 37%). [corrected]. However, climate and litter quality differently modulated the effects of soil fauna on decomposition rates between biomes, from climate-driven biomes to those where climate effects were mediated by changes in litter quality. Our results advocate for the inclusion of biome-specific soil fauna effects on litter decomposition as a mean to reduce the unexplained variation in large-scale decomposition models. © 2013 John Wiley & Sons Ltd/CNRS.

  10. An Integrated Biochemistry Laboratory, Including Molecular Modeling

    Science.gov (United States)

    Hall, Adele J. Wolfson Mona L.; Branham, Thomas R.

    1996-11-01

    ) experience with methods of protein purification; (iii) incorporation of appropriate controls into experiments; (iv) use of basic statistics in data analysis; (v) writing papers and grant proposals in accepted scientific style; (vi) peer review; (vii) oral presentation of results and proposals; and (viii) introduction to molecular modeling. Figure 1 illustrates the modular nature of the lab curriculum. Elements from each of the exercises can be separated and treated as stand-alone exercises, or combined into short or long projects. We have been able to offer the opportunity to use sophisticated molecular modeling in the final module through funding from an NSF-ILI grant. However, many of the benefits of the research proposal can be achieved with other computer programs, or even by literature survey alone. Figure 1.Design of project-based biochemistry laboratory. Modules (projects, or portions of projects) are indicated as boxes. Each of these can be treated independently, or used as part of a larger project. Solid lines indicate some suggested paths from one module to the next. The skills and knowledge required for protein purification and design are developed in three units: (i) an introduction to critical assays needed to monitor degree of purification, including an evaluation of assay parameters; (ii) partial purification by ion-exchange techniques; and (iii) preparation of a grant proposal on protein design by mutagenesis. Brief descriptions of each of these units follow, with experimental details of each project at the end of this paper. Assays for Lysozyme Activity and Protein Concentration (4 weeks) The assays mastered during the first unit are a necessary tool for determining the purity of the enzyme during the second unit on purification by ion exchange. These assays allow an introduction to the concept of specific activity (units of enzyme activity per milligram of total protein) as a measure of purity. In this first sequence, students learn a turbidimetric assay

  11. Deacidification effect of the litter layer on forest soil during snowmelt runoff--laboratory experiment and its basic formularization for simulation modeling.

    Science.gov (United States)

    Kikuchi, Ryunosuke

    2004-02-01

    The forest soil ecosystem can buffer and neutralize acidic airborne pollutants to some extent, but extensive acidification degrades the soil ecosystem. Several investigations have shown that surface flows often show particularly low pH values in rivers and lakes during snowmelt and that this acidification phenomenon takes place in a short time frame. Acid water from snowmelt first makes contact with the litter layer in the soil ecosystem. Therefore, a laboratory experiment was performed to study the impact of forest litter on the chemical composition of the water solution. The experiment presented in this paper confirmed that deacidification with a little leachate of organic matter is caused by cation exchange not only in upper mineral soil but also in the litter layer and that leachate of labile Al is restrained in the presence of litter. An attempt was made to incorporate these factors into the biogeochemical module of the model (ILWAS) to accurately estimate damage by acidification.

  12. Seepage Model for PA Including Dift Collapse

    Energy Technology Data Exchange (ETDEWEB)

    G. Li; C. Tsang

    2000-12-20

    The purpose of this Analysis/Model Report (AMR) is to document the predictions and analysis performed using the Seepage Model for Performance Assessment (PA) and the Disturbed Drift Seepage Submodel for both the Topopah Spring middle nonlithophysal and lower lithophysal lithostratigraphic units at Yucca Mountain. These results will be used by PA to develop the probability distribution of water seepage into waste-emplacement drifts at Yucca Mountain, Nevada, as part of the evaluation of the long term performance of the potential repository. This AMR is in accordance with the ''Technical Work Plan for Unsaturated Zone (UZ) Flow and Transport Process Model Report'' (CRWMS M&O 2000 [153447]). This purpose is accomplished by performing numerical simulations with stochastic representations of hydrological properties, using the Seepage Model for PA, and evaluating the effects of an alternative drift geometry representing a partially collapsed drift using the Disturbed Drift Seepage Submodel. Seepage of water into waste-emplacement drifts is considered one of the principal factors having the greatest impact of long-term safety of the repository system (CRWMS M&O 2000 [153225], Table 4-1). This AMR supports the analysis and simulation that are used by PA to develop the probability distribution of water seepage into drift, and is therefore a model of primary (Level 1) importance (AP-3.15Q, ''Managing Technical Product Inputs''). The intended purpose of the Seepage Model for PA is to support: (1) PA; (2) Abstraction of Drift-Scale Seepage; and (3) Unsaturated Zone (UZ) Flow and Transport Process Model Report (PMR). Seepage into drifts is evaluated by applying numerical models with stochastic representations of hydrological properties and performing flow simulations with multiple realizations of the permeability field around the drift. The Seepage Model for PA uses the distribution of permeabilities derived from air injection testing in

  13. The Litter Problem. Environmental Education Supplementary Instructional Guide, Secondary Level.

    Science.gov (United States)

    Hawaii State Dept. of Education, Honolulu. Office of Instructional Services.

    Presented is a guide for helping secondary school students investigate the litter problem, acquire litter control skills, and develop an anti-litter ethic. The manual contains a hierarchy of learning objectives, a pretest/posttest, background information on litter, and activities keyed to the learning objectives. Each lesson includes brief…

  14. Enhanced battery model including temperature effects

    NARCIS (Netherlands)

    Rosca, B.; Wilkins, S.

    2013-01-01

    Within electric and hybrid vehicles, batteries are used to provide/buffer the energy required for driving. However, battery performance varies throughout the temperature range specific to automotive applications, and as such, models that describe this behaviour are required. This paper presents a dy

  15. Enhanced battery model including temperature effects

    NARCIS (Netherlands)

    Rosca, B.; Wilkins, S.

    2013-01-01

    Within electric and hybrid vehicles, batteries are used to provide/buffer the energy required for driving. However, battery performance varies throughout the temperature range specific to automotive applications, and as such, models that describe this behaviour are required. This paper presents a dy

  16. Enhanced battery model including temperature effects

    NARCIS (Netherlands)

    Rosca, B.; Wilkins, S.

    2013-01-01

    Within electric and hybrid vehicles, batteries are used to provide/buffer the energy required for driving. However, battery performance varies throughout the temperature range specific to automotive applications, and as such, models that describe this behaviour are required. This paper presents a

  17. Selection for number of live piglets at five-days of age increased litter size and reduced mortality

    DEFF Research Database (Denmark)

    Nielsen, Bjarne; Madsen, Per; Henryon, Mark

    2012-01-01

    Breeding for increased litter size in Danish Landrace and Yorkshire started in 1992. Since then, litter size has in-creased significantly. Commercial pig producers and nucleus breeders argue that increases in litter size increase the number of dead piglets. Pig breeders in Denmark responded...... by including the total number of live piglets at day five (TN5) in the breeding goal. The objective of this study was to investigate whether breeding for TN5 has affected total number of born (TNB) and the mortality rate in five-day-old piglets. Data included records of first litter from 43,432 Landrace sows...... and 34,446 Yorkshire sows in Danish nucleus herds from January 2004 to December 2010. At far-rowing, litter size was recorded as TNB including number of still-births. Litter size and mortality rate up to day five after birth were analyzed using a two-trait animal model assuming normality...

  18. Environmentally-friendly animal litter

    Energy Technology Data Exchange (ETDEWEB)

    Boxley, Chett; McKelvie, Jessica

    2012-08-28

    An animal litter composition including geopolymerized ash particulates having a network of repeating aluminum-silicon units is described herein. Generally, the animal litter is made from a quantity of a pozzolanic ash mixed with a sufficient quantity of water and an alkaline activator to initiate a geopolymerization reaction that forms geopolymerized ash. After the geopolymerized ash is formed, it is dried, broken into particulates, and sieved to a desired size. These geopolymerized ash particulates are used to make a non-clumping or clumping animal litter. Odor control is accomplished with the addition of a urease inhibitor, pH buffer, an odor eliminating agent, and/or fragrance.

  19. Environmentally-friendly animal litter

    Science.gov (United States)

    Boxley, Chett; McKelvie, Jessica

    2013-09-03

    An animal litter composition that includes geopolymerized ash particulates having a network of repeating aluminum-silicon units is described herein. Generally, the animal litter is made from a quantity of a pozzolanic ash mixed with an alkaline activator to initiate a geopolymerization reaction that forms geopolymerized ash. This geopolymerization reaction may occur within a pelletizer. After the geopolymerized ash is formed, it may be dried and sieved to a desired size. These geopolymerized ash particulates may be used to make a non-clumping or clumping animal litter or other absorbing material. Aluminum sulfate, clinoptilolite, silica gel, sodium alginate and mineral oil may be added as additional ingredients.

  20. Environmentally-friendly animal litter

    Energy Technology Data Exchange (ETDEWEB)

    Boxley, Chett; McKelvie, Jessica

    2013-09-03

    An animal litter composition that includes geopolymerized ash particulates having a network of repeating aluminum-silicon units is described herein. Generally, the animal litter is made from a quantity of a pozzolanic ash mixed with an alkaline activator to initiate a geopolymerization reaction that forms geopolymerized ash. This geopolymerization reaction may occur within a pelletizer. After the geopolymerized ash is formed, it may be dried and sieved to a desired size. These geopolymerized ash particulates may be used to make a non-clumping or clumping animal litter or other absorbing material. Aluminum sulfate, clinoptilolite, silica gel, sodium alginate and mineral oil may be added as additional ingredients.

  1. Multiple-trait structured antedependence model to study the relationship between litter size and birth weight in pigs and rabbits.

    Science.gov (United States)

    David, Ingrid; Garreau, Hervé; Balmisse, Elodie; Billon, Yvon; Canario, Laurianne

    2017-01-20

    Some genetic studies need to take into account correlations between traits that are repeatedly measured over time. Multiple-trait random regression models are commonly used to analyze repeated traits but suffer from several major drawbacks. In the present study, we developed a multiple-trait extension of the structured antedependence model (SAD) to overcome this issue and validated its usefulness by modeling the association between litter size (LS) and average birth weight (ABW) over parities in pigs and rabbits. The single-trait SAD model assumes that a random effect at time [Formula: see text] can be explained by the previous values of the random effect (i.e. at previous times). The proposed multiple-trait extension of the SAD model consists in adding a cross-antedependence parameter to the single-trait SAD model. This model can be easily fitted using ASReml and the OWN Fortran program that we have developed. In comparison with the random regression model, we used our multiple-trait SAD model to analyze the LS and ABW of 4345 litters from 1817 Large White sows and 8706 litters from 2286 L-1777 does over a maximum of five successive parities. For both species, the multiple-trait SAD fitted the data better than the random regression model. The difference between AIC of the two models (AIC_random regression-AIC_SAD) were equal to 7 and 227 for pigs and rabbits, respectively. A similar pattern of heritability and correlation estimates was obtained for both species. Heritabilities were lower for LS (ranging from 0.09 to 0.29) than for ABW (ranging from 0.23 to 0.39). The general trend was a decrease of the genetic correlation for a given trait between more distant parities. Estimates of genetic correlations between LS and ABW were negative and ranged from -0.03 to -0.52 across parities. No correlation was observed between the permanent environmental effects, except between the permanent environmental effects of LS and ABW of the same parity, for which the estimate of

  2. HOMER Based Feasibility Study of Off-Grid Biogas Power Generation Model Using Poultry Litter for Rural Bangladesh

    Directory of Open Access Journals (Sweden)

    Sharmin Sobhan

    2016-06-01

    Full Text Available Lack of access to electricity is one of the major impediments to the economic growth and development for any developing country. As well as limited reserve of conventional fuel and geo-location of Bangladesh arise the demand to find an effective alternative energy source for rural electrification. This document approaches a poultry-home based power generation model for rural Bangladesh and diagnosis its feasibility through HOMER, a micro power modelling and optimization software. The introduction on renewable energy and its importance is followed by present energy state in Bangladesh and prospect of biogas electrification technology, specially focused on poultry litter base system. Theoretical foundations on formation of biogas and electricity generation process are also presented. Main objective of the study is to diminish energy scarcity and connect rural people with the country’s development through electrification

  3. Biological and climatic controls on leaf litter decomposition across European forests and grasslands revealed by reciprocal litter transplantation experiments

    Science.gov (United States)

    Portillo-Estrada, M.; Pihlatie, M.; Korhonen, J. F. J.; Levula, J.; Frumau, A. K. F.; Ibrom, A.; Lembrechts, J. J.; Morillas, L.; Horváth, L.; Jones, S. K.; Niinemets, Ü.

    2015-11-01

    Projection of carbon and nitrogen cycles to future climates is associated with large uncertainties, in particular due to uncertainties how changes in climate alter soil turnover, including litter decomposition. In addition, future conditions are expected to result in changes in vegetation composition, and accordingly in litter type and quality, but it is unclear how such changes could potentially alter litter decomposition. Litter transplantation experiments were carried out across 6 European sites (4 forest and 2 grasslands) spanning a large geographical and climatic gradient (5.6-11.4 °C in annual temperature 511-878 mm in precipitation) to gain insight into biological (litter origin and type, soil type) and climatic controls on litter decomposition. The decomposition k rates were overall higher in warmer and wetter sites than in colder and drier sites, and positively correlated to the litter total specific leaf area. Also, litter N content increased as less litter mass remained and decay went further. Surprisingly, this study demonstrates that climatic controls on litter decomposition are quantitatively more important than species, litter origin and soil type. Cumulative climatic variables, precipitation and air temperature (ignoring days with air temperatures below 0 °C), were appropriate to predict the litter remaining mass during decomposition (Mr). And Mr and cumulative air temperature were found to be the best predictors for litter carbon and nitrogen remaining during decomposition. We concluded with an equation for predicting the decomposition k rate by using mean annual air temperature and litter total specific leaf area.

  4. Broiler house litter sampling: the final frontier

    Science.gov (United States)

    Today, the sustainability of broiler operations reaches beyond the need for litter nutrient management plans that came to the forefront of the industry’s attention in the last fifteen years. Thorough characterization of litter within houses provides the basis for emission models to benefit growers,...

  5. Current status on marine litter indicators in Nordic waters

    DEFF Research Database (Denmark)

    Strand, Jakob; Tairova, Zhanna; Magnusson, Kerstin

    Status for project on Marine litter in the Nordic waters. This includes a review of Nordic studies on marine litter indicators. Various studies as part of either research or existing monitoring have provided information on occurrence of marine litter in Nordic waters from Baltic Sea to the Arctic....

  6. Facilitation and predation structure a grassland detrital food web: the responses of soil nematodes to isopod processing of litter.

    Science.gov (United States)

    Bastow, Justin L

    2011-09-01

    1. Detritus can support successive consumers, whose interactions may be structured by changes in the condition of their shared resource. One model of such species interactions is a processing chain, in which consumers feeding on the resource in a less processed state change the resource condition for subsequent consumers. 2. In a series of experiments, the hypothesis was tested that a common detritivore, the terrestrial isopod Porcellio scaber, affects soil nematodes through the processing of plant litter. Different detrital resources were added to soil from a California coastal prairie in order to simulate litter processing by the detritivore. Treatments that included only whole grass litter corresponded to detrital food webs lacking detritivores, while treatments that included mixtures of P. scaber faeces and grass litter corresponded to different densities or feeding rates of P. scaber. 3. Simulated litter processing by P. scaber increased the abundance of bacterivorous nematodes by between 32% and 202% after 24-44 days in laboratory experiments, but had no effect on fungivorous or predaceous nematodes. 4. In a subsequent field experiment, however, fungivorous nematodes were suppressed by isopod litter processing while bacterivores showed no response. Instead, P. scaber processing of litter increased the abundance of predaceous nematodes in the field experiment by 176%. 5. When simulated litter processing of litter was crossed in laboratory experiments with predaceous nematode addition (comparable to the response of predators in the field experiment), the abundance of bacterivores was increased by isopod processing of litter (by an average of 122%), but suppressed by elevated densities of predaceous nematodes (by an average of 41%). 6. This suggests that litter processing by P. scaber facilitates the bacterial channel of the soil food web, but that predaceous nematodes suppress the response of bacterivores in the field. Processing chain interactions may

  7. Genetic parameters for litter size in Black Slavonian pigs

    Energy Technology Data Exchange (ETDEWEB)

    Skorput, D.; Gorjanc, G.; Dikic, M.; Lujovic, Z.

    2014-06-01

    The objective of this study was to estimate genetic parameters for litter size of Black Slavonian pigs using the repeatability, multiple trait, and random regression models, and to consider the possibility to increase litter size in Black Slavonian pigs by selection. A total of 4,733 litter records from the first to the sixth parity from sows that farrowed between January 1998 and December 2010 were included in the analysis. Individual record consisted of the following variables: breeding organisation (eight regions), parity (1-6), service boar, and farrowing season (monthyear interaction). Estimation of all the covariance components with three different models was based on the residual maximum likelihood method. Estimate of additive genetic variance and heritability for number of piglets born alive with repeatability model was 0.23 and 0.10, respectively. Estimates of additive genetic variance with multiple trait and random regression model were in a wider range from 0.05 to 0.65 across parities, and heritabilities were estimated in the range between 0.03 and 0.26. Estimates of phenotypic and additive genetic correlations were much smoother with random regression model in comparison with multiple trait model. Due to unexpected changes of variances along trajectory obtained with multiple trait and random regression model, the best option for genetic evaluation of litter size for now could be the use of repeatability model. With increasing number of data with proper data structure alternative modelling of litter size of Black Slavonian pig using multiple trait and random regression model could be taken into consideration. (Author)

  8. Dynamic hysteresis modeling including skin effect using diffusion equation model

    Science.gov (United States)

    Hamada, Souad; Louai, Fatima Zohra; Nait-Said, Nasreddine; Benabou, Abdelkader

    2016-07-01

    An improved dynamic hysteresis model is proposed for the prediction of hysteresis loop of electrical steel up to mean frequencies, taking into account the skin effect. In previous works, the analytical solution of the diffusion equation for low frequency (DELF) was coupled with the inverse static Jiles-Atherton (JA) model in order to represent the hysteresis behavior for a lamination. In the present paper, this approach is improved to ensure the reproducibility of measured hysteresis loops at mean frequency. The results of simulation are compared with the experimental ones. The selected results for frequencies 50 Hz, 100 Hz, 200 Hz and 400 Hz are presented and discussed.

  9. Dynamic hysteresis modeling including skin effect using diffusion equation model

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, Souad, E-mail: souadhamada@yahoo.fr [LSP-IE: Research Laboratory, Electrical Engineering Department, University of Batna, 05000 Batna (Algeria); Louai, Fatima Zohra, E-mail: fz_louai@yahoo.com [LSP-IE: Research Laboratory, Electrical Engineering Department, University of Batna, 05000 Batna (Algeria); Nait-Said, Nasreddine, E-mail: n_naitsaid@yahoo.com [LSP-IE: Research Laboratory, Electrical Engineering Department, University of Batna, 05000 Batna (Algeria); Benabou, Abdelkader, E-mail: Abdelkader.Benabou@univ-lille1.fr [L2EP, Université de Lille1, 59655 Villeneuve d’Ascq (France)

    2016-07-15

    An improved dynamic hysteresis model is proposed for the prediction of hysteresis loop of electrical steel up to mean frequencies, taking into account the skin effect. In previous works, the analytical solution of the diffusion equation for low frequency (DELF) was coupled with the inverse static Jiles-Atherton (JA) model in order to represent the hysteresis behavior for a lamination. In the present paper, this approach is improved to ensure the reproducibility of measured hysteresis loops at mean frequency. The results of simulation are compared with the experimental ones. The selected results for frequencies 50 Hz, 100 Hz, 200 Hz and 400 Hz are presented and discussed.

  10. Unsteady panel method for complex configurations including wake modeling

    CSIR Research Space (South Africa)

    Van Zyl, Lourens H

    2008-01-01

    Full Text Available implementations of the DLM are however not very versatile in terms of geometries that can be modeled. The ZONA6 code offers a versatile surface panel body model including a separated wake model, but uses a pressure panel method for lifting surfaces. This paper...

  11. Modeling Electric Double-Layers Including Chemical Reaction Effects

    DEFF Research Database (Denmark)

    Paz-Garcia, Juan Manuel; Johannesson, Björn; Ottosen, Lisbeth M.

    2014-01-01

    A physicochemical and numerical model for the transient formation of an electric double-layer between an electrolyte and a chemically-active flat surface is presented, based on a finite elements integration of the nonlinear Nernst-Planck-Poisson model including chemical reactions. The model works...

  12. Circuit Modeling of a MEMS Varactor Including Dielectric Charging Dynamics

    Science.gov (United States)

    Giounanlis, P.; Andrade-Miceli, D.; Gorreta, S.; Pons-Nin, J.; Dominguez-Pumar, M.; Blokhina, E.

    2016-10-01

    Electrical models for MEMS varactors including the effect of dielectric charging dynamics are not available in commercial circuit simulators. In this paper a circuit model using lumped ideal elements available in the Cadence libraries and a basic Verilog-A model, has been implemented. The model has been used to simulate the dielectric charging in function of time and its effects over the MEMS capacitance value.

  13. Animal model estimation of genetic parameters and response to selection for litter size and weight, growth, and backfat in closed seedstock populations of large white and Landrace swine.

    Science.gov (United States)

    Ferraz, J B; Johnson, R K

    1993-04-01

    Records from 2,495 litters and 14,605 Landrace and Large White pigs from two farms, but established from the same base population and run as replicated selection lines, were analyzed. Selection within herd was on estimated breeding values weighted by economic values. Animal models and REML procedures were used to estimate genetic, phenotypic, and environmental parameters for the number of pigs born alive (NBA), litter weight at 21 d (LW), average daily gain form approximately 30 to 104 kg (ADG), and backfat thickness adjusted to 104 kg (BF). Random animal genetic effects (o), permanent (NBA and LW) or litter (ADG and BF) environmental effects, maternal genetic effects (m), and the covariance between o and m were sequentially added to the model. Estimates of total heritability calculated from all data (ht2 = sigma o2 + 1/2 sigma m2 + 3/2 sigma om) ranged from .01 to .14 for NBA, from .18 to .22 for LW, from .23 to .34 for ADG, and from .40 to .50 for BF. Maternal genetic variance was from 2.4 to 3.8% of phenotypic variance in NBA, from 1.2 to 3.6% in LW, from .5 to 1.5% in ADG, and from 1.9 to 3.4% in BF. The correlation between o and m was -.07 for NBA, -.25 for LW, -.34 for ADG, and -.26 for BF. Permanent environmental effects explained from 16 to 17% of total phenotypic variation for NBA and from 1.6 to 5.3% for LW. Approximately 7% of the variation in ADG and 5% in BF was due to litter environmental effects.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Myxomycetes of the litter

    Directory of Open Access Journals (Sweden)

    Wanda Stojakowska

    2014-08-01

    Full Text Available The litter is a useful substratum for developmen t of the Myxomycetes. On the basis of our own observations and literature data 50 species of the slime molds were found occuring on litter. Species from the order Physarales (33 species are dominant.

  15. Including investment risk in large-scale power market models

    DEFF Research Database (Denmark)

    Lemming, Jørgen Kjærgaard; Meibom, P.

    2003-01-01

    can be included in large-scale partial equilibrium models of the power market. The analyses are divided into a part about risk measures appropriate for power market investors and a more technical part about the combination of a risk-adjustment model and a partial-equilibrium model. To illustrate......Long-term energy market models can be used to examine investments in production technologies, however, with market liberalisation it is crucial that such models include investment risks and investor behaviour. This paper analyses how the effect of investment risk on production technology selection...... the analyses quantitatively, a framework based on an iterative interaction between the equilibrium model and a separate risk-adjustment module was constructed. To illustrate the features of the proposed modelling approach we examined how uncertainty in demand and variable costs affects the optimal choice...

  16. Effect of environmental factor on some litter traits of sows in the tropics Mexican

    Directory of Open Access Journals (Sweden)

    Jesús Ek M.

    2015-12-01

    Full Text Available Objective. To determine the effect of environmental factors on litter traits at birth and weaning, and their repeatabilities in four farms in the sub-humid tropics of Mexico. Materials and methods. Data from 46.249 to 50.316 litters for litter size at birth (LSB, number of piglets born alive (NBA, litter weight at birth (LWB, number of piglets weaned (NPW and litter weight at weaning (LWW were used. The statistical model for LSB, NBA and LWB included the effects of farm, farrowing year, farrowing season, parity number, simple interactions, random effects of sow and the error term. NPW and LWW were analyzed using the previous model plus the linear and quadratic effects of lactation length (LL. Results. The means for LSB, NBA, LWB, NPW and LWW were 11.7 piglets, 11.0 piglets, 16.1 kg, 10.3 piglets and 61.3 kg, respectively. All effects in the model affected the litter traits. Farrowing year x season interaction was significant for NPW, LWB and LWW. The dry season had the highest LSB, NBA y NPW. First parity sows had higher LSB and NBA means than for second parity sows. Parity increase until parity 4 to decrease thereafter. LL had a quadratic effect on NPW and LWW. Repeatability estimates for LSB, NBA, and LWB were 0.12, 0.12 and 0.14, respectively. Conclusions. All traits studied were influenced by the environmental factors studied. Repeatabilities for LSB, NBA and LWB were low.

  17. Variance component estimates for alternative litter size traits in swine.

    Science.gov (United States)

    Putz, A M; Tiezzi, F; Maltecca, C; Gray, K A; Knauer, M T

    2015-11-01

    Litter size at d 5 (LS5) has been shown to be an effective trait to increase total number born (TNB) while simultaneously decreasing preweaning mortality. The objective of this study was to determine the optimal litter size day for selection (i.e., other than d 5). Traits included TNB, number born alive (NBA), litter size at d 2, 5, 10, 30 (LS2, LS5, LS10, LS30, respectively), litter size at weaning (LSW), number weaned (NW), piglet mortality at d 30 (MortD30), and average piglet birth weight (BirthWt). Litter size traits were assigned to biological litters and treated as a trait of the sow. In contrast, NW was the number of piglets weaned by the nurse dam. Bivariate animal models included farm, year-season, and parity as fixed effects. Number born alive was fit as a covariate for BirthWt. Random effects included additive genetics and the permanent environment of the sow. Variance components were plotted for TNB, NBA, and LS2 to LS30 using univariate animal models to determine how variances changed over time. Additive genetic variance was minimized at d 7 in Large White and at d 14 in Landrace pigs. Total phenotypic variance for litter size traits decreased over the first 10 d and then stabilized. Heritability estimates increased between TNB and LS30. Genetic correlations between TNB, NBA, and LS2 to LS29 with LS30 plateaued within the first 10 d. A genetic correlation with LS30 of 0.95 was reached at d 4 for Large White and at d 8 for Landrace pigs. Heritability estimates ranged from 0.07 to 0.13 for litter size traits and MortD30. Birth weight had an h of 0.24 and 0.26 for Large White and Landrace pigs, respectively. Genetic correlations among LS30, LSW, and NW ranged from 0.97 to 1.00. In the Large White breed, genetic correlations between MortD30 with TNB and LS30 were 0.23 and -0.64, respectively. These correlations were 0.10 and -0.61 in the Landrace breed. A high genetic correlation of 0.98 and 0.97 was observed between LS10 and NW for Large White and

  18. Litter decay controlled by temperature, not soil properties, affecting future soil carbon.

    Science.gov (United States)

    Gregorich, Edward G; Janzen, Henry; Ellert, Benjamin H; Helgason, Bobbi L; Qian, Budong; Zebarth, Bernie J; Angers, Denis A; Beyaert, Ronald P; Drury, Craig F; Duguid, Scott D; May, William E; McConkey, Brian G; Dyck, Miles F

    2017-04-01

    Widespread global changes, including rising atmospheric CO2 concentrations, climate warming and loss of biodiversity, are predicted for this century; all of these will affect terrestrial ecosystem processes like plant litter decomposition. Conversely, increased plant litter decomposition can have potential carbon-cycle feedbacks on atmospheric CO2 levels, climate warming and biodiversity. But predicting litter decomposition is difficult because of many interacting factors related to the chemical, physical and biological properties of soil, as well as to climate and agricultural management practices. We applied (13) C-labelled plant litter to soil at ten sites spanning a 3500-km transect across the agricultural regions of Canada and measured its decomposition over five years. Despite large differences in soil type and climatic conditions, we found that the kinetics of litter decomposition were similar once the effect of temperature had been removed, indicating no measurable effect of soil properties. A two-pool exponential decay model expressing undecomposed carbon simply as a function of thermal time accurately described kinetics of decomposition. (R(2)  = 0.94; RMSE = 0.0508). Soil properties such as texture, cation exchange capacity, pH and moisture, although very different among sites, had minimal discernible influence on decomposition kinetics. Using this kinetic model under different climate change scenarios, we projected that the time required to decompose 50% of the litter (i.e. the labile fractions) would be reduced by 1-4 months, whereas time required to decompose 90% of the litter (including recalcitrant fractions) would be reduced by 1 year in cooler sites to as much as 2 years in warmer sites. These findings confirm quantitatively the sensitivity of litter decomposition to temperature increases and demonstrate how climate change may constrain future soil carbon storage, an effect apparently not influenced by soil properties.

  19. Genetic determinism for within-litter birth weight variation and its relationship with litter weight and litter size in the Ripollesa ewe breed.

    Science.gov (United States)

    Casellas, J; Caja, G; Piedrafita, J

    2007-06-01

    Birth weight plays a central role in lamb survival and growth, and the knowledge of its genetic determinism has become essential in worldwide selection programmes. Within this context, within-litter birth weight variation (BWV) has been suggested as an attractive trait to homogenise litters in prolific species, although it has not been analysed in sheep. The objective of this study was to ascertain whether maternal additive genetic variance exists for BWV in Ripollesa ewes, and to study its genetic, permanent environmental and residual relationships with litter weight (LW) and litter size (LS) at birth. Data were recorded in the Ripollesa experimental flock of the Universitat Autònoma of Barcelona, between 1986 and 2005, and included 1 662 litters from 380 ewes, with 712 records of BWV and 1 530 records of LW. Traits were analysed with a multivariate animal model solved through Bayesian methodologies, and with a threshold characterisation of LS. Additionally, the effect of BWV on lamb survival was studied. Additive genetic variance was observed for BWV (h2 = 0.061), as well as for LW (h2 = 0.200) and LS (h2 = 0.141). Nevertheless, genetic correlations among those traits were not substantial (BWV and LW = 0.151; BWV and LS = - 0.219; LW and LS = - 0.320) and suffered from a high degree of uncertainly, with the null correlation included within the highest posterior interval at 95%. Within-litter birth weight variation and LS showed a negative and large permanent environmental correlation ( - 0.872), and LW and LS were negatively correlated due to residual ( - 0.762) and permanent environmental ( - 0.449) random sources of variation. Within-litter birth weight variation influenced lamb mortality during the first 7 days of life (P 0.05). The low heritability found indicates that slow genetic progress may be expected from selecting for BWV. Close to zero genetic correlations suggest that this selection will probably not affect LS and LW, although

  20. Temporal dynamics of biotic and abiotic drivers of litter decomposition.

    Science.gov (United States)

    García-Palacios, Pablo; Shaw, E Ashley; Wall, Diana H; Hättenschwiler, Stephan

    2016-05-01

    Climate, litter quality and decomposers drive litter decomposition. However, little is known about whether their relative contribution changes at different decomposition stages. To fill this gap, we evaluated the relative importance of leaf litter polyphenols, decomposer communities and soil moisture for litter C and N loss at different stages throughout the decomposition process. Although both microbial and nematode communities regulated litter C and N loss in the early decomposition stages, soil moisture and legacy effects of initial differences in litter quality played a major role in the late stages of the process. Our results provide strong evidence for substantial shifts in how biotic and abiotic factors control litter C and N dynamics during decomposition. Taking into account such temporal dynamics will increase the predictive power of decomposition models that are currently limited by a single-pool approach applying control variables uniformly to the entire decay process.

  1. The impact of alum addition on organic P transformations in poultry litter and litter-amended soil.

    Science.gov (United States)

    Warren, Jason G; Penn, Chad J; McGrath, Joshua M; Sistani, Karamat

    2008-01-01

    Poultry litter treatment with alum (Al(2)(SO(4))(3) . 18H(2)O) lowers litter phosphorus (P) solubility and therefore can lower litter P release to runoff after land application. Lower P solubility in litter is generally attributed to aluminum-phosphate complex formation. However, recent studies suggest that alum additions to poultry litter may influence organic P mineralization. Therefore, alum-treated and untreated litters were incubated for 93 d to assess organic P transformations during simulated storage. A 62-d soil incubation was also conducted to determine the fate of incorporated litter organic P, which included alum-treated litter, untreated litter, KH(2)PO(4) applied at 60 mg P kg(-1) of soil, and an unamended control. Liquid-state (31)P nuclear magnetic resonance indicated that phytic acid was the only organic P compound present, accounting for 50 and 45% of the total P in untreated and alum-treated litters, respectively, before incubation and declined to 9 and 37% after 93 d of storage-simulating incubation. Sequential fractionation of litters showed that alum addition to litter transformed 30% of the organic P from the 1.0 mol L(-1) HCl to the 0.1 mol L(-1) NaOH extractable fraction and that both organic P fractions were more persistent in alum-treated litter compared with untreated litter. The soil incubation revealed that 0.1 mol L(-1) NaOH-extractable organic P was more recalcitrant after mixing than was the 1.0 mol L(-1) HCl-extractable organic P. Thus, adding alum to litter inhibits organic P mineralization during storage and promotes the formation of alkaline extractable organic P that sustains lower P solubility in the soil environment.

  2. Progressive IRP Models for Power Resources Including EPP

    Directory of Open Access Journals (Sweden)

    Yiping Zhu

    2017-01-01

    Full Text Available In the view of optimizing regional power supply and demand, the paper makes effective planning scheduling of supply and demand side resources including energy efficiency power plant (EPP, to achieve the target of benefit, cost, and environmental constraints. In order to highlight the characteristics of different supply and demand resources in economic, environmental, and carbon constraints, three planning models with progressive constraints are constructed. Results of three models by the same example show that the best solutions to different models are different. The planning model including EPP has obvious advantages considering pollutant and carbon emission constraints, which confirms the advantages of low cost and emissions of EPP. The construction of progressive IRP models for power resources considering EPP has a certain reference value for guiding the planning and layout of EPP within other power resources and achieving cost and environmental objectives.

  3. Modeling heart rate variability including the effect of sleep stages

    Science.gov (United States)

    Soliński, Mateusz; Gierałtowski, Jan; Żebrowski, Jan

    2016-02-01

    We propose a model for heart rate variability (HRV) of a healthy individual during sleep with the assumption that the heart rate variability is predominantly a random process. Autonomic nervous system activity has different properties during different sleep stages, and this affects many physiological systems including the cardiovascular system. Different properties of HRV can be observed during each particular sleep stage. We believe that taking into account the sleep architecture is crucial for modeling the human nighttime HRV. The stochastic model of HRV introduced by Kantelhardt et al. was used as the initial starting point. We studied the statistical properties of sleep in healthy adults, analyzing 30 polysomnographic recordings, which provided realistic information about sleep architecture. Next, we generated synthetic hypnograms and included them in the modeling of nighttime RR interval series. The results of standard HRV linear analysis and of nonlinear analysis (Shannon entropy, Poincaré plots, and multiscale multifractal analysis) show that—in comparison with real data—the HRV signals obtained from our model have very similar properties, in particular including the multifractal characteristics at different time scales. The model described in this paper is discussed in the context of normal sleep. However, its construction is such that it should allow to model heart rate variability in sleep disorders. This possibility is briefly discussed.

  4. Microbiological Safety of Chicken Litter or Chicken Litter-Based Organic Fertilizers: A Review

    Directory of Open Access Journals (Sweden)

    Zhao Chen

    2014-01-01

    Full Text Available Chicken litter or chicken litter-based organic fertilizers are usually recycled into the soil to improve the structure and fertility of agricultural land. As an important source of nutrients for crop production, chicken litter may also contain a variety of human pathogens that can threaten humans who consume the contaminated food or water. Composting can inactivate pathogens while creating a soil amendment beneficial for application to arable agricultural land. Some foodborne pathogens may have the potential to survive for long periods of time in raw chicken litter or its composted products after land application, and a small population of pathogenic cells may even regrow to high levels when the conditions are favorable for growth. Thermal processing is a good choice for inactivating pathogens in chicken litter or chicken litter-based organic fertilizers prior to land application. However, some populations may become acclimatized to a hostile environment during build-up or composting and develop heat resistance through cross-protection during subsequent high temperature treatment. Therefore, this paper reviews currently available information on the microbiological safety of chicken litter or chicken litter-based organic fertilizers, and discusses about further research on developing novel and effective disinfection techniques, including physical, chemical, and biological treatments, as an alternative to current methods.

  5. Littering Behavior in Public Places

    Science.gov (United States)

    Robinson, Stuart N.

    1976-01-01

    This review summarizes the present state of knowledge concerning littering behavior. Available studies are categorized according to the variables that influence littering--individual and environmental. Theoretical issues of attitude-behavior consistency and incentive effectiveness are analyzed with respect to littering and litter control. Results…

  6. Field Experiments in Litter Control

    Science.gov (United States)

    Finnie, William C.

    1973-01-01

    A series of urban and highway litter experiments in Richmond (Virginia), St. Louis, and Philadelphia indicated well-designed litter cans reduced littering about 15 percent along city streets and nearly 30 percent along highways. Also, the propensity to litter is critically affected by the characteristics of the individual and environmental…

  7. A hydrodynamic model for granular material flows including segregation effects

    Science.gov (United States)

    Gilberg, Dominik; Klar, Axel; Steiner, Konrad

    2017-06-01

    The simulation of granular flows including segregation effects in large industrial processes using particle methods is accurate, but very time-consuming. To overcome the long computation times a macroscopic model is a natural choice. Therefore, we couple a mixture theory based segregation model to a hydrodynamic model of Navier-Stokes-type, describing the flow behavior of the granular material. The granular flow model is a hybrid model derived from kinetic theory and a soil mechanical approach to cover the regime of fast dilute flow, as well as slow dense flow, where the density of the granular material is close to the maximum packing density. Originally, the segregation model has been formulated by Thornton and Gray for idealized avalanches. It is modified and adapted to be in the preferred form for the coupling. In the final coupled model the segregation process depends on the local state of the granular system. On the other hand, the granular system changes as differently mixed regions of the granular material differ i.e. in the packing density. For the modeling process the focus lies on dry granular material flows of two particle types differing only in size but can be easily extended to arbitrary granular mixtures of different particle size and density. To solve the coupled system a finite volume approach is used. To test the model the rotational mixing of small and large particles in a tumbler is simulated.

  8. Synaptic channel model including effects of spike width variation

    OpenAIRE

    2015-01-01

    Synaptic Channel Model Including Effects of Spike Width Variation Hamideh Ramezani Next-generation and Wireless Communications Laboratory (NWCL) Department of Electrical and Electronics Engineering Koc University, Istanbul, Turkey Ozgur B. Akan Next-generation and Wireless Communications Laboratory (NWCL) Department of Electrical and Electronics Engineering Koc University, Istanbul, Turkey ABSTRACT An accu...

  9. A sonic boom propagation model including mean flow atmospheric effects

    Science.gov (United States)

    Salamone, Joe; Sparrow, Victor W.

    2012-09-01

    This paper presents a time domain formulation of nonlinear lossy propagation in onedimension that also includes the effects of non-collinear mean flow in the acoustic medium. The model equation utilized is an augmented Burgers equation that includes the effects of nonlinearity, geometric spreading, atmospheric stratification, and also absorption and dispersion due to thermoviscous and molecular relaxation effects. All elements of the propagation are implemented in the time domain and the effects of non-collinear mean flow are accounted for in each term of the model equation. Previous authors have presented methods limited to showing the effects of wind on ray tracing and/or using an effective speed of sound in their model equation. The present work includes the effects of mean flow for all terms included in the augmented Burgers equation with all of the calculations performed in the time-domain. The capability to include the effects of mean flow in the acoustic medium allows one to make predictions more representative of real-world atmospheric conditions. Examples are presented for nonlinear propagation of N-waves and shaped sonic booms. [Work supported by Gulfstream Aerospace Corporation.

  10. Litter Decomposition Rates, 2015

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set contains decomposition rates for litter of Salicornia pacifica, Distichlis spicata, and Deschampsia cespitosa buried at 7 tidal marsh sites in 2015....

  11. Effect of temperature and moisture on the mineralization and humification of leaf litter in a model incubation experiment

    Science.gov (United States)

    Larionova, A. A.; Maltseva, A. N.; Lopes de Gerenyu, V. O.; Kvitkina, A. K.; Bykhovets, S. S.; Zolotareva, B. N.; Kudeyarov, V. N.

    2017-04-01

    The mineralization and humification of leaf litter collected in a mixed forest of the Prioksko-Terrasny Reserve depending on temperature (2, 12, and 22°C) and moisture (15, 30, 70, 100, and 150% of water holding capacity ( WHC)) has been studied in long-term incubation experiments. Mineralization is the most sensitive to temperature changes at the early stage of decomposition; the Q 10 value at the beginning of the experiment (1.5-2.7) is higher than at the later decomposition stages (0.3-1.3). Carbon losses usually exceed nitrogen losses during decomposition. Intensive nitrogen losses are observed only at the high temperature and moisture of litter (22°C and 100% WHC). Humification determined from the accumulation of humic substances in the end of incubation decreases from 34 to 9% with increasing moisture and temperature. The degree of humification CHA/CFA is maximum (1.14) at 12°C and 15% WHC; therefore, these temperature and moisture conditions are considered optimal for humification. Humification calculated from the limit value of litter mineralization is almost independent of temperature, but it significantly decreases from 70 to 3% with increasing moisture. A possible reason for the difference between the humification values measured by two methods is the conservation of a significant part of hemicelluloses, cellulose, and lignin during the transformation of litter and the formation of a complex of humic substances with plant residues, where HSs fulfill a protectoral role and decrease the decomposition rate of plant biopolymers.

  12. Do Laboratory Mouse Females that Lose Their Litters Behave Differently around Parturition?

    Science.gov (United States)

    Weber, Elin M.; Hultgren, Jan

    2016-01-01

    Efficiency in laboratory mouse breeding is hampered by poor reproductive performance, including the loss of entire litters shortly after birth. However, the underlying mechanisms are not yet fully understood and establishing the cause of death in laboratory mouse pups can be complicated. Newborn mouse pups are generally hidden in nests, dead pups are often eaten by the female, and the widespread practice of leaving periparturient females undisturbed complicates inspection, which may delay the discovery of pup loss. In order to efficiently prevent problems with litter loss, it is important to find key factors for survival. We investigated differences in periparturient behavior between female laboratory mice whose pups survived until weaning and females whose entire litters were lost. Video recordings of 82 primiparous females of the C57BL/6 strain or knockouts with C57BL/6 background were used. The mice were observed from 24 h before until 24 h after parturition and female behaviors coded using a pre-established ethogram. The relationship between behavior and survival was analyzed using logistic models, where litter survival was regressed on the proportion of 30-s observations with at least one occurrence of the behavior. We found that females with surviving litters performed more nest building behavior during the last 24 h before parturition (p = 0.004) and spent less time outside the nest during the entire observation period (p = 0.001). Increased litter survival was also associated with more passive maternal behaviors and the female ignoring still pups less. Females that lost their litters performed more parturition-related behaviors, suggesting prolonged labor. The results indicate that maternal behavior plays a significant role in laboratory mouse pup survival. Complications at parturition also contribute to litter mortality. PMID:27575720

  13. Do Laboratory Mouse Females that Lose Their Litters Behave Differently around Parturition?

    Science.gov (United States)

    Weber, Elin M; Hultgren, Jan; Algers, Bo; Olsson, I Anna S

    2016-01-01

    Efficiency in laboratory mouse breeding is hampered by poor reproductive performance, including the loss of entire litters shortly after birth. However, the underlying mechanisms are not yet fully understood and establishing the cause of death in laboratory mouse pups can be complicated. Newborn mouse pups are generally hidden in nests, dead pups are often eaten by the female, and the widespread practice of leaving periparturient females undisturbed complicates inspection, which may delay the discovery of pup loss. In order to efficiently prevent problems with litter loss, it is important to find key factors for survival. We investigated differences in periparturient behavior between female laboratory mice whose pups survived until weaning and females whose entire litters were lost. Video recordings of 82 primiparous females of the C57BL/6 strain or knockouts with C57BL/6 background were used. The mice were observed from 24 h before until 24 h after parturition and female behaviors coded using a pre-established ethogram. The relationship between behavior and survival was analyzed using logistic models, where litter survival was regressed on the proportion of 30-s observations with at least one occurrence of the behavior. We found that females with surviving litters performed more nest building behavior during the last 24 h before parturition (p = 0.004) and spent less time outside the nest during the entire observation period (p = 0.001). Increased litter survival was also associated with more passive maternal behaviors and the female ignoring still pups less. Females that lost their litters performed more parturition-related behaviors, suggesting prolonged labor. The results indicate that maternal behavior plays a significant role in laboratory mouse pup survival. Complications at parturition also contribute to litter mortality.

  14. A model of Barchan dunes including lateral shear stress.

    Science.gov (United States)

    Schwämmle, V; Herrmann, H J

    2005-01-01

    Barchan dunes are found where sand availability is low and wind direction quite constant. The two dimensional shear stress of the wind field and the sand movement by saltation and avalanches over a barchan dune are simulated. The model with one dimensional shear stress is extended including surface diffusion and lateral shear stress. The resulting final shape is compared to the results of the model with a one dimensional shear stress and confirmed by comparison to measurements. We found agreement and improvements with respect to the model with one dimensional shear stress. Additionally, a characteristic edge at the center of the windward side is discovered which is also observed for big barchans. Diffusion effects reduce this effect for small dunes.

  15. Goldilocks Models of Higher-Dimensional Inflation (including modulus stabilization)

    CERN Document Server

    Burgess, C P; Hayman, Peter; Patil, Subodh P

    2016-01-01

    We explore the mechanics of inflation in simplified extra-dimensional models involving an inflaton interacting with the Einstein-Maxwell system in two extra dimensions. The models are Goldilocks-like in that they are just complicated enough to include a mechanism to stabilize the extra-dimensional size, yet simple enough to solve the full 6D field equations using basic tools. The solutions are not limited to the effective 4D regime with H m_KK, but when they do standard 4D fluctuation calculations need not apply. When in a 4D regime the solutions predict eta ~ 0 hence n_s ~ 0.96 and r ~ 0.096 and so are ruled out if tensor modes remain unseen. Analysis of general parameters is difficult without a full 6D fluctuation calculation.

  16. Preliminary investigation of the transport of small plastic litter along a vegetated riverbank

    Science.gov (United States)

    Liu, Da; Valyrakis, Manousos

    2017-04-01

    Plastics are widely used in consumer products, due to its low cost, low weight and high durability compared to other types of materials. Contamination of marine ecosystems due to plastics (including microplastics) is a challenge that has received a lot of attention due to the significant risks it poses for the environment and human health. Plastics find their way to the ocean from land via the river system. Studying and obtaining a better understanding of the mechanisms contributing to the fate of plastic litter is therefore important in proactively devising methods to reduce their quantity or produce designs to trap plastic pollutants and prevent them from entering the ocean through estuaries. In this context, it is a common observation of hydraulic practitioners and field geomorphologists, that plastic litter can be trapped within riparian vegetation patches along streams or canals, which can be washed away in periods of high flows. To this goal this study aims to use a series of purpose specific physical experiments to examine the mechanisms of dispersion of plastic litter along the water surface of a channel with simulated riparian vegetation. The set of experiments are conducted in a recirculating flume with rigid riverbank and riparian vegetation modeled by a large number of acrylic rods, placed on the top of the riverbank section. Six different sizes of pieces of Styrofoam are used to simulate plastic litter. These are released from different locations upstream and in the vicinity of the riparian vegetation for various configurations (linear, staggered and random) of characteristic solid density. The trajectory of the plastic litter is recorded with a camera offering a top view of the arrangement. From the analysis of this a variety of results are obtained including transport metrics (including transport velocity and time to trapping) and litter-trapping location. The relation between the size of the litter, the vegetation configuration and the traveling

  17. Kinetic models of gene expression including non-coding RNAs

    Science.gov (United States)

    Zhdanov, Vladimir P.

    2011-03-01

    In cells, genes are transcribed into mRNAs, and the latter are translated into proteins. Due to the feedbacks between these processes, the kinetics of gene expression may be complex even in the simplest genetic networks. The corresponding models have already been reviewed in the literature. A new avenue in this field is related to the recognition that the conventional scenario of gene expression is fully applicable only to prokaryotes whose genomes consist of tightly packed protein-coding sequences. In eukaryotic cells, in contrast, such sequences are relatively rare, and the rest of the genome includes numerous transcript units representing non-coding RNAs (ncRNAs). During the past decade, it has become clear that such RNAs play a crucial role in gene expression and accordingly influence a multitude of cellular processes both in the normal state and during diseases. The numerous biological functions of ncRNAs are based primarily on their abilities to silence genes via pairing with a target mRNA and subsequently preventing its translation or facilitating degradation of the mRNA-ncRNA complex. Many other abilities of ncRNAs have been discovered as well. Our review is focused on the available kinetic models describing the mRNA, ncRNA and protein interplay. In particular, we systematically present the simplest models without kinetic feedbacks, models containing feedbacks and predicting bistability and oscillations in simple genetic networks, and models describing the effect of ncRNAs on complex genetic networks. Mathematically, the presentation is based primarily on temporal mean-field kinetic equations. The stochastic and spatio-temporal effects are also briefly discussed.

  18. Progress Towards an LES Wall Model Including Unresolved Roughness

    Science.gov (United States)

    Craft, Kyle; Redman, Andrew; Aikens, Kurt

    2015-11-01

    Wall models used in large eddy simulations (LES) are often based on theories for hydraulically smooth walls. While this is reasonable for many applications, there are also many where the impact of surface roughness is important. A previously developed wall model has been used primarily for jet engine aeroacoustics. However, jet simulations have not accurately captured thick initial shear layers found in some experimental data. This may partly be due to nozzle wall roughness used in the experiments to promote turbulent boundary layers. As a result, the wall model is extended to include the effects of unresolved wall roughness through appropriate alterations to the log-law. The methodology is tested for incompressible flat plate boundary layers with different surface roughness. Correct trends are noted for the impact of surface roughness on the velocity profile. However, velocity deficit profiles and the Reynolds stresses do not collapse as well as expected. Possible reasons for the discrepancies as well as future work will be presented. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1053575. Computational resources on TACC Stampede were provided under XSEDE allocation ENG150001.

  19. Reconciling Phylogeny and Function During Plant Litter Decomposition by High-Throughput Functional Metagenomics

    Science.gov (United States)

    Nyyssonen, M.; Weihe, C.; Goulden, M.; Treseder, K. K.; Martiny, J.; Martiny, A.; Allison, S. D.; Brodie, E. L.

    2012-12-01

    Integrating information on microbial diversity and functionality with ecosystem processes may be critical to predicting how ecosystems respond to environmental change. While theoretical models can be used to link microbial processes to environmental responses and rates, accurate predictions of ecosystem functioning would benefit from detailed information on microbial community composition and function. In this study, our aim was to identify functional traits involved in plant litter decomposition, a model process for carbon cycling, from decomposing plant litter. The overall goal is then to link these traits with individual microbial taxa and use this information to build predictive trait-based models of ecosystem responses to global change. In order to identify activities involved in plant litter decomposition we used automated high-throughput assays for functional screening of metagenomic fosmid libraries prepared from decomposing plant litter. Litter was collected over 15 month period from a global change field experiment undergoing rainfall and nitrogen manipulations. We identified over 600 cellulose, hemicellulose, chitin and starch hydrolyzing clones following screening of over 300,000 clones. The frequency of positive clones was ten times lower during dry season but no significant differences in hit rates were observed between different treatments. The positive clones were shotgun sequenced on the Illumina sequencing platform and the identified hydrolytic genes were shown to represent variety bacterial taxonomic groups including Proteobacteria and Bacteroidetes.

  20. Heritabilities and genetic and phenotypic correlations of litter uniformity and litter size in Large White sows

    Institute of Scientific and Technical Information of China (English)

    ZHANG Tian; ZHAO Ke-bin; WANG Li-xian; WANG Li-gang; SHI Hui-bi; YAN Hua; ZHANG Long-chao; LIU Xin; PU Lei; LIANG Jing; ZHANG Yue-bo

    2016-01-01

    Litter uniformity, which is usualy represented by within-litter weight coefifcient of variation at birth (CVB), could inlfuence litter performance of sows and the proiftability of pig enterprises. The objective of this study was to characterize CVB and its effect on other reproductive traits in Large White sows. Genetic parameters and genetic correlation of the reproductive traits, including CVB, within-litter weight coefifcient of variation at three weeks (CVT), total number born (TNB), number born alive (NBA), number born dead (NBD), gestation length (GL), piglet mortality at birth (M0), piglet mortality at three weeks (M3), total litter weight at birth (TLW0), and total litter weight at three weeks (TLW3) were estimated for 2032 Large White litters. The effects of parity and classiifed litter size on CVB, CVT, TNB, NBA, NBD, GL, M0, M3, TLW0, and TLW3 were also estimated. The heritabilities of these reproductive traits ranged from 0.06 to 0.17, with the lowest heritability for CVB and the highest heritability for TLW0. Phenotypic and genetic correlations between these reproductive traits were low to highly positive and negative (ranging from −0.03 to 0.93, and −0.53 to 0.93, respectively). The genetic correlations between TNB and CVB, and between M0 and CVB were 0.32 and 0.29, respectively. In addition, CVB was signiifcantly inlfuenced by parity and litter size class (P<0.05). Al the results suggest that piglet uniformity should be maintained in pig production practices and pig breeding programs.

  1. Large litter sizes

    DEFF Research Database (Denmark)

    Sandøe, Peter; Rutherford, K.M.D.; Berg, Peer

    2012-01-01

    This paper presents some key results and conclusions from a review (Rutherford et al. 2011) undertaken regarding the ethical and welfare implications of breeding for large litter size in the domestic pig and about different ways of dealing with these implications. Focus is primarily on the direct...... adverse consequences for animal welfare of Danish breeding for large litter sizes due to increased piglet mortality and the subsequent attempts to reverse these consequences by breeding for number of live piglets at day five rather than number of piglets born. By this change of breeding goal it seems...

  2. Ecological controls on N2O emission in surface litter and near-surface soil of a managed grassland: modelling and measurements

    Science.gov (United States)

    Grant, Robert F.; Neftel, Albrecht; Calanca, Pierluigi

    2016-06-01

    Large variability in N2O emissions from managed grasslands may occur because most emissions originate in surface litter or near-surface soil where variability in soil water content (θ) and temperature (Ts) is greatest. To determine whether temporal variability in θ and Ts of surface litter and near-surface soil could explain this in N2O emissions, a simulation experiment was conducted with ecosys, a comprehensive mathematical model of terrestrial ecosystems in which processes governing N2O emissions were represented at high temporal and spatial resolution. Model performance was verified by comparing N2O emissions, CO2 and energy exchange, and θ and Ts modelled by ecosys with those measured by automated chambers, eddy covariance (EC) and soil sensors on an hourly timescale during several emission events from 2004 to 2009 in an intensively managed pasture at Oensingen, Switzerland. Both modelled and measured events were induced by precipitation following harvesting and subsequent fertilizing or manuring. These events were brief (2-5 days) with maximum N2O effluxes that varied from Nm-2h-1 in early spring and autumn to > 3 mgNm-2h-1 in summer. Only very small emissions were modelled or measured outside these events. In the model, emissions were generated almost entirely in surface litter or near-surface (0-2 cm) soil, at rates driven by N availability with fertilization vs. N uptake with grassland regrowth and by O2 supply controlled by litter and soil wetting relative to O2 demand from microbial respiration. In the model, NOx availability relative to O2 limitation governed both the reduction of more oxidized electron acceptors to N2O and the reduction of N2O to N2, so that the magnitude of N2O emissions was not simply related to surface and near-surface θ and Ts. Modelled N2O emissions were found to be sensitive to defoliation intensity and timing which controlled plant N uptake and soil θ and Ts prior to and during emission events. Reducing leaf area index (LAI

  3. The Experimental Control of Littering

    Science.gov (United States)

    Clark, Roger N.; And Others

    1972-01-01

    Behavior, incentives, and education programs were researched as factors relating to littering. Experiments in theaters, forest campgrounds, and hiking and dispersed car camping areas indicate incentive systems are necessary and feasible for curbing litter problems. (BL)

  4. Numerical Modeling of Electroacoustic Logging Including Joule Heating

    Science.gov (United States)

    Plyushchenkov, Boris D.; Nikitin, Anatoly A.; Turchaninov, Victor I.

    It is well known that electromagnetic field excites acoustic wave in a porous elastic medium saturated with fluid electrolyte due to electrokinetic conversion effect. Pride's equations describing this process are written in isothermal approximation. Update of these equations, which allows to take influence of Joule heating on acoustic waves propagation into account, is proposed here. This update includes terms describing the initiation of additional acoustic waves excited by thermoelastic stresses and the heat conduction equation with right side defined by Joule heating. Results of numerical modeling of several problems of propagation of acoustic waves excited by an electric field source with and without consideration of Joule heating effect in their statements are presented. From these results, it follows that influence of Joule heating should be taken into account at the numerical simulation of electroacoustic logging and at the interpretation of its log data.

  5. Carbon and nitrogen dynamics in early stages of forest litter decomposition as affected by nitrogen addition

    Institute of Scientific and Technical Information of China (English)

    DENG Xiao-wen; LIU Ying; HAN Shi-jie

    2009-01-01

    The effects of nitrogen (N) availability and tree species on the dynamics of carbon and nitrogen at early stage of decomposition of forest litter were studied in a 13-week laboratory incubation experiment. Fresh litter samples including needle litter (Pinus koraiensis) and two types of broadleaf litters (Quercus mongolica and Tilia amurensis) were collected from a broadleaf-korean pine mixed forest in the northern slope of Changbai Mountain (China). Different doses of N (equal to 0, 30 and 50 kg·ha-1yr-1, respectively, as NH4NO3) were added to litter during the experiment period. The litter decomposition rate expressed as mass loss and respiration rate increased significantly with increasing N availability. The mass loss and cumulative CO2-C emission were higher in leaf litter compared to that in needle litter. The dissolved organic Carbon (DOC) concentrations in litter leachate varied widely between the species, but were not greatly affected by N treatments. Regardless of the N addition rate, both N treatments and species had no significant effect on dissolved organic N (DON) concentrations in litter leachate. About 52·78% of added N was retained in the litter. The percentage of N retention was positively correlated (R2=0.91, p<0.05) with the litter mass loss. This suggested that a forest floor with easily decomposed litter might have higher potential N sink strength than that with more slowly decomposed litter.

  6. Genotype by environment interaction for litter size in pigs as quantified by reaction norms analysis

    DEFF Research Database (Denmark)

    Knap, P W; Su, G

    2008-01-01

    A Bayesian procedure was used to estimate linear reaction norms (i.e. individual G × E plots) on 297 518 litter size records of 121 104 sows, daughters of 2040 sires, recorded on 144 farms in North and Latin America, Europe, Asia and Australia. The method allowed for simultaneous estimation of all...... in the estimates of the additive genetic effect; the reaction norms model removes this confounding. The intercept estimates from the largest data subset show correlations with litter size estimated breeding values (EBV) from routine genetic evaluation (without reaction norms included) of 0.78 to 0.85 for sows...... with one to seven litter records, and 0.75 for sires. Hence, including reaction norms in genetic evaluation would increase the reliability of the EBV of young selection candidates without own performance or progeny data by considerably more than 100 × (1/0.75-1) = 33%. Reaction norm slope estimates turn...

  7. Goldilocks models of higher-dimensional inflation (including modulus stabilization)

    Science.gov (United States)

    Burgess, C. P.; Enns, Jared J. H.; Hayman, Peter; Patil, Subodh P.

    2016-08-01

    We explore the mechanics of inflation within simplified extra-dimensional models involving an inflaton interacting with the Einstein-Maxwell system in two extra dimensions. The models are Goldilocks-like inasmuch as they are just complicated enough to include a mechanism to stabilize the extra-dimensional size (or modulus), yet simple enough to solve explicitly the full extra-dimensional field equations using only simple tools. The solutions are not restricted to the effective 4D regime with H ll mKK (the latter referring to the characteristic mass splitting of the Kaluza-Klein excitations) because the full extra-dimensional Einstein equations are solved. This allows an exploration of inflationary physics in a controlled calculational regime away from the usual four-dimensional lamp-post. The inclusion of modulus stabilization is important because experience with string models teaches that this is usually what makes models fail: stabilization energies easily dominate the shallow potentials required by slow roll and so open up directions to evolve that are steeper than those of the putative inflationary direction. We explore (numerically and analytically) three representative kinds of inflationary scenarios within this simple setup. In one the radion is trapped in an inflaton-dependent local minimum whose non-zero energy drives inflation. Inflation ends as this energy relaxes to zero when the inflaton finds its own minimum. The other two involve power-law scaling solutions during inflation. One of these is a dynamical attractor whose features are relatively insensitive to initial conditions but whose slow-roll parameters cannot be arbitrarily small; the other is not an attractor but can roll much more slowly, until eventually transitioning to the attractor. The scaling solutions can satisfy H > mKK, but when they do standard 4D fluctuation calculations need not apply. When in a 4D regime the solutions predict η simeq 0 and so r simeq 0.11 when ns simeq 0.96 and so

  8. Large litter sizes

    DEFF Research Database (Denmark)

    Sandøe, Peter; Rutherford, K.M.D.; Berg, Peer

    2012-01-01

    This paper presents some key results and conclusions from a review (Rutherford et al. 2011) undertaken regarding the ethical and welfare implications of breeding for large litter size in the domestic pig and about different ways of dealing with these implications. Focus is primarily on the direct...

  9. Anti-Litter Curriculum Packet, Interdisciplinary, K-12.

    Science.gov (United States)

    Tillis, Richard

    This curriculum packet consists of 20 illustrated cards with 15 activities designed to create "positive feelings" about a clean environment. Activities range from picture coloring for younger students, to lessons such as the economic and health problems litter creates for older students. Objectives include encouraging anti-litter and…

  10. Including spatial data in nutrient balance modelling on dairy farms

    Science.gov (United States)

    van Leeuwen, Maricke; van Middelaar, Corina; Stoof, Cathelijne; Oenema, Jouke; Stoorvogel, Jetse; de Boer, Imke

    2017-04-01

    The Annual Nutrient Cycle Assessment (ANCA) calculates the nitrogen (N) and phosphorus (P) balance at a dairy farm, while taking into account the subsequent nutrient cycles of the herd, manure, soil and crop components. Since January 2016, Dutch dairy farmers are required to use ANCA in order to increase understanding of nutrient flows and to minimize nutrient losses to the environment. A nutrient balance calculates the difference between nutrient inputs and outputs. Nutrients enter the farm via purchased feed, fertilizers, deposition and fixation by legumes (nitrogen), and leave the farm via milk, livestock, manure, and roughages. A positive balance indicates to which extent N and/or P are lost to the environment via gaseous emissions (N), leaching, run-off and accumulation in soil. A negative balance indicates that N and/or P are depleted from soil. ANCA was designed to calculate average nutrient flows on farm level (for the herd, manure, soil and crop components). ANCA was not designed to perform calculations of nutrient flows at the field level, as it uses averaged nutrient inputs and outputs across all fields, and it does not include field specific soil characteristics. Land management decisions, however, such as the level of N and P application, are typically taken at the field level given the specific crop and soil characteristics. Therefore the information that ANCA provides is likely not sufficient to support farmers' decisions on land management to minimize nutrient losses to the environment. This is particularly a problem when land management and soils vary between fields. For an accurate estimate of nutrient flows in a given farming system that can be used to optimize land management, the spatial scale of nutrient inputs and outputs (and thus the effect of land management and soil variation) could be essential. Our aim was to determine the effect of the spatial scale of nutrient inputs and outputs on modelled nutrient flows and nutrient use efficiencies

  11. The Effect of Litter Position on Ultraviolet Photodegradation of Standing Dead Litter

    Science.gov (United States)

    Lin, Y.; King, J. Y.

    2012-12-01

    In dryland ecosystems, models incorporating only biotic mechanisms usually underestimate the decay rate of plant litter. Photodegradation, an abiotic process through which solar radiation breaks down organic matter, has recently been proposed as an important pathway of litter decomposition in dryland ecosystems, accounting for as much as 25 to 60% of mass loss. However, it remains unclear what factors control the relative importance of photodegradation and biotic decomposition. It is hypothesized that this balance is affected by the location of litter within the litter layer (or thatch): in upper layers of thatch, photodegradation is significant because litter is exposed to sunlight; in lower layers where litter is strongly shaded, photodegradation is negligible compared to biotic decomposition. In August 2011, a field experiment was initiated at the University of California's Sedgwick Reserve, Santa Ynez, CA, in order to understand how ultraviolet (UV) radiation and litter position within the thatch affect litter decomposition. Two levels of UV radiation (280-400 nm) are achieved by screens: "UV-Pass" (transmitting > 81% of UV radiation) and "UV-Block" (transmitting exposure show that at the top of the thatch, litter mass loss was 13% higher in UV-Pass than in UV-Block, suggesting the occurrence of UV photodegradation. Surprisingly, litter mass loss was 52% higher in UV-Pass at the bottom of the thatch, even though very limited UV radiation penetrated through the thatch (at least 10 cm thick). The relative humidity in the thatch was higher in UV-Pass than in UV-Block treatments, especially at night; thus it is speculated that the UV manipulation not only alters the incoming radiation spectrum but also affects microclimate, consequently changing biotic decomposition. At the bottom of the thatch, lignin concentration of plant litter was 19% higher in UV-Pass than in UV-Block treatments, but there was no difference at the top of the thatch. Because lignin is

  12. A Discrete Velocity Traffic Kinetic Model Including Desired Speed

    Directory of Open Access Journals (Sweden)

    Shoufeng Lu

    2013-05-01

    Full Text Available We introduce the desired speed variable into the table of games and formulate a new table of games and the corresponding discrete traffic kinetic model. We use the hybrid programming technique of VB and MATLAB to develop the program. Lastly, we compared the proposed model result and the detector data. The results show that the proposed model can describe the traffic flow evolution.

  13. Semi-holographic model including the radiation component

    CERN Document Server

    del Campo, Sergio; Magaña, Juan; Villanueva, J R

    2014-01-01

    In this letter we study the semi holographic model which corresponds to the radiative version of the model proposed by Zhang et al. (Phys. Lett. B 694 (2010), 177) and revisited by C\\'ardenas et al. (Mon. Not. Roy. Astron. Soc. 438 (2014), 3603). This inclusion makes the model more realistic, so allows us to test it with current observational data and then answer if the inconsistency reported by C\\'ardenas et al. is relaxed.

  14. A Fault Evolution Model Including the Rupture Dynamic Simulation

    Science.gov (United States)

    Wu, Y.; Chen, X.

    2011-12-01

    We perform a preliminary numerical simulation of seismicity and stress evolution along a strike-slip fault in a 3D elastic half space. Following work of Ben-Zion (1996), the fault geometry is devised as a vertical plane which is about 70 km long and 17 km wide, comparable to the size of San Andreas Fault around Parkfield. The loading mechanism is described by "backslip" method. The fault failure is governed by a static/kinetic friction law, and induced stress transfer is calculated with Okada's static solution. In order to track the rupture propagation in detail, we allow induced stress to propagate through the medium at the shear wave velocity by introducing a distance-dependent time delay to responses to stress changes. Current simulation indicates small to moderate earthquakes following the Gutenberg-Richter law and quasi-periodical characteristic large earthquakes, which are consistent with previous work by others. Next we will consider introducing a more realistic friction law, namely, the laboratory-derived rate- and state- dependent law, which can simulate more realistic and complicated sliding behavior such as the stable and unstable slip, the aseismic sliding and the slip nucleation process. In addition, the long duration of aftershocks is expected to be reproduced due to this time-dependent friction law, which is not available in current seismicity simulation. The other difference from previous work is that we are trying to include the dynamic ruptures in this study. Most previous study on seismicity simulation is based on the static solution when dealing with failure induced stress changes. However, studies of numerical simulation of rupture dynamics have revealed lots of important details which are missing in the quasi-static/quasi- dynamic simulation. For example, dynamic simulations indicate that the slip on the ground surface becomes larger if the dynamic rupture process reaches the free surface. The concentration of stress on the propagating crack

  15. Evacuation modeling including traveler information and compliance behavior

    NARCIS (Netherlands)

    Pel, A.J.; Hoogendoorn, S.P.; Bliemer, M.C.J.

    2010-01-01

    Traffic simulation models are often used to support decisions when planning an evacuation. Scenario analyses based on these models then typically focus on traffic dynamics and the effect of traffic control measures in order to locate possible bottlenecks and predict evacuation times. A clear approac

  16. Global atmospheric model for mercury including oxidation by bromine atoms

    Directory of Open Access Journals (Sweden)

    C. D. Holmes

    2010-12-01

    Full Text Available Global models of atmospheric mercury generally assume that gas-phase OH and ozone are the main oxidants converting Hg0 to HgII and thus driving mercury deposition to ecosystems. However, thermodynamic considerations argue against the importance of these reactions. We demonstrate here the viability of atomic bromine (Br as an alternative Hg0 oxidant. We conduct a global 3-D simulation with the GEOS-Chem model assuming gas-phase Br to be the sole Hg0 oxidant (Hg + Br model and compare to the previous version of the model with OH and ozone as the sole oxidants (Hg + OH/O3 model. We specify global 3-D Br concentration fields based on our best understanding of tropospheric and stratospheric Br chemistry. In both the Hg + Br and Hg + OH/O3 models, we add an aqueous photochemical reduction of HgII in cloud to impose a tropospheric lifetime for mercury of 6.5 months against deposition, as needed to reconcile observed total gaseous mercury (TGM concentrations with current estimates of anthropogenic emissions. This added reduction would not be necessary in the Hg + Br model if we adjusted the Br oxidation kinetics downward within their range of uncertainty. We find that the Hg + Br and Hg + OH/O3 models are equally capable of reproducing the spatial distribution of TGM and its seasonal cycle at northern mid-latitudes. The Hg + Br model shows a steeper decline of TGM concentrations from the tropics to southern mid-latitudes. Only the Hg + Br model can reproduce the springtime depletion and summer rebound of TGM observed at polar sites; the snowpack component of GEOS-Chem suggests that 40% of HgII deposited to snow in the Arctic is transferred to the ocean and land reservoirs, amounting to a net deposition flux to the Arctic of 60 Mg a−1. Summertime events of depleted Hg0 at Antarctic sites due to subsidence are much better simulated by

  17. Pilot Wave model that includes creation and annihilation of particles

    CERN Document Server

    Sverdlov, Roman

    2010-01-01

    The purpose of this paper is to come up with a Pilot Wave model of quantum field theory that incorporates particle creation and annihilation without sacrificing determinism. This has been previously attempted in an article by the same author titled "Incorporating particle creation and annihilation in Pilot Wave model", in a much less satisfactory way. In this paper I would like to "clean up" some of the things. In particular, I would like to get rid of a very unnatural concept of "visibility" of particles, which makes the model much simpler. On the other hand, I would like to add a mechanism for decoherence, which was absent in the previous version.

  18. Global atmospheric model for mercury including oxidation by bromine atoms

    Directory of Open Access Journals (Sweden)

    C. D. Holmes

    2010-08-01

    Full Text Available Global models of atmospheric mercury generally assume that OH and ozone are the main oxidants converting Hg0 to HgII and thus driving mercury deposition to ecosystems. However, thermodynamic considerations argue against the importance of these reactions. We demonstrate here the viability of atomic bromine (Br as an alternative Hg0 oxidant. We conduct a global 3-D simulation with the GEOS-Chem model assuming Br to be the sole Hg0 oxidant (Hg + Br model and compare to the previous version of the model with OH and ozone as the sole oxidants (Hg + OH/O3 model. We specify global 3-D Br concentration fields based on our best understanding of tropospheric and stratospheric Br chemistry. In both the Hg + Br and Hg + OH/O3 models, we add an aqueous photochemical reduction of HgII in cloud to impose a tropospheric lifetime for mercury of 6.5 months against deposition, as needed to reconcile observed total gaseous mercury (TGM concentrations with current estimates of anthropogenic emissions. This added reduction would not be necessary in the Hg + Br model if we adjusted the Br oxidation kinetics downward within their range of uncertainty. We find that the Hg + Br and Hg + OH/O3 models are equally capable of reproducing the spatial distribution of TGM and its seasonal cycle at northern mid-latitudes. The Hg + Br model shows a steeper decline of TGM concentrations from the tropics to southern mid-latitudes. Only the Hg + Br model can reproduce the springtime depletion and summer rebound of TGM observed at polar sites; the snowpack component of GEOS-Chem suggests that 40% of HgII deposited to snow in the Arctic is transferred to the ocean and land reservoirs, amounting to a net deposition flux of 60 Mg a−1. Summertime events of depleted Hg0 at Antarctic sites due to subsidence are much better simulated by the Hg + Br model. Model

  19. Leaf litter decomposition in temperate deciduous forest stands with a decreasing fraction of beech (Fagus sylvatica).

    Science.gov (United States)

    Jacob, Mascha; Viedenz, Karin; Polle, Andrea; Thomas, Frank M

    2010-12-01

    We hypothesised that the decomposition rates of leaf litter will increase along a gradient of decreasing fraction of the European beech (Fagus sylvatica) and increasing tree species diversity in the generally beech-dominated Central European temperate deciduous forests due to an increase in litter quality. We studied the decomposition of leaf litter including its lignin fraction in monospecific (pure beech) stands and in stands with up to five tree genera (Acer spp., Carpinus betulus, Fagus sylvatica, Fraxinus excelsior, Tilia spp.) using a litterbag approach. Litter and lignin decomposition was more rapid in stand-representative litter from multispecific stands than in litter from pure beech stands. Except for beech litter, the decomposition rates of species-specific tree litter did not differ significantly among the stand types, but were most rapid in Fraxinus excelsior and slowest in beech in an interspecific comparison. Pairwise comparisons of the decomposition of beech litter with litter of the other tree species (except for Acer platanoides) revealed a "home field advantage" of up to 20% (more rapid litter decomposition in stands with a high fraction of its own species than in stands with a different tree species composition). Decomposition of stand-representative litter mixtures displayed additive characteristics, not significantly more rapid than predicted by the decomposition of litter from the individual tree species. Leaf litter decomposition rates were positively correlated with the initial N and Ca concentrations of the litter, and negatively with the initial C:N, C:P and lignin:N ratios. The results support our hypothesis that the overall decomposition rates are mainly influenced by the chemical composition of the individual litter species. Thus, the fraction of individual tree species in the species composition seems to be more important for the litter decomposition rates than tree species diversity itself.

  20. Direct and indirect effects of UV-B exposure on litter decomposition: a meta-analysis.

    Science.gov (United States)

    Song, Xinzhang; Peng, Changhui; Jiang, Hong; Zhu, Qiuan; Wang, Weifeng

    2013-01-01

    Ultraviolet-B (UV-B) exposure in the course of litter decomposition may have a direct effect on decomposition rates via changing states of photodegradation or decomposer constitution in litter while UV-B exposure during growth periods may alter chemical compositions and physical properties of plants. Consequently, these changes will indirectly affect subsequent litter decomposition processes in soil. Although studies are available on both the positive and negative effects (including no observable effects) of UV-B exposure on litter decomposition, a comprehensive analysis leading to an adequate understanding remains unresolved. Using data from 93 studies across six biomes, this introductory meta-analysis found that elevated UV-B directly increased litter decomposition rates by 7% and indirectly by 12% while attenuated UV-B directly decreased litter decomposition rates by 23% and indirectly increased litter decomposition rates by 7%. However, neither positive nor negative effects were statistically significant. Woody plant litter decomposition seemed more sensitive to UV-B than herbaceous plant litter except under conditions of indirect effects of elevated UV-B. Furthermore, levels of UV-B intensity significantly affected litter decomposition response to UV-B (PUV-B effects on litter decomposition were to a large degree compounded by climatic factors (e.g., MAP and MAT) (PUV-B on litter decomposition. No significant differences in UV-B effects on litter decomposition were found between study types (field experiment vs. laboratory incubation), litter forms (leaf vs. needle), and decay duration. Indirect effects of elevated UV-B on litter decomposition significantly increased with decay duration (PUV-B exposure intensity (30%) had significant direct effects on litter decomposition (PUV-B on litter decomposition.

  1. An Intracellular Calcium Oscillations Model Including Mitochondrial Calcium Cycling

    Institute of Scientific and Technical Information of China (English)

    SHI Xiao-Min; LIU Zeng-Rong

    2005-01-01

    @@ Calcium is a ubiquitous second messenger. Mitochondria contributes significantly to intracellular Ca2+ dynamics.The experiment of Kaftan et al. [J. Biol. Chem. 275(2000) 25465] demonstrated that inhibiting mitochondrial Ca2+ uptake can reduce the frequency of cytosolic Ca2+ concentration oscillations of gonadotropes. By considering the mitochondrial Ca2+ cycling we develop a three-variable model of intracellular Ca2+ oscillations based on the models of Atri et al. [Biophys. J. 65 (1993) 1727] and Falcke et al. [Biophys. J. 77 (1999) 37]. The model reproduces the fact that mitochondrial Ca2+ cycling increases the frequency of cytosolic Ca2+ oscillations, which accords with Kaftan's results. Moreover the model predicts that when the mitochondria overload with Ca2+, the cytosolic Ca2+ oscillations vanish, which may trigger apoptosis.

  2. Cement-aggregate compatibility and structure property relationships including modelling

    Energy Technology Data Exchange (ETDEWEB)

    Jennings, H.M.; Xi, Y.

    1993-07-15

    The role of aggregate, and its interface with cement paste, is discussed with a view toward establishing models that relate structure to properties. Both short (nm) and long (mm) range structure must be considered. The short range structure of the interface depends not only on the physical distribution of the various phases, but also on moisture content and reactivity of aggregate. Changes that occur on drying, i.e. shrinkage, may alter the structure which, in turn, feeds back to alter further drying and shrinkage. The interaction is dynamic, even without further hydration of cement paste, and the dynamic characteristic must be considered in order to fully understand and model its contribution to properties. Microstructure and properties are two subjects which have been pursued somewhat separately. This review discusses both disciplines with a view toward finding common research goals in the future. Finally, comment is made on possible chemical reactions which may occur between aggregate and cement paste.

  3. Including lateral interactions into microkinetic models of catalytic reactions

    DEFF Research Database (Denmark)

    Hellman, Anders; Honkala, Johanna Karoliina

    2007-01-01

    In many catalytic reactions lateral interactions between adsorbates are believed to have a strong influence on the reaction rates. We apply a microkinetic model to explore the effect of lateral interactions and how to efficiently take them into account in a simple catalytic reaction. Three differ...... different approximations are investigated: site, mean-field, and quasichemical approximations. The obtained results are compared to accurate Monte Carlo numbers. In the end, we apply the approximations to a real catalytic reaction, namely, ammonia synthesis....

  4. Reducing Children's Littering on a Nature Trail

    Science.gov (United States)

    LaHart, David E.; Bailey, Jon S.

    1975-01-01

    This study compared incentives and educational methods to motivate children to pick up litter and to prevent littering. Incentives did aid in getting litter picked up. One-sentence anti-litter statements, educational materials, and lectures reduced littering, but incentives did not. (MR)

  5. Comparison of Joint Modeling Approaches Including Eulerian Sliding Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lomov, I; Antoun, T; Vorobiev, O

    2009-12-16

    Accurate representation of discontinuities such as joints and faults is a key ingredient for high fidelity modeling of shock propagation in geologic media. The following study was done to improve treatment of discontinuities (joints) in the Eulerian hydrocode GEODYN (Lomov and Liu 2005). Lagrangian methods with conforming meshes and explicit inclusion of joints in the geologic model are well suited for such an analysis. Unfortunately, current meshing tools are unable to automatically generate adequate hexahedral meshes for large numbers of irregular polyhedra. Another concern is that joint stiffness in such explicit computations requires significantly reduced time steps, with negative implications for both the efficiency and quality of the numerical solution. An alternative approach is to use non-conforming meshes and embed joint information into regular computational elements. However, once slip displacement on the joints become comparable to the zone size, Lagrangian (even non-conforming) meshes could suffer from tangling and decreased time step problems. The use of non-conforming meshes in an Eulerian solver may alleviate these difficulties and provide a viable numerical approach for modeling the effects of faults on the dynamic response of geologic materials. We studied shock propagation in jointed/faulted media using a Lagrangian and two Eulerian approaches. To investigate the accuracy of this joint treatment the GEODYN calculations have been compared with results from the Lagrangian code GEODYN-L which uses an explicit treatment of joints via common plane contact. We explore two approaches to joint treatment in the code, one for joints with finite thickness and the other for tight joints. In all cases the sliding interfaces are tracked explicitly without homogenization or blending the joint and block response into an average response. In general, rock joints will introduce an increase in normal compliance in addition to a reduction in shear strength. In the

  6. Neighboring extremal optimal control design including model mismatch errors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, T.J. [Sandia National Labs., Albuquerque, NM (United States); Hull, D.G. [Texas Univ., Austin, TX (United States). Dept. of Aerospace Engineering and Engineering Mechanics

    1994-11-01

    The mismatch control technique that is used to simplify model equations of motion in order to determine analytic optimal control laws is extended using neighboring extremal theory. The first variation optimal control equations are linearized about the extremal path to account for perturbations in the initial state and the final constraint manifold. A numerical example demonstrates that the tuning procedure inherent in the mismatch control method increases the performance of the controls to the level of a numerically-determined piecewise-linear controller.

  7. Double pendulum model for tennis stroke including a collision process

    CERN Document Server

    Youn, Sun-Hyun

    2015-01-01

    By means of adding a collision process between the ball and racket in double pendulum model, we analyzed the tennis stroke. It is possible that the speed of the rebound ball does not simply depend on the angular velocity of the racket, and higher angular velocity sometimes gives lower ball speed. We numerically showed that the proper time lagged racket rotation increases the speed of the rebound ball by 20%. We also showed that the elbow should move in order to add the angular velocity of the racket.

  8. Harm caused by Marine Litter

    OpenAIRE

    Werner, S.; Budziak, A.; Franeker, van, J.A.; Galgani, F.; Hanke, G.; Maes, T.; Matiddi, M.; Nilsson, P; Oosterbaan, L.; Priestland, E.; Thompson, R.; Veiga, J.; Vlachogianni, T. (Thomais)

    2016-01-01

    Marine litter is a global concern with a range of problems associated to it, as recognised by the Marine Strategy Framework Directive (MSFD). Marine litter can impact organisms at different levels of biological organization and habitats in a number of ways namely: through entanglement in, or ingestion of, litter items by individuals, resulting in death and/or severe suffering; through chemical and microbial transfer; as a vector for transport of biota and by altering or modifying assemblages ...

  9. Spatial and temporal analysis of litter in the Celtic Sea from Groundfish Survey data: Lessons for monitoring.

    Science.gov (United States)

    Moriarty, M; Pedreschi, D; Stokes, D; Dransfeld, L; Reid, D G

    2016-02-15

    The Marine Strategy Framework Directive requires EU Member States to sample and monitor marine litter. Criteria for sampling and detecting spatial and/or temporal variation in the amount of litter present have been developed and initiated throughout Europe. These include implementing standardised sampling and recording methods to enable cross-comparison and consistency between neighbours. Parameters of interest include; litter occurrence, composition, distribution and source. This paper highlights the litter-related initiatives occurring in Irish waters; presents an offshore benthic litter sampling series; provides a power analysis to determine trend detection thresholds; identifies areas and sources of litter; and proposes improvements to meet reporting obligations. Litter was found to be distributed throughout Irish waters with highest occurrences in the Celtic Sea. Over 50% of litter encountered was attributed to fishing activities: however only a small proportion of the variability in litter occurrence could be explained by spatial patterns in fishing effort. Issues in implementing standardised protocol were observed and addressed.

  10. Modelling of Dual-Junction Solar Cells including Tunnel Junction

    Directory of Open Access Journals (Sweden)

    Abdelaziz Amine

    2013-01-01

    Full Text Available Monolithically stacked multijunction solar cells based on III–V semiconductors materials are the state-of-art of approach for high efficiency photovoltaic energy conversion, in particular for space applications. The individual subcells of the multi-junction structure are interconnected via tunnel diodes which must be optically transparent and connect the component cells with a minimum electrical resistance. The quality of these diodes determines the output performance of the solar cell. The purpose of this work is to contribute to the investigation of the tunnel electrical resistance of such a multi-junction cell through the analysis of the current-voltage (J-V characteristics under illumination. Our approach is based on an equivalent circuit model of a diode for each subcell. We examine the effect of tunnel resistance on the performance of a multi-junction cell using minimization of the least squares technique.

  11. Human sperm chromatin stabilization: a proposed model including zinc bridges.

    Science.gov (United States)

    Björndahl, Lars; Kvist, Ulrik

    2010-01-01

    The primary focus of this review is to challenge the current concepts on sperm chromatin stability. The observations (i) that zinc depletion at ejaculation allows a rapid and total sperm chromatin decondensation without the addition of exogenous disulfide cleaving agents and (ii) that the human sperm chromatin contains one zinc for every protamine for every turn of the DNA helix suggest an alternative model for sperm chromatin structure may be plausible. An alternative model is therefore proposed, that the human spermatozoon could at ejaculation have a rapidly reversible zinc dependent chromatin stability: Zn(2+) stabilizes the structure and prevents the formation of excess disulfide bridges by a single mechanism, the formation of zinc bridges with protamine thiols of cysteine and potentially imidazole groups of histidine. Extraction of zinc enables two biologically totally different outcomes: immediate decondensation if chromatin fibers are concomitantly induced to repel (e.g. by phosphorylation in the ooplasm); otherwise freed thiols become committed into disulfide bridges creating a superstabilized chromatin. Spermatozoa in the zinc rich prostatic fluid (normally the first expelled ejaculate fraction) represent the physiological situation. Extraction of chromatin zinc can be accomplished by the seminal vesicular fluid. Collection of the ejaculate in one single container causes abnormal contact between spermatozoa and seminal vesicular fluid affecting the sperm chromatin stability. There are men in infertile couples with low content of sperm chromatin zinc due to loss of zinc during ejaculation and liquefaction. Tests for sperm DNA integrity may give false negative results due to decreased access for the assay to the DNA in superstabilized chromatin.

  12. Global model including multistep ionizations in helium plasmas

    Science.gov (United States)

    Oh, Seung-Ju; Lee, Hyo-Chang; Chung, Chin-Wook

    2016-12-01

    Particle and power balance equations including stepwise ionizations are derived and solved in helium plasmas. In the balance equations, two metastable states (21S1 in singlet and 23S1 triplet) are considered and the followings are obtained. The plasma density linearly increases and the electron temperature is relatively in a constant value against the absorbed power. It is also found that the contribution to multi-step ionization with respect to the single-step ionization is in the range of 8%-23%, as the gas pressure increases from 10 mTorr to 100 mTorr. Compared to the results in the argon plasma, there is little variation in the collisional energy loss per electron-ion pair created (ɛc) with absorbed power and gas pressure due to the small collision cross section and higher inelastic collision threshold energy.

  13. The Effects of Litter on Littering Behavior in a Forest Environment

    Science.gov (United States)

    Crump, S. Larry; And Others

    1977-01-01

    The effects of littered and nonlittered areas on littering behavior were determined in picnic areas in the Uinta National Forest, Utah. Littered and nonlittered conditions were controlled by spreading or removing litter from specified areas. Observations revealed that in the nonlittered areas there was more litter than in the littered areas. (CS)

  14. Modelization of a water tank including a PCM module

    Energy Technology Data Exchange (ETDEWEB)

    Ibanez, Manuel [Dept. de Medi Ambient i Ciencies del Sol, Universitat de Lleida, Rovira Roure 191, 25198 Lleida (Spain); Cabeza, Luisa F.; Sole, Cristian; Roca, Joan; Nogues, Miquel [Dept. d' Informatica i Eng. Industrial, Universitat de Lleida, Jaume II 69, 25001 Lleida (Spain)

    2006-08-15

    The reduction of CO{sub 2} emissions is a key component for today's governments. Therefore, implementation of more and more systems with renewable energies is necessary. Solar systems for single family houses or residential buildings need a big water tank that many times is not easy to locate. This paper studies the modelization of a new technology where PCM modules are implemented in domestic hot water tanks to reduce their size without reducing the energy stored. A new TRNSYS component, based in the already existing TYPE 60, was developed, called TYPE 60PCM. After tuning the new component with experimental results, two more experiences were developed to validate the simulation of a water tank with two cylindrical PCM modules using type 60PCM, the cooldown and reheating experiments. Concordance between experimental and simulated data was very good. Since the new TRNSYS component was developed to simulate full solar systems, comparison of experimental results from a pilot plant solar system with simulations were performed, and they confirmed that the type 60PCM is a powerful tool to evaluate the performance of PCM modules in water tanks. (author)

  15. Mower/Litter Removal

    Science.gov (United States)

    1996-01-01

    The Burg Corporation needed to get more power out of the suction system in their Vac 'N Bag grass mower/litter remover. The president submitted a problem statement to the Marshall Space Flight Center Technology Transfer Office, which devised a way to guide heavier items of trash to a point where suction was greatest, and made changes to the impeller and the exhaust port, based on rocket propulsion technology. The improved system is used by highway departments, city governments and park authorities, reducing work time by combining the tasks of grass cutting and vacuuming trash and grass clippings.

  16. Influence of packaging design on littering behavior

    OpenAIRE

    Wever, R.

    2006-01-01

    Litter is an environmental and social problem that is closely related to packaging. Many attempts have been made to reduce litter. So far these attempts have mainly focused on influencing littering behavior either through general campaigns or through manipulating the environment. The latter might be done through strategic placement of prompts and litter bins and through cleaning up any previous litter. So far, little or no attention has been paid to the influence of the littered object itself...

  17. Impact of Conifer Forest Litter on Microwave Emission at L-Band

    Science.gov (United States)

    Kurum, Mehmet; O'Neill, Peggy E.; Lang, Roger H.; Cosh, Michael H.; Joseph, Alicia T.; Jackson, Thomas J.

    2011-01-01

    This study reports on the utilization of microwave modeling, together with ground truth, and L-band (1.4-GHz) brightness temperatures to investigate the passive microwave characteristics of a conifer forest floor. The microwave data were acquired over a natural Virginia Pine forest in Maryland by a ground-based microwave active/passive instrument system in 2008/2009. Ground measurements of the tree biophysical parameters and forest floor characteristics were obtained during the field campaign. The test site consisted of medium-sized evergreen conifers with an average height of 12 m and average diameters at breast height of 12.6 cm. The site is a typical pine forest site in that there is a surface layer of loose debris/needles and an organic transition layer above the mineral soil. In an effort to characterize and model the impact of the surface litter layer, an experiment was conducted on a day with wet soil conditions, which involved removal of the surface litter layer from one half of the test site while keeping the other half undisturbed. The observations showed detectable decrease in emissivity for both polarizations after the surface litter layer was removed. A first-order radiative transfer model of the forest stands including the multilayer nature of the forest floor in conjunction with the ground truth data are used to compute forest emission. The model calculations reproduced the major features of the experimental data over the entire duration, which included the effects of surface litter and ground moisture content on overall emission. Both theory and experimental results confirm that the litter layer increases the observed canopy brightness temperature and obscure the soil emission.

  18. Harm caused by Marine Litter

    NARCIS (Netherlands)

    Werner, S.; Budziak, A.; Franeker, van J.A.; Galgani, F.; Hanke, G.; Maes, T.; Matiddi, M.; Nilsson, P.; Oosterbaan, L.; Priestland, E.; Thompson, R.; Veiga, J.; Vlachogianni, T.

    2016-01-01

    Marine litter is a global concern with a range of problems associated to it, as recognised by the Marine Strategy Framework Directive (MSFD). Marine litter can impact organisms at different levels of biological organization and habitats in a number of ways namely: through entanglement in, or

  19. Morphogenetic Litter Types of Bog Spruce Forests

    Directory of Open Access Journals (Sweden)

    T. T. Efremova

    2015-02-01

    Full Text Available For the first time the representation of moss litter morphogenetic structure of valley-riverside and streamside spruce forests was determined for the wetland intermountain area of Kuznetsk Alatau. In general, the litter of (green moss-hypnum spruce forest can be characterized as medium thickness (9–17 cm with high storage of organic matter (77–99 t/ha, which differs in neutral environmental conditions pH 6.8–7.0 and high percentage of ash 11–28 %. Formation litter types were identified, which depend on the content of mineral inclusions in organogenic substrate and the degree of its drainage. The differentiation of litter subhorizons was performed, visual diagnostic indicators of fermentative layers were characterized, and additional (indexes to indicate their specificity were developed. Peat- and peaty-fermentative, humified-fermentative and (black mold humus-fermentative layers were selected. Peat- and peaty-fermentative layers are characterized by content of platy peat macroaggregates of coarse vegetable composition, the presence of abundant fungal mycelium and soil animals are the primary decomposers – myriopoda, gastropoda mollusks. Humified-fermentative layers are identified by including the newly formed amorphous humus-like substances, nutty-granular structural parts of humus nature and soil animals’ humificators – enchytraeids and earthworms. (Black mold humus-fermentative layers are diagnosed by indicators with similar humified-fermentative, but differ from them in clay-humus composition of nutty-granular blue-grey parts. The nomenclature and classification of moss litter were developed on the basis of their diagnostic characteristics of fermentative layers – peat, peaty, reduced peaty, (black mold humus-peaty, reduced (black mold humus-peaty. Using the method of discriminant analysis, we revealed that the physical-chemical properties, mainly percentage of ash and decomposition degree of plant substrate, objectively

  20. Do nurse sows and foster litters have impaired animal welfare? Results from a cross-sectional study in sow herds.

    Science.gov (United States)

    Sørensen, J T; Rousing, T; Kudahl, A B; Hansted, H J; Pedersen, L J

    2016-04-01

    Increasing litter size has led to introduction of so-called nurse sows in several EU countries. A nurse sow is a sow receiving piglets after having weaned her own piglets and thereby experiencing an extended lactation. In order to analyse whether nurse sows have more welfare problems than non-nurse sows a cross-sectional study was conducted in 57 sow herds in Denmark. Clinical observations were made on nurse and non-nurse sows and their litters. The clinical observations were dichotomized and the effect of being a nurse sow was analysed based on eight parameters: thin (body condition scoresow (yes=1/no=0), age of piglets (weeks old, 1 to 7), parity (1 to 8+) and all first order interactions between these three variables. The effect of using nurse sows on piglet welfare was analysed with five models. The outcomes were: huddling, poor hygiene, lameness, snout cuts and carpal abrasions. The explanatory variables included in the five models were: nurse sow (yes=1/no=0), age of piglets (weeks old, 1 to 7), parity (1 to 8+) and all first order interactions between these three variables. Herd identity was included as a random factor in all models. The nurse sows had a significantly higher risk of swollen bursae on legs (P=0.038) and udder wounds (P=0.001). No differences in risk of being thin or having shoulder lesions were found. Foster litters had significantly higher risk of being dirty (P=0.026) and getting carpal abrasions (P=0.024) than non-foster litters. There was a tendency for higher lameness in foster litters than in non-foster litters (P=0.052). The results show that nurse sows and their piglets to some extent experience more welfare problems than non-nurse sows with piglets at a similar age.

  1. Den litterære blog

    DEFF Research Database (Denmark)

    Serup, Martin Glaz; Kromann, Thomas Hvid

    2012-01-01

    Hvad er en litterær blog og hvordan arbejder den som en aktiv del af den litterære offentlighed.......Hvad er en litterær blog og hvordan arbejder den som en aktiv del af den litterære offentlighed....

  2. 33 CFR 144.01-35 - Litter.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Litter. 144.01-35 Section 144.01... CONTINENTAL SHELF ACTIVITIES LIFESAVING APPLIANCES Manned Platforms § 144.01-35 Litter. On each manned platform a Stokes litter, or other suitable safety litter capable of being safely hoisted with an...

  3. Sow and litter factors influencing colostrum yield and nutritional composition.

    Science.gov (United States)

    Declerck, I; Dewulf, J; Piepers, S; Decaluwé, R; Maes, D

    2015-03-01

    One of the main characteristics of colostrum intake (CI), colostrum yield (CY), and colostrum composition (CC) in pigs is its variability. The present observational study aimed to investigate factors influencing CY and CC in 10 commercial herds. In total, 100 sows of 5 different breeds and their 1,455 live-born piglets were included. Sows' CY was estimated by the CI of their suckling piglets. Colostrum composition was analyzed by LactoScope Fourier transform infrared spectroscopy. Colostrum yield averaged 3,500 ± 110 g and the percentage of colostral fat (CF), protein, and lactose in colostrum averaged 5.39 ± 0.12, 16.49 ± 0.14, and 2.02 ± 0.05 %, respectively. The effect of sow, litter, and parturition factors on CY and CC were evaluated with a linear mixed regression model with herd included as a random factor. Sows with a gestation length (GL) of 113 d had a higher CY (4,178 ± 506 g) than sows with a GL of 114 to 115 d (3,342 ± 107 g; = 0.04). An interaction was found between the litter birth weight of suckling piglets (LW) and GL ( = 0.03). In sows with a GL of 114 to 115 d, CY increased with higher LW ( = 0.009). A shorter interval between birth and first suckling of the litter was related to a higher CY ( colostrums was higher in Hypor sows (6.35 ± 0.51) than in PIC (4.98 ± 0.27; = 0.001), Topigs 20 (5.05 ± 0.14; < 0.001), and Danbred (5.34 ± 0.22; < 0.001) sows. The percentage of CF was negatively associated with parity ( = 0.02) and positively associated with the number of live-born piglets ( = 0.03). The percentages of colostral protein and lactose were not significantly associated with any factor in the multivariable model. In conclusion, this study demonstrated that CY and CF are affected by different sow and litter factors. Pig producers may implement these observations in their management to maximize production or reproduction potential by optimizing CI, CY, and CC.

  4. Runoff quality from no-till cotton fertilized with broiler litter in subsurface bands.

    Science.gov (United States)

    Adeli, A; Tewolde, H; Shankle, M W; Way, T R; Brooks, J P; McLaughlin, M R

    2013-01-01

    Surface broadcast of broiler litter to no-till row crops exposes the litter and its nutrients to risks of loss in runoff water and volatilization and may limit the potential benefit of litter to the crops. Subsurface banding of litter could alleviate these risks. A field study was conducted in 2008 and 2009 on an upland Falkner silt loam soil to determine the effect of broiler litter placement on runoff nutrient losses from no-till cotton ( L.). Treatments included surface broadcast broiler litter applied manually, subsurface-banded litter applied by tractor-drawn equipment, and no broiler litter, all in combination with or without winter wheat ( L.) cover crop residue. Broiler litter rate was 5.6 Mg ha. The experimental design was a randomized complete block with a split-plot arrangement of treatments replicated three times. In 2008, simulated rainfall was used to generate runoff 27 d after litter application. Subsurface-banded litter reduced runoff total C, N, P, NH, NO, Cu, Zn and water-soluble P (WP) concentrations by 72, 64, 51, 49, 70, 36, 65, and 77%, respectively, compared with surface broadcast. The reductions were greater in 2009 where runoff occurred 1 d after litter application. Bacterial runoff was decreased by one log with subsurface-banded litter compared to surface broadcast. Except for C, NH, N, and WP, the presence of winter cover crop residue did not affect the load or runoff nutrient concentrations in either year. The results indicate that subsurface banding litter to no-till cotton substantially reduces nutrient and bacterial losses in runoff compared with surface broadcasting.

  5. Modelos de regressão aleatória com diferentes estruturas de variância residual para descrever o tamanho da leitegada Random regression models with different residual variance structures for describing litter size in swine

    Directory of Open Access Journals (Sweden)

    Aderbal Cavalcante-Neto

    2011-12-01

    random-regression, single-characteristic animal model. The fixed and random regressions were represented by continuous functions over the farrowing order, adjusted by third-order Legendre's orthogonal polynomials. To obtain the best modeling for the residual variance, variance heterogeneity was assumed by means of 1 to 7 classes of residual variance. The general analysis model included a contemporary group; the fixed regression coefficients for modeling the population's average trajectory; the random regression coefficients of the direct additive genetic effects both of the litter and of the animal's permanent environment; and the residual random effect. The likelihood-ratio test, Akaike's information criterion, and Schwarz's Bayesian information criterion appointed the model that considered variance homogeneity as being the one that provided the best adjustment to the data used. Overall, the heritabilities obtained were close to zero (0.002 to 0.006. Regarding the permanent environment proportion, different magnitudes were observed for the farrowing order: increasing from the 1st (0.06 to the 5th (0.28 orders and decreasing from there to the 7th order (0.18. The common litter effect presented low values (from 0.01 to 0.02. The use of residual variance homogeneity was more suitable for modeling variances associated to the trait litter size at birth in this data set.

  6. BALANCED SCORECARDS EVALUATION MODEL THAT INCLUDES ELEMENTS OF ENVIRONMENTAL MANAGEMENT SYSTEM USING AHP MODEL

    Directory of Open Access Journals (Sweden)

    Jelena Jovanović

    2010-03-01

    Full Text Available The research is oriented on improvement of environmental management system (EMS using BSC (Balanced Scorecard model that presents strategic model of measurem ents and improvement of organisational performance. The research will present approach of objectives and environmental management me trics involvement (proposed by literature review in conventional BSC in "Ad Barska plovi dba" organisation. Further we will test creation of ECO-BSC model based on business activities of non-profit organisations in order to improve envir onmental management system in parallel with other systems of management. Using this approach we may obtain 4 models of BSC that includ es elements of environmen tal management system for AD "Barska plovidba". Taking into acc ount that implementation and evaluation need long period of time in AD "Barska plovidba", the final choice will be based on 14598 (Information technology - Software product evaluation and ISO 9126 (Software engineering - Product quality using AHP method. Those standards are usually used for evaluation of quality software product and computer programs that serve in organisation as support and factors for development. So, AHP model will be bas ed on evolution criteria based on suggestion of ISO 9126 standards and types of evaluation from two evaluation teams. Members of team & will be experts in BSC and environmental management system that are not em ployed in AD "Barska Plovidba" organisation. The members of team 2 will be managers of AD "Barska Plovidba" organisation (including manage rs from environmental department. Merging results based on previously cr eated two AHP models, one can obtain the most appropriate BSC that includes elements of environmental management system. The chosen model will present at the same time suggestion for approach choice including ecological metrics in conventional BSC model for firm that has at least one ECO strategic orientation.

  7. Lambing Ease is Heritable but not Correlated to Litter Size in Danish Meat Sheep Breeds

    DEFF Research Database (Denmark)

    Sørensen, Anders Christian; Valasek, P; Pedersen, Jørn;

    The aim of this study was to estimate genetic parameters of lambing ease (LE) and litter size (LS) in four common Danish meat sheep breeds. Data from 1990 to 2006 were analysed. A bivariate animal model was used for estimation of genetic parameters. Lambing ease showed a low heritability, both...... the LE and LS was found, which means that selection to improve one trait should not affect the other trait. Lambing ease should therefore be included in the selection criterion....

  8. The interactions between soil-biosphere-atmosphere (ISBA) land surface model multi-energy balance (MEB) option in SURFEXv8 - Part 2: Introduction of a litter formulation and model evaluation for local-scale forest sites

    Science.gov (United States)

    Napoly, Adrien; Boone, Aaron; Samuelsson, Patrick; Gollvik, Stefan; Martin, Eric; Seferian, Roland; Carrer, Dominique; Decharme, Bertrand; Jarlan, Lionel

    2017-04-01

    Land surface models (LSMs) need to balance a complicated trade-off between computational cost and complexity in order to adequately represent the exchanges of energy, water and matter with the atmosphere and the ocean. Some current generation LSMs use a simplified or composite canopy approach that generates recurrent errors in simulated soil temperature and turbulent fluxes. In response to these issues, a new version of the interactions between soil-biosphere-atmosphere (ISBA) land surface model has recently been developed that explicitly solves the transfer of energy and water from the upper canopy and the forest floor, which is characterized as a litter layer. The multi-energy balance (MEB) version of ISBA is first evaluated for three well-instrumented contrasting local-scale sites, and sensitivity tests are performed to explore the behavior of new model parameters. Second, ISBA-MEB is benchmarked against observations from 42 forested sites from the global micro-meteorological network (FLUXNET) for multiple annual cycles.It is shown that ISBA-MEB outperforms the composite version of ISBA in improving the representation of soil temperature, ground, sensible and, to a lesser extent, latent heat fluxes. Both versions of ISBA give comparable results in terms of simulated latent heat flux because of the similar formulations of the water uptake and the stomatal resistance. However, MEB produces a better agreement with the observations of sensible heat flux than the previous version of ISBA for 87.5 % of the simulated years across the 42 forested FLUXNET sites. Most of this improvement arises owing to the improved simulation of the ground conduction flux, which is greatly improved using MEB, especially owing to the forest litter parameterization. It is also shown that certain processes are also modeled more realistically (such as the partitioning of evapotranspiration into transpiration and ground evaporation), even if certain statistical performances are neutral. The

  9. Rainfall timing and poultry litter application rate effects on phosphorus loss in surface runoff.

    Science.gov (United States)

    Schroeder, P D; Radcliffe, D E; Cabrera, M L

    2004-01-01

    Phosphorus (P) in runoff from pastures amended with poultry litter may be a significant contributor to eutrophication of lakes and streams in Georgia and other areas in the southeastern United States. The objectives of this research were to determine the effects of litter application rate and initial runoff timing on the long-term loss of P in runoff from surface-applied poultry litter and to develop equations that predict P loss in runoff under these conditions. Litter application rates of 2, 7, and 13 Mg ha(-1), and three rainfall scenarios applied to 1- x 2-m plots in a 3 x 3 randomized complete block design with three replications. The rainfall scenarios included (i) sufficient rainfall to produce runoff immediately after litter application; (ii) no rainfall for 30 d after litter application; and (iii) small rainfall events every 7 d (5 min at 75 mm h(-1)) for 30 d. Phosphorus loss was greatest from the high litter rate and immediate runoff treatments. Nonlinear regression equations based on the small plot study produced fairly accurate (r(2) = 0.52-0.62) prediction of P concentrations in runoff water from larger (0.75 ha) fields over a 2-yr period. Predicted P concentrations were closest to observed values for events that occurred shortly after litter application, and the relative error in predictions increased with time after litter application. In addition, previously developed equations relating soil test P levels to runoff P concentrations were ineffective in the presence of surface-applied litter.

  10. Forest composition modifies litter dynamics and decomposition in regenerating tropical dry forest.

    Science.gov (United States)

    Schilling, Erik M; Waring, Bonnie G; Schilling, Jonathan S; Powers, Jennifer S

    2016-09-01

    We investigated how forest composition, litter quality, and rainfall interact to affect leaf litter decomposition across three successional tropical dry forests in Costa Rica. We monitored litter stocks and bulk litter turnover in 18 plots that exhibit substantial variation in soil characteristics, tree community structure, fungal communities (including forests dominated by ecto- or arbuscular mycorrhizal host trees), and forest age. Simultaneously, we decomposed three standard litter substrates over a 6-month period spanning an unusually intense drought. Decay rates of standard substrates depended on the interaction between litter identity and forest type. Decomposition rates were correlated with tree and soil fungal community composition as well as soil fertility, but these relationships differed among litter types. In low fertility soils dominated by ectomycorrhizal oak trees, bulk litter turnover rates were low, regardless of soil moisture. By contrast, in higher fertility soils that supported mostly arbuscular mycorrhizal trees, bulk litter decay rates were strongly dependent on seasonal water availability. Both measures of decomposition increased with forest age, as did the frequency of termite-mediated wood decay. Taken together, our results demonstrate that soils and forest age exert strong control over decomposition dynamics in these tropical dry forests, either directly through effects on microclimate and nutrients, or indirectly by affecting tree and microbial community composition and traits, such as litter quality.

  11. Consequences of biodiversity loss for litter decomposition across biomes.

    Science.gov (United States)

    Handa, I Tanya; Aerts, Rien; Berendse, Frank; Berg, Matty P; Bruder, Andreas; Butenschoen, Olaf; Chauvet, Eric; Gessner, Mark O; Jabiol, Jérémy; Makkonen, Marika; McKie, Brendan G; Malmqvist, Björn; Peeters, Edwin T H M; Scheu, Stefan; Schmid, Bernhard; van Ruijven, Jasper; Vos, Veronique C A; Hättenschwiler, Stephan

    2014-05-08

    The decomposition of dead organic matter is a major determinant of carbon and nutrient cycling in ecosystems, and of carbon fluxes between the biosphere and the atmosphere. Decomposition is driven by a vast diversity of organisms that are structured in complex food webs. Identifying the mechanisms underlying the effects of biodiversity on decomposition is critical given the rapid loss of species worldwide and the effects of this loss on human well-being. Yet despite comprehensive syntheses of studies on how biodiversity affects litter decomposition, key questions remain, including when, where and how biodiversity has a role and whether general patterns and mechanisms occur across ecosystems and different functional types of organism. Here, in field experiments across five terrestrial and aquatic locations, ranging from the subarctic to the tropics, we show that reducing the functional diversity of decomposer organisms and plant litter types slowed the cycling of litter carbon and nitrogen. Moreover, we found evidence of nitrogen transfer from the litter of nitrogen-fixing plants to that of rapidly decomposing plants, but not between other plant functional types, highlighting that specific interactions in litter mixtures control carbon and nitrogen cycling during decomposition. The emergence of this general mechanism and the coherence of patterns across contrasting terrestrial and aquatic ecosystems suggest that biodiversity loss has consistent consequences for litter decomposition and the cycling of major elements on broad spatial scales.

  12. Interactions of tissue and fertilizer nitrogen on decomposition dynamics of lignin-rich conifer litter

    Science.gov (United States)

    Perakis, Steven S.; Matkins, Joselin J.; Hibbs, David E.

    2012-01-01

    yet accelerate N release differs from findings where litter quality variation across species promotes coupled C and N release during decomposition. We suggest reevaluation of ecosystem models and projected global change effects to account for a potential decoupling of ecosystem C and N feedbacks through litter decomposition in lignin-rich conifer forests.

  13. Direct and indirect effects of UV-B exposure on litter decomposition: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Xinzhang Song

    Full Text Available Ultraviolet-B (UV-B exposure in the course of litter decomposition may have a direct effect on decomposition rates via changing states of photodegradation or decomposer constitution in litter while UV-B exposure during growth periods may alter chemical compositions and physical properties of plants. Consequently, these changes will indirectly affect subsequent litter decomposition processes in soil. Although studies are available on both the positive and negative effects (including no observable effects of UV-B exposure on litter decomposition, a comprehensive analysis leading to an adequate understanding remains unresolved. Using data from 93 studies across six biomes, this introductory meta-analysis found that elevated UV-B directly increased litter decomposition rates by 7% and indirectly by 12% while attenuated UV-B directly decreased litter decomposition rates by 23% and indirectly increased litter decomposition rates by 7%. However, neither positive nor negative effects were statistically significant. Woody plant litter decomposition seemed more sensitive to UV-B than herbaceous plant litter except under conditions of indirect effects of elevated UV-B. Furthermore, levels of UV-B intensity significantly affected litter decomposition response to UV-B (P<0.05. UV-B effects on litter decomposition were to a large degree compounded by climatic factors (e.g., MAP and MAT (P<0.05 and litter chemistry (e.g., lignin content (P<0.01. Results suggest these factors likely have a bearing on masking the important role of UV-B on litter decomposition. No significant differences in UV-B effects on litter decomposition were found between study types (field experiment vs. laboratory incubation, litter forms (leaf vs. needle, and decay duration. Indirect effects of elevated UV-B on litter decomposition significantly increased with decay duration (P<0.001. Additionally, relatively small changes in UV-B exposure intensity (30% had significant direct effects

  14. The Influence of Plant Litter on Soil Water Repellency: Insight from 13C NMR Spectroscopy.

    Science.gov (United States)

    Cesarano, Gaspare; Incerti, Guido; Bonanomi, Giuliano

    2016-01-01

    Soil water repellency (SWR, i.e. reduced affinity for water owing to the presence of organic hydrophobic coatings on soil particles) has relevant hydrological implications because low rates of infiltration enhance water runoff, and untargeted diffusion of fertilizers and pesticides. Previous studies investigated the occurrence of SWR in ecosystems with different vegetation cover but did not clarify its relationships with litter biochemical quality. Here, we investigated the capability of different plant litter types to induce SWR by using fresh and decomposed leaf materials from 12 species, to amend a model sandy soil over a year-long microcosm experiment. Water repellency, measured by the Molarity of an Ethanol Droplet (MED) test, was tested for the effects of litter species and age, and compared with litter quality assessed by 13C-CPMAS NMR in solid state and elemental chemical parameters. All litter types were highly water repellent, with MED values of 18% or higher. In contrast, when litter was incorporated into the soil, only undecomposed materials induced SWR, but with a large variability of onset and peak dynamics among litter types. Surprisingly, SWR induced by litter addition was unrelated to the aliphatic fraction of litter. In contrast, lignin-poor but labile C-rich litter, as defined by O-alkyl C and N-alkyl and methoxyl C of 13C-CPMAS NMR spectral regions, respectively, induced a stronger SWR. This study suggests that biochemical quality of plant litter is a major controlling factor of SWR and, by defining litter quality with 13C-CPMAS NMR, our results provide a significant novel contribution towards a full understanding of the relationships between plant litter biochemistry and SWR.

  15. Indirect effects of precipitation variation on the decomposition process of Mongolian oak (Quercus mongolica) leaf litter

    Institute of Scientific and Technical Information of China (English)

    LI Xuefeng; HAN Shijie; ZHANG Yan

    2007-01-01

    The effect of precipitation variation on the chemistry of Mongolian oak(Quercus mongolica)leaf litters was examined by analyzing litters of Mongolia oak saplings under four precipitation gradients.The decomposing process of these leaf litters in the Mongolian oak dominated forest was assessed using litter bag method.Compared with the litters of the Mongolian oak saplings from the natural precipitation site(A),litters produced by Mongolian oak from the driest precipitation gradient(A450)had significantly higher concentrations of nitrogen(N),phosphorus(P)and potassium(K)while lower acid-insoluble fraction(A/F)concentration.The decomposition study showed that A450 exhibited significantly higher decomposition rate,mineralization rates of N,P and K as well as much shorter N and P net immobilization periods.On the contrary,litters produced by seedlings from wettest gradient(Ass0)showed a totally opposite pattern.Litters from saplings that received comparable precipitation(A650)to those at the natural site(A)had significantly higher N concentration and faster decomposition rate as well as release rates of N,P and K.The mass loss patterns for the four litter types fitted the exponential model and the decay constant(k)can be well predicted by initial AIF/N.During the decomposition period,N concentration was best related to the percentage of mass remaining of the litters with relatively higher AIF concentrations and lower N concentrations,but the percentage of mass remaining of litters with lower AIF concentrations and higher N concentrations correlates strongly with AIF concentration.Our study proved that changes in precipitation significantly altered the litter quality,and therefore indirectly changed the decay process of leaf litters.

  16. The Influence of Plant Litter on Soil Water Repellency: Insight from 13C NMR Spectroscopy.

    Directory of Open Access Journals (Sweden)

    Gaspare Cesarano

    Full Text Available Soil water repellency (SWR, i.e. reduced affinity for water owing to the presence of organic hydrophobic coatings on soil particles has relevant hydrological implications because low rates of infiltration enhance water runoff, and untargeted diffusion of fertilizers and pesticides. Previous studies investigated the occurrence of SWR in ecosystems with different vegetation cover but did not clarify its relationships with litter biochemical quality. Here, we investigated the capability of different plant litter types to induce SWR by using fresh and decomposed leaf materials from 12 species, to amend a model sandy soil over a year-long microcosm experiment. Water repellency, measured by the Molarity of an Ethanol Droplet (MED test, was tested for the effects of litter species and age, and compared with litter quality assessed by 13C-CPMAS NMR in solid state and elemental chemical parameters. All litter types were highly water repellent, with MED values of 18% or higher. In contrast, when litter was incorporated into the soil, only undecomposed materials induced SWR, but with a large variability of onset and peak dynamics among litter types. Surprisingly, SWR induced by litter addition was unrelated to the aliphatic fraction of litter. In contrast, lignin-poor but labile C-rich litter, as defined by O-alkyl C and N-alkyl and methoxyl C of 13C-CPMAS NMR spectral regions, respectively, induced a stronger SWR. This study suggests that biochemical quality of plant litter is a major controlling factor of SWR and, by defining litter quality with 13C-CPMAS NMR, our results provide a significant novel contribution towards a full understanding of the relationships between plant litter biochemistry and SWR.

  17. Litter chemistry prevails over litter consumers in mediating effects of past steel industry activities on leaf litter decomposition.

    Science.gov (United States)

    Lucisine, Pierre; Lecerf, Antoine; Danger, Michaël; Felten, Vincent; Aran, Delphine; Auclerc, Apolline; Gross, Elisabeth M; Huot, Hermine; Morel, Jean-Louis; Muller, Serge; Nahmani, Johanne; Maunoury-Danger, Florence

    2015-12-15

    Soil pollution has adverse effects on the performance and life history traits of microorganisms, plants, and animals, yet evidence indicates that even the most polluted sites can support structurally-complex and dynamic ecosystems. The present study aims at determining whether and how litter decomposition, one of the most important soil ecological processes leaf, is affected in a highly trace-metal polluted site. We postulated that past steel mill activities resulting in soil pollution and associated changes in soil characteristics would influence the rate of litter decomposition through two non-exclusive pathways: altered litter chemistry and responses of decomposers to lethal and sub-lethal toxic stress. We carried out a litter-bag experiment using Populus tremula L. leaf litter collected at, and allowed to decompose in, a trace metal polluted site and in three unpolluted sites used as controls. We designed a fully-factorial transplant experimental design to assess effects of litter origin and exposure site on the rate of litter decomposition. We further determined initial litter chemistry, fungal biomass, mesofauna abundance in litter bags, and the soil macrofauna community. Irrespective of the site of litter exposure, litter originating from the polluted site had a two-fold faster decomposition than litter from the unpolluted sites. Litter chemistry, notably the lignin content, seemed most important in explaining the degradation rate of the leaf litter. Abundance of meso and macro-detritivores was higher at the polluted site than at the unpolluted sites. However, litter decomposition proceeded at similar rates in polluted and unpolluted sites. Our results show that trace metal pollution and associated soil and litter changes do not necessarily weaken consumer control on litter decomposition through lethal and sub-lethal toxic stress.

  18. Smart Voyage Planning Model Sensitivity Analysis Using Ocean and Atmospheric Models Including Ensemble Methods

    Science.gov (United States)

    2012-09-01

    ATMOSPHERIC MODELS INCLUDING ENSEMBLE METHODS Scott E. Miller Lieutenant Commander, United States Navy B.S., University of South Carolina, 2000 B.S...Typical gas turbine fuel consumption curve and relationship to sea state .......51  Figure 16.  DDG 58 speed reduction curves for bow seas...Day Time Group ECDIS-N Electronic Chart Display and Information System – Navy ECMWF European Center for Medium Range Weather Forecasts EFAS

  19. Arsenic species in broiler (Gallus gallus domesticus) litter, soils, maize (Zea mays L.), and groundwater from litter-amended fields.

    Science.gov (United States)

    D'Angelo, Elisa; Zeigler, Georgia; Beck, E Glenn; Grove, John; Sikora, Frank

    2012-11-01

    Manure and bedding material (litter) generated by the broiler industry (Gallus gallus domesticus) often contain high levels of arsenic (As) when organoarsenical roxarsone and p-arsanilic acid are included in feed to combat disease and improve weight gain of the birds. This study was conducted to determine As levels and species in litter from three major broiler producing companies, and As levels in soils, corn tissue (Zea mays L.), and groundwater in fields where litter was applied. Total As in litter from the three different integrators ranged between bioavailable As (extractable with Mehlich 3 solution and taken up by corn leaves). Arsenic concentrations in plant tissue and groundwater, however, were below the World Health Organization thresholds, which was attributed to strong sorption/precipitation of arsenate in Fe- and Al-rich soils. Ecological impacts of amending soils with As-laden litter depend on the As species in the litter, and chemical and physical properties of soil that strongly affect As mobility and bioavailability in the environment. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Highly consistent effects of plant litter identity and functional traits on decomposition across a latitudinal gradient.

    Science.gov (United States)

    Makkonen, Marika; Berg, Matty P; Handa, I Tanya; Hättenschwiler, Stephan; van Ruijven, Jasper; van Bodegom, Peter M; Aerts, Rien

    2012-09-01

    Plant litter decomposition is a key process in terrestrial carbon cycling, yet the relative importance of various control factors remains ambiguous at a global scale. A full reciprocal litter transplant study with 16 litter species that varied widely in traits and originated from four forest sites covering a large latitudinal gradient (subarctic to tropics) showed a consistent interspecific ranking of decomposition rates. At a global scale, variation in decomposition was driven by a small subset of litter traits (water saturation capacity and concentrations of magnesium and condensed tannins). These consistent findings, that were largely independent of the varying local decomposer communities, suggest that decomposer communities show little specialisation and high metabolic flexibility in processing plant litter, irrespective of litter origin. Our results provide strong support for using trait-based approaches in modelling the global decomposition component of biosphere-atmosphere carbon fluxes. © 2012 Blackwell Publishing Ltd/CNRS.

  1. Improved Subseasonal Prediction with Advanced Coupled Models including the 30km FIM-HYCOM Coupled Model

    Science.gov (United States)

    Benjamin, Stan; Sun, Shan; Grell, Georg; Green, Benjamin; Bleck, Rainer; Li, Haiqin

    2017-04-01

    Extreme events for subseasonal duration have been linked to multi-week processes related to onset, duration, and cessation of blocking events or, more generally, quasi-stationary waves. Results will be shown from different sets of 32-day prediction experiments (3200 runs each) over a 16-year period for earth system processes key for subseasonal prediction for different resolution, numerics, and physics using the FIM-HYCOM coupled model. The coupled atmosphere (FIM) and ocean (HYCOM) modeling system is a relatively new coupled atmosphere-ocean model developed for subseasonal to seasonal prediction (Green et al. 2017 Mon.Wea.Rev. accepted, Bleck et al 2015 Mon. Wea. Rev.). Both component models operate on a common icosahedral horizontal grid and use an adaptive hybrid vertical coordinate (sigma-isentropic in FIM and sigma-isopycnic in HYCOM). FIM-HYCOM has been used to conduct 16 years of subseasonal retrospective forecasts following the NOAA Subseasonal (SubX) NMME protocol (32-day forward integrations), run with 4 ensemble members per week. Results from this multi-year FIM-HYCOM hindcast include successful forecasts out to 14-20 days for stratospheric warming events (from archived 10 hPa fields), improved MJO predictability (Green et al. 2017) using the Grell-Freitas (2014, ACP) scale-aware cumulus scheme instead of the Simplified Arakawa-Schubert scheme, and little sensitivity to resolution for blocking frequency. Forecast skill of metrics from FIM-HYCOM including 500 hPa heights and MJO index is at least comparable to that of the operational Climate Forecast System (CFSv2) used by the National Centers for Environmental Prediction. Subseasonal skill is improved with a limited multi-model (FIM-HYCOM and CFSv2), consistent with previous seasonal multi-model ensemble results. Ongoing work will also be reported on for adding inline aerosol/chemistry treatment to the coupled FIM-HYCOM model and for advanced approaches to subgrid-scale clouds to address regional biases

  2. Supplying dextrose before insemination and L-arginine during the last third of pregnancy in sow diets: effects on within-litter variation of piglet birth weight.

    Science.gov (United States)

    Quesnel, H; Quiniou, N; Roy, H; Lottin, A; Boulot, S; Gondret, F

    2014-04-01

    Preweaning piglet mortality is largely attributed to the incidence of low birth weight and birth weight variation within the litter. Therefore, developing strategies to increase within-litter uniformity of piglet birth weight is important. This study investigated the effects of different feeding strategies based on specific nutrient supplies in sow diet on the within-litter variation of piglet birth weight (BW0). Four batches of highly prolific crossbred Landrace × Large White sows were used. Three dietary treatments were compared: supplies of dextrose during the week before insemination (190 g/d) and of L-arginine (25.5 g/d) from d 77 of pregnancy until term (DEXA, n = 26); a dietary supplementation of L-arginine only (25.5 g/d), from d 77 of pregnancy until term (ARGI, n = 24); and no supplementation to a standard gestation diet (CTL; n = 23). Total born piglets (TB), i.e., piglets born alive (BA) and stillborn piglets, were numbered and weighed at birth and at weaning. Data were analyzed by ANOVA using the MIXED procedure in a model that included dietary treatment (ARGI, DEXA, and CTL), initial parity (1, 2 and 3, 4, and more), and backfat thickness (below or above the average value at the onset of the experiment: 15.7 mm) as the main effects and batch as random effect. The treatment did not influence (P > 0.10) the number of piglets at birth (on average 15.6 ± 3.8 and 14.2 ± 3.6 for TB and BA, respectively) or piglet BW0 (on average 1.48 ± 0.26 and 1.50 ± 0.26 kg for TB and BA, respectively). The coefficient of variation of piglet BW0 (CV(BW0)) was less in litters from ARGI sows than in litters from CTL sows and intermediate in litters from DEXA sows (for TB: 21.4, 23.4, and 25.7%, P = 0.08; for BA: 20.6, 22.5, and 25.4%, P = 0.03, in the ARGI, DEXA, and CTL groups, respectively). Irrespective of diet, CV(BW0) was less (P piglets or less than in the largest litters (20.9 vs. 26.5%). Litter growth rate during lactation and litter size at weaning were not

  3. 46 CFR 108.709 - Litter.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Litter. 108.709 Section 108.709 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Miscellaneous Equipment § 108.709 Litter. Each unit must have a litter that is— (a) Stowed in a location that...

  4. Influence of packaging design on littering behavior

    NARCIS (Netherlands)

    Wever, R.

    2006-01-01

    Litter is an environmental and social problem that is closely related to packaging. Many attempts have been made to reduce litter. So far these attempts have mainly focused on influencing littering behavior either through general campaigns or through manipulating the environment. The latter might be

  5. Influence of packaging design on littering behavior

    NARCIS (Netherlands)

    Wever, R.

    2006-01-01

    Litter is an environmental and social problem that is closely related to packaging. Many attempts have been made to reduce litter. So far these attempts have mainly focused on influencing littering behavior either through general campaigns or through manipulating the environment. The latter might be

  6. Methane, nitrous oxide and ammonia emissions from pigs housed on litter and from stockpiling of spent litter

    KAUST Repository

    Phillips, F. A.

    2016-05-05

    Mitigation of agricultural greenhouse gas emissions is a target area for the Australian Government and the pork industry. The present study measured methane (CH4), nitrous oxide (N2O) and ammonia (NH3) from a deep-litter piggery and litter stockpile over two trials in southern New South Wales, to compare emissions from housing pigs on deep litter with those of pigs from conventional housing with uncovered anaerobic effluent-treatment ponds. Emissions were measured using open-path Fourier transform infrared spectrometry, in conjunction with a backward Lagrangian stochastic model. Manure excretion was determined by mass balance and emission factors (EFs) were developed to report emissions relative to volatile solids and nitrogen (N) input. Nitrous oxide emissions per animal unit (1 AU ≤ 500 kg liveweight) from deep-litter sheds were negligible in winter, and 8.4 g/AU.day in summer. Ammonia emissions were 39.1 in winter and 52.2 g/AU.day in summer, while CH4 emissions were 16.1 and 21.6 g/AU.day in winter and summer respectively. Emission factors averaged from summer and winter emissions showed a CH4 conversion factor of 3.6%, an NH3-N EF of 10% and a N2O-N EF of 0.01 kg N2O-N/kg N excreted. For the litter stockpile, the simple average of summer and winter showed an EF for NH3-N of 14%, and a N2O-N EF of 0.02 kg N2O-N/kg-N of spent litter added to the stockpile. We observed a 66% and 80% decrease in emissions from the manure excreted in litter-based housing with litter stockpiling or without litter stockpiling, compared with conventional housing with an uncovered anaerobic effluent-treatment pond. This provides a sound basis for mitigation strategies that utilise litter-based housing as an alternative to conventional housing with uncovered anaerobic effluent-treatment ponds. © CSIRO 2016.

  7. Transcriptomic Analysis of Ovaries from Pigs with High And Low Litter Size.

    Directory of Open Access Journals (Sweden)

    Xiaodong Zhang

    Full Text Available Litter size is one of the most important economic traits for pig production as it is directly related to the production efficiency. Litter size is affected by interactions between multiple genes and the environment. While recent studies have identified some genes associated with prolificacy in pigs, transcriptomic studies of specific genes affecting litter size in porcine ovaries are rare. In order to identify candidate genes associated with litter size in swine, we assessed gene expression differences between the ovaries of Yorkshire pigs with extremely high and low litter sizes using the RNA-Seq method. A total of 1 243 differentially expressed genes were identified: 897 genes were upregulated and 346 genes were downregulated in high litter size ovary samples compared with low litter size ovary samples. A large number of these genes related to steroid hormone regulation in animal ovaries, including 59 Gene Ontology terms and 27 Kyoto Encyclopedia of Genes and Genomes pathways involved in steroid biosynthesis and ovarian steroidogenesis. From these differentially expressed genes, we identified a total of 11 genes using a bioinformatics screen that may be associated with high litter size in Yorkshire pigs. These results provide a list of new candidate genes for porcine litter size and prolificacy to be further investigated.

  8. Proceedings: Community Leader's Litter Control Workshop (Painesville, Ohio, December 2, 1981). Bulletin 694.

    Science.gov (United States)

    Rohrer, John D., Ed.; Heimlich, Joe E., Ed.

    Proceedings from a workshop for community leaders on litter control held in Painesville, Ohio on December 2, 1981 are presented. Complete and abbreviated texts of the different sessions provide an overview of litter control information, issues, and programs in Ohio. Topics covered include results from a statewide study of the amount and content of…

  9. Litter Fall and Energy Flux in a Mangrove Ecosystem

    Science.gov (United States)

    Wafar, S.; Untawale, A. G.; Wafar, M.

    1997-01-01

    Production, elemental composition and in situdecomposition of litter of Rhizophora apiculata, R. mucronata, Sonneratia albaand Avicenna officinaliswere studied in a mangrove ecosystem fringing Madovi-Zuari Estuaries on the Central West Coast of India. Litter yield ranged from 10.2 tonnes ha -1year -1in A. officinalisthrough 11.8 ( R. apiculataand R. mucronata) to 17 tonnes ha -1year -1in S. alba. Seasonally maximum litter fall was in pre- and post-monsoon monthe, with the lowest production in the monsoon. Modelling of litter fall as a function of Julian day and six environmental parameters showed that the observed changes can be explained in terms of dry/wet season and wind speed, with a 1000. Total decomposition (98-100% loss in dry weight and C, and >90% loss in N and P) of yellow leaves was within 15 weeks in the two Rhizosporaspp. and S. alba, and within 8 weeks in A. officinalis. In all four species, mass changes during decomposition obeyed first-order kinetics. Comparison of C, N and P fluxes from the decomposing mangrove litter with phytoplankton, bacterial and secondary production in the estuarine waters showed that mangrove production is important mainly for the C budget of the Estuaries and in sustaining the microbial food chain and nutrient regeneration, rather than the particulate food chain directly.

  10. Observations of mixed-aged litters in brown bears

    Science.gov (United States)

    Swenson, J.E.; Haroldson, M.A.

    2008-01-01

    We report on 3 cases of mixed-aged litters (young born in different years) in brown bears (Ursus arctos); in 1 instance the cub-of-the-year (hereafter called cubs) died in the den. Two cases occurred in Sweden after mothers were separated from their young during the breeding season. In one, the mother was separated from the accompanying cub for at least 12.5 hours and possibly up to 3.3 days, and later possibly separated for 4 days. In the other, the mother was separated from her yearling at least 3 times for 1-14, 1-6 and 1-6 days. She was with a male during the first separation. Specific events that produced the mixed-aged litter observed in Greater Yellowstone Ecosystem were unknown and our interpretation is based on estimates of ages of accompanying young from photographs. The observation of only 2 mixed-aged litters, after den emergence, from a sample of 406 observed cub litters accompanying radiomarked females confirms the rarity of this phenomenon. The mechanism apparently includes a short separation of mother and young, and, in the case of cubs, the mother must mate while lactating. Better understanding of the physiological mechanisms that allow mixed-age litters would help us in the debate about the occurrence of sexually selected infanticide in bears.

  11. Role of arthropod communities in bioenergy crop litter decomposition†.

    Science.gov (United States)

    Zangerl, Arthur R; Miresmailli, Saber; Nabity, Paul; Lawrance, Allen; Yanahan, Alan; Mitchell, Corey A; Anderson-Teixeira, Kristina J; David, Mark B; Berenbaum, May R; DeLucia, Evan H

    2013-10-01

    The extensive land use conversion expected to occur to meet demands for bioenergy feedstock production will likely have widespread impacts on agroecosystem biodiversity and ecosystem services, including carbon sequestration. Although arthropod detritivores are known to contribute to litter decomposition and thus energy flow and nutrient cycling in many plant communities, their importance in bioenergy feedstock communities has not yet been assessed. We undertook an experimental study quantifying rates of litter mass loss and nutrient cycling in the presence and absence of these organisms in three bioenergy feedstock crops-miscanthus (Miscanthus x giganteus), switchgrass (Panicum virgatum), and a planted prairie community. Overall arthropod abundance and litter decomposition rates were similar in all three communities. Despite effective reduction of arthropods in experimental plots via insecticide application, litter decomposition rates, inorganic nitrogen leaching, and carbon-nitrogen ratios did not differ significantly between control (with arthropods) and treatment (without arthropods) plots in any of the three community types. Our findings suggest that changes in arthropod faunal composition associated with widespread adoption of bioenergy feedstock crops may not be associated with profoundly altered arthropod-mediated litter decomposition and nutrient release.

  12. Influence of breed on postweaning litter growth and litter feed efficiency of meat rabbits%品种对肉兔断奶后窝生长性状的影响

    Institute of Scientific and Technical Information of China (English)

    张翔宇; 李丛艳; 邝良德; 郑洁; 张翠霞

    2013-01-01

    本研究旨在明确影响肉兔断奶后窝生长性状和料肉比的重要因素.利用一般线性模型分析了来自5个不同肉兔品种(新西兰白兔,加利福尼亚兔,比利时兔,青紫蓝兔和福建黄兔)的909只173窝肉兔断奶后窝生长和料肉比性状.结果表明,品种和断奶数对断奶窝重(5周龄窝重),窝增重,窝上市体重(10周龄窝重),个体平均上市体重,窝采食量和料肉比的影响极显著(P<0.01).出生月份对窝采食量影响极显著(P<0.01),对断奶窝重和窝上市体重的影响显著(P<0.05).比利时兔的断奶窝重、窝增重、窝上市体重、窝采食量和平均上市体重显著高于其他品种,而福建黄兔的上述5项指标显著低于其他品种(P<0.05).断奶数与断奶窝重、窝采食量、窝增重、窝上市体重和料肉比的回归系数为正且显著.品种、断奶数和出生月份是影响肉兔断奶后窝性状和料肉比的重要因素.本研究的结果为将比利时兔作为杂交的终端父本提供重要依据.%The major factors influencing post-weaning litter growth and litter feed efficiency were analyzed with the General Linear Model (GLM) using 909 meat rabbits, from 173 litters representing 5 breeds (New Zealand White, Californian, Flemish Giant, Chinchilla, and Fujian Yellow). Breed and number weaned per litter had a significant effect on litter weaning weight at 5 weeks, litter weight gain, litter market weight at 10 weeks, average market weight, litter feed intake, and litter feed efficiency (P<0. 01). Month of birth had a significant (P<0. 01) difference on litter feed intake and on litter weaning weight and litter market weight (P<0. 05). Litter weaning weight, litter weight gain, litter market weight and average market weight were heavier and litter feed intake was higher in Flemish Giant litters than in other breed litters (P<0. 05). However, the five traits mentioned above were lower in Fujian Yellow litters than in other breed

  13. The abiotic litter decomposition in the drylands

    Science.gov (United States)

    Lee, H.; Throop, H.; Rahn, T. A.

    2009-12-01

    The decomposition of litter is an important ecosystem function that controls carbon and nutrient cycling, which is well understood from the relationship between temperature and moisture. However, the decomposition in the arid and semiarid environments (hereafter drylands) is relatively poorly predicted due to several abiotic factors such as the effect of ultraviolet radiation and physical mixing of fallen litter with soil. The relative magnitude of these abiotic factors to ecosystem scale litter decomposition is still in debate. Here, we examine the effect of two major abiotic factors in the drylands litter decomposition by conducting a controlled laboratory study using plant litter and soil collected from Sonoran and Chihuahuan desert areas. The first part of the experiment focused on the effect of soil-litter mixing. We established a complete block design of three levels of soil and litter mixing (no mixing, light soil-litter mixing, and complete soil-litter mixing) in combination with three levels of soil moisture (1%, 2%, and 6% volumetric water content) using 2g of two most dominant species litter, grass and mesquite, and 50g of air-dried soils in 500ml mason jar and incubated them under 25C. We measured CO2 fluxes from these soil-litter incubations and harvested the soil and litter at 0, 1, 2, 4, 8, and 16 weeks and analyzed them of carbon and nitrogen content as well as the actual mass loss in the litter. The second part of the experiment focused on the effect of ultraviolet radiation. We established short-term litter incubation on a quartz chamber and used different temperature, moisture, and minerals to find the mechanism of photodegradation of litter. We measured CO2 fluxes from the litter incubation under ultraviolet radiation and also measured 13CO2 from these emissions. We were able to detect changes in the rate of carbon mineralization as a result of our treatments in the first week of soil-litter mixing experiment. The carbon mineralization rate was

  14. Factors influencing litter size and puppy losses in the Entlebucher Mountain dog.

    Science.gov (United States)

    Schrack, J; Dolf, G; Reichler, I M; Schelling, C

    2017-06-01

    A good reproductive performance is a central element of animal breeding. The breeders of Entlebucher Mountain dogs observed a decrease of the mean litter size and an increase of the number of unsuccessful matings in the past years. The aim of the present study was to identify factors with an influence on fertility in this breed. In total, 915 litters from 202 sires and 348 dams from 1986 to 2013 entered the analyses. The total puppy losses (7.4%) reduced the mean litter size at birth of 5.49 ± 2.13 to a mean litter size at registration of 5.08 ± 2.05. There was no deviation from the expected equal sex distribution for puppies at birth and at registration, as well as for puppy losses consisting of stillborn puppies and puppies which died or had to be euthanized before registration. The mean annual litter inbreeding coefficient increased from 0.37 in 1986 to 0.40 in 2013 and was correlated with the year of birth of the litter (Kendall's tau b = 0.46). The age of the dam and parental inbreeding were identified as significant predictors with a negative effect on litter size at birth. For the litter size at registration the age and inbreeding of the dam had a significant negative effect and a 1% increase of dam inbreeding is expected to decrease the litter size at birth and registration by 0.1 and 0.09 puppies, respectively. The occurrence of total puppy losses decreased during the years and was more frequent in larger litters. In addition, in litters of older parents the occurrence of puppy losses was more frequent than in litters from younger parents. The final generalized linear mixed-effects models for litter size at birth, litter size at registration and for total puppy losses explained 36%, 33% and 22% of the total variance, respectively. The impact of inbreeding and parental age on fertility of the Entlebucher Mountain dog was small and the influence of the dam was much bigger than the one of the sire. Other factors must be responsible for the variability

  15. Shrub encroachment in Arctic tundra: Betula nana effects on above- and below-ground litter decomposition.

    Science.gov (United States)

    McLaren, Jennie R; Buckeridge, Kate M; van de Weg, Martine J; Shaver, Gaius R; Schimel, Joshua P; Gough, Laura

    2017-03-06

    Rapid arctic vegetation change as a result of global warming includes an increase in the cover and biomass of deciduous shrubs. Increases in shrub abundance will result in a proportional increase of shrub litter in the litter community, potentially affecting carbon turnover rates in arctic ecosystems. We investigated the effects of leaf and root litter of a deciduous shrub, Betula nana, on decomposition, by examining species-specific decomposition patterns, as well as effects of Betula litter on the decomposition of other species. We conducted a two-year decomposition experiment in moist acidic tundra in northern Alaska, where we decomposed three tundra species (Vaccinium vitis-idaea, Rhododendron palustre, and Eriophorum vaginatum) alone and in combination with Betula litter. Decomposition patterns for leaf and root litter were determined using three different measures of decomposition (mass loss, respiration, extracellular enzyme activity). We report faster decomposition of Betula leaf litter compared to other species, with support for species differences coming from all three measures of decomposition. Mixing effects were less consistent among the measures, with negative mixing effects shown only for mass loss. In contrast, there were few species differences or mixing effects for root decomposition. Overall, we attribute longer-term litter mass loss patterns in to patterns created by early decomposition processes in the first winter. We note numerous differences for species patterns between leaf and root decomposition, indicating that conclusions from leaf litter experiments should not be extrapolated to below-ground decomposition. The high decomposition rates of Betula leaf litter aboveground, and relatively similar decomposition rates of multiple species below, suggest a potential for increases in turnover in the fast-decomposing carbon pool of leaves and fine roots as the dominance of deciduous shrubs in the Arctic increases, but this outcome may be tempered

  16. ATEFlap aerodynamic model, a dynamic stall model including the effects of trailing edge flap deflection

    Energy Technology Data Exchange (ETDEWEB)

    Bergami, L.; Gaunaa, M.

    2012-02-15

    The report presents the ATEFlap aerodynamic model, which computes the unsteady lift, drag and moment on a 2D airfoil section equipped with Adaptive Trailing Edge Flap. The model captures the unsteady response related to the effects of the vorticity shed into the wake, and the dynamics of flow separation a thin-airfoil potential flow model is merged with a dynamic stall model of the Beddoes-Leishmann type. The inputs required by the model are steady data for lift, drag, and moment coefficients as function of angle of attack and flap deflection. Further steady data used by the Beddoes- Leishmann dynamic stall model are computed in an external preprocessor application, which gives the user the possibility to verify, and eventually correct, the steady data passed to the aerodynamic model. The ATEFlap aerodynamic model is integrated in the aeroelastic simulation tool HAWC2, thus al- lowing to simulate the response of a wind turbine with trailing edge flaps on the rotor. The algorithms used by the preprocessor, and by aerodynamic model are presented, and modifications to previous implementations of the aerodynamic model are briefly discussed. The performance and the validity of the model are verified by comparing the dynamic response computed by the ATEFlap with solutions from CFD simulations. (Author)

  17. Estimating litter carbon stocks on forest land in the United States.

    Science.gov (United States)

    Domke, Grant M; Perry, Charles H; Walters, Brian F; Woodall, Christopher W; Russell, Matthew B; Smith, James E

    2016-07-01

    Forest ecosystems are the largest terrestrial carbon sink on earth, with more than half of their net primary production moving to the soil via the decomposition of litter biomass. Therefore, changes in the litter carbon (C) pool have important implications for global carbon budgets and carbon emissions reduction targets and negotiations. Litter accounts for an estimated 5% of all forest ecosystem carbon stocks worldwide. Given the cost and time required to measure litter attributes, many of the signatory nations to the United Nations Framework Convention on Climate Change report estimates of litter carbon stocks and stock changes using default values from the Intergovernmental Panel on Climate Change or country-specific models. In the United States, the country-specific model used to predict litter C stocks is sensitive to attributes on each plot in the national forest inventory, but these predictions are not associated with the litter samples collected over the last decade in the national forest inventory. Here we present, for the first time, estimates of litter carbon obtained using more than 5000 field measurements from the national forest inventory of the United States. The field-based estimates mark a 44% reduction (2081±77Tg) in litter carbon stocks nationally when compared to country-specific model predictions reported in previous United Framework Convention on Climate Change submissions. Our work suggests that Intergovernmental Panel on Climate Change defaults and country-specific models used to estimate litter carbon in temperate forest ecosystems may grossly overestimate the contribution of this pool in national carbon budgets.

  18. Soil and Litter Animals.

    Science.gov (United States)

    Lippert, George

    1991-01-01

    A lesson plan for soil study utilizes the Tullgren extraction method to illustrate biological concepts. It includes background information, equipment, collection techniques, activities, and references for identification guides about soil fauna. (MCO)

  19. Importance of global aerosol modeling including secondary organic aerosol formed from monoterpene

    OpenAIRE

    Goto, Daisuke; Takemura, Toshihiko; Nakajima, Teruyuki

    2008-01-01

    A global three-dimensional aerosol transport-radiation model, coupled to an atmospheric general circulation model (AGCM), has been extended to improve the model process for organic aerosols, particularly secondary organic aerosols (SOA), and to estimate SOA contributions to direct and indirect radiative effects. Because the SOA formation process is complicated and unknown, the results in different model simulations include large differences. In this work, we simulate SOA production assuming v...

  20. MODEL ANALYSIS AND PARAMETER EXTRACTION FOR MOS CAPACITOR INCLUDING QUANTUM MECHANICAL EFFECTS

    Institute of Scientific and Technical Information of China (English)

    Hai-yan Jiang; Ping-wen Zhang

    2006-01-01

    The high frequency CV curves of MOS capacitor have been studied. It is shown that semiclassical model is a good approximation to quantum model and approaches to classical model when the oxide layer is thick. This conclusion provides us an efficient (semiclassical) model including quantum mechanical effects to do parameter extraction for ultrathi noxide device. Here the effective extracting strategy is designed and numerical experiments demonstrate the validity of the strategy.

  1. A finite element model of the face including an orthotropic skin model under in vivo tension.

    Science.gov (United States)

    Flynn, Cormac; Stavness, Ian; Lloyd, John; Fels, Sidney

    2015-01-01

    Computer models of the human face have the potential to be used as powerful tools in surgery simulation and animation development applications. While existing models accurately represent various anatomical features of the face, the representation of the skin and soft tissues is very simplified. A computer model of the face is proposed in which the skin is represented by an orthotropic hyperelastic constitutive model. The in vivo tension inherent in skin is also represented in the model. The model was tested by simulating several facial expressions by activating appropriate orofacial and jaw muscles. Previous experiments calculated the change in orientation of the long axis of elliptical wounds on patients' faces for wide opening of the mouth and an open-mouth smile (both 30(o)). These results were compared with the average change of maximum principal stress direction in the skin calculated in the face model for wide opening of the mouth (18(o)) and an open-mouth smile (25(o)). The displacements of landmarks on the face for four facial expressions were compared with experimental measurements in the literature. The corner of the mouth in the model experienced the largest displacement for each facial expression (∼11-14 mm). The simulated landmark displacements were within a standard deviation of the measured displacements. Increasing the skin stiffness and skin tension generally resulted in a reduction in landmark displacements upon facial expression.

  2. Association between litterers' profile and littering behavior: A chi-square approach

    Science.gov (United States)

    Asmui, Mas'udah; Zaki, Suhanom Mohd; Wahid, Sharifah Norhuda Syed; Mokhtar, Noorsuraya Mohd; Harith, Siti Suhaila

    2017-05-01

    Littering is not a novelty, yet a prolonged issue. The solutions have been discussed for a long time; however this issue still remains unresolved. Littering is commonly associated with littering behavior and awareness. The littering behavior is normally influenced by the litter profile such as gender, family income, education level and age. Jengka Street market, which is located in Pahang, is popularly known as a trade market. It offers diversities of wet and dry goods and is awaited by local residents and tourists. This study analyzes association between litterers' profile and littering behavior. Littering behavior is measured based on factors of trash bin facilities, awareness campaign and public littering behavior. 114 respondents were involved in this study with 62 (54.39%) are female aged more than 18 years old and majority of these female respondents are diploma holders. In addition, 78.95% of the respondents have family income below than RM3,000.00 per month. Based on the data analysis, it was found that first-time visitors littered higher than frequent visitors, lack of providing trash bin facilities contributes to positive littering behavior and there is a significant association between litterers' age and littering behavior by using chi-square approach.

  3. Biotic and abiotic variables influencing plant litter breakdown in streams: a global study

    Science.gov (United States)

    Pearson, Richard G.; Hui, Cang; Gessner, Mark O.; Pérez, Javier; Alexandrou, Markos A.; Graça, Manuel A. S.; Cardinale, Bradley J.; Albariño, Ricardo J.; Arunachalam, Muthukumarasamy; Barmuta, Leon A.; Boulton, Andrew J.; Bruder, Andreas; Callisto, Marcos; Chauvet, Eric; Death, Russell G.; Dudgeon, David; Encalada, Andrea C.; Ferreira, Verónica; Figueroa, Ricardo; Flecker, Alexander S.; Gonçalves, José F.; Helson, Julie; Iwata, Tomoya; Jinggut, Tajang; Mathooko, Jude; Mathuriau, Catherine; M'Erimba, Charles; Moretti, Marcelo S.; Pringle, Catherine M.; Ramírez, Alonso; Ratnarajah, Lavenia; Rincon, José; Yule, Catherine M.

    2016-01-01

    Plant litter breakdown is a key ecological process in terrestrial and freshwater ecosystems. Streams and rivers, in particular, contribute substantially to global carbon fluxes. However, there is little information available on the relative roles of different drivers of plant litter breakdown in fresh waters, particularly at large scales. We present a global-scale study of litter breakdown in streams to compare the roles of biotic, climatic and other environmental factors on breakdown rates. We conducted an experiment in 24 streams encompassing latitudes from 47.8° N to 42.8° S, using litter mixtures of local species differing in quality and phylogenetic diversity (PD), and alder (Alnus glutinosa) to control for variation in litter traits. Our models revealed that breakdown of alder was driven by climate, with some influence of pH, whereas variation in breakdown of litter mixtures was explained mainly by litter quality and PD. Effects of litter quality and PD and stream pH were more positive at higher temperatures, indicating that different mechanisms may operate at different latitudes. These results reflect global variability caused by multiple factors, but unexplained variance points to the need for expanded global-scale comparisons. PMID:27122551

  4. Biotic and abiotic variables influencing plant litter breakdown in streams: a global study.

    Science.gov (United States)

    Boyero, Luz; Pearson, Richard G; Hui, Cang; Gessner, Mark O; Pérez, Javier; Alexandrou, Markos A; Graça, Manuel A S; Cardinale, Bradley J; Albariño, Ricardo J; Arunachalam, Muthukumarasamy; Barmuta, Leon A; Boulton, Andrew J; Bruder, Andreas; Callisto, Marcos; Chauvet, Eric; Death, Russell G; Dudgeon, David; Encalada, Andrea C; Ferreira, Verónica; Figueroa, Ricardo; Flecker, Alexander S; Gonçalves, José F; Helson, Julie; Iwata, Tomoya; Jinggut, Tajang; Mathooko, Jude; Mathuriau, Catherine; M'Erimba, Charles; Moretti, Marcelo S; Pringle, Catherine M; Ramírez, Alonso; Ratnarajah, Lavenia; Rincon, José; Yule, Catherine M

    2016-04-27

    Plant litter breakdown is a key ecological process in terrestrial and freshwater ecosystems. Streams and rivers, in particular, contribute substantially to global carbon fluxes. However, there is little information available on the relative roles of different drivers of plant litter breakdown in fresh waters, particularly at large scales. We present a global-scale study of litter breakdown in streams to compare the roles of biotic, climatic and other environmental factors on breakdown rates. We conducted an experiment in 24 streams encompassing latitudes from 47.8° N to 42.8° S, using litter mixtures of local species differing in quality and phylogenetic diversity (PD), and alder (Alnus glutinosa) to control for variation in litter traits. Our models revealed that breakdown of alder was driven by climate, with some influence of pH, whereas variation in breakdown of litter mixtures was explained mainly by litter quality and PD. Effects of litter quality and PD and stream pH were more positive at higher temperatures, indicating that different mechanisms may operate at different latitudes. These results reflect global variability caused by multiple factors, but unexplained variance points to the need for expanded global-scale comparisons.

  5. Heterosis and genetic variation in litter size in purebred and crossbred mink

    DEFF Research Database (Denmark)

    Thirstrup, Janne Pia; Larsen, Peter Foged; Pertoldi, Cino

    2014-01-01

    were analyzed and the effects of parity and production year were included in the analyses. Genetic trend and the proportions of the total variance explained by the effects of additive genetics (h2) , common environment (due to repeated litters from the same female; c2), and dam of the female (granddame......Crosses between different mink lines from 3 Danish mink farms that use different breeding strategies were studied to estimate heterosis and variance components for litter size. The study was designed to analyze crosses between lines of the same color type, between different color types, and between...... of the born litter; d2) were estimated. The results showed that mink of the Black color type potentially produced smaller litters compared to mink of the other studied color types. We found significant general maternal effect of heterosis for litter size. Analyses of specific heterosis showed a significant...

  6. A Field Experiment on Behavioural Effects of Humorous, Environmentally Oriented and Authoritarian Posters against Littering

    Directory of Open Access Journals (Sweden)

    Ralph Hansmann

    2016-06-01

    Full Text Available A humorous, an environmentally oriented and an authoritarian poster against littering were tested in a field experiment on their behavioural effectiveness. Corresponding slogans were placed on anti-littering posters designed for this study and used experimentally at four railway stations. The experimental design entailed 4 communication conditions including a control condition where no poster was presented. In each experimental run (N = 96, flyers were distributed for 30 minutes. The number of distributed flyers was counted, and the proportion of littered flyers was determined for each experimental run. It was found that the humorous and environmentally oriented posters achieved a reduction of 58% and 64%, respectively, in littering as compared with the control condition. The authoritarian poster was significantly less effective, but achieved a significant reduction of 25%. Considered together with some previous findings and theories, the results indicate that environmentally oriented and humorous anti-littering posters are more effective than authoritarian ones

  7. Littering dynamics in a coastal industrial setting: the influence of non-resident populations.

    Science.gov (United States)

    Campbell, Marnie L; Paterson de Heer, Chloe; Kinslow, Amber

    2014-03-15

    We examined if there is truth to the preconceptions that non-resident workers (including FIFO/DIDO's) detract from communities. We used marine debris to test this, specifically focussing on littering behaviour and evidence of awareness of local environmental programs that focus on marine debris. Littering was most common at recreational areas, then beaches and whilst boating. Twenty-five percent of respondents that admit to littering, reported no associated guilt with their actions. Younger respondents litter more frequently. Thus, non-resident workers litter at the same rate as permanent residents, visitors and tourists in this region, within this study. Few respondents are aware of the environmental programs that operate in their local region. Awareness was influenced by a respondent's residency (non-residents are less aware), age, and level of education. To address this failure we recommend that industries, that use non-resident workers, should develop inductions that expose new workers to the environmental programs in their region.

  8. Patient Litter System Response in a Full-Scale CH-46 Crash Test.

    Science.gov (United States)

    Weisenbach, Charles A; Rooks, Tyler; Bowman, Troy; Fralish, Vince; McEntire, B Joseph

    2017-03-01

    U.S. Military aeromedical patient litter systems are currently required to meet minimal static strength performance requirements at the component level. Operationally, these components must function as a system and are subjected to the dynamics of turbulent flight and potentially crash events. The first of two full-scale CH-46 crash tests was conducted at NASA's Langley Research Center and included an experiment to assess patient and litter system response during a severe but survivable crash event. A three-tiered strap and pole litter system was mounted into the airframe and occupied by three anthropomorphic test devices (ATDs). During the crash event, the litter system failed to maintain structural integrity and collapsed. Component structural failures were recorded from the litter support system and the litters. The upper ATD was displaced laterally into the cabin, while the middle ATD was displaced longitudinally into the cabin. Acceleration, force, and bending moment data from the instrumented middle ATD were analyzed using available injury criteria. Results indicated that a patient might sustain a neck injury. The current test illustrates that a litter system, with components designed and tested to static requirements only, experiences multiple component structural failures during a dynamic crash event and does not maintain restraint control of its patients. It is unknown if a modern litter system, with components tested to the same static criteria, would perform differently. A systems level dynamic performance requirement needs to be developed so that patients can be provided with protection levels equivalent to that provided to seated aircraft occupants.

  9. Impacts of poultry house environment on poultry litter bacterial community composition.

    Science.gov (United States)

    Dumas, Michael D; Polson, Shawn W; Ritter, Don; Ravel, Jacques; Gelb, Jack; Morgan, Robin; Wommack, K Eric

    2011-01-01

    Viral and bacterial pathogens are a significant economic concern to the US broiler industry and the ecological epicenter for poultry pathogens is the mixture of bedding material, chicken excrement and feathers that comprises the litter of a poultry house. This study used high-throughput sequencing to assess the richness and diversity of poultry litter bacterial communities, and to look for connections between these communities and the environmental characteristics of a poultry house including its history of gangrenous dermatitis (GD). Cluster analysis of 16S rRNA gene sequences revealed differences in the distribution of bacterial phylotypes between Wet and Dry litter samples and between houses. Wet litter contained greater diversity with 90% of total bacterial abundance occurring within the top 214 OTU clusters. In contrast, only 50 clusters accounted for 90% of Dry litter bacterial abundance. The sixth largest OTU cluster across all samples classified as an Arcobacter sp., an emerging human pathogen, occurring in only the Wet litter samples of a house with a modern evaporative cooling system. Ironically, the primary pathogenic clostridial and staphylococcal species associated with GD were not found in any house; however, there were thirteen 16S rRNA gene phylotypes of mostly gram-positive phyla that were unique to GD-affected houses and primarily occurred in Wet litter samples. Overall, the poultry house environment appeared to substantially impact the composition of litter bacterial communities and may play a key role in the emergence of food-borne pathogens.

  10. Impacts of poultry house environment on poultry litter bacterial community composition.

    Directory of Open Access Journals (Sweden)

    Michael D Dumas

    Full Text Available Viral and bacterial pathogens are a significant economic concern to the US broiler industry and the ecological epicenter for poultry pathogens is the mixture of bedding material, chicken excrement and feathers that comprises the litter of a poultry house. This study used high-throughput sequencing to assess the richness and diversity of poultry litter bacterial communities, and to look for connections between these communities and the environmental characteristics of a poultry house including its history of gangrenous dermatitis (GD. Cluster analysis of 16S rRNA gene sequences revealed differences in the distribution of bacterial phylotypes between Wet and Dry litter samples and between houses. Wet litter contained greater diversity with 90% of total bacterial abundance occurring within the top 214 OTU clusters. In contrast, only 50 clusters accounted for 90% of Dry litter bacterial abundance. The sixth largest OTU cluster across all samples classified as an Arcobacter sp., an emerging human pathogen, occurring in only the Wet litter samples of a house with a modern evaporative cooling system. Ironically, the primary pathogenic clostridial and staphylococcal species associated with GD were not found in any house; however, there were thirteen 16S rRNA gene phylotypes of mostly gram-positive phyla that were unique to GD-affected houses and primarily occurred in Wet litter samples. Overall, the poultry house environment appeared to substantially impact the composition of litter bacterial communities and may play a key role in the emergence of food-borne pathogens.

  11. Hot DA white dwarf model atmosphere calculations: Including improved Ni PI cross sections

    CERN Document Server

    Preval, S P; Badnell, N R; Hubeny, I; Holberg, J B

    2016-01-01

    To calculate realistic models of objects with Ni in their atmospheres, accurate atomic data for the relevant ionization stages needs to be included in model atmosphere calculations. In the context of white dwarf stars, we investigate the effect of changing the Ni {\\sc iv}-{\\sc vi} bound-bound and bound-free atomic data has on model atmosphere calculations. Models including PICS calculated with {\\sc autostructure} show significant flux attenuation of up to $\\sim 80$\\% shortward of 180\\AA\\, in the EUV region compared to a model using hydrogenic PICS. Comparatively, models including a larger set of Ni transitions left the EUV, UV, and optical continua unaffected. We use models calculated with permutations of this atomic data to test for potential changes to measured metal abundances of the hot DA white dwarf G191-B2B. Models including {\\sc autostructure} PICS were found to change the abundances of N and O by as much as $\\sim 22$\\% compared to models using hydrogenic PICS, but heavier species were relatively unaf...

  12. Mathematical Model of Thyristor Inverter Including a Series-parallel Resonant Circuit

    Directory of Open Access Journals (Sweden)

    Miroslaw Luft

    2008-01-01

    Full Text Available The article presents a mathematical model of thyristor inverter including a series-parallel resonant circuit with theaid of state variable method. Maple procedures are used to compute current and voltage waveforms in the inverter.

  13. A Verilog-A large signal model for InP DHBT including thermal effects

    Science.gov (United States)

    Yuxia, Shi; Zhi, Jin; Zhijian, Pan; Yongbo, Su; Yuxiong, Cao; Yan, Wang

    2013-06-01

    A large signal model for InP/InGaAs double heterojunction bipolar transistors including thermal effects has been reported, which demonstrated good agreements of simulations with measurements. On the basis of the previous model in which the double heterojunction effect, current blocking effect and high current effect in current expression are considered, the effect of bandgap narrowing with temperature has been considered in transport current while a formula for model parameters as a function of temperature has been developed. This model is implemented by Verilog-A and embedded in ADS. The proposed model is verified with DC and large signal measurements.

  14. Modelling Mediterranean agro-ecosystems by including agricultural trees in the LPJmL model

    Science.gov (United States)

    Fader, M.; von Bloh, W.; Shi, S.; Bondeau, A.; Cramer, W.

    2015-11-01

    In the Mediterranean region, climate and land use change are expected to impact on natural and agricultural ecosystems by warming, reduced rainfall, direct degradation of ecosystems and biodiversity loss. Human population growth and socioeconomic changes, notably on the eastern and southern shores, will require increases in food production and put additional pressure on agro-ecosystems and water resources. Coping with these challenges requires informed decisions that, in turn, require assessments by means of a comprehensive agro-ecosystem and hydrological model. This study presents the inclusion of 10 Mediterranean agricultural plants, mainly perennial crops, in an agro-ecosystem model (Lund-Potsdam-Jena managed Land - LPJmL): nut trees, date palms, citrus trees, orchards, olive trees, grapes, cotton, potatoes, vegetables and fodder grasses. The model was successfully tested in three model outputs: agricultural yields, irrigation requirements and soil carbon density. With the development presented in this study, LPJmL is now able to simulate in good detail and mechanistically the functioning of Mediterranean agriculture with a comprehensive representation of ecophysiological processes for all vegetation types (natural and agricultural) and in a consistent framework that produces estimates of carbon, agricultural and hydrological variables for the entire Mediterranean basin. This development paves the way for further model extensions aiming at the representation of alternative agro-ecosystems (e.g. agroforestry), and opens the door for a large number of applications in the Mediterranean region, for example assessments of the consequences of land use transitions, the influence of management practices and climate change impacts.

  15. Modelling Mediterranean agro-ecosystems by including agricultural trees in the LPJmL model

    Directory of Open Access Journals (Sweden)

    M. Fader

    2015-06-01

    Full Text Available Climate and land use change in the Mediterranean region is expected to affect natural and agricultural ecosystems by decreases in precipitation, increases in temperature as well as biodiversity loss and anthropogenic degradation of natural resources. Demographic growth in the Eastern and Southern shores will require increases in food production and put additional pressure on agro-ecosystems and water resources. Coping with these challenges requires informed decisions that, in turn, require assessments by means of a comprehensive agro-ecosystem and hydrological model. This study presents the inclusion of 10 Mediterranean agricultural plants, mainly perennial crops, in an agro-ecosystem model (LPJmL: nut trees, date palms, citrus trees, orchards, olive trees, grapes, cotton, potatoes, vegetables and fodder grasses. The model was successfully tested in three model outputs: agricultural yields, irrigation requirements and soil carbon density. With the development presented in this study, LPJmL is now able to simulate in good detail and mechanistically the functioning of Mediterranean agriculture with a comprehensive representation of ecophysiological processes for all vegetation types (natural and agricultural and in a consistent framework that produces estimates of carbon, agricultural and hydrological variables for the entire Mediterranean basin. This development pave the way for further model extensions aiming at the representation of alternative agro-ecosystems (e.g. agroforestry, and opens the door for a large number of applications in the Mediterranean region, for example assessments on the consequences of land use transitions, the influence of management practices and climate change impacts.

  16. Numerical Acoustic Models Including Viscous and Thermal losses: Review of Existing and New Methods

    DEFF Research Database (Denmark)

    Andersen, Peter Risby; Cutanda Henriquez, Vicente; Aage, Niels

    2017-01-01

    This work presents an updated overview of numerical methods including acoustic viscous and thermal losses. Numerical modelling of viscothermal losses has gradually become more important due to the general trend of making acoustic devices smaller. Not including viscothermal acoustic losses in such...

  17. Cigarette litter: smokers' attitudes and behaviors.

    Science.gov (United States)

    Rath, Jessica M; Rubenstein, Rebecca A; Curry, Laurel E; Shank, Sarah E; Cartwright, Julia C

    2012-06-01

    Cigarette butts are consistently the most collected items in litter clean-up efforts, which are a costly burden to local economies. In addition, tobacco waste may be detrimental to our natural environment. The tobacco industry has conducted or funded numerous studies on smokers' littering knowledge and behavior, however, non-industry sponsored research is rare. We sought to examine whether demographics and smokers' knowledge and beliefs toward cigarette waste as litter predicts littering behavior. Smokers aged 18 and older (n = 1,000) were interviewed about their knowledge and beliefs towards cigarette waste as litter. Respondents were members of the Research Now panel, an online panel of over three million respondents in the United States. Multivariate logistic regressions were conducted to determine factors significantly predictive of ever having littered cigarette butts or having littered cigarette butts within the past month (p-value littered cigarette butts at least once in their life, by disposing of them on the ground or throwing them out of a car window. Over half (55.7%) reported disposing of cigarette butts on the ground, in a sewer/gutter, or down a drain in the past month. Those who did not consider cigarette butts to be litter were over three and half times as likely to report having ever littered cigarette butts (OR = 3.68, 95%CI = 2.04, 6.66) and four times as likely to have littered cigarette butts in the past month (OR = 4.00, 95%CI = 2.53, 6.32). Males were significantly more likely to have littered cigarette butts in the past month compared to females (OR = 1.49, 95%CI = 1.14, 1.94). Holding the belief that cigarette butts are not litter was the only belief in this study that predicted ever or past-month littering of cigarette waste. Messages in anti-cigarette-litter campaigns should emphasize that cigarette butts are not just litter but are toxic waste and are harmful when disposed of improperly.

  18. Cigarette Litter: Smokers’ Attitudes and Behaviors

    Directory of Open Access Journals (Sweden)

    Julia C. Cartwright

    2012-06-01

    Full Text Available Cigarette butts are consistently the most collected items in litter clean-up efforts, which are a costly burden to local economies. In addition, tobacco waste may be detrimental to our natural environment. The tobacco industry has conducted or funded numerous studies on smokers’ littering knowledge and behavior, however, non-industry sponsored research is rare. We sought to examine whether demographics and smokers’ knowledge and beliefs toward cigarette waste as litter predicts littering behavior. Smokers aged 18 and older (n = 1,000 were interviewed about their knowledge and beliefs towards cigarette waste as litter. Respondents were members of the Research Now panel, an online panel of over three million respondents in the United States. Multivariate logistic regressions were conducted to determine factors significantly predictive of ever having littered cigarette butts or having littered cigarette butts within the past month (p-value < 0.05. The majority (74.1% of smokers reported having littered cigarette butts at least once in their life, by disposing of them on the ground or throwing them out of a car window. Over half (55.7% reported disposing of cigarette butts on the ground, in a sewer/gutter, or down a drain in the past month. Those who did not consider cigarette butts to be litter were over three and half times as likely to report having ever littered cigarette butts (OR = 3.68, 95%CI = 2.04, 6.66 and four times as likely to have littered cigarette butts in the past month (OR = 4.00, 95%CI = 2.53, 6.32. Males were significantly more likely to have littered cigarette butts in the past month compared to females (OR = 1.49, 95%CI = 1.14, 1.94. Holding the belief that cigarette butts are not litter was the only belief in this study that predicted ever or past-month littering of cigarette waste. Messages in anti-cigarette-litter campaigns should emphasize that cigarette butts are not just litter but are toxic

  19. Relationships among leaf functional traits, litter traits, and mass loss during early phases of leaf litter decomposition in 12 woody plant species.

    Science.gov (United States)

    Zukswert, Jenna M; Prescott, Cindy E

    2017-09-08

    Litter 'quality' or decomposability has historically been estimated through measuring chemical attributes, such as concentrations of nitrogen or 'lignin'. More recently, foliar functional traits, which may incorporate indications of the physical structures of tissues, have been found to correlate with litter mass loss rates. However, these traits may not be adequate to predict early rates of mass loss, in which two factors are crucial: the amount of material quickly lost through leaching, and the ease of access of decomposer organisms to the more labile tissues in the interior of the litter. We investigated relationships among physical and chemical traits in foliage and litter of 12 species native to British Columbia and then observed how these traits related to mass loss during the first 3 months (Phase I) and between 3 and 12 months (Phase II). Novel traits measured in this study include cuticle thickness, litter leaching loss, and litter water uptake. Foliar and litter traits both co-varied along spectra, but several chemical traits, such as nitrogen concentration, changed from foliage to litter, i.e., during senescence. Phase I mass loss was best predicted by leaching loss and traits relating to leaching, such as cuticle thickness and specific leaf area. Phase II mass loss was predicted by traits that may relate to decomposer access and activity, such as leaf dry matter content and foliar nitrogen. Physical traits predicted mass loss as well or better than chemical traits, suggesting that physical characteristics of litter are important in determining early rates of decomposition.

  20. Litter composition effects on decomposition across the litter-soil interface

    Science.gov (United States)

    Background/Question/Methods Many studies have investigated the influence of plant litter species composition on decomposition dynamics, but given the variety of communities and environments around the world, a variety of consequences of litter-mixing have been reported. Litter ...

  1. McDonald's Litter Hunt: A Community Litter Control System for Youth.

    Science.gov (United States)

    McNees, M. Patrick; And Others

    1979-01-01

    Describes a community litter control program. Special adhesive stickers were randomly placed on existing litter throughout a community and youth were rewarded with special prizes for participating in the program. Litter was reduced 32 percent across the city. (Author/MA)

  2. Leaf litter quality drives litter mixing effects through complementary resource use among detritivores

    NARCIS (Netherlands)

    Vos, V.C.A.; Ruijven, van J.; Berg, M.P.; Peeters, E.T.H.M.; Berendse, F.

    2013-01-01

    To comprehend the potential consequences of biodiversity loss on the leaf litter decomposition process, a better understanding of its underlying mechanisms is necessary. Here, we hypothesize that positive litter mixture effects occur via complementary resource use, when litter species complement eac

  3. Catalytic conversion of lignin pyrolysis model compound- guaiacol and its kinetic model including coke formation

    Science.gov (United States)

    Zhang, Huiyan; Wang, Yun; Shao, Shanshan; Xiao, Rui

    2016-11-01

    Lignin is the most difficult to be converted and most easy coking component in biomass catalytic pyrolysis to high-value liquid fuels and chemicals. Catalytic conversion of guaiacol as a lignin model compound was conducted in a fixed-bed reactor over ZSM-5 to investigate its conversion and coking behaviors. The effects of temperature, weight hourly space velocity (WHSV) and partial pressure on product distribution were studied. The results show the maximum aromatic carbon yield of 28.55% was obtained at temperature of 650 °C, WHSV of 8 h‑1 and partial pressure of 2.38 kPa, while the coke carbon yield was 19.55%. The reaction pathway was speculated to be removing methoxy group to form phenols with further aromatization to form aromatics. The amount of coke increased with increasing reaction time. The surface area and acidity of catalysts declined as coke formed on the acid sites and blocked the pore channels, which led to the decrease of aromatic yields. Finally, a kinetic model of guaiacol catalytic conversion considering coke deposition was built based on the above reaction pathway to properly predict product distribution. The experimental and model predicting data agreed well. The correlation coefficient of all equations were all higher than 0.90.

  4. Including operational data in QMRA model: development and impact of model inputs.

    Science.gov (United States)

    Jaidi, Kenza; Barbeau, Benoit; Carrière, Annie; Desjardins, Raymond; Prévost, Michèle

    2009-03-01

    A Monte Carlo model, based on the Quantitative Microbial Risk Analysis approach (QMRA), has been developed to assess the relative risks of infection associated with the presence of Cryptosporidium and Giardia in drinking water. The impact of various approaches for modelling the initial parameters of the model on the final risk assessments is evaluated. The Monte Carlo simulations that we performed showed that the occurrence of parasites in raw water was best described by a mixed distribution: log-Normal for concentrations > detection limit (DL), and a uniform distribution for concentrations risks significantly. The mean annual risks for conventional treatment are: 1.97E-03 (removal credit adjusted by log parasite = log spores), 1.58E-05 (log parasite = 1.7 x log spores) or 9.33E-03 (regulatory credits based on the turbidity measurement in filtered water). Using full scale validated SCADA data, the simplified calculation of CT performed at the plant was shown to largely underestimate the risk relative to a more detailed CT calculation, which takes into consideration the downtime and system failure events identified at the plant (1.46E-03 vs. 3.93E-02 for the mean risk).

  5. Nonlinear Modeling of a High Precision Servo Injection Molding Machine Including Novel Molding Approach

    Institute of Scientific and Technical Information of China (English)

    何雪松; 王旭永; 冯正进; 章志新; 杨钦廉

    2003-01-01

    A nonlinear mathematical model of the injection molding process for electrohydraulic servo injection molding machine (IMM) is developed.It was found necessary to consider the characteristics of asymmetric cylinder for electrohydraulic servo IMM.The model is based on the dynamics of the machine including servo valve,asymmetric cylinder and screw,and the non-Newtonian flow behavior of polymer melt in injection molding is also considered.The performance of the model was evaluated based on novel approach of molding - injection and compress molding,and the results of simulation and experimental data demonstrate the effectiveness of the model.

  6. a Better Description of Liquid Jet Breakup Using a Spatial Model Including Viscous Effects.

    Science.gov (United States)

    Hammerschlag, William Brian

    Theoretical models describing the operation and disintegration of a liquid jet are often based on an approximate solution of an inviscid jet in the temporal frame of reference. These models provide only a fair first order prediction of growth rate and breakoff length, and are based solely on a surface tension induced instability. A spatial model yielding jet growth rate and including both jet and surrounding atmosphere viscosity and density is now developed. This model is seen to reproduce all the features and limitations of the Weber viscous jet theory. When tested against experiments of water, water and glycerol mixes and binary eutectic tin/lead solder, only fair agreement is observed.

  7. Long-term presence of tree species but not chemical diversity affect litter mixture effects on decomposition in a neotropical rainforest.

    Science.gov (United States)

    Barantal, Sandra; Roy, Jacques; Fromin, Nathalie; Schimann, Heidy; Hättenschwiler, Stephan

    2011-09-01

    Plant litter diversity effects on decomposition rates are frequently reported, but with a strong bias towards temperate ecosystems. Altered decomposition and nutrient recycling with changing litter diversity may be particularly important in tree species-rich tropical rainforests on nutrient-poor soils. Using 28 different mixtures of leaf litter from 16 Amazonian rainforest tree species, we tested the hypothesis that litter mixture effects on decomposition increase with increasing functional litter diversity. Litter mixtures and all single litter species were exposed in the field for 9 months using custom-made microcosms with soil fauna access. In order to test the hypothesis that the long-term presence of tree species contributing to the litter mixtures increases mixture effects on decomposition, microcosms were installed in a plantation at sites including the respective tree species composition and in a nearby natural forest where these tree species are absent. We found that mixture decomposition deviated from predictions based on single species, with predominantly synergistic effects. Functional litter diversity, defined as either richness, evenness, or divergence based on a wide range of chemical traits, did not explain the observed litter mixture effects. However, synergistic effects in litter mixtures increased with the long-term presence of tree species contributing to these mixtures as the home field advantage hypothesis assumes. Our data suggest that complementarity effects on mixed litter decomposition may emerge through long-term interactions between aboveground and belowground biota.

  8. Dry-season ultraviolet radiation primes litter for wet season decomposition in a Mediterranean grassland

    Science.gov (United States)

    Baker, N. R.; Allison, S. D.

    2013-12-01

    Traditional decomposition models developed in mesic ecosystems often consistently underestimate rates of decomposition in more arid ecosystems such as deserts and Mediterranean grasslands. Photodegradation of plant litter by ultraviolet radiation (UV) is hypothesized to be one of the mechanisms accounting for the greater-than-expected rates of decomposition observed in these ecosystems. Putatively, photodegradation preferentially degrades complex aromatic compounds in litter such as lignin, whose decomposition is considered a rate-limiting step in the microbial decomposition of plant litter. This study tested the effects of attenuated ultraviolet radiation on the decomposition of two litter types over the course of a year in a Southern California Mediterranean grassland. The two types of litter differed primarily in lignin content to test for a differential effect of UV on high-lignin versus low-lignin litter. Rates of litter mass loss, changes in litter chemistry, and changes in microbial activity and microbial biomass were observed, and assays of extracellular enzymes were conducted at 5 points through the year, beginning during the dry season and continuing until the end of the following dry season. Litter exposed to attenuated ultraviolet radiation during the dry season had lower rates of mass loss than litter exposed to ambient radiation (6.1% vs. 8.6%, respectively, p peroxidase in high-lignin, ambient UV samples was 85.9 μmol/hr*g during the wet season, compared to 44.1 μmol/hr*g in attenuated UV samples (p production. Similarly, the reduced potential oxidative enzyme activity in high-lignin samples exposed to attenuated UV may indicate that photodegradation is necessary to facilitate the breakdown of more complex compounds such as lignin by microbial decomposers. We conclude that while abiotic factors such as photodegradation can have a significant effect on the mechanisms of plant matter decomposition in semiarid ecosystems, these effects are not only

  9. Litter assessment on 99 Cuban beaches: A baseline to identify sources of pollution and impacts for tourism and recreation.

    Science.gov (United States)

    Botero, C M; Anfuso, G; Milanes, C; Cabrera, A; Casas, G; Pranzini, E; Williams, A T

    2017-05-15

    Litter presence was assessed on the entire Cuban coastline, and includes 99 beaches from all Cuban regions, during field work carried out in 2012 and 2015. A standard method verified in several countries was applied, which classified beaches for nine types of litter into four grades (A-excellent to D-poor). Almost half of the Cuban beaches obtained excellent cleanliness scores, although many needed to be better managed. In this baseline, the most common types of residue were general litter (8% grade D and 35% grades B/C) and potentially harmful litter (litter management. Tourism Impacts seems to be related to visitor origin therefore choices to develop sustainable tourism in rural and village beaches (64%) appears low, if beach cleaning gross investment is focused on resort beaches (24%). Finally, this paper highlights geographical distribution and types of litter patterns. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Including hydrological self-regulating processes in peatland models: Effects on peatmoss drought projections.

    Science.gov (United States)

    Nijp, Jelmer J; Metselaar, Klaas; Limpens, Juul; Teutschbein, Claudia; Peichl, Matthias; Nilsson, Mats B; Berendse, Frank; van der Zee, Sjoerd E A T M

    2017-02-15

    The water content of the topsoil is one of the key factors controlling biogeochemical processes, greenhouse gas emissions and biosphere - atmosphere interactions in many ecosystems, particularly in northern peatlands. In these wetland ecosystems, the water content of the photosynthetic active peatmoss layer is crucial for ecosystem functioning and carbon sequestration, and is sensitive to future shifts in rainfall and drought characteristics. Current peatland models differ in the degree in which hydrological feedbacks are included, but how this affects peatmoss drought projections is unknown. The aim of this paper was to systematically test whether the level of hydrological detail in models could bias projections of water content and drought stress for peatmoss in northern peatlands using downscaled projections for rainfall and potential evapotranspiration in the current (1991-2020) and future climate (2061-2090). We considered four model variants that either include or exclude moss (rain)water storage and peat volume change, as these are two central processes in the hydrological self-regulation of peatmoss carpets. Model performance was validated using field data of a peatland in northern Sweden. Including moss water storage as well as peat volume change resulted in a significant improvement of model performance, despite the extra parameters added. The best performance was achieved if both processes were included. Including moss water storage and peat volume change consistently reduced projected peatmoss drought frequency with >50%, relative to the model excluding both processes. Projected peatmoss drought frequency in the growing season was 17% smaller under future climate than current climate, but was unaffected by including the hydrological self-regulating processes. Our results suggest that ignoring these two fine-scale processes important in hydrological self-regulation of northern peatlands will have large consequences for projected climate change impact on

  11. Modeling an elastic beam with piezoelectric patches by including magnetic effects

    CERN Document Server

    Ozer, A O

    2014-01-01

    Models for piezoelectric beams using Euler-Bernoulli small displacement theory predict the dynamics of slender beams at the low frequency accurately but are insufficient for beams vibrating at high frequencies or beams with low length-to-width aspect ratios. A more thorough model that includes the effects of rotational inertia and shear strain, Mindlin-Timoshenko small displacement theory, is needed to predict the dynamics more accurately for these cases. Moreover, existing models ignore the magnetic effects since the magnetic effects are relatively small. However, it was shown recently \\cite{O-M1} that these effects can substantially change the controllability and stabilizability properties of even a single piezoelectric beam. In this paper, we use a variational approach to derive models that include magnetic effects for an elastic beam with two piezoelectric patches actuated by different voltage sources. Both Euler-Bernoulli and Mindlin-Timoshenko small displacement theories are considered. Due to the magne...

  12. Stability analysis of the extended ADI-FDTD technique including lumped models

    Institute of Scientific and Technical Information of China (English)

    CHEN ZhiHui; CHU QingXin

    2008-01-01

    The numerical stability of the extended alternating-direction-implicit-finite-difference-time-domain (ADI-FDTD) method including lumped models is analyzed.Three common lumped models are investigated:resistor,capacitor,and inductor,and three different formulations for each model are analyzed:the explicit,semi-implicit and implicit schemes.Analysis results show that the extended ADI-FDTD algorithm is not unconditionally stable in the explicit scheme case,and the stability criterion depends on the value of lumped models,but in the semi-implicit and implicit cases,the algorithm is stable.Finally,two simple microstrip circuits including lumped elements are simulated to demonstrate validity of the theoretical results.

  13. The Dynamic Modeling of Multiple Pairs of Spur Gears in Mesh, Including Friction and Geometrical Errors

    Directory of Open Access Journals (Sweden)

    Shengxiang Jia

    2003-01-01

    Full Text Available This article presents a dynamic model of three shafts and two pair of gears in mesh, with 26 degrees of freedom, including the effects of variable tooth stiffness, pitch and profile errors, friction, and a localized tooth crack on one of the gears. The article also details howgeometrical errors in teeth can be included in a model. The model incorporates the effects of variations in torsional mesh stiffness in gear teeth by using a common formula to describe stiffness that occurs as the gears mesh together. The comparison between the presence and absence of geometrical errors in teeth was made by using Matlab and Simulink models, which were developed from the equations of motion. The effects of pitch and profile errors on the resultant input pinion angular velocity coherent-signal of the input pinion's average are discussed by investigating some of the common diagnostic functions and changes to the frequency spectra results.

  14. SAMI2-PE: A model of the ionosphere including multistream interhemispheric photoelectron transport

    Science.gov (United States)

    Varney, R. H.; Swartz, W. E.; Hysell, D. L.; Huba, J. D.

    2012-06-01

    In order to improve model comparisons with recently improved incoherent scatter radar measurements at the Jicamarca Radio Observatory we have added photoelectron transport and energy redistribution to the two dimensional SAMI2 ionospheric model. The photoelectron model uses multiple pitch angle bins, includes effects associated with curved magnetic field lines, and uses an energy degradation procedure which conserves energy on coarse, non-uniformly spaced energy grids. The photoelectron model generates secondary electron production rates and thermal electron heating rates which are then passed to the fluid equations in SAMI2. We then compare electron and ion temperatures and electron densities of this modified SAMI2 model with measurements of these parameters over a range of altitudes from 90 km to 1650 km (L = 1.26) over a 24 hour period. The new electron heating model is a significant improvement over the semi-empirical model used in SAMI2. The electron temperatures above the F-peak from the modified model qualitatively reproduce the shape of the measurements as functions of time and altitude and quantitatively agree with the measurements to within ˜30% or better during the entire day, including during the rapid temperature increase at dawn.

  15. General spherical anisotropic Jeans models of stellar kinematics: including proper motions and radial velocities

    CERN Document Server

    Cappellari, Michele

    2015-01-01

    Cappellari (2008) presented a flexible and efficient method to model the stellar kinematics of anisotropic axisymmetric and spherical stellar systems. The spherical formalism could be used to model the line-of-sight velocity second moments allowing for essentially arbitrary radial variation in the anisotropy and general luminous and total density profiles. Here we generalize the spherical formalism by providing the expressions for all three components of the projected second moments, including the two proper motion components. A reference implementation is now included in the public JAM package available at http://purl.org/cappellari/software

  16. Modeling Within-Host Dynamics of Influenza Virus Infection Including Immune Responses

    OpenAIRE

    Pawelek, Kasia A.; Huynh, Giao T; Michelle Quinlivan; Ann Cullinane; Libin Rong; Perelson, Alan S.

    2012-01-01

    Influenza virus infection remains a public health problem worldwide. The mechanisms underlying viral control during an uncomplicated influenza virus infection are not fully understood. Here, we developed a mathematical model including both innate and adaptive immune responses to study the within-host dynamics of equine influenza virus infection in horses. By comparing modeling predictions with both interferon and viral kinetic data, we examined the relative roles of target cell availability, ...

  17. A lumped element transformer model including core losses and winding impedances

    OpenAIRE

    Ribbenfjärd, David

    2007-01-01

    In order to design a power transformer it is important to understand its internal electromagnetic behaviour. That can be obtained by measurements on physical transformers, analytical expressions and computer simulations. One benefit with simulations is that the transformer can be studied before it is built physically and that the consequences of changing dimensions and parameters easily can be tested. In this thesis a time-domain transformer model is presented. The model includes core losses ...

  18. Target echo strength modelling at FOI, including results from the BeTSSi II workshop

    CERN Document Server

    Östberg, Martin

    2016-01-01

    An overview of the target echo strength (TS) modelling capacity at the Swedish Defense Research Agency (FOI) is presented. The modelling methods described range from approximate ones, such as raytracing and Kirchhoff approximation codes, to high accuracy full field codes including boundary integral equation methods and finite elements methods. Illustrations of the applicability of the codes are given for a few simple cases tackled during the BeTTSi II (Benchmark Target Echo Strength Simulation) workshop held in Kiel 2014.

  19. Including leakage in network models: an application to calibrate leak valves in EPANET

    OpenAIRE

    Cobacho Jordán, Ricardo; Arregui de la Cruz, Francisco; Soriano Olivares, Javier; Cabrera Rochera, Enrique

    2015-01-01

    EPANET is one of the most widely used software packages for water network hydraulic modelling, and is especially interesting for educational and research purposes because it is in the public domain. However, EPANET simulations are demand-driven, and the program does not include a specific functionality to model water leakage, which is pressure-driven. Consequently, users are required to deal with this drawback by themselves. As a general solution for this problem, this paper presents a method...

  20. Key Characteristics of Combined Accident including TLOFW accident for PSA Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bo Gyung; Kang, Hyun Gook [KAIST, Daejeon (Korea, Republic of); Yoon, Ho Joon [Khalifa University of Science, Technology and Research, Abu Dhabi (United Arab Emirates)

    2015-05-15

    The conventional PSA techniques cannot adequately evaluate all events. The conventional PSA models usually focus on single internal events such as DBAs, the external hazards such as fire, seismic. However, the Fukushima accident of Japan in 2011 reveals that very rare event is necessary to be considered in the PSA model to prevent the radioactive release to environment caused by poor treatment based on lack of the information, and to improve the emergency operation procedure. Especially, the results from PSA can be used to decision making for regulators. Moreover, designers can consider the weakness of plant safety based on the quantified results and understand accident sequence based on human actions and system availability. This study is for PSA modeling of combined accidents including total loss of feedwater (TLOFW) accident. The TLOFW accident is a representative accident involving the failure of cooling through secondary side. If the amount of heat transfer is not enough due to the failure of secondary side, the heat will be accumulated to the primary side by continuous core decay heat. Transients with loss of feedwater include total loss of feedwater accident, loss of condenser vacuum accident, and closure of all MSIVs. When residual heat removal by the secondary side is terminated, the safety injection into the RCS with direct primary depressurization would provide alternative heat removal. This operation is called feed and bleed (F and B) operation. Combined accidents including TLOFW accident are very rare event and partially considered in conventional PSA model. Since the necessity of F and B operation is related to plant conditions, the PSA modeling for combined accidents including TLOFW accident is necessary to identify the design and operational vulnerabilities.The PSA is significant to assess the risk of NPPs, and to identify the design and operational vulnerabilities. Even though the combined accident is very rare event, the consequence of combined

  1. Analysis of a generalized model for influenza including differential susceptibility due to immunosuppression

    Science.gov (United States)

    Hincapié, Doracelly; Ospina, Juan

    2014-06-01

    Recently, a mathematical model of pandemic influenza was proposed including typical control strategies such as antivirals, vaccination and school closure; and considering explicitly the effects of immunity acquired from the early outbreaks on the ulterior outbreaks of the disease. In such model the algebraic expression for the basic reproduction number (without control strategies) and the effective reproduction number (with control strategies) were derived and numerically estimated. A drawback of this model of pandemic influenza is that it ignores the effects of the differential susceptibility due to immunosuppression and the effects of the complexity of the actual contact networks between individuals. We have developed a generalized model which includes such effects of heterogeneity. Specifically we consider the influence of the air network connectivity in the spread of pandemic influenza and the influence of the immunosuppresion when the population is divided in two immune classes. We use an algebraic expression, namely the Tutte polynomial, to characterize the complexity of the contact network. Until now, The influence of the air network connectivity in the spread of pandemic influenza has been studied numerically, but not algebraic expressions have been used to summarize the level of network complexity. The generalized model proposed here includes the typical control strategies previously mentioned (antivirals, vaccination and school closure) combined with restrictions on travel. For the generalized model the corresponding reproduction numbers will be algebraically computed and the effect of the contact network will be established in terms of the Tutte polynomial of the network.

  2. Evaluation of Dormer sires for litter size and lamb mortality using a ...

    African Journals Online (AJOL)

    Keywords: Categorical traits, Dormer sheep, sire evaluation, threshold model. * To whom .... for Newton-Raphson iterations was l0 and 12 for litter size and mortality, respectively. ... The mathematical theory of quantitative gene- tics. Clarendon ...

  3. SOA Formation Potential of Emissions from Soil and Leaf Litter

    Science.gov (United States)

    Faiola, C. L.; Vanderschelden, G. S.; Wen, M.; Cobos, D. R.; Jobson, B. T.; VanReken, T. M.

    2013-12-01

    In the United States, emissions of volatile organic compounds (VOCs) from natural sources exceed all anthropogenic sources combined. VOCs participate in oxidative chemistry in the atmosphere and impact the concentrations of ozone and particulate material. The formation of secondary organic aerosol (SOA) is particularly complex and is frequently underestimated using state-of-the-art modeling techniques. We present findings that suggest emissions of important SOA precursors from soil and leaf litter are higher than current inventories would suggest, particularly under conditions typical of Fall and Spring. Soil and leaf litter samples were collected at Big Meadow Creek from the University of Idaho Experimental Forest. The dominant tree species in this area of the forest are ponderosa pine, Douglas-fir, and western larch. Samples were transported to the laboratory and housed within a 0.9 cubic meter Teflon dynamic chamber where VOC emissions were continuously monitored with a GC-FID-MS and PTR-MS. Aerosol was generated from soil and leaf litter emissions by pumping the emissions into a 7 cubic meter Teflon aerosol growth chamber where they were oxidized with ozone in the absence of light. The evolution of particle microphysical and chemical characteristics was monitored over the following eight hours. Particle size distribution and chemical composition were measured with a SMPS and HR-ToF-AMS respectively. Monoterpenes dominated the emission profile with emission rates up to 283 micrograms carbon per meter squared per hour. The dominant monoterpenes emitted were beta-pinene, alpha-pinene, and delta-3-carene in descending order. The composition of the SOA produced was similar to biogenic SOA formed from oxidation of ponderosa pine emissions and alpha-pinene. Measured soil/litter monoterpene emission rates were compared with modeled canopy emissions. Results suggest that during fall and spring when tree emissions are lower, monoterpene emissions within forests may be

  4. The No-Core Gamow Shell Model: Including the continuum in the NCSM

    CERN Document Server

    Barrett, B R; Michel, N; Płoszajczak, M

    2015-01-01

    We are witnessing an era of intense experimental efforts that will provide information about the properties of nuclei far from the line of stability, regarding resonant and scattering states as well as (weakly) bound states. This talk describes our formalism for including these necessary ingredients into the No-Core Shell Model by using the Gamow Shell Model approach. Applications of this new approach, known as the No-Core Gamow Shell Model, both to benchmark cases as well as to unstable nuclei will be given.

  5. Leaf litter mixtures alter microbial community development: mechanisms for non-additive effects in litter decomposition.

    Directory of Open Access Journals (Sweden)

    Samantha K Chapman

    Full Text Available To what extent microbial community composition can explain variability in ecosystem processes remains an open question in ecology. Microbial decomposer communities can change during litter decomposition due to biotic interactions and shifting substrate availability. Though relative abundance of decomposers may change due to mixing leaf litter, linking these shifts to the non-additive patterns often recorded in mixed species litter decomposition rates has been elusive, and links community composition to ecosystem function. We extracted phospholipid fatty acids (PLFAs from single species and mixed species leaf litterbags after 10 and 27 months of decomposition in a mixed conifer forest. Total PLFA concentrations were 70% higher on litter mixtures than single litter types after 10 months, but were only 20% higher after 27 months. Similarly, fungal-to-bacterial ratios differed between mixed and single litter types after 10 months of decomposition, but equalized over time. Microbial community composition, as indicated by principal components analyses, differed due to both litter mixing and stage of litter decomposition. PLFA biomarkers a15∶0 and cy17∶0, which indicate gram-positive and gram-negative bacteria respectively, in particular drove these shifts. Total PLFA correlated significantly with single litter mass loss early in decomposition but not at later stages. We conclude that litter mixing alters microbial community development, which can contribute to synergisms in litter decomposition. These findings advance our understanding of how changing forest biodiversity can alter microbial communities and the ecosystem processes they mediate.

  6. Leaf Litter Mixtures Alter Microbial Community Development: Mechanisms for Non-Additive Effects in Litter Decomposition

    Science.gov (United States)

    Chapman, Samantha K.; Newman, Gregory S.; Hart, Stephen C.; Schweitzer, Jennifer A.; Koch, George W.

    2013-01-01

    To what extent microbial community composition can explain variability in ecosystem processes remains an open question in ecology. Microbial decomposer communities can change during litter decomposition due to biotic interactions and shifting substrate availability. Though relative abundance of decomposers may change due to mixing leaf litter, linking these shifts to the non-additive patterns often recorded in mixed species litter decomposition rates has been elusive, and links community composition to ecosystem function. We extracted phospholipid fatty acids (PLFAs) from single species and mixed species leaf litterbags after 10 and 27 months of decomposition in a mixed conifer forest. Total PLFA concentrations were 70% higher on litter mixtures than single litter types after 10 months, but were only 20% higher after 27 months. Similarly, fungal-to-bacterial ratios differed between mixed and single litter types after 10 months of decomposition, but equalized over time. Microbial community composition, as indicated by principal components analyses, differed due to both litter mixing and stage of litter decomposition. PLFA biomarkers a15∶0 and cy17∶0, which indicate gram-positive and gram-negative bacteria respectively, in particular drove these shifts. Total PLFA correlated significantly with single litter mass loss early in decomposition but not at later stages. We conclude that litter mixing alters microbial community development, which can contribute to synergisms in litter decomposition. These findings advance our understanding of how changing forest biodiversity can alter microbial communities and the ecosystem processes they mediate. PMID:23658639

  7. The Watts-Strogatz network model developed by including degree distribution: theory and computer simulation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y W [Surface Physics Laboratory and Department of Physics, Fudan University, Shanghai 200433 (China); Zhang, L F [Surface Physics Laboratory and Department of Physics, Fudan University, Shanghai 200433 (China); Huang, J P [Surface Physics Laboratory and Department of Physics, Fudan University, Shanghai 200433 (China)

    2007-07-20

    By using theoretical analysis and computer simulations, we develop the Watts-Strogatz network model by including degree distribution, in an attempt to improve the comparison between characteristic path lengths and clustering coefficients predicted by the original Watts-Strogatz network model and those of the real networks with the small-world property. Good agreement between the predictions of the theoretical analysis and those of the computer simulations has been shown. It is found that the developed Watts-Strogatz network model can fit the real small-world networks more satisfactorily. Some other interesting results are also reported by adjusting the parameters in a model degree-distribution function. The developed Watts-Strogatz network model is expected to help in the future analysis of various social problems as well as financial markets with the small-world property.

  8. Dynamics Analysis of an HIV Infection Model including Infected Cells in an Eclipse Stage

    Directory of Open Access Journals (Sweden)

    Shengyu Zhou

    2013-01-01

    Full Text Available In this paper, an HIV infection model including an eclipse stage of infected cells is considered. Some quicker cells in this stage become productively infected cells, a portion of these cells are reverted to the uninfected class, and others will be latent down in the body. We consider CTL-response delay in this model and analyze the effect of time delay on stability of equilibrium. It is shown that the uninfected equilibrium and CTL-absent infection equilibrium are globally asymptotically stable for both ODE and DDE model. And we get the global stability of the CTL-present equilibrium for ODE model. For DDE model, we have proved that the CTL-present equilibrium is locally asymptotically stable in a range of delays and also have studied the existence of Hopf bifurcations at the CTL-present equilibrium. Numerical simulations are carried out to support our main results.

  9. Modeling of the dynamics of wind to power conversion including high wind speed behavior

    DEFF Research Database (Denmark)

    Litong-Palima, Marisciel; Bjerge, Martin Huus; Cutululis, Nicolaos Antonio

    2016-01-01

    of power system studies, but the idea of the proposed wind turbine model is to include the main dynamic effects in order to have a better representation of the fluctuations in the output power and of the fast power ramping especially because of high wind speed shutdowns of the wind turbine. The high wind......This paper proposes and validates an efficient, generic and computationally simple dynamic model for the conversion of the wind speed at hub height into the electrical power by a wind turbine. This proposed wind turbine model was developed as a first step to simulate wind power time series...... for power system studies. This paper focuses on describing and validating the single wind turbine model, and is therefore neither describing wind speed modeling nor aggregation of contributions from a whole wind farm or a power system area. The state-of-the-art is to use static power curves for the purpose...

  10. A statistical model including age to predict passenger postures in the rear seats of automobiles.

    Science.gov (United States)

    Park, Jangwoon; Ebert, Sheila M; Reed, Matthew P; Hallman, Jason J

    2016-06-01

    Few statistical models of rear seat passenger posture have been published, and none has taken into account the effects of occupant age. This study developed new statistical models for predicting passenger postures in the rear seats of automobiles. Postures of 89 adults with a wide range of age and body size were measured in a laboratory mock-up in seven seat configurations. Posture-prediction models for female and male passengers were separately developed by stepwise regression using age, body dimensions, seat configurations and two-way interactions as potential predictors. Passenger posture was significantly associated with age and the effects of other two-way interaction variables depended on age. A set of posture-prediction models are presented for women and men, and the prediction results are compared with previously published models. This study is the first study of passenger posture to include a large cohort of older passengers and the first to report a significant effect of age for adults. The presented models can be used to position computational and physical human models for vehicle design and assessment. Practitioner Summary: The significant effects of age, body dimensions and seat configuration on rear seat passenger posture were identified. The models can be used to accurately position computational human models or crash test dummies for older passengers in known rear seat configurations.

  11. Do nurse sows and foster litters have impaired animal welfare? Results from a cross-sectional study in sow herds

    DEFF Research Database (Denmark)

    Sørensen, Jan Tind; Rousing, Tine; Kudahl, Anne Braad;

    2016-01-01

    Increasing litter size has led to introduction of so-called nurse sows in several EU countries. A nurse sow is a sow receiving piglets after having weaned her own piglets and thereby experiencing an extended lactation. In order to analyse whether nurse sows have more welfare problems than non-nurse...... sows a cross-sectional study was conducted in 57 sow herds in Denmark. Clinical observations were made on nurse and non-nurse sows and their litters. The clinical observations were dichotomized and the effect of being a nurse sow was analysed based on eight parameters: thin (body condition score....5), swollen bursae on legs, dew claw wounds, vulva lesions, poor hygiene, poor skin condition, shoulder lesions and cuts and wounds on the udder. Explanatory variables included in the eight models were: nurse sow (yes=1/no=0), age of piglets (weeks old, 1 to 7), parity (1 to 8+) and all first order...

  12. Innovative Liner Concepts: Experiments and Impedance Modeling of Liners Including the Effect of Bias Flow

    Science.gov (United States)

    Kelly, Jeff; Betts, Juan Fernando; Fuller, Chris

    2000-01-01

    The study of normal impedance of perforated plate acoustic liners including the effect of bias flow was studied. Two impedance models were developed by modeling the internal flows of perforate orifices as infinite tubes with the inclusion of end corrections to handle finite length effects. These models assumed incompressible and compressible flows, respectively, between the far field and the perforate orifice. The incompressible model was used to predict impedance results for perforated plates with percent open areas ranging from 5% to 15%. The predicted resistance results showed better agreement with experiments for the higher percent open area samples. The agreement also tended to deteriorate as bias flow was increased. For perforated plates with percent open areas ranging from 1% to 5%, the compressible model was used to predict impedance results. The model predictions were closer to the experimental resistance results for the 2% to 3% open area samples. The predictions tended to deteriorate as bias flow was increased. The reactance results were well predicted by the models for the higher percent open area, but deteriorated as the percent open area was lowered (5%) and bias flow was increased. A fit was done on the incompressible model to the experimental database. The fit was performed using an optimization routine that found the optimal set of multiplication coefficients to the non-dimensional groups that minimized the least squares slope error between predictions and experiments. The result of the fit indicated that terms not associated with bias flow required a greater degree of correction than the terms associated with the bias flow. This model improved agreement with experiments by nearly 15% for the low percent open area (5%) samples when compared to the unfitted model. The fitted model and the unfitted model performed equally well for the higher percent open area (10% and 15%).

  13. Fusion rules for the logarithmic $N=1$ superconformal minimal models II: including the Ramond sector

    CERN Document Server

    Canagasabey, Michael

    2015-01-01

    The Virasoro logarithmic minimal models were intensively studied by several groups over the last ten years with much attention paid to the fusion rules and the structures of the indecomposable representations that fusion generates. The analogous study of the fusion rules of the $N=1$ superconformal logarithmic minimal models was initiated in arXiv:1504.03155 as a continuum counterpart to the lattice explorations of arXiv:1312.6763. These works restricted fusion considerations to Neveu-Schwarz representations. Here, this is extended to include the Ramond sector. Technical advances that make this possible include a fermionic Verlinde formula applicable to logarithmic conformal field theories and a twisted version of the fusion algorithm of Nahm and Gaberdiel-Kausch. The results include the first construction and detailed analysis of logarithmic structures in the Ramond sector.

  14. MEMLS3&a: Microwave Emission Model of Layered Snowpacks adapted to include backscattering

    Directory of Open Access Journals (Sweden)

    M. Proksch

    2015-08-01

    Full Text Available The Microwave Emission Model of Layered Snowpacks (MEMLS was originally developed for microwave emissions of snowpacks in the frequency range 5–100 GHz. It is based on six-flux theory to describe radiative transfer in snow including absorption, multiple volume scattering, radiation trapping due to internal reflection and a combination of coherent and incoherent superposition of reflections between horizontal layer interfaces. Here we introduce MEMLS3&a, an extension of MEMLS, which includes a backscatter model for active microwave remote sensing of snow. The reflectivity is decomposed into diffuse and specular components. Slight undulations of the snow surface are taken into account. The treatment of like- and cross-polarization is accomplished by an empirical splitting parameter q. MEMLS3&a (as well as MEMLS is set up in a way that snow input parameters can be derived by objective measurement methods which avoid fitting procedures of the scattering efficiency of snow, required by several other models. For the validation of the model we have used a combination of active and passive measurements from the NoSREx (Nordic Snow Radar Experiment campaign in Sodankylä, Finland. We find a reasonable agreement between the measurements and simulations, subject to uncertainties in hitherto unmeasured input parameters of the backscatter model. The model is written in Matlab and the code is publicly available for download through the following website: http://www.iapmw.unibe.ch/research/projects/snowtools/memls.html.

  15. MEMLS3&a: Microwave Emission Model of Layered Snowpacks adapted to include backscattering

    Directory of Open Access Journals (Sweden)

    M. Proksch

    2015-03-01

    Full Text Available The Microwave Emission Model of Layered Snowpacks (MEMLS was originally developed for microwave emissions of snowpacks in the frequency range 5–100 GHz. It is based on six-flux theory to describe radiative transfer in snow including absorption, multiple volume scattering, radiation trapping due to internal reflection and a combination of coherent and incoherent superposition of reflections between horizontal layer interfaces. Here we introduce MEMLS3&a, an extension of MEMLS, which includes a backscatter model for active microwave remote sensing of snow. The reflectivity is decomposed into diffuse and specular components. Slight undulations of the snow surface are taken into account. The treatment of like and cross polarization is accomplished by an empirical splitting parameter q. MEMLS3&a (as well as MEMLS is set up in a way that snow input parameters can be derived by objective measurement methods which avoids fitting procedures of the scattering efficiency of snow, required by several other models. For the validation of the model we have used a combination of active and passive measurements from the NoSREx campaign in Sodankylä, Finland. We find a reasonable agreement between the measurements and simulations, subject to uncertainties in hitherto unmeasured input parameters of the backscatter model. The model is written in MATLAB and the code is publicly available for download through the following website: http://www.iapmw.unibe.ch/research/projects/snowtools/memls.html.

  16. MEMLS3&a: Microwave Emission Model of Layered Snowpacks adapted to include backscattering

    Science.gov (United States)

    Proksch, M.; Mätzler, C.; Wiesmann, A.; Lemmetyinen, J.; Schwank, M.; Löwe, H.; Schneebeli, M.

    2015-08-01

    The Microwave Emission Model of Layered Snowpacks (MEMLS) was originally developed for microwave emissions of snowpacks in the frequency range 5-100 GHz. It is based on six-flux theory to describe radiative transfer in snow including absorption, multiple volume scattering, radiation trapping due to internal reflection and a combination of coherent and incoherent superposition of reflections between horizontal layer interfaces. Here we introduce MEMLS3&a, an extension of MEMLS, which includes a backscatter model for active microwave remote sensing of snow. The reflectivity is decomposed into diffuse and specular components. Slight undulations of the snow surface are taken into account. The treatment of like- and cross-polarization is accomplished by an empirical splitting parameter q. MEMLS3&a (as well as MEMLS) is set up in a way that snow input parameters can be derived by objective measurement methods which avoid fitting procedures of the scattering efficiency of snow, required by several other models. For the validation of the model we have used a combination of active and passive measurements from the NoSREx (Nordic Snow Radar Experiment) campaign in Sodankylä, Finland. We find a reasonable agreement between the measurements and simulations, subject to uncertainties in hitherto unmeasured input parameters of the backscatter model. The model is written in Matlab and the code is publicly available for download through the following website: http://www.iapmw.unibe.ch/research/projects/snowtools/memls.html.

  17. Diagnosing Lee Wave Rotor Onset Using a Linear Model Including a Boundary Layer

    Directory of Open Access Journals (Sweden)

    Miguel A. C. Teixeira

    2017-01-01

    Full Text Available A linear model is used to diagnose the onset of rotors in flow over 2D hills, for atmospheres that are neutrally stratified near the surface and stably stratified aloft, with a sharp temperature inversion in between, where trapped lee waves may propagate. This is achieved by coupling an inviscid two-layer mountain-wave model and a bulk boundary-layer model. The full model shows some ability to diagnose flow stagnation associated with rotors as a function of key input parameters, such as the Froude number and the height of the inversion, in numerical simulations and laboratory experiments carried out by previous authors. While calculations including only the effects of mean flow attenuation and velocity perturbation amplification within the surface layer represent flow stagnation fairly well in the more non-hydrostatic cases, only the full model, taking into account the feedback of the surface layer on the inviscid flow, satisfactorily predicts flow stagnation in the most hydrostatic case, although the corresponding condition is unable to discriminate between rotors and hydraulic jumps. Versions of the model not including this feedback severely underestimate the amplitude of trapped lee waves in that case, where the Fourier transform of the hill has zeros, showing that those waves are not forced directly by the orography.

  18. Steady-state analysis of activated sludge processes with a settler model including sludge compression.

    Science.gov (United States)

    Diehl, S; Zambrano, J; Carlsson, B

    2016-01-01

    A reduced model of a completely stirred-tank bioreactor coupled to a settling tank with recycle is analyzed in its steady states. In the reactor, the concentrations of one dominant particulate biomass and one soluble substrate component are modelled. While the biomass decay rate is assumed to be constant, growth kinetics can depend on both substrate and biomass concentrations, and optionally model substrate inhibition. Compressive and hindered settling phenomena are included using the Bürger-Diehl settler model, which consists of a partial differential equation. Steady-state solutions of this partial differential equation are obtained from an ordinary differential equation, making steady-state analysis of the entire plant difficult. A key result showing that the ordinary differential equation can be replaced with an approximate algebraic equation simplifies model analysis. This algebraic equation takes the location of the sludge-blanket during normal operation into account, allowing for the limiting flux capacity caused by compressive settling to easily be included in the steady-state mass balance equations for the entire plant system. This novel approach grants the possibility of more realistic solutions than other previously published reduced models, comprised of yet simpler settler assumptions. The steady-state concentrations, solids residence time, and the wastage flow ratio are functions of the recycle ratio. Solutions are shown for various growth kinetics; with different values of biomass decay rate, influent volumetric flow, and substrate concentration.

  19. Latest cosmological constraints on Cardassian expansion models including the updated gamma-ray bursts

    Institute of Scientific and Technical Information of China (English)

    Nan Liang; Pu-Xun Wua; Zong-Hong Zhu

    2011-01-01

    We constrain the Cardassian expansion models from the latest observations,including the updated Gamma-ray bursts (GRBs),which are calibrated using a cosmology independent method from the Union2 compilation of type Ia supernovae (SNe Ia).By combining the GRB data with the joint observations from the Union2SNe Ia set,along with the results from the Cosmic Microwave Background radiation observation from the seven-year Wilkinson Microwave Anisotropy Probe and the baryonic acoustic oscillation observation galaxy sample from the spectroscopic Sloan Digital Sky Survey Data Release,we find significant constraints on the model parameters of the original Cardassian model ΩM0=n 282+0.015-0.014,n=0.03+0.05-0.05;and n = -0.16+0.25-3.26,β=-0.76+0.34-0.58 of the modified polytropic Cardassian model,which are consistent with the ACDM model in a l-σ confidence region.From the reconstruction of the deceleration parameter q(z) in Cardassian models,we obtain the transition redshift ZT = 0.73 ± 0.04 for the original Cardassian model and ZT = 0.68 ± 0.04 for the modified polytropic Cardassian model.

  20. Safe distance car-following model including backward-looking and its stability analysis

    Science.gov (United States)

    Yang, Da; Jin, Peter Jing; Pu, Yun; Ran, Bin

    2013-03-01

    The focus of this paper is the car-following behavior including backward-looking, simply called the bi-directional looking car-following behavior. This study is motivated by the potential changes of the physical properties of traffic flow caused by the fast developing intelligent transportation system (ITS), especially the new connected vehicle technology. Existing studies on this topic focused on general motors (GM) models and optimal velocity (OV) models. The safe distance car-following model, Gipps' model, which is more widely used in practice have not drawn too much attention in the bi-directional looking context. This paper explores the property of the bi-directional looking extension of Gipps' safe distance model. The stability condition of the proposed model is derived using the linear stability theory and is verified using numerical simulations. The impacts of the driver and vehicle characteristics appeared in the proposed model on the traffic flow stability are also investigated. It is found that taking into account the backward-looking effect in car-following has three types of effect on traffic flow: stabilizing, destabilizing and producing non-physical phenomenon. This conclusion is more sophisticated than the study results based on the OV bi-directional looking car-following models. Moreover, the drivers who have the smaller reaction time or the larger additional delay and think the other vehicles have larger maximum decelerations can stabilize traffic flow.

  1. Litter dominates surface fluxes of carbonyl sulfide in a Californian oak woodland

    Science.gov (United States)

    Sun, Wu; Maseyk, Kadmiel; Lett, Céline; Seibt, Ulli

    2016-02-01

    Carbonyl sulfide (COS) is a promising tracer for partitioning terrestrial photosynthesis and respiration from net carbon fluxes, based on its daytime co-uptake alongside CO2 through leaf stomata. Because ecosystem COS fluxes are the sum of plant and soil fluxes, using COS as a photosynthesis tracer requires accurate knowledge of soil COS fluxes. At an oak woodland in Southern California, we monitored below-canopy surface (soil + litter) COS and CO2 fluxes for 40 days using chambers and laser spectroscopy. We also measured litter fluxes separately and used a depth-resolved diffusion-reaction model to quantify the role of litter uptake in surface COS fluxes. Soil and litter were primarily COS sinks, and mean surface COS uptake was small (˜1 pmol m-2 s-1). After rainfall, uptake rates were higher (6-8 pmol m-2 s-1), and litter contributed a significant fraction (up to 90%) to surface fluxes. We observed rapid concurrent increases in COS uptake and CO2 efflux following the onset of rain. The patterns were similar to the Birch effect widely documented for soils; however, both COS and CO2 flux increases originated mainly in the litter. The synchronous COS-CO2 litter Birch effect indicates that it results from a rapid increase in litter microbial activity after rainfall. We expect that the drying-rewetting cycles typical for mediterranean and other semiarid ecosystems create a pronounced seasonality in surface COS fluxes. Our results highlight that litter uptake is an important component of surface COS exchange that needs to be taken into account in ecosystem COS budgets and model simulations.

  2. Approaches to understanding the semi-stable phase of litter decomposition

    Science.gov (United States)

    Preston, C. M.; Trofymow, J. A.

    2012-12-01

    The slowing or even apparent cessation of litter decomposition with time has been widely observed, but causes remain poorly understood. We examine the question in part through data from CIDET (the Canadian Intersite Decomposition Experiment) for 10 foliar litters at one site with MAT 6.7 degrees C. The initial rapid C loss in the first year for some litters is followed by a second phase (1-7y) with decay rates from 0.21-0.79/y, influenced by initial litter chemistry especially the ratio AUR/N (acid-unhydrolyzable residue, negative). By contrast, 10-23% of the initial litter C mass entered the semi-stable decay phase (>7 y) with modeled decay rates of 0.0021-0.0035/y. The slowing and convergence of k values was similar to trends in chemical composition. From 7-12 y, concentrations of Ca, Mg, K, P, Mn and Zn generally declined and became more similar among litters, and total N converged around 20 mg/g. Non-polar and water-soluble extractables and acid solubles continued to decrease slowly and AUR to increase. Solid-state C-13 NMR showed continuing slight declines in O- and di-O-alkyl C and increases in alkyl, methoxyl, aryl and carboxyl C. CIDET and other studies now clearly show that lignin is not selectively preserved, and that AUR is not a measure of foliar lignin as it includes components from condensed tannins and long-chain alkyl C. Interaction with soil minerals strongly enhances soil C stabilization, but what slows decomposition so much in organic horizons? The role of inherent "chemical recalcitrance" or possible formation of new covalent bonds is hotly debated in soil science, but increasingly complex or random molecular structures no doubt present greater challenges to enzymes. A relevant observation from soils and geochemistry is that decomposition results in a decline in individual compounds that can be identified from chemical analysis and a corresponding increase in the "molecularly uncharacterizable component" (MUC). Long-term declines in Ca, Mg, K

  3. A Lumped Thermal Model Including Thermal Coupling and Thermal Boundary Conditions for High Power IGBT Modules

    DEFF Research Database (Denmark)

    Bahman, Amir Sajjad; Ma, Ke; Blaabjerg, Frede

    2017-01-01

    Detailed thermal dynamics of high power IGBT modules are important information for the reliability analysis and thermal design of power electronic systems. However, the existing thermal models have their limits to correctly predict these complicated thermal behavior in the IGBTs: The typically used...... thermal distribution under long-term studies. Meanwhile the boundary conditions for the thermal analysis are modeled and included, which can be adapted to different real field applications of power electronic converters. Finally, the accuracy of the proposed thermal model is verified by FEM simulations...... thermal model based on one-dimensional RC lumps have limits to provide temperature distributions inside the device, moreover some variable factors in the real-field applications like the cooling and heating conditions of the converter cannot be adapted. On the other hand, the more advanced three...

  4. A Lumped Thermal Model Including Thermal Coupling and Thermal Boundary Conditions for High Power IGBT Modules

    DEFF Research Database (Denmark)

    Bahman, Amir Sajjad; Ma, Ke; Blaabjerg, Frede

    2017-01-01

    Detailed thermal dynamics of high power IGBT modules are important information for the reliability analysis and thermal design of power electronic systems. However, the existing thermal models have their limits to correctly predict these complicated thermal behavior in the IGBTs: The typically used...... thermal distribution under long-term studies. Meanwhile the boundary conditions for the thermal analysis are modeled and included, which can be adapted to different real-field applications of power electronic converters. Finally, the accuracy of the proposed thermal model is verified by FEM simulations...... thermal model based on one-dimensional RC lumps have limits to provide temperature distributions inside the device, moreover some variable factors in the real-field applications like the cooling and heating conditions of the converter cannot be adapted. On the other hand, the more advanced three...

  5. A review of factors influencing litter size in Irish sows

    Directory of Open Access Journals (Sweden)

    Lawlor Peadar G

    2007-06-01

    Full Text Available Abstract Many factors influence litter size. These include genetics, gilt management, lactation length, parity distribution, disease, stress and boar fertility. In the past 20 years, litter size in Irish sows has increased by only one pig. Born alive figures now average at 11.2 pigs per litter. In this regard, Ireland is falling behind our European competitors who have made significant advances over this time. Denmark, for example, has an average figure of 12.7 pigs born alive per litter and France an average of 12.5. The single area that could be improved immediately is sow feeding. It is important that sows are fed correctly throughout pregnancy. If over-fed during pregnancy, sows will have depressed appetite during lactation. If underfed in pregnancy, sows will be too thin at farrowing. The correct way to feed a pregnant sow is to match her feed allocation to her requirement for maintenance, body growth and growth of her developing foetuses. During lactation, sows should be given as much feed as they can eat to prevent excessive loss of body condition. Liquid-feed curves should be such that lactating sows are provided with a minimum mean daily feed supply of 6.2 kg. A small proportion of sows will eat more and this could be given as supplementary dry feed. Where dry feeding is practised in the farrowing house, it is difficult to hand-feed sows to match their appetite. Ideally ad libitum wet/dry feeders should be used. From weaning to service, sows should once again be fed ad libitum. If liquid feeding, this means giving at least 60 MJ DE (digestible energy per day during this period. If dry feeding, at least 4 kg of lactation diet should be fed daily. The effort spent perfecting sow feeding management on units should yield high dividends in the form of increased pigs born alive per litter.

  6. A review of factors influencing litter size in Irish sows

    Science.gov (United States)

    2007-01-01

    Many factors influence litter size. These include genetics, gilt management, lactation length, parity distribution, disease, stress and boar fertility. In the past 20 years, litter size in Irish sows has increased by only one pig. Born alive figures now average at 11.2 pigs per litter. In this regard, Ireland is falling behind our European competitors who have made significant advances over this time. Denmark, for example, has an average figure of 12.7 pigs born alive per litter and France an average of 12.5. The single area that could be improved immediately is sow feeding. It is important that sows are fed correctly throughout pregnancy. If over-fed during pregnancy, sows will have depressed appetite during lactation. If underfed in pregnancy, sows will be too thin at farrowing. The correct way to feed a pregnant sow is to match her feed allocation to her requirement for maintenance, body growth and growth of her developing foetuses. During lactation, sows should be given as much feed as they can eat to prevent excessive loss of body condition. Liquid-feed curves should be such that lactating sows are provided with a minimum mean daily feed supply of 6.2 kg. A small proportion of sows will eat more and this could be given as supplementary dry feed. Where dry feeding is practised in the farrowing house, it is difficult to hand-feed sows to match their appetite. Ideally ad libitum wet/dry feeders should be used. From weaning to service, sows should once again be fed ad libitum. If liquid feeding, this means giving at least 60 MJ DE (digestible energy) per day during this period. If dry feeding, at least 4 kg of lactation diet should be fed daily. The effort spent perfecting sow feeding management on units should yield high dividends in the form of increased pigs born alive per litter. PMID:21851695

  7. Biotic degradation at night, abiotic degradation at day: positive feedbacks on litter decomposition in drylands.

    Science.gov (United States)

    Gliksman, Daniel; Rey, Ana; Seligmann, Ron; Dumbur, Rita; Sperling, Or; Navon, Yael; Haenel, Sabine; De Angelis, Paolo; Arnone, John A; Grünzweig, José M

    2017-04-01

    The arid and semi-arid drylands of the world are increasingly recognized for their role in the terrestrial net carbon dioxide (CO2 ) uptake, which depends largely on plant litter decomposition and the subsequent release of CO2 back to the atmosphere. Observed decomposition rates in drylands are higher than predictions by biogeochemical models, which are traditionally based on microbial (biotic) degradation enabled by precipitation as the main mechanism of litter decomposition. Consequently, recent research in drylands has focused on abiotic mechanisms, mainly photochemical and thermal degradation, but they only partly explain litter decomposition under dry conditions, suggesting the operation of an additional mechanism. Here we show that in the absence of precipitation, absorption of dew and water vapor by litter in the field enables microbial degradation at night. By experimentally manipulating solar irradiance and nighttime air humidity, we estimated that most of the litter CO2 efflux and decay occurring in the dry season was due to nighttime microbial degradation, with considerable additional contributions from photochemical and thermal degradation during the daytime. In a complementary study, at three sites across the Mediterranean Basin, litter CO2 efflux was largely explained by litter moisture driving microbial degradation and ultraviolet radiation driving photodegradation. We further observed mutual enhancement of microbial activity and photodegradation at a daily scale. Identifying the interplay of decay mechanisms enhances our understanding of carbon turnover in drylands, which should improve the predictions of the long-term trend of global carbon sequestration.

  8. Quantification of toxic metals derived from macroplastic litter on Ookushi Beach, Japan.

    Science.gov (United States)

    Nakashima, Etsuko; Isobe, Atsuhiko; Kako, Shin'ichiro; Itai, Takaaki; Takahashi, Shin

    2012-09-18

    The potential risk of toxic metals that could leach into a beach environment from plastic litter washed ashore on Ookushi Beach, Goto Islands, Japan was estimated by balloon aerial photography, in situ beach surveys, and leaching experiments in conjunction with a Fickian diffusion model analysis. Chromium (Cr), cadmium (Cd), tin (Sn), antimony (Sb), and lead (Pb) were detected in plastic litter collected during the beach surveys. Polyvinyl chloride (PVC) fishing floats contained the highest quantity of Pb. Balloon aerial photography in conjunction with a beach survey gave an estimated mass of Pb derived from plastic litter of 313 ± 247 g. Lead leaching experiments on collected PVC floats showed that Pb in the plastic litter could leach into surrounding water on the actual beach, and that plastic litter may act as a "transport vector" of toxic metals to the beach environment. Using the experimental data, the total mass of Pb that could leach from PVC plastic litter over a year onto Ookushi Beach was estimated as 0.6 ± 0.6 g/year, suggesting that toxic metals derived from plastic beach litter are a potential "pathway" to contamination of the beach environment due to their accumulation in beach soil over time.

  9. Beach litter occurrence in sandy littorals: The potential role of urban areas, rivers and beach users in central Italy

    Science.gov (United States)

    Poeta, Gianluca; Conti, Luisa; Malavasi, Marco; Battisti, Corrado; Acosta, Alicia Teresa Rosario

    2016-11-01

    Litter washed ashore on the coastline, also called beach litter, constitutes one of the most obvious signs of marine litter pollution. Surveys of beach litter represent a fundamental tool for monitoring pollution in the marine environment and have been used world-wide to classify and quantify marine litter. Identifying the sources of marine and beach litter is, together with education, the prime weapon in combating this type of pollution. This work investigates the impact of three main potential land sources on litter occurrence: urban areas, rivers and beach users. Three sources were analyzed simultaneously on a broad scale (Lazio region, central Italy) using a random sampling design and fitting a generalized linear mixed-effect model. The results show that urban areas are the main drivers for the occurrence of marine litter along central Italy's coastal ecosystems, suggesting that the presence of such litter on Lazio beaches could be effectively reduced by identifying failings in recycling and waste collection procedures and by improving waste processing systems and sewage treatment in urban areas.

  10. Genetic parameters for canalisation analysis of litter size and litter weight traits at birth in mice

    Directory of Open Access Journals (Sweden)

    Salgado Concepción

    2006-09-01

    Full Text Available Abstract The aim of this research was to explore the genetic parameters associated with environmental variability for litter size (LS, litter weight (LW and mean individual birth weight (IW in mice before canalisation. The analyses were conducted on an experimental mice population designed to reduce environmental variability for LS. The analysed database included 1976 records for LW and IW and 4129 records for LS. The total number of individuals included in the analysed pedigree was 3997. Heritabilities estimated for the traits under an initial exploratory approach varied from 0.099 to 0.101 for LS, from 0.112 to 0.148 for LW and from 0.028 to 0.033 for IW. The means of the posterior distribution of the heritability under a Bayesian approach were the following: 0.10 (LS, 0.13 (LW and 0.03 (IW. In general, the heritabilities estimated under the initial exploratory approach for the environmental variability of the analysed traits were low. Genetic correlations estimated between the trait and its variability reached values of -0.929 (LS, -0.815 (LW and 0.969 (IW. The results presented here for the first time in mice may suggest a genetic basis for variability of the evaluated traits, thus opening the possibility to be implemented in selection schemes.

  11. Analysis of organic acids in selected forest litters of Northeast China

    Institute of Scientific and Technical Information of China (English)

    SONGJin-feng; CUIXiao-yang

    2003-01-01

    Larch (Larix olgensis), Manchurian ash (Fraxinus mandshurica), Korean pine (Pinus koraiensis) and White birch (Betula platyphylla) are the major planting species in northeast China. The samples of forest litters were collected from the stands of the above 4 species in Laoyeling and Jianlagou experiment stations of Maorshan Exp. Forest Farm (45°12′-45°30′N,127°30′-127°48′E), Northeast Forestry University, in early October 2002. Quantitative analysis and qualitative analysis were carried out on the organic acids existing in freshly fallen litters (L layer) and hemi-decomposed litters (F layer) of the four forest species by using Gas Chromatogram system. A wide variety of organic acids were identified, including oxalic, malonic, fumaric,succinic, maleic, malic, citric, C16:0, C18:0, C18:1, C18:2, C18:3 and C20:0 acids. In respect of L litters of all samples, the oxalic acid content (over 30 mg/g) was the highest of the seven low-molecular-weight organic acids identified, while the content of oleic or linoleic (above 40 mg/g) was found to be highest among the six high aliphatic acids identified. As to F litters, oxalic acid content was also the highest, followed by linoleic and oleic. For the same tree species or the same forest, the kinds and contents of organic acids in L litters were more abundant than that in F litters.

  12. Larger phylogenetic distances in litter mixtures: lower microbial biomass and higher C/N ratios but equal mass loss.

    Science.gov (United States)

    Pan, Xu; Berg, Matty P; Butenschoen, Olaf; Murray, Phil J; Bartish, Igor V; Cornelissen, Johannes H C; Dong, Ming; Prinzing, Andreas

    2015-05-07

    Phylogenetic distances of coexisting species differ greatly within plant communities, but their consequences for decomposers and decomposition remain unknown. We hypothesized that large phylogenetic distance of leaf litter mixtures increases differences of their litter traits, which may, in turn, result in increased resource complementarity or decreased resource concentration for decomposers and hence increased or decreased chemical transformation and reduction of litter. We conducted a litter mixture experiment including 12 common temperate tree species (evolutionarily separated by up to 106 Myr), and sampled after seven months, at which average mass loss was more than 50%. We found no effect of increased phylogenetic distance on litter mass loss or on abundance and diversity of invertebrate decomposers. However, phylogenetic distance decreased microbial biomass and increased carbon/nitrogen (C/N) ratios of litter mixtures. Consistently, four litter traits showed (marginally) significant phylogenetic signal and in three of these traits increasing trait difference decreased microbial biomass and increased C/N. We suggest that phylogenetic proximity of litter favours microbial decomposers and chemical transformation of litter owing to a resource concentration effect. This leads to a new hypothesis: closely related plant species occurring in the same niche should promote and profit from increased nutrient availability.

  13. Failure of vitamin A to increase litter size in sows receiving injections at various stages of gestation.

    Science.gov (United States)

    Pusateri, A E; Diekman, M A; Singleton, W L

    1999-06-01

    To determine the effectiveness of a single injection of vitamin A to increase litter size, 1,375 sows were assigned randomly to 11 treatment groups (125 sows per treatment). Treatments included injection of 1 x 10(6) IU of vitamin A dissolved in corn oil at weaning or on d 0, 2, 6, 10, 13, 19, 30, 70, or 110 after breeding. Sows in the control group were injected with corn oil on corresponding days. A total of 396 sows were removed from the study following treatment or treatment assignment. Therefore, farrowing data were collected for 979 sows. Injection of vitamin A did not influence (P > . 10) total litter size, live litter size, litter weight, pig weight, number of runts, or number of mummies. Mean live litter size was 10.1 +/- .1 for all sows that farrowed in the experiment. Parity group affected total litter size, live litter size, live litter weight, and number stillborn (P pig weight, number of runts, number of mummies, or gestation length (P > . 10). In this study, a single injection of vitamin A at any time from weaning to farrowing did not increase litter size in sows.

  14. Transmission line model for strained quantum well lasers including carrier transport and carrier heating effects.

    Science.gov (United States)

    Xia, Mingjun; Ghafouri-Shiraz, H

    2016-03-01

    This paper reports a new model for strained quantum well lasers, which are based on the quantum well transmission line modeling method where effects of both carrier transport and carrier heating have been included. We have applied this new model and studied the effect of carrier transport on the output waveform of a strained quantum well laser both in time and frequency domains. It has been found that the carrier transport increases the turn-on, turn-off delay times and damping of the quantum well laser transient response. Also, analysis in the frequency domain indicates that the carrier transport causes the output spectrum of the quantum well laser in steady state to exhibit a redshift which has a narrower bandwidth and lower magnitude. The simulation results of turning-on transients obtained by the proposed model are compared with those obtained by the rate equation laser model. The new model has also been used to study the effects of pump current spikes on the laser output waveforms properties, and it was found that the presence of current spikes causes (i) wavelength blueshift, (ii) larger bandwidth, and (iii) reduces the magnitude and decreases the side-lobe suppression ratio of the laser output spectrum. Analysis in both frequency and time domains confirms that the new proposed model can accurately predict the temporal and spectral behaviors of strained quantum well lasers.

  15. A numerical model including PID control of a multizone crystal growth furnace

    Science.gov (United States)

    Panzarella, Charles H.; Kassemi, Mohammad

    This paper presents a 2D axisymmetric combined conduction and radiation model of a multizone crystal growth furnace. The model is based on a programmable multizone furnace (PMZF) designed and built at NASA Lewis Research Center for growing high quality semiconductor crystals. A novel feature of this model is a control algorithm which automatically adjusts the power in any number of independently controlled heaters to establish the desired crystal temperatures in the furnace model. The control algorithm eliminates the need for numerous trial and error runs previously required to obtain the same results. The finite element code, FIDAP, used to develop the furnace model, was modified to directly incorporate the control algorithm. This algorithm, which presently uses PID control, and the associated heat transfer model are briefly discussed. Together, they have been used to predict the heater power distributions for a variety of furnace configurations and desired temperature profiles. Examples are included to demonstrate the effectiveness of the PID controlled model in establishing isothermal, Bridgman, and other complicated temperature profies in the sample. Finally, an example is given to show how the algorithm can be used to change the desired profile with time according to a prescribed temperature-time evolution.

  16. A continuum model of solvation energies including electrostatic, dispersion, and cavity contributions.

    Science.gov (United States)

    Duignan, Timothy T; Parsons, Drew F; Ninham, Barry W

    2013-08-15

    Physically accurate continuum solvent models that can calculate solvation energies are crucial to explain and predict the behavior of solute particles in water. Here, we present such a model applied to small spherical ions and neutral atoms. It improves upon a basic Born electrostatic model by including a standard cavity energy and adding a dispersion component, consistent with the Born electrostatic energy and using the same cavity size parameter. We show that the well-known, puzzling differences between the solvation energies of ions of the same size is attributable to the neglected dispersion contribution. This depends on dynamic polarizability as well as size. Generally, a large cancellation exists between the cavity and dispersion contributions. This explains the surprising success of the Born model. The model accurately reproduces the solvation energies of the alkali halide ions, as well as the silver(I) and copper(I) ions with an error of 12 kJ mol(-1) (±3%). The solvation energy of the noble gases is also reproduced with an error of 2.6 kJ mol(-1) (±30%). No arbitrary fitting parameters are needed to achieve this. This model significantly improves our understanding of ionic solvation and forms a solid basis for the investigation of other ion-specific effects using a continuum solvent model.

  17. Model for resistance evolution in shape memory alloys including R-phase

    Science.gov (United States)

    Brammajyosula, Ravindra; Buravalla, Vidyashankar; Khandelwal, Ashish

    2011-03-01

    The electrical resistance behavior of a shape memory alloy (SMA) wire can be used for sensing the state of an SMA device. Hence, this study investigates the resistance evolution in SMAs. A lumped parameter model with cosine kinetics to capture the resistance variation during the phase transformation is developed. Several SMA materials show the presence of trigonal or rhombohedral (R) phase as an intermediate phase, apart from the commonly recognized austenite and martensite phases. Most of the SMA models ignore the R-phase effect in their prediction of thermomechanical response. This may be acceptable since the changes in thermomechanical response associated with the R-phase are relatively less. However, the resistivity related effects are pronounced in the presence of the R-phase and its appearance introduces non-monotonicity in the resistivity evolution. This leads to additional complexities in the use of resistance signal for sensing and control. Hence, a lumped model is developed here for resistance evolution including the R-phase effects. A phase-diagram-based model is proposed for predicting electro-thermomechanical response. Both steady state hysteretic response and transient response are modeled. The model predictions are compared with the available test data. Numerical studies have shown that the model is able to capture all the essential features of the resistance evolution in SMAs in the presence of the R-phase.

  18. A New Circuit Model for Spin-Torque Oscillator Including Perpendicular Torque of Magnetic Tunnel Junction

    Directory of Open Access Journals (Sweden)

    Hyein Lim

    2013-01-01

    Full Text Available Spin-torque oscillator (STO is a promising new technology for the future RF oscillators, which is based on the spin-transfer torque (STT effect in magnetic multilayered nanostructure. It is expected to provide a larger tunability, smaller size, lower power consumption, and higher level of integration than the semiconductor-based oscillators. In our previous work, a circuit-level model of the giant magnetoresistance (GMR STO was proposed. In this paper, we present a physics-based circuit-level model of the magnetic tunnel junction (MTJ-based STO. MTJ-STO model includes the effect of perpendicular torque that has been ignored in the GMR-STO model. The variations of three major characteristics, generation frequency, mean oscillation power, and generation linewidth of an MTJ-STO with respect to the amount of perpendicular torque, are investigated, and the results are applied to our model. The operation of the model was verified by HSPICE simulation, and the results show an excellent agreement with the experimental data. The results also prove that a full circuit-level simulation with MJT-STO devices can be made with our proposed model.

  19. Does including physiology improve species distribution model predictions of responses to recent climate change?

    Science.gov (United States)

    Buckley, Lauren B; Waaser, Stephanie A; MacLean, Heidi J; Fox, Richard

    2011-12-01

    Thermal constraints on development are often invoked to predict insect distributions. These constraints tend to be characterized in species distribution models (SDMs) by calculating development time based on a constant lower development temperature (LDT). Here, we assessed whether species-specific estimates of LDT based on laboratory experiments can improve the ability of SDMs to predict the distribution shifts of six U.K. butterflies in response to recent climate warming. We find that species-specific and constant (5 degrees C) LDT degree-day models perform similarly at predicting distributions during the period of 1970-1982. However, when the models for the 1970-1982 period are projected to predict distributions in 1995-1999 and 2000-2004, species-specific LDT degree-day models modestly outperform constant LDT degree-day models. Our results suggest that, while including species-specific physiology in correlative models may enhance predictions of species' distribution responses to climate change, more detailed models may be needed to adequately account for interspecific physiological differences.

  20. Modeling of single char combustion, including CO oxidation in its boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C.H.; Longwell, J.P.; Sarofim, A.F.

    1994-10-25

    The combustion of a char particle can be divided into a transient phase where its temperature increases as it is heated by oxidation, and heat transfer from the surrounding gas to an approximately constant temperature stage where gas phase reaction is important and which consumes most of the carbon and an extinction stage caused by carbon burnout. In this work, separate models were developed for the transient heating where gas phase reactions were unimportant and for the steady temperature stage where gas phase reactions were treated in detail. The transient char combustion model incorporates intrinsic char surface production of CO and CO{sub 2}, internal pore diffusion and external mass and heat transfer. The model provides useful information for particle ignition, burning temperature profile, combustion time, and carbon consumption rate. A gas phase reaction model incorporating the full set of 28 elementary C/H/O reactions was developed. This model calculated the gas phase CO oxidation reaction in the boundary layer at particle temperatures of 1250 K and 2500 K by using the carbon consumption rate and the burning temperature at the pseudo-steady state calculated from the temperature profile model but the transient heating was not included. This gas phase model can predict the gas species, and the temperature distributions in the boundary layer, the CO{sub 2}/CO ratio, and the location of CO oxidation. A mechanistic heat and mass transfer model was added to the temperature profile model to predict combustion behavior in a fluidized bed. These models were applied to data from the fluidized combustion of Newlands coal char particles. 52 refs., 60 figs.

  1. Including source uncertainty and prior information in the analysis of stable isotope mixing models.

    Science.gov (United States)

    Ward, Eric J; Semmens, Brice X; Schindler, Daniel E

    2010-06-15

    Stable isotope mixing models offer a statistical framework for estimating the contribution of multiple sources (such as prey) to a mixture distribution. Recent advances in these models have estimated the source proportions using Bayesian methods, but have not explicitly accounted for uncertainty in the mean and variance of sources. We demonstrate that treating these quantities as unknown parameters can reduce bias in the estimated source contributions, although model complexity is increased (thereby increasing the variance of estimates). The advantages of this fully Bayesian approach are particularly apparent when the source geometry is poor or sample sizes are small. A second benefit to treating source quantities as parameters is that prior source information can be included. We present findings from 9 lake food-webs, where the consumer of interest (fish) has a diet composed of 5 sources: aquatic insects, snails, zooplankton, amphipods, and terrestrial insects. We compared the traditional Bayesian stable isotope mixing model with fixed source parameters to our fully Bayesian model-with and without an informative prior. The informative prior has much less impact than the choice of model-the traditional mixing model with fixed source parameters estimates the diet to be dominated by aquatic insects, while the fully Bayesian model estimates the diet to be more balanced but with greater importance of zooplankton. The findings from this example demonstrate that there can be stark differences in inference between the two model approaches, particularly when the source geometry of the mixing model is poor. These analyses also emphasize the importance of investing substantial effort toward characterizing the variation in the isotopic characteristics of source pools to appropriately quantify uncertainties in their contributions to consumers in food webs.

  2. Kinetic modeling of rhamnolipid production by Pseudomonas aeruginosa PAO1 including cell density-dependent regulation.

    Science.gov (United States)

    Henkel, Marius; Schmidberger, Anke; Vogelbacher, Markus; Kühnert, Christian; Beuker, Janina; Bernard, Thomas; Schwartz, Thomas; Syldatk, Christoph; Hausmann, Rudolf

    2014-08-01

    The production of rhamnolipid biosurfactants by Pseudomonas aeruginosa is under complex control of a quorum sensing-dependent regulatory network. Due to a lack of understanding of the kinetics applicable to the process and relevant interrelations of variables, current processes for rhamnolipid production are based on heuristic approaches. To systematically establish a knowledge-based process for rhamnolipid production, a deeper understanding of the time-course and coupling of process variables is required. By combining reaction kinetics, stoichiometry, and experimental data, a process model for rhamnolipid production with P. aeruginosa PAO1 on sunflower oil was developed as a system of coupled ordinary differential equations (ODEs). In addition, cell density-based quorum sensing dynamics were included in the model. The model comprises a total of 36 parameters, 14 of which are yield coefficients and 7 of which are substrate affinity and inhibition constants. Of all 36 parameters, 30 were derived from dedicated experimental results, literature, and databases and 6 of them were used as fitting parameters. The model is able to describe data on biomass growth, substrates, and products obtained from a reference batch process and other validation scenarios. The model presented describes the time-course and interrelation of biomass, relevant substrates, and products on a process level while including a kinetic representation of cell density-dependent regulatory mechanisms.

  3. Codigestion of solid wastes: a review of its uses and perspectives including modeling.

    Science.gov (United States)

    Mata-Alvarez, Joan; Dosta, Joan; Macé, Sandra; Astals, Sergi

    2011-06-01

    The last two years have witnessed a dramatic increase in the number of papers published on the subject of codigestion, highlighting the relevance of this topic within anaerobic digestion research. Consequently, it seems appropriate to undertake a review of codigestion practices starting from the late 1970s, when the first papers related to this concept were published, and continuing to the present day, demonstrating the exponential growth in the interest shown in this approach in recent years. Following a general analysis of the situation, state-of-the-art codigestion is described, focusing on the two most important areas as regards publication: codigestion involving sewage sludge and the organic fraction of municipal solid waste (including a review of the secondary advantages for wastewater treatment plant related to biological nutrient removal), and codigestion in the agricultural sector, that is, including agricultural - farm wastes, and energy crops. Within these areas, a large number of oversized digesters appear which can be used to codigest other substrates, resulting in economic and environmental advantages. Although the situation may be changing, there is still a need for good examples on an industrial scale, particularly with regard to wastewater treatment plants, in order to extend this beneficial practice. In the last section, a detailed analysis of papers addressing the important aspect of modelisation is included. This analysis includes the first codigestion models to be developed as well as recent applications of the standardised anaerobic digestion model ADM1 to codigestion. (This review includes studies ranging from laboratory to industrial scale.).

  4. Enhanced UWB Radio Channel Model for Short-Range Communication Scenarios Including User Dynamics

    DEFF Research Database (Denmark)

    Kovacs, Istvan Zsolt; Nguyen, Tuan Hung; Eggers, Patrick Claus F.

    2005-01-01

    In this paper we propose a SISO UWB radio channel model for short-range radio link scenarios between a fixed device and a dynamic user hand-held device. The channel model is derived based on novel experimental UWB radio propagation investigations carried out in typical indoor PAN scenarios...... including realistic device and user terminal antenna configurations. The radio channel measurements have been performed in the lower UWB frequency band of 3GHz to 5GHz with a 2x4 MIMO antenna configuration. Several environments, user scenarios and two types of user terminals have been used. The developed...

  5. Fuzzy Control of Yaw and Roll Angles of a Simulated Helicopter Model Includes Articulated Manipulators

    Directory of Open Access Journals (Sweden)

    Hossein Sadegh Lafmejani

    2015-09-01

    Full Text Available Fuzzy logic controller (FLC is a heuristic method by If-Then Rules which resembles human intelligence and it is a good method for designing Non-linear control systems. In this paper, an arbitrary helicopter model includes articulated manipulators has been simulated with Matlab SimMechanics toolbox. Due to the difficulties of modeling this complex system, a fuzzy controller with simple fuzzy rules has been designed for its yaw and roll angles in order to stabilize the helicopter while it is in the presence of disturbances or its manipulators are moving for a task. Results reveal that a simple FLC can appropriately control this system.

  6. Including Finite Surface Span Effects in Empirical Jet-Surface Interaction Noise Models

    Science.gov (United States)

    Brown, Clifford A.

    2016-01-01

    The effect of finite span on the jet-surface interaction noise source and the jet mixing noise shielding and reflection effects is considered using recently acquired experimental data. First, the experimental setup and resulting data are presented with particular attention to the role of surface span on far-field noise. These effects are then included in existing empirical models that have previously assumed that all surfaces are semi-infinite. This extended abstract briefly describes the experimental setup and data leaving the empirical modeling aspects for the final paper.

  7. Analytical model for investigation of interior noise characteristics in aircraft with multiple propellers including synchrophasing

    Science.gov (United States)

    Fuller, C. R.

    1986-01-01

    A simplified analytical model of transmission of noise into the interior of propeller-driven aircraft has been developed. The analysis includes directivity and relative phase effects of the propeller noise sources, and leads to a closed form solution for the coupled motion between the interior and exterior fields via the shell (fuselage) vibrational response. Various situations commonly encountered in considering sound transmission into aircraft fuselages are investigated analytically and the results obtained are compared to measurements in real aircraft. In general the model has proved successful in identifying basic mechanisms behind noise transmission phenomena.

  8. Effect of in ovo vaccination and anticoccidials on the distribution of Eimeria spp. in poultry litter and serum antibody titers against coccidia in broiler chickens raised on used litter

    Science.gov (United States)

    The present study reports the effects of various field anticoccidial programs on the distribution of Eimeria spp. in poultry litter and serum antibody titers against coccidia in broiler chickens raised on used litter. The programs included in ovo vaccination and various medications with either chemi...

  9. An air/sea flux model including the effects of capillary waves

    Science.gov (United States)

    Bourassa, Mark A.

    1993-01-01

    An improved model of the air/sea interface is developed. The improvements consist in including the effect of capillary (surface tension) waves on the tropical surface fluxes and the consideration of the sea state, both of which increase the magnitude of tropical surface fluxes. Changes in surface stress are most significant in the low wind-speed regions, which include the areas where westerly bursts occur. It is shown that the changes, from the regular wind conditions to those of a westerly burst or El-Nino, can double when the effects of capillary waves are considered. This implies a much stronger coupling between the ocean and the atmosphere than is predicted by other boundary layer models.

  10. A complete model of CH+ rotational excitation including radiative and chemical pumping processes

    CERN Document Server

    Godard, Benjamin

    2012-01-01

    Aims. Excitation of far-infrared and submillimetric molecular lines may originate from nonreactive collisions, chemical formation, or far infrared, near-infrared, and optical fluorescences. As a template, we investigate the impact of each of these processes on the excitation of the methylidyne cation CH+ and on the intensities of its rotational transitions recently detected in emission in dense photodissociation regions (PDRs) and in planetary nebulae. Methods. We have developed a nonlocal thermodynamic equilibrium (non-LTE) excitation model that includes the entire energy structure of CH+, i.e. taking into account the pumping of its vibrational and bound and unbound electronic states by near-infrared and optical photons. The model includes the theoretical cross-sections of nonreactive collisions with H, H2, He, and e-, and a Boltzmann distribution is used to describe the probability of populating the excited levels of CH+ during its chemical formation by hydrogenation of C+. To confirm our results we also pe...

  11. Including Flocculation in a Numerical Sediment Transport Model for a Partially-Mixed Estuary

    Science.gov (United States)

    Tarpley, D.; Harris, C. K.; Friedrichs, C. T.

    2016-12-01

    Particle settling velocity impacts the transport of suspended sediment to the first order but fine-grained material like muds tend to form loosely bound aggregates (flocs) whose settling velocity can vary widely. Properties of flocculated sediment such as settling velocity and particle density are difficult to predict because they change in response to several factors including salinity, suspended sediment concentration, turbulent mixing, and organic content. Knowledge of the mechanisms governing flocculation of cohesive sediment is rapidly expanding; especially in response to recent technical advances. As the understanding of particle dynamics progresses, numerical models describing flocculation and break-up are being developed with varying degrees of complexity. While complex models capture the dynamics of the system, their computational costs may prohibit their incorporation into larger model domains. It is important to determine if the computational costs of intricate floc models are justifiable compared to simpler formulations. For this study, we implement an idealized two-dimensional model designed to represent a longitudinal section of a partially mixed estuary that neglects across-channel variation but exhibits salinity driven estuarine circulation. The idealized domain is designed to mimic the primary features of the York River, VA. Suspended load, erosion and deposition are calculated within the sediment transport routines of the COAWST modeling system. We compare different methods for prescribing settling velocity of fine-grained material. The simplest, standard model neglects flocculation dynamics while the complex treatment is a size-class-based flocculation model (FLOCMOD). Differences in tidal and daily averages of suspended load, bulk settling velocity and bed deposition are compared between the standard and FLOCMOD runs, to examine the relative impact of flocculation on sediment transport patterns. We expect FLOCMOD to have greater variability and

  12. Multistate Statistical Modeling: A Tool to Build a Lung Cancer Microsimulation Model That Includes Parameter Uncertainty and Patient Heterogeneity.

    Science.gov (United States)

    Bongers, Mathilda L; de Ruysscher, Dirk; Oberije, Cary; Lambin, Philippe; Uyl-de Groot, Carin A; Coupé, V M H

    2016-01-01

    With the shift toward individualized treatment, cost-effectiveness models need to incorporate patient and tumor characteristics that may be relevant to treatment planning. In this study, we used multistate statistical modeling to inform a microsimulation model for cost-effectiveness analysis of individualized radiotherapy in lung cancer. The model tracks clinical events over time and takes patient and tumor features into account. Four clinical states were included in the model: alive without progression, local recurrence, metastasis, and death. Individual patients were simulated by repeatedly sampling a patient profile, consisting of patient and tumor characteristics. The transitioning of patients between the health states is governed by personalized time-dependent hazard rates, which were obtained from multistate statistical modeling (MSSM). The model simulations for both the individualized and conventional radiotherapy strategies demonstrated internal and external validity. Therefore, MSSM is a useful technique for obtaining the correlated individualized transition rates that are required for the quantification of a microsimulation model. Moreover, we have used the hazard ratios, their 95% confidence intervals, and their covariance to quantify the parameter uncertainty of the model in a correlated way. The obtained model will be used to evaluate the cost-effectiveness of individualized radiotherapy treatment planning, including the uncertainty of input parameters. We discuss the model-building process and the strengths and weaknesses of using MSSM in a microsimulation model for individualized radiotherapy in lung cancer.

  13. Effects of Nitrogen Addition on Litter Decomposition and CO2 Release: Considering Changes in Litter Quantity.

    Science.gov (United States)

    Li, Hui-Chao; Hu, Ya-Lin; Mao, Rong; Zhao, Qiong; Zeng, De-Hui

    2015-01-01

    This study aims to evaluate the impacts of changes in litter quantity under simulated N deposition on litter decomposition, CO2 release, and soil C loss potential in a larch plantation in Northeast China. We conducted a laboratory incubation experiment using soil and litter collected from control and N addition (100 kg ha-1 year-1 for 10 years) plots. Different quantities of litter (0, 1, 2 and 4 g) were placed on 150 g soils collected from the same plots and incubated in microcosms for 270 days. We found that increased litter input strongly stimulated litter decomposition rate and CO2 release in both control and N fertilization microcosms, though reduced soil microbial biomass C (MBC) and dissolved inorganic N (DIN) concentration. Carbon input (C loss from litter decomposition) and carbon output (the cumulative C loss due to respiration) elevated with increasing litter input in both control and N fertilization microcosms. However, soil C loss potentials (C output-C input) reduced by 62% in control microcosms and 111% in N fertilization microcosms when litter addition increased from 1 g to 4 g, respectively. Our results indicated that increased litter input had a potential to suppress soil organic C loss especially for N addition plots.

  14. PAHs in decaying Quercus ilex leaf litter: mutual effects on litter decomposition and PAH dynamics.

    Science.gov (United States)

    De Nicola, F; Baldantoni, D; Alfani, A

    2014-11-01

    The investigation of the relationships between litter decomposition and polycyclic aromatic hydrocarbons (PAHs) is important to shed light not only on the effects of these pollutants on fundamental ecosystem processes, such as litter decomposition, but also on the degradation of these pollutants by soil microbial community. This allows to understand the effect of atmospheric PAH contamination on soil PAH content via litterfall. At this aim, we studied mass and PAH dynamics of Quercus ilex leaf litters collected from urban, industrial and remote sites, incubated in mesocosms under controlled conditions for 361d. The results highlighted a litter decomposition rate of leaves sampled in urban>industrial>remote sites; the faster decomposition of litter of the urban site is also related to the low C/N ratio of the leaves. The PAHs showed concentrations at the beginning of the incubation of 887, 650 and 143 ng g(-1)d.w., respectively in leaf litters from urban, industrial and remote sites. The PAHs in litter decreased along the time, with the same trend observed for mass litter, showing the highest decrease at 361 d for the urban leaf litter. Anyway, PAH dynamics in all the litters exhibited two phases of loss, separated by a PAH increase observed at 246 d and mainly linked to benzo[e]pyrene.

  15. Model for safety reports including descriptive examples; Mall foer saekerhetsrapporter med beskrivande exempel

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-01

    Several safety reports will be produced in the process of planning and constructing the system for disposal of high-level radioactive waste in Sweden. The present report gives a model, with detailed examples, of how these reports should be organized and what steps they should include. In the near future safety reports will deal with the encapsulation plant and the repository. Later reports will treat operation of the handling systems and the repository.

  16. Extending the formal model of a spatial data infrastructure to include volunteered geographical information

    CSIR Research Space (South Africa)

    Cooper, Antony K

    2011-07-01

    Full Text Available an aggregator of VGI, such as Ushahidi, and the provider of the infrastructure for collecting VGI, such as OpenStreetMap. 3) Broker: A stakeholder who brings End Users and Providers together and assists in the negotiation of contracts between them... model of a spatial data infrastructure to include volunteered geographical information Antony K Cooper*, Petr Rapant?, Jan Hjelmager?, Dominique Laurent?, Adam Iwaniak#, Serena Coetzee$, Harold Moellering? and Ulrich D?ren? *Logistics...

  17. QCD Equation of State From a Chiral Hadronic Model Including Quark Degrees of Freedom

    CERN Document Server

    Rau, Philip; Schramm, Stefan; Stöcker, Horst

    2013-01-01

    This work presents an effective model for strongly interacting matter and the QCD equation of state (EoS). The model includes both hadron and quark degrees of freedom and takes into account the transition of chiral symmetry restoration as well as the deconfinement phase transition. At low temperatures $T$ and baryonic densities $\\rho_B$ a hadron resonance gas is described using a SU(3)-flavor sigma-omega model and a quark phase is introduced in analogy to PNJL models for higher $T$ and $\\rho_B$. In this way, the correct asymptotic degrees of freedom are used in a wide range of $T$ and $\\rho_B$. Here, results of this model concerning the chiral and deconfinement phase transitions and thermodynamic model properties are presented. Large hadron resonance multiplicities in the transition region emphasize the importance of heavy-mass resonance states in this region and their impact on the chiral transition behavior. The resulting phase diagram of QCD matter at small chemical potentials is in line with latest lattic...

  18. A full model for simulation of electrochemical cells including complex behavior

    Science.gov (United States)

    Esperilla, J. J.; Félez, J.; Romero, G.; Carretero, A.

    This communication presents a model of electrochemical cells developed in order to simulate their electrical, chemical and thermal behavior showing the differences when thermal effects are or not considered in the charge-discharge process. The work presented here has been applied to the particular case of the Pb,PbSO 4|H 2SO 4 (aq)|PbO 2,Pb cell, which forms the basis of the lead-acid batteries so widely used in the automotive industry and as traction batteries in electric or hybrid vehicles. Each half-cell is considered independently in the model. For each half-cell, in addition to the main electrode reaction, a secondary reaction is considered: the hydrogen evolution reaction in the negative electrode and the oxygen evolution reaction in the positive. The equilibrium potential is calculated with the Nernst equation, in which the activity coefficients are fitted to an exponential function using experimental data. On the other hand, the two main mechanisms that produce the overpotential are considered, that is the activation or charge transfer and the diffusion mechanisms. First, an isothermal model has been studied in order to show the behavior of the main phenomena. A more complex model has also been studied including thermal behavior. This model is very useful in the case of traction batteries in electric and hybrid vehicles where high current intensities appear. Some simulation results are also presented in order to show the accuracy of the proposed models.

  19. A High-Rate, Single-Crystal Model including Phase Transformations, Plastic Slip, and Twinning

    Energy Technology Data Exchange (ETDEWEB)

    Addessio, Francis L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Bronkhorst, Curt Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Bolme, Cynthia Anne [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Explosive Science and Shock Physics Division; Brown, Donald William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology Division; Cerreta, Ellen Kathleen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology Division; Lebensohn, Ricardo A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology Division; Lookman, Turab [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Luscher, Darby Jon [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Mayeur, Jason Rhea [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Morrow, Benjamin M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology Division; Rigg, Paulo A. [Washington State Univ., Pullman, WA (United States). Dept. of Physics. Inst. for Shock Physics

    2016-08-09

    An anisotropic, rate-­dependent, single-­crystal approach for modeling materials under the conditions of high strain rates and pressures is provided. The model includes the effects of large deformations, nonlinear elasticity, phase transformations, and plastic slip and twinning. It is envisioned that the model may be used to examine these coupled effects on the local deformation of materials that are subjected to ballistic impact or explosive loading. The model is formulated using a multiplicative decomposition of the deformation gradient. A plate impact experiment on a multi-­crystal sample of titanium was conducted. The particle velocities at the back surface of three crystal orientations relative to the direction of impact were measured. Molecular dynamics simulations were conducted to investigate the details of the high-­rate deformation and pursue issues related to the phase transformation for titanium. Simulations using the single crystal model were conducted and compared to the high-­rate experimental data for the impact loaded single crystals. The model was found to capture the features of the experiments.

  20. Litter Control Achievement - Ohio 4-H Club Score Sheet [and] Activity Guides 1 through 7. 4-H Pilot Program 918.

    Science.gov (United States)

    Ohio State Univ., Columbus. Cooperative Extension Service.

    Seven activity guides, evaluation sheet, and club scoresheet have been prepared for Ohio 4-H clubs' litter education program. Topics of the seven activity guides include: (1) general guidelines and types of activities; (2) little known facts about waste/litter; (3) guidelines for a walking tour; (4) fact sheet (questionnaire) related to garbage;…

  1. 9 CFR 72.24 - Litter and manure from carriers and premises of tick-infested animals; destruction or treating...

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Litter and manure from carriers and... ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS TEXAS (SPLENETIC) FEVER IN CATTLE § 72.24 Litter and manure from carriers and premises of tick-infested animals; destruction or treating required. The...

  2. Biochemical Control of Fungal Biomass and Enzyme Production During Native Hawaiian Litter Degradation

    Science.gov (United States)

    Amatangelo, K. L.; Cordova, T. P.; Vitousek, P. M.

    2007-12-01

    Microbial growth and enzyme production during decomposition is controlled by the availability of carbon substrates, essential elements, and the ratios of these (such as lignin:N). We manipulated carbon:nutrient stoichiometry during decomposition using a natural fertility gradient in Hawaii and litter of varying initial biochemistry. We collected freshly senesced litter of seven biochemically distinct species from three sites offering differing levels of N, P, cations, and 15N , but similar yearly rainfall and temperature patterns. Litter types were decomposed at both the sites they were collected, and at the other site(s) that species was found. Litter was collected at multiple time points, and after one year of decomposition, calculated K constants varied an order of magnitude, from 0.276 to 2.76. Decomposition rates varied significantly with both litter site of origin and deployment, except at the oldest, P-limited site, where litter site of origin was not significantly correlated with decomposition within species. As microbial exocellular enzymes provide the catalyst for the breakdown of organic molecules including phenols, cellulose, and cutin, we assayed polyphenol oxidase, cellobiohydrolase, cutinase, chitinase, and lignin peroxidase to evaluate the breakdown sequence of different litter types. To measure the fungal biomass accumulating during decomposition, we extracted (22E)-Ergosta-5,7,22-trien-3beta- ol (ergosterol) on a subset of samples. The production of particular exocellular enzymes on litter species responded distinctly to origin and decomposition sites: after six months, chitinase and cellobiohydrolase were significantly affected by origin site, whereas polyphenol oxidase activity was controlled by deployment site. We conclude that site characteristics can alter the interaction between litter carbon:nutrient ratios and decomposition rate, mediated through microbial biomass and enzyme production.

  3. A 3D model of the oculomotor plant including the pulley system

    Energy Technology Data Exchange (ETDEWEB)

    Viegener, A; Armentano, R L [Fundacion Universitaria Dr. Rene G. Favaloro, SolIs 453 (1078) Buenos Aires (Argentina)

    2007-11-15

    Early models of the oculomotor plant only considered the eye globes and the muscles that move them. Recently, connective tissue structures have been found enveloping the extraocular muscles (EOMs) and firmly anchored to the orbital wall. These structures act as pulleys; they determine the functional origin of the EOMs and, in consequence, their effective pulling direction. A three dimensional model of the oculomotor plant, including pulleys, has been developed and simulations in Simulink were performed during saccadic eye movements. Listing's law was implemented based on the supposition that there exists an eye orientation related signal. The inclusion of the pulleys in the model makes this assumption plausible and simplifies the problem of the plant noncommutativity.

  4. A flexible and qualitatively stable model for cell cycle dynamics including DNA damage effects.

    Science.gov (United States)

    Jeffries, Clark D; Johnson, Charles R; Zhou, Tong; Simpson, Dennis A; Kaufmann, William K

    2012-01-01

    This paper includes a conceptual framework for cell cycle modeling into which the experimenter can map observed data and evaluate mechanisms of cell cycle control. The basic model exhibits qualitative stability, meaning that regardless of magnitudes of system parameters its instances are guaranteed to be stable in the sense that all feasible trajectories converge to a certain trajectory. Qualitative stability can also be described by the signs of real parts of eigenvalues of the system matrix. On the biological side, the resulting model can be tuned to approximate experimental data pertaining to human fibroblast cell lines treated with ionizing radiation, with or without disabled DNA damage checkpoints. Together these properties validate a fundamental, first order systems view of cell dynamics. Classification Codes: 15A68.

  5. RELAP5-3D Code Includes Athena Features and Models

    Energy Technology Data Exchange (ETDEWEB)

    Richard A. Riemke; Cliff B. Davis; Richard R. Schultz

    2006-07-01

    Version 2.3 of the RELAP5-3D computer program includes all features and models previously available only in the ATHENA version of the code. These include the addition of new working fluids (i.e., ammonia, blood, carbon dioxide, glycerol, helium, hydrogen, lead-bismuth, lithium, lithium-lead, nitrogen, potassium, sodium, and sodium-potassium) and a magnetohydrodynamic model that expands the capability of the code to model many more thermal-hydraulic systems. In addition to the new working fluids along with the standard working fluid water, one or more noncondensable gases (e.g., air, argon, carbon dioxide, carbon monoxide, helium, hydrogen, krypton, nitrogen, oxygen, sf6, xenon) can be specified as part of the vapor/gas phase of the working fluid. These noncondensable gases were in previous versions of RELAP5- 3D. Recently four molten salts have been added as working fluids to RELAP5-3D Version 2.4, which has had limited release. These molten salts will be in RELAP5-3D Version 2.5, which will have a general release like RELAP5-3D Version 2.3. Applications that use these new features and models are discussed in this paper.

  6. Including policy and management in socio-hydrology models: initial conceptualizations

    Science.gov (United States)

    Hermans, Leon; Korbee, Dorien

    2017-04-01

    Socio-hydrology studies the interactions in coupled human-water systems. So far, the use of dynamic models that capture the direct feedback between societal and hydrological systems has been dominant. What has not yet been included with any particular emphasis, is the policy or management layer, which is a central element in for instance integrated water resources management (IWRM) or adaptive delta management (ADM). Studying the direct interactions between human-water systems generates knowledges that eventually helps influence these interactions in ways that may ensure better outcomes - for society and for the health and sustainability of water systems. This influence sometimes occurs through spontaneous emergence, uncoordinated by societal agents - private sector, citizens, consumers, water users. However, the term 'management' in IWRM and ADM also implies an additional coordinated attempt through various public actors. This contribution is a call to include the policy and management dimension more prominently into the research focus of the socio-hydrology field, and offers first conceptual variables that should be considered in attempts to include this policy or management layer in socio-hydrology models. This is done by drawing on existing frameworks to study policy processes throughout both planning and implementation phases. These include frameworks such as the advocacy coalition framework, collective learning and policy arrangements, which all emphasis longer-term dynamics and feedbacks between actor coalitions in strategic planning and implementation processes. A case about longter-term dynamics in the management of the Haringvliet in the Netherlands is used to illustrate the paper.

  7. EXACT SOLUTIONS FOR NONLINEAR TRANSIENT FLOW MODEL INCLUDING A QUADRATIC GRADIENT TERM

    Institute of Scientific and Technical Information of China (English)

    曹绪龙; 同登科; 王瑞和

    2004-01-01

    The models of the nonlinear radial flow for the infinite and finite reservoirs including a quadratic gradient term were presented. The exact solution was given in real space for flow equation including quadratic gradiet term for both constant-rate and constant pressure production cases in an infinite system by using generalized Weber transform. Analytical solutions for flow equation including quadratic gradient term were also obtained by using the Hankel transform for a finite circular reservoir case. Both closed and constant pressure outer boundary conditions are considered. Moreover, both constant rate and constant pressure inner boundary conditions are considered. The difference between the nonlinear pressure solution and linear pressure solution is analyzed. The difference may be reached about 8% in the long time. The effect of the quadratic gradient term in the large time well test is considered.

  8. SPheno 3.1: extensions including flavour, CP-phases and models beyond the MSSM

    Science.gov (United States)

    Porod, W.; Staub, F.

    2012-11-01

    We describe recent extensions of the program SPhenoincluding flavour aspects, CP-phases, R-parity violation and low energy observables. In case of flavour mixing all masses of supersymmetric particles are calculated including the complete flavour structure and all possible CP-phases at the 1-loop level. We give details on implemented seesaw models, low energy observables and the corresponding extension of the SUSY Les Houches Accord. Moreover, we comment on the possibilities to include MSSM extensions in SPheno. Catalogue identifier: ADRV_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADRV_v2_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 154062 No. of bytes in distributed program, including test data, etc.: 1336037 Distribution format: tar.gz Programming language: Fortran95. Computer: PC running under Linux, should run in every Unix environment. Operating system: Linux, Unix. Classification: 11.6. Catalogue identifier of previous version: ADRV_v1_0 Journal reference of previous version: Comput. Phys. Comm. 153(2003)275 Does the new version supersede the previous version?: Yes Nature of problem: The first issue is the determination of the masses and couplings of supersymmetric particles in various supersymmetric models, the R-parity conserved MSSM with generation mixing and including CP-violating phases, various seesaw extensions of the MSSM and the MSSM with bilinear R-parity breaking. Low energy data on Standard Model fermion masses, gauge couplings and electroweak gauge boson masses serve as constraints. Radiative corrections from supersymmetric particles to these inputs must be calculated. Theoretical constraints on the soft SUSY breaking parameters from a high scale theory are imposed and the parameters at the electroweak scale are obtained from the

  9. DISPLAY-2: a two-dimensional shallow layer model for dense gas dispersion including complex features.

    Science.gov (United States)

    Venetsanos, A G; Bartzis, J G; Würtz, J; Papailiou, D D

    2003-04-25

    A two-dimensional shallow layer model has been developed to predict dense gas dispersion, under realistic conditions, including complex features such as two-phase releases, obstacles and inclined ground. The model attempts to predict the time and space evolution of the cloud formed after a release of a two-phase pollutant into the atmosphere. The air-pollutant mixture is assumed ideal. The cloud evolution is described mathematically through the Cartesian, two-dimensional, shallow layer conservation equations for mixture mass, mixture momentum in two horizontal directions, total pollutant mass fraction (vapor and liquid) and mixture internal energy. Liquid mass fraction is obtained assuming phase equilibrium. Account is taken in the conservation equations for liquid slip and eventual liquid rainout through the ground. Entrainment of ambient air is modeled via an entrainment velocity model, which takes into account the effects of ground friction, ground heat transfer and relative motion between cloud and surrounding atmosphere. The model additionally accounts for thin obstacles effects in three ways. First a stepwise description of the obstacle is generated, following the grid cell faces, taking into account the corresponding area blockage. Then obstacle drag on the passing cloud is modeled by adding flow resistance terms in the momentum equations. Finally the effect of extra vorticity generation and entrainment enhancement behind obstacles is modeled by adding locally into the entrainment formula without obstacles, a characteristic velocity scale defined from the obstacle pressure drop and the local cloud height.The present model predictions have been compared against theoretical results for constant volume and constant flux gravity currents. It was found that deviations of the predicted cloud footprint area change with time from the theoretical were acceptably small, if one models the frictional forces between cloud and ambient air, neglecting the Richardson

  10. Sensitivity of an atmospheric photochemistry model to chlorine perturbations including consideration of uncertainty propagation

    Science.gov (United States)

    Stolarski, R. S.; Douglass, A. R.

    1986-01-01

    Models of stratospheric photochemistry are generally tested by comparing their predictions for the composition of the present atmosphere with measurements of species concentrations. These models are then used to make predictions of the atmospheric sensitivity to perturbations. Here the problem of the sensitivity of such a model to chlorine perturbations ranging from the present influx of chlorine-containing compounds to several times that influx is addressed. The effects of uncertainties in input parameters, including reaction rate coefficients, cross sections, solar fluxes, and boundary conditions, are evaluated using a Monte Carlo method in which the values of the input parameters are randomly selected. The results are probability distributions for present atmosheric concentrations and for calculated perturbations due to chlorine from fluorocarbons. For more than 300 Monte Carlo runs the calculated ozone perturbation for continued emission of fluorocarbons at today's rates had a mean value of -6.2 percent, with a 1-sigma width of 5.5 percent. Using the same runs but only allowing the cases in which the calculated present atmosphere values of NO, NO2, and ClO at 25 km altitude fell within the range of measurements yielded a mean ozone depletion of -3 percent, with a 1-sigma deviation of 2.2 percent. The model showed a nonlinear behavior as a function of added fluorocarbons. The mean of the Monte Carlo runs was less nonlinear than the model run using mean value of the input parameters.

  11. Health Promotion Behavior of Chinese International Students in Korea Including Acculturation Factors: A Structural Equation Model.

    Science.gov (United States)

    Kim, Sun Jung; Yoo, Il Young

    2016-03-01

    The purpose of this study was to explain the health promotion behavior of Chinese international students in Korea using a structural equation model including acculturation factors. A survey using self-administered questionnaires was employed. Data were collected from 272 Chinese students who have resided in Korea for longer than 6 months. The data were analyzed using structural equation modeling. The p value of final model is .31. The fitness parameters of the final model such as goodness of fit index, adjusted goodness of fit index, normed fit index, non-normed fit index, and comparative fit index were more than .95. Root mean square of residual and root mean square error of approximation also met the criteria. Self-esteem, perceived health status, acculturative stress and acculturation level had direct effects on health promotion behavior of the participants and the model explained 30.0% of variance. The Chinese students in Korea with higher self-esteem, perceived health status, acculturation level, and lower acculturative stress reported higher health promotion behavior. The findings can be applied to develop health promotion strategies for this population. Copyright © 2016. Published by Elsevier B.V.

  12. S5-4: Formal Modeling of Affordance in Human-Included Systems

    Directory of Open Access Journals (Sweden)

    Namhun Kim

    2012-10-01

    Full Text Available In spite of it being necessary for humans to consider modeling, analysis, and control of human-included systems, it has been considered a challenging problem because of the critical role of humans in complex systems and of humans' capability of executing unanticipated actions–both beneficial and detrimental ones. Thus, to provide systematic approaches to modeling human actions as a part of system behaviors, a formal modeling framework for human-involved systems in which humans play a controlling role based on their perceptual information is presented. The theory of affordance provides definitions of human actions and their associated properties; Finite State Automata (FSA based modeling is capable of mapping nondeterministic humans into computable components in the system representation. In this talk, we investigate the role of perception in human actions in the system operation and examine the representation of perceptual elements in affordance-based modeling formalism. The proposed framework is expected to capture the natural ways in which humans participate in the system as part of its operation. A human-machine cooperative manufacturing system control example and a human agent simulation example will be introduced for the illustrative purposes at the end of the presentation.

  13. An extended gene protein/products Boolean network model including post-transcriptional regulation.

    Science.gov (United States)

    Benso, Alfredo; Di Carlo, Stefano; Politano, Gianfranco; Savino, Alessandro; Vasciaveo, Alessandro

    2014-05-07

    Networks Biology allows the study of complex interactions between biological systems using formal, well structured, and computationally friendly models. Several different network models can be created, depending on the type of interactions that need to be investigated. Gene Regulatory Networks (GRN) are an effective model commonly used to study the complex regulatory mechanisms of a cell. Unfortunately, given their intrinsic complexity and non discrete nature, the computational study of realistic-sized complex GRNs requires some abstractions. Boolean Networks (BNs), for example, are a reliable model that can be used to represent networks where the possible state of a node is a boolean value (0 or 1). Despite this strong simplification, BNs have been used to study both structural and dynamic properties of real as well as randomly generated GRNs. In this paper we show how it is possible to include the post-transcriptional regulation mechanism (a key process mediated by small non-coding RNA molecules like the miRNAs) into the BN model of a GRN. The enhanced BN model is implemented in a software toolkit (EBNT) that allows to analyze boolean GRNs from both a structural and a dynamic point of view. The open-source toolkit is compatible with available visualization tools like Cytoscape and allows to run detailed analysis of the network topology as well as of its attractors, trajectories, and state-space. In the paper, a small GRN built around the mTOR gene is used to demonstrate the main capabilities of the toolkit. The extended model proposed in this paper opens new opportunities in the study of gene regulation. Several of the successful researches done with the support of BN to understand high-level characteristics of regulatory networks, can now be improved to better understand the role of post-transcriptional regulation for example as a network-wide noise-reduction or stabilization mechanisms.

  14. An extended gene protein/products boolean network model including post-transcriptional regulation

    Science.gov (United States)

    2014-01-01

    Background Networks Biology allows the study of complex interactions between biological systems using formal, well structured, and computationally friendly models. Several different network models can be created, depending on the type of interactions that need to be investigated. Gene Regulatory Networks (GRN) are an effective model commonly used to study the complex regulatory mechanisms of a cell. Unfortunately, given their intrinsic complexity and non discrete nature, the computational study of realistic-sized complex GRNs requires some abstractions. Boolean Networks (BNs), for example, are a reliable model that can be used to represent networks where the possible state of a node is a boolean value (0 or 1). Despite this strong simplification, BNs have been used to study both structural and dynamic properties of real as well as randomly generated GRNs. Results In this paper we show how it is possible to include the post-transcriptional regulation mechanism (a key process mediated by small non-coding RNA molecules like the miRNAs) into the BN model of a GRN. The enhanced BN model is implemented in a software toolkit (EBNT) that allows to analyze boolean GRNs from both a structural and a dynamic point of view. The open-source toolkit is compatible with available visualization tools like Cytoscape and allows to run detailed analysis of the network topology as well as of its attractors, trajectories, and state-space. In the paper, a small GRN built around the mTOR gene is used to demonstrate the main capabilities of the toolkit. Conclusions The extended model proposed in this paper opens new opportunities in the study of gene regulation. Several of the successful researches done with the support of BN to understand high-level characteristics of regulatory networks, can now be improved to better understand the role of post-transcriptional regulation for example as a network-wide noise-reduction or stabilization mechanisms. PMID:25080304

  15. The Litter Problem. Environmental Education Supplementary Instructional Guide, Elementary Level.

    Science.gov (United States)

    Hawaii State Dept. of Education, Honolulu. Office of Instructional Services.

    Presented is a guide for helping elementary school students become aware of the litter problem, acquire litter control skills, and develop an anti-litter ethic. The manual contains a hierarchy of learning objectives, a pretest/posttest instrument, background information on litter, and 12 lessons designed to promote attainment of the learning…

  16. An Approach to Litter Generation and Littering Practices in a Mexico City Neighborhood

    Directory of Open Access Journals (Sweden)

    Cecilia E. Muñoz-Cadena

    2012-08-01

    Full Text Available Urban litter is generated by human societies everywhere. Some litter is recyclable waste. In this study, the acronym RMSW is used to refer to recyclable municipal solid waste generated in streets. Public attitude towards RMSW generation, generators’ perceptions, and quantification of RMSW in streets were examined in a Mexico City neighborhood, where litter presence causes major environmental problems affecting the population year after year. Interviews with neighborhood residents and item counts were carried out from 2010 to 2011. In all, 58% of interviewees reported generating RMSW at variable frequencies while 42% said they did not generate this kind of waste. Laziness, lack of vigilance by municipal authorities, no litter bins in streets, and imitation were the main causes identified by interviewees as reasons for littering. Potential litter generators may be of any age, educational level or income. Interviewees’ perception of RMSW generation was compared with item counts in the neighborhood studied.

  17. General hypothesis and shell model for the synthesis of semiconductor nanotubes, including carbon nanotubes

    Science.gov (United States)

    Mohammad, S. Noor

    2010-09-01

    Semiconductor nanotubes, including carbon nanotubes, have vast potential for new technology development. The fundamental physics and growth kinetics of these nanotubes are still obscured. Various models developed to elucidate the growth suffer from limited applicability. An in-depth investigation of the fundamentals of nanotube growth has, therefore, been carried out. For this investigation, various features of nanotube growth, and the role of the foreign element catalytic agent (FECA) in this growth, have been considered. Observed growth anomalies have been analyzed. Based on this analysis, a new shell model and a general hypothesis have been proposed for the growth. The essential element of the shell model is the seed generated from segregation during growth. The seed structure has been defined, and the formation of droplet from this seed has been described. A modified definition of the droplet exhibiting adhesive properties has also been presented. Various characteristics of the droplet, required for alignment and organization of atoms into tubular forms, have been discussed. Employing the shell model, plausible scenarios for the formation of carbon nanotubes, and the variation in the characteristics of these carbon nanotubes have been articulated. The experimental evidences, for example, for the formation of shell around a core, dipole characteristics of the seed, and the existence of nanopores in the seed, have been presented. They appear to justify the validity of the proposed model. The diversities of nanotube characteristics, fundamentals underlying the creation of bamboo-shaped carbon nanotubes, and the impurity generation on the surface of carbon nanotubes have been elucidated. The catalytic action of FECA on growth has been quantified. The applicability of the proposed model to the nanotube growth by a variety of mechanisms has been elaborated. These mechanisms include the vapor-liquid-solid mechanism, the oxide-assisted growth mechanism, the self

  18. Combining litter observations with a regional ocean model to identify sources and sinks of floating debris in a semi-enclosed basin: The Adriatic Sea

    DEFF Research Database (Denmark)

    Carlson, Daniel F.; Suaria, Giuseppe; Aliani, Stefano

    2017-01-01

    originated from the Istrian peninsula to the Italian city of Termoli, as well as the Croatian island of Cres and the Kornati archipelago. Particles spent a total of roughly 47 days afloat. Coastal currents, notably the eastern and western Adriatic currents, resulted in large alongshore displacements. Our...... model. Sources and sinks for debris observed in the central and southern Adriatic in May 2013 and March 2015 included the Italian coastline from Pescara to Brindisi, the Croatian island of Mljet, and the coastline from Dubrovnik through Montenegro to Albania. Debris observed in the northern Adriatic...... results indicate that anthropogenic macro debris originates largely from coastal sources near population centers and is advected by the cyclonic surface circulation until it strands on the southwest (Italian) coast, exits the Adriatic, or recirculates in the southern gyre....

  19. Litter quality mediated nitrogen effect on plant litter decomposition regardless of soil fauna presence.

    Science.gov (United States)

    Zhang, Weidong; Chao, Lin; Yang, Qingpeng; Wang, Qingkui; Fang, Yunting; Wang, Silong

    2016-10-01

    Nitrogen addition has been shown to affect plant litter decomposition in terrestrial ecosystems. The way that nitrogen deposition impacts the relationship between plant litter decomposition and altered soil nitrogen availability is unclear, however. This study examined 18 co-occurring litter types in a subtropical forest in China in terms of their decomposition (1 yr of exposure in the field) with nitrogen addition treatment (0, 0.4, 1.6, and 4.0 mol·N·m(-2) ·yr(-1) ) and soil fauna exclusion (litter bags with 0.1 and 2 cm mesh size). Results showed that the plant litter decomposition rate is significantly reduced because of nitrogen addition; the strength of the nitrogen addition effect is closely related to the nitrogen addition levels. Plant litters with diverse quality responded to nitrogen addition differently. When soil fauna was present, the nitrogen addition effect on medium-quality or high-quality plant litter decomposition rate was -26% ± 5% and -29% ± 4%, respectively; these values are significantly higher than that of low-quality plant litter decomposition. The pattern is similar when soil fauna is absent. In general, the plant litter decomposition rate is decreased by soil fauna exclusion; an average inhibition of -17% ± 1.5% was exhibited across nitrogen addition treatment and litter quality groups. However, this effect is weakly related to nitrogen addition treatment and plant litter quality. We conclude that the variations in plant litter quality, nitrogen deposition, and soil fauna are important factors of decomposition and nutrient cycling in a subtropical forest ecosystem.

  20. Analysis of electronic models for solar cells including energy resolved defect densities

    Energy Technology Data Exchange (ETDEWEB)

    Glitzky, Annegret

    2010-07-01

    We introduce an electronic model for solar cells including energy resolved defect densities. The resulting drift-diffusion model corresponds to a generalized van Roosbroeck system with additional source terms coupled with ODEs containing space and energy as parameters for all defect densities. The system has to be considered in heterostructures and with mixed boundary conditions from device simulation. We give a weak formulation of the problem. If the boundary data and the sources are compatible with thermodynamic equilibrium the free energy along solutions decays monotonously. In other cases it may be increasing, but we estimate its growth. We establish boundedness and uniqueness results and prove the existence of a weak solution. This is done by considering a regularized problem, showing its solvability and the boundedness of its solutions independent of the regularization level. (orig.)

  1. Nonlinear Acoustics FDTD method including Frequency Power Law Attenuation for Soft Tissue Modeling

    CERN Document Server

    Jiménez, Noé; Sánchez-Morcillo, Víctor; Camarena, Francisco; Hou, Yi; Konofagou, Elisa E

    2014-01-01

    This paper describes a model for nonlinear acoustic wave propagation through absorbing and weakly dispersive media, and its numerical solution by means of finite differences in time domain method (FDTD). The attenuation is based on multiple relaxation processes, and provides frequency dependent absorption and dispersion without using computational expensive convolutional operators. In this way, by using an optimization algorithm the coefficients for the relaxation processes can be obtained in order to fit a frequency power law that agrees the experimentally measured attenuation data for heterogeneous media over the typical frequency range for ultrasound medical applications. Our results show that two relaxation processes are enough to fit attenuation data for most soft tissues in this frequency range including the fundamental and the first ten harmonics. Furthermore, this model can fit experimental attenuation data that do not follow exactly a frequency power law over the frequency range of interest. The main...

  2. Particle-based modeling of heterogeneous chemical kinetics including mass transfer

    Science.gov (United States)

    Sengar, A.; Kuipers, J. A. M.; van Santen, Rutger A.; Padding, J. T.

    2017-08-01

    Connecting the macroscopic world of continuous fields to the microscopic world of discrete molecular events is important for understanding several phenomena occurring at physical boundaries of systems. An important example is heterogeneous catalysis, where reactions take place at active surfaces, but the effective reaction rates are determined by transport limitations in the bulk fluid and reaction limitations on the catalyst surface. In this work we study the macro-micro connection in a model heterogeneous catalytic reactor by means of stochastic rotation dynamics. The model is able to resolve the convective and diffusive interplay between participating species, while including adsorption, desorption, and reaction processes on the catalytic surface. Here we apply the simulation methodology to a simple straight microchannel with a catalytic strip. Dimensionless Damkohler numbers are used to comment on the spatial concentration profiles of reactants and products near the catalyst strip and in the bulk. We end the discussion with an outlook on more complicated geometries and increasingly complex reactions.

  3. Models of epidemics: when contact repetition and clustering should be included

    Directory of Open Access Journals (Sweden)

    Scholz Roland W

    2009-06-01

    Full Text Available Abstract Background The spread of infectious disease is determined by biological factors, e.g. the duration of the infectious period, and social factors, e.g. the arrangement of potentially contagious contacts. Repetitiveness and clustering of contacts are known to be relevant factors influencing the transmission of droplet or contact transmitted diseases. However, we do not yet completely know under what conditions repetitiveness and clustering should be included for realistically modelling disease spread. Methods We compare two different types of individual-based models: One assumes random mixing without repetition of contacts, whereas the other assumes that the same contacts repeat day-by-day. The latter exists in two variants, with and without clustering. We systematically test and compare how the total size of an outbreak differs between these model types depending on the key parameters transmission probability, number of contacts per day, duration of the infectious period, different levels of clustering and varying proportions of repetitive contacts. Results The simulation runs under different parameter constellations provide the following results: The difference between both model types is highest for low numbers of contacts per day and low transmission probabilities. The number of contacts and the transmission probability have a higher influence on this difference than the duration of the infectious period. Even when only minor parts of the daily contacts are repetitive and clustered can there be relevant differences compared to a purely random mixing model. Conclusion We show that random mixing models provide acceptable estimates of the total outbreak size if the number of contacts per day is high or if the per-contact transmission probability is high, as seen in typical childhood diseases such as measles. In the case of very short infectious periods, for instance, as in Norovirus, models assuming repeating contacts will also behave

  4. Standardized Competencies for Parenteral Nutrition Order Review and Parenteral Nutrition Preparation, Including Compounding: The ASPEN Model.

    Science.gov (United States)

    Boullata, Joseph I; Holcombe, Beverly; Sacks, Gordon; Gervasio, Jane; Adams, Stephen C; Christensen, Michael; Durfee, Sharon; Ayers, Phil; Marshall, Neil; Guenter, Peggi

    2016-08-01

    Parenteral nutrition (PN) is a high-alert medication with a complex drug use process. Key steps in the process include the review of each PN prescription followed by the preparation of the formulation. The preparation step includes compounding the PN or activating a standardized commercially available PN product. The verification and review, as well as preparation of this complex therapy, require competency that may be determined by using a standardized process for pharmacists and for pharmacy technicians involved with PN. An American Society for Parenteral and Enteral Nutrition (ASPEN) standardized model for PN order review and PN preparation competencies is proposed based on a competency framework, the ASPEN-published interdisciplinary core competencies, safe practice recommendations, and clinical guidelines, and is intended for institutions and agencies to use with their staff.

  5. A generalized model for optimal transport of images including dissipation and density modulation

    KAUST Repository

    Maas, Jan

    2015-11-01

    © EDP Sciences, SMAI 2015. In this paper the optimal transport and the metamorphosis perspectives are combined. For a pair of given input images geodesic paths in the space of images are defined as minimizers of a resulting path energy. To this end, the underlying Riemannian metric measures the rate of transport cost and the rate of viscous dissipation. Furthermore, the model is capable to deal with strongly varying image contrast and explicitly allows for sources and sinks in the transport equations which are incorporated in the metric related to the metamorphosis approach by Trouvé and Younes. In the non-viscous case with source term existence of geodesic paths is proven in the space of measures. The proposed model is explored on the range from merely optimal transport to strongly dissipative dynamics. For this model a robust and effective variational time discretization of geodesic paths is proposed. This requires to minimize a discrete path energy consisting of a sum of consecutive image matching functionals. These functionals are defined on corresponding pairs of intensity functions and on associated pairwise matching deformations. Existence of time discrete geodesics is demonstrated. Furthermore, a finite element implementation is proposed and applied to instructive test cases and to real images. In the non-viscous case this is compared to the algorithm proposed by Benamou and Brenier including a discretization of the source term. Finally, the model is generalized to define discrete weighted barycentres with applications to textures and objects.

  6. Fluid-structure interaction including volumetric coupling with homogenised subdomains for modeling respiratory mechanics.

    Science.gov (United States)

    Yoshihara, Lena; Roth, Christian J; Wall, Wolfgang A

    2017-04-01

    In this article, a novel approach is presented for combining standard fluid-structure interaction with additional volumetric constraints to model fluid flow into and from homogenised solid domains. The proposed algorithm is particularly interesting for investigations in the field of respiratory mechanics as it enables the mutual coupling of airflow in the conducting part and local tissue deformation in the respiratory part of the lung by means of a volume constraint. In combination with a classical monolithic fluid-structure interaction approach, a comprehensive model of the human lung can be established that will be useful to gain new insights into respiratory mechanics in health and disease. To illustrate the validity and versatility of the novel approach, three numerical examples including a patient-specific lung model are presented. The proposed algorithm proves its capability of computing clinically relevant airflow distribution and tissue strain data at a level of detail that is not yet achievable, neither with current imaging techniques nor with existing computational models. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  7. Empirical Validation of a Thermal Model of a Complex Roof Including Phase Change Materials

    Directory of Open Access Journals (Sweden)

    Stéphane Guichard

    2015-12-01

    Full Text Available This paper deals with the empirical validation of a building thermal model of a complex roof including a phase change material (PCM. A mathematical model dedicated to PCMs based on the heat apparent capacity method was implemented in a multi-zone building simulation code, the aim being to increase the understanding of the thermal behavior of the whole building with PCM technologies. In order to empirically validate the model, the methodology is based both on numerical and experimental studies. A parametric sensitivity analysis was performed and a set of parameters of the thermal model has been identified for optimization. The use of the generic optimization program called GenOpt® coupled to the building simulation code enabled to determine the set of adequate parameters. We first present the empirical validation methodology and main results of previous work. We then give an overview of GenOpt® and its coupling with the building simulation code. Finally, once the optimization results are obtained, comparisons of the thermal predictions with measurements are found to be acceptable and are presented.

  8. Habitability of super-Earth planets around other suns: models including Red Giant Branch evolution.

    Science.gov (United States)

    von Bloh, W; Cuntz, M; Schröder, K-P; Bounama, C; Franck, S

    2009-01-01

    The unexpected diversity of exoplanets includes a growing number of super-Earth planets, i.e., exoplanets with masses of up to several Earth masses and a similar chemical and mineralogical composition as Earth. We present a thermal evolution model for a 10 Earth-mass planet orbiting a star like the Sun. Our model is based on the integrated system approach, which describes the photosynthetic biomass production and takes into account a variety of climatological, biogeochemical, and geodynamical processes. This allows us to identify a so-called photosynthesis-sustaining habitable zone (pHZ), as determined by the limits of biological productivity on the planetary surface. Our model considers solar evolution during the main-sequence stage and along the Red Giant Branch as described by the most recent solar model. We obtain a large set of solutions consistent with the principal possibility of life. The highest likelihood of habitability is found for "water worlds." Only mass-rich water worlds are able to realize pHZ-type habitability beyond the stellar main sequence on the Red Giant Branch.

  9. A transient energy function for power systems including the induction motor model

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A construction method for power system transient energy function is studied in the paper, which is simple and universal, and can unify the forms of some current energy functions. A transient energy function including the induction motor model is derived using the method. The unintegrable term is dealt with to get an approximate energy function. Simulations in a 3-bus system and in the WSCC 4-generator system verify the validity of the proposed energy function. The function can be applied to direct transient stability analysis of multi-machine large power systems and provides a tool for analysis of the interaction between the generator angle stability and the load voltage stability.

  10. A laboratory model of the aortic root flow including the coronary arteries

    Science.gov (United States)

    Querzoli, Giorgio; Fortini, Stefania; Espa, Stefania; Melchionna, Simone

    2016-08-01

    Cardiovascular flows have been extensively investigated by means of in vitro models to assess the prosthetic valve performances and to provide insight into the fluid dynamics of the heart and proximal aorta. In particular, the models for the study of the flow past the aortic valve have been continuously improved by including, among other things, the compliance of the vessel and more realistic geometries. The flow within the sinuses of Valsalva is known to play a fundamental role in the dynamics of the aortic valve since they host a recirculation region that interacts with the leaflets. The coronary arteries originate from the ostia located within two of the three sinuses, and their presence may significantly affect the fluid dynamics of the aortic root. In spite of their importance, to the extent of the authors' knowledge, coronary arteries were not included so far when modeling in vitro the transvalvular aortic flow. We present a pulse duplicator consisting of a passively pulsing ventricle, a compliant proximal aorta, and coronary arteries connected to the sinuses of Valsalva. The coronary flow is modulated by a self-regulating device mimicking the physiological mechanism, which is based on the contraction and relaxation of the heart muscle during the cardiac cycle. Results show that the model reproduces satisfyingly the coronary flow. The analysis of the time evolution of the velocity and vorticity fields within the aortic root reveals the main characteristics of the backflow generated through the aorta in order to feed the coronaries during the diastole. Experiments without coronary flow have been run for comparison. Interestingly, the lifetime of the vortex forming in the sinus of Valsalva during the systole is reduced by the presence of the coronaries. As a matter of fact, at the end of the systole, that vortex is washed out because of the suction generated by the coronary flow. Correspondingly, the valve closure is delayed and faster compared to the case with

  11. Home-field advantages of litter decomposition increase with increasing N deposition rates: a litter and soil perspective

    NARCIS (Netherlands)

    Li, Y.; Li, Q.; Yang, J.; Xiaotao, L.; Liang, W.; Han, X.; Bezemer, T.M.

    2017-01-01

    1.Differences in litter quality and in soil microbial community composition can influence the litter decomposition and “home-field advantage” (HFA). However, our knowledge about the relative role of litter and soil characteristics on litter decomposition and HFA effects is still limited, especially

  12. Effects of litter manipulation on litter decomposition in a successional gradients of tropical forests in southern China

    DEFF Research Database (Denmark)

    Chen, Hao; Gurmesa, Geshere A.; Liu, Lei;

    2014-01-01

    Global changes such as increasing CO2, rising temperature, and land-use change are likely to drive shifts in litter inputs to forest floors, but the effects of such changes on litter decomposition remain largely unknown. We initiated a litter manipulation experiment to test the response of litter...

  13. Can't See the Wood for the Litter: Evaluation of Litter Behavior Modification in a Forest

    Science.gov (United States)

    Lindemann-Matthies, Petra; Bonigk, Isabel; Benkowitz, Dorothee

    2012-01-01

    This study investigated elementary school children's (n = 171) litter behavior during guided forest tours following two different treatments. Four classes received a verbal appeal not to litter in the forest, while another four classes received both a verbal appeal and a demonstration of the desired litter behavior (picking up litter, putting it…

  14. Can't See the Wood for the Litter: Evaluation of Litter Behavior Modification in a Forest

    Science.gov (United States)

    Lindemann-Matthies, Petra; Bonigk, Isabel; Benkowitz, Dorothee

    2012-01-01

    This study investigated elementary school children's (n = 171) litter behavior during guided forest tours following two different treatments. Four classes received a verbal appeal not to litter in the forest, while another four classes received both a verbal appeal and a demonstration of the desired litter behavior (picking up litter, putting it…

  15. Including sugar cane in the agro-ecosystem model ORCHIDEE-STICS

    Science.gov (United States)

    Valade, A.; Vuichard, N.; Ciais, P.; Viovy, N.

    2010-12-01

    With 4 million ha currently grown for ethanol in Brazil only, approximately half the global bioethanol production in 2005 (Smeets 2008), and a devoted land area expected to expand globally in the years to come, sugar cane is at the heart of the biofuel debate. Indeed, ethanol made from biomass is currently the most widespread option for alternative transportation fuels. It was originally promoted as a carbon neutral energy resource that could bring energy independence to countries and local opportunities to farmers, until attention was drawn to its environmental and socio-economical drawbacks. It is still not clear to which extent it is a solution or a contributor to climate change mitigation. Dynamic Global Vegetation models can help address these issues and quantify the potential impacts of biofuels on ecosystems at scales ranging from on-site to global. The global agro-ecosystem model ORCHIDEE describes water, carbon and energy exchanges at the soil-atmosphere interface for a limited number of natural and agricultural vegetation types. In order to integrate agricultural management to the simulations and to capture more accurately the specificity of crops' phenology, ORCHIDEE has been coupled with the agronomical model STICS. The resulting crop-oriented vegetation model ORCHIDEE-STICS has been used so far to simulate temperate crops such as wheat, corn and soybean. As a generic ecosystem model, each grid cell can include several vegetation types with their own phenology and management practices, making it suitable to spatial simulations. Here, ORCHIDEE-STICS is altered to include sugar cane as a new agricultural Plant functional Type, implemented and parametrized using the STICS approach. An on-site calibration and validation is then performed based on biomass and flux chamber measurements in several sites in Australia and variables such as LAI, dry weight, heat fluxes and respiration are used to evaluate the ability of the model to simulate the specific

  16. No Litter Will Make a Better Place.

    Science.gov (United States)

    Rodgers, Amy

    1987-01-01

    Describes a community anti-litter campaign developed by second grades, involving letter writing, dramatics, photography, and the creation of posters and a videotape. Identifies skills from the Kentucky Essential Skills list that were taught by the project. (SV)

  17. Arst on patsiendi poolel / Galina Litter

    Index Scriptorium Estoniae

    Litter, Galina, 1956-

    2006-01-01

    Naistearst Galina Litter seadusest, mis lubab alaealistel ilma vanema nõusolekuta aborti teha. Vastus artiklile : Varro Vooglaid. Vanemate vastutus - kas reaalne või paljasõnaline? // Õpetajate Leht (2006) 13. okt., lk. 1, 7

  18. Arst on patsiendi poolel / Galina Litter

    Index Scriptorium Estoniae

    Litter, Galina, 1956-

    2006-01-01

    Naistearst Galina Litter seadusest, mis lubab alaealistel ilma vanema nõusolekuta aborti teha. Vastus artiklile : Varro Vooglaid. Vanemate vastutus - kas reaalne või paljasõnaline? // Õpetajate Leht (2006) 13. okt., lk. 1, 7

  19. Linear loss of litter over time, 2015

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This table contains data on dry mass remaining in a subset of Salicornia pacifica and Deschampsia cespitosa litter bags removed over a series of time points spanning...

  20. A range of complex probabilistic models for RNA secondary structure prediction that includes the nearest-neighbor model and more.

    Science.gov (United States)

    Rivas, Elena; Lang, Raymond; Eddy, Sean R

    2012-02-01

    The standard approach for single-sequence RNA secondary structure prediction uses a nearest-neighbor thermodynamic model with several thousand experimentally determined energy parameters. An attractive alternative is to use statistical approaches with parameters estimated from growing databases of structural RNAs. Good results have been reported for discriminative statistical methods using complex nearest-neighbor models, including CONTRAfold, Simfold, and ContextFold. Little work has been reported on generative probabilistic models (stochastic context-free grammars [SCFGs]) of comparable complexity, although probabilistic models are generally easier to train and to use. To explore a range of probabilistic models of increasing complexity, and to directly compare probabilistic, thermodynamic, and discriminative approaches, we created TORNADO, a computational tool that can parse a wide spectrum of RNA grammar architectures (including the standard nearest-neighbor model and more) using a generalized super-grammar that can be parameterized with probabilities, energies, or arbitrary scores. By using TORNADO, we find that probabilistic nearest-neighbor models perform comparably to (but not significantly better than) discriminative methods. We find that complex statistical models are prone to overfitting RNA structure and that evaluations should use structurally nonhomologous training and test data sets. Overfitting has affected at least one published method (ContextFold). The most important barrier to improving statistical approaches for RNA secondary structure prediction is the lack of diversity of well-curated single-sequence RNA secondary structures in current RNA databases.

  1. Plant diversity does not buffer drought effects on early-stage litter mass loss rates and microbial properties.

    Science.gov (United States)

    Vogel, Anja; Eisenhauer, Nico; Weigelt, Alexandra; Scherer-Lorenzen, Michael

    2013-09-01

    Human activities are decreasing biodiversity and changing the climate worldwide. Both global change drivers have been shown to affect ecosystem functioning, but they may also act in concert in a non-additive way. We studied early-stage litter mass loss rates and soil microbial properties (basal respiration and microbial biomass) during the summer season in response to plant species richness and summer drought in a large grassland biodiversity experiment, the Jena Experiment, Germany. In line with our expectations, decreasing plant diversity and summer drought decreased litter mass loss rates and soil microbial properties. In contrast to our hypotheses, however, this was only true for mass loss of standard litter (wheat straw) used in all plots, and not for plant community-specific litter mass loss. We found no interactive effects between global change drivers, that is, drought reduced litter mass loss rates and soil microbial properties irrespective of plant diversity. High mass loss rates of plant community-specific litter and low responsiveness to drought relative to the standard litter indicate that soil microbial communities were adapted to decomposing community-specific plant litter material including lower susceptibility to dry conditions during summer months. Moreover, higher microbial enzymatic diversity at high plant diversity may have caused elevated mass loss of standard litter. Our results indicate that plant diversity loss and summer drought independently impede soil processes. However, soil decomposer communities may be highly adapted to decomposing plant community-specific litter material, even in situations of environmental stress. Results of standard litter mass loss moreover suggest that decomposer communities under diverse plant communities are able to cope with a greater variety of plant inputs possibly making them less responsive to biotic changes.

  2. Marine litter on deep Arctic seafloor continues to increase and spreads to the North at the HAUSGARTEN observatory

    Science.gov (United States)

    Tekman, Mine B.; Krumpen, Thomas; Bergmann, Melanie

    2017-02-01

    The increased global production of plastics has been mirrored by greater accumulations of plastic litter in marine environments worldwide. Global plastic litter estimates based on field observations account only for 1% of the total volumes of plastic assumed to enter the marine ecosystem from land, raising again the question 'Where is all the plastic? '. Scant information exists on temporal trends on litter transport and litter accumulation on the deep seafloor. Here, we present the results of photographic time-series surveys indicating a strong increase in marine litter over the period of 2002-2014 at two stations of the HAUSGARTEN observatory in the Arctic (2500 m depth). Plastic accounted for the highest proportion (47%) of litter recorded at HAUSGARTEN for the whole study period. When the most southern station was considered separately, the proportion of plastic items was even higher (65%). Increasing quantities of small plastics raise concerns about fragmentation and future microplastic contamination. Analysis of litter types and sizes indicate temporal and spatial differences in the transport pathways to the deep sea for different categories of litter. Litter densities were positively correlated with the counts of ship entering harbour at Longyearbyen, the number of active fishing vessels and extent of summer sea ice. Sea ice may act as a transport vehicle for entrained litter, being released during periods of melting. The receding sea ice coverage associated with global change has opened hitherto largely inaccessible environments to humans and the impacts of tourism, industrial activities including shipping and fisheries, all of which are potential sources of marine litter.

  3. Water addition, evaporation and water holding capacity of poultry litter.

    Science.gov (United States)

    Dunlop, Mark W; Blackall, Patrick J; Stuetz, Richard M

    2015-12-15

    Litter moisture content has been related to ammonia, dust and odour emissions as well as bird health and welfare. Improved understanding of the water holding properties of poultry litter as well as water additions to litter and evaporation from litter will contribute to improved litter moisture management during the meat chicken grow-out. The purpose of this paper is to demonstrate how management and environmental conditions over the course of a grow-out affect the volume of water A) applied to litter, B) able to be stored in litter, and C) evaporated from litter on a daily basis. The same unit of measurement has been used to enable direct comparison-litres of water per square metre of poultry shed floor area, L/m(2), assuming a litter depth of 5cm. An equation was developed to estimate the amount of water added to litter from bird excretion and drinking spillage, which are sources of regular water application to the litter. Using this equation showed that water applied to litter from these sources changes over the course of a grow-out, and can be as much as 3.2L/m(2)/day. Over a 56day grow-out, the total quantity of water added to the litter was estimated to be 104L/m(2). Litter porosity, water holding capacity and water evaporation rates from litter were measured experimentally. Litter porosity decreased and water holding capacity increased over the course of a grow-out due to manure addition. Water evaporation rates at 25°C and 50% relative humidity ranged from 0.5 to 10L/m(2)/day. Evaporation rates increased with litter moisture content and air speed. Maintaining dry litter at the peak of a grow-out is likely to be challenging because evaporation rates from dry litter may be insufficient to remove the quantity of water added to the litter on a daily basis.

  4. a New Model for Describing Evolution and Control of Disaster System Including Instantaneous and Continuous Actions

    Science.gov (United States)

    Chen, Chang-Kun; Li, Zhi; Sun, Yun-Feng

    A new model for describing the disaster system including instantaneous and continuous action synchronously has been developed. The model is composed of three primary parts, that is, the impact from its causative disaster events, stochastic noise of disaster node and self-healing function, and every part is modeled concretely in terms of their characteristics in practice. Some key parameters, namely link appearance probability, retardation coefficient, ultimate repair capacity of government, dynamical modes considering different disaster evolving chains, and the positions of link with the specific performance in disaster network system are involved. Combined with a case study, the proposed model is applied to a certain disaster evolution system, and the influence law of different parameters on disaster evolution process, in disaster networks with instantaneous-action and/or continuous-action, is presented and compared. The results indicate that the destructive impact in the networks by link in continuous action is far greater an order of magnitude than that in instantaneous action. If a link in continuous action emerges in the disaster network system, properties of the causative event for the link, link appearance probability and its position in the network all have a notable influence to the severity of the disaster network. In addition, some peculiar phenomena are also commendably observed in the disaster evolution process based on the model, such as the multipeaks emerging in the destroyed rate number curve for some crisis nodes caused by their various inducing paths together with the relevant retardation coefficients, the existence of the critical value for ultimate repair capacity to recover the disaster node, and so on.

  5. A model predicting fluindione dose requirement in elderly inpatients including genotypes, body weight, and amiodarone.

    Science.gov (United States)

    Moreau, Caroline; Pautas, Eric; Duverlie, Charlotte; Berndt, Celia; Andro, Marion; Mahé, Isabelle; Emmerich, Joseph; Lacut, Karine; Le Gal, Grégoire; Peyron, Isabelle; Gouin-Thibault, Isabelle; Golmard, Jean-Louis; Loriot, Marie-Anne; Siguret, Virginie

    2014-04-01

    Indandione VKAs have been widely used for decades, especially in Eastern Europe and France. Contrary to coumarin VKAs, the relative contribution of individual factors to the indandione-VKA response is poorly known. In the present multicentre study, we sought to develop and validate a model including genetic and non-genetic factors to predict the daily fluindione dose requirement in elderly patients in whom VKA dosing is challenging. We prospectively recorded clinical and therapeutic data in 230 Caucasian inpatients mean aged 85 ± 6 years, who had reached international normalized ratio stabilisation (range 2.0-3.0) on fluindione. In the derivation cohort (n=156), we analysed 13 polymorphisms in seven genes potentially involved in the pharmacological effect or vitamin-K cycle (VKORC1, CYP4F2, EPHX1) and fluindione metabolism/transport (CYP2C9, CYP2C19, CYP3A5, ABCB1). We built a regression model incorporating non-genetic and genetic data and evaluated the model performances in a separate cohort (n=74).Body-weight, amiodarone intake, VKORC1, CYP4F2, ABCB1 genotypes were retained in the final model, accounting for 31.5% of dose variability. None influence of CYP2C9 was observed. Our final model showed good performances: in 83.3% of the validation cohort patients, the dose was accurately predicted within 5 mg, i.e.the usual step used for adjusting fluindione dosage. In conclusion, in addition to body-weight and amiodarone-intake, pharmacogenetic factors (VKORC1, CYP4F2, ABCB1) related to the pharmacodynamic effect and transport of fluindione significantly influenced the dose requirement in elderly patients while CYP2C9 did not. Studies are required to know whether fluindione could be an alternative VKA in carriers of polymorphic CYP2C9 alleles, hypersensitive to coumarins.

  6. ISOLATION OF HEPATIC OVAL CELLS FROM DIFFERENT MODEL RATS INCLUDING DIABETIC RATS

    Institute of Scientific and Technical Information of China (English)

    LU Ying-li; YE Ting-ting; XIA Fang-zhen; WANG Ning-jian; YANG Hua; CHEN Yi

    2009-01-01

    Objective To acquire oval cells (progenitor stem cells) from adult rat liver of different models including diabetic rats. Methods Thirty Sprague-Dawley (SD) rats were divided into 5 groups randomly: control, 2-acetylaminofluorene (2-AAF), 2-AAF+partial hepatectomy (PH), 2-AAF+carbon tetrachloride (CCl4), and diabetic groups. As two-step collagenase perfusion protocol of Seglen, oval cells were isolated by Percoll density gradient centrifugation. Thy1.1 positive cells were sorted by flow cytometry, and then cultured in Dulbeccos minimum Eagles medium (DMEM). Immunofluorescence staining was applied to labelling Thy1.1. Results Different rates of Thy1.1 positive oval cells were found in different rat model groups: 0.5% in 2-AAF, 0.3% in 2-hAAF+PH, 0.2% in 2-AAF+CCl4 , 0.1% in diabetic, and 0.0% in control. Isolated cells adhered to plate with fusiform or polygon as epithelial cells. Conclusion Progenitor stem cells exist in injured liver tissue including those from diabetic rats.

  7. Genetic components of litter size variability in sheep

    Directory of Open Access Journals (Sweden)

    Chevalet Claude

    2001-05-01

    Full Text Available Abstract Classical selection for increasing prolificacy in sheep leads to a concomitant increase in its variability, even though the objective of the breeder is to maximise the frequency of an intermediate litter size rather than the frequency of high litter sizes. For instance, in the Lacaune sheep breed raised in semi-intensive conditions, ewes lambing twins represent the economic optimum. Data for this breed, obtained from the national recording scheme, were analysed. Variance components were estimated in an infinitesimal model involving genes controlling the mean level as well as its environmental variability. Large heritability was found for the mean prolificacy, but a high potential for increasing the percentage of twins at lambing while reducing the environmental variability of prolificacy is also suspected. Quantification of the response to such a canalising selection was achieved.

  8. Genetic components of litter size variability in sheep

    Science.gov (United States)

    SanCristobal-Gaudy, Magali; Bodin, Loys; Elsen, Jean-Michel; Chevalet, Claude

    2001-01-01

    Classical selection for increasing prolificacy in sheep leads to a concomitant increase in its variability, even though the objective of the breeder is to maximise the frequency of an intermediate litter size rather than the frequency of high litter sizes. For instance, in the Lacaune sheep breed raised in semi-intensive conditions, ewes lambing twins represent the economic optimum. Data for this breed, obtained from the national recording scheme, were analysed. Variance components were estimated in an infinitesimal model involving genes controlling the mean level as well as its environmental variability. Large heritability was found for the mean prolificacy, but a high potential for increasing the percentage of twins at lambing while reducing the environmental variability of prolificacy is also suspected. Quantification of the response to such a canalising selection was achieved. PMID:11403747

  9. Dynamic modelling and analysis of multi-machine power systems including wind farms

    Science.gov (United States)

    Tabesh, Ahmadreza

    2005-11-01

    This thesis introduces a small-signal dynamic model, based on a frequency response approach, for the analysis of a multi-machine power system with special focus on an induction machine based wind farm. The proposed approach is an alternative method to the conventional eigenvalue analysis method which is widely employed for small-signal dynamic analyses of power systems. The proposed modelling approach is successfully applied and evaluated for a power system that (i) includes multiple synchronous generators, and (ii) a wind farm based on either fixed-speed, variable-speed, or doubly-fed induction machine based wind energy conversion units. The salient features of the proposed method, as compared with the conventional eigenvalue analysis method, are: (i) computational efficiency since the proposed method utilizes the open-loop transfer-function matrix of the system, (ii) performance indices that are obtainable based on frequency response data and quantitatively describe the dynamic behavior of the system, and (iii) capability to formulate various wind energy conversion unit, within a wind farm, in a modular form. The developed small-signal dynamic model is applied to a set of multi-machine study systems and the results are validated based on comparison (i) with digital time-domain simulation results obtained from PSCAD/EMTDC software tool, and (ii) where applicable with eigenvalue analysis results.

  10. A Hydrological Concept including Lateral Water Flow Compatible with the Biogeochemical Model ForSAFE

    Directory of Open Access Journals (Sweden)

    Giuliana Zanchi

    2016-03-01

    Full Text Available The study presents a hydrology concept developed to include lateral water flow in the biogeochemical model ForSAFE. The hydrology concept was evaluated against data collected at Svartberget in the Vindeln Research Forest in Northern Sweden. The results show that the new concept allows simulation of a saturated and an unsaturated zone in the soil as well as water flow that reaches the stream comparable to measurements. The most relevant differences compared to streamflow measurements are that the model simulates a higher base flow in winter and lower flow peaks after snowmelt. These differences are mainly caused by the assumptions made to regulate the percolation at the bottom of the simulated soil columns. The capability for simulating lateral flows and a saturated zone in ForSAFE can greatly improve the simulation of chemical exchange in the soil and export of elements from the soil to watercourses. Such a model can help improve the understanding of how environmental changes in the forest landscape will influence chemical loads to surface waters.

  11. Modeling within-host dynamics of influenza virus infection including immune responses.

    Directory of Open Access Journals (Sweden)

    Kasia A Pawelek

    Full Text Available Influenza virus infection remains a public health problem worldwide. The mechanisms underlying viral control during an uncomplicated influenza virus infection are not fully understood. Here, we developed a mathematical model including both innate and adaptive immune responses to study the within-host dynamics of equine influenza virus infection in horses. By comparing modeling predictions with both interferon and viral kinetic data, we examined the relative roles of target cell availability, and innate and adaptive immune responses in controlling the virus. Our results show that the rapid and substantial viral decline (about 2 to 4 logs within 1 day after the peak can be explained by the killing of infected cells mediated by interferon activated cells, such as natural killer cells, during the innate immune response. After the viral load declines to a lower level, the loss of interferon-induced antiviral effect and an increased availability of target cells due to loss of the antiviral state can explain the observed short phase of viral plateau in which the viral level remains unchanged or even experiences a minor second peak in some animals. An adaptive immune response is needed in our model to explain the eventual viral clearance. This study provides a quantitative understanding of the biological factors that can explain the viral and interferon kinetics during a typical influenza virus infection.

  12. A phase-field model for incoherent martensitic transformations including plastic accommodation processes in the austenite

    Science.gov (United States)

    Kundin, J.; Raabe, D.; Emmerich, H.

    2011-10-01

    If alloys undergo an incoherent martensitic transformation, then plastic accommodation and relaxation accompany the transformation. To capture these mechanisms we develop an improved 3D microelastic-plastic phase-field model. It is based on the classical concepts of phase-field modeling of microelastic problems (Chen, L.Q., Wang Y., Khachaturyan, A.G., 1992. Philos. Mag. Lett. 65, 15-23). In addition to these it takes into account the incoherent formation of accommodation dislocations in the austenitic matrix, as well as their inheritance into the martensitic plates based on the crystallography of the martensitic transformation. We apply this new phase-field approach to the butterfly-type martensitic transformation in a Fe-30 wt%Ni alloy in direct comparison to recent experimental data (Sato, H., Zaefferer, S., 2009. Acta Mater. 57, 1931-1937). It is shown that the therein proposed mechanisms of plastic accommodation during the transformation can indeed explain the experimentally observed morphology of the martensitic plates as well as the orientation between martensitic plates and the austenitic matrix. The developed phase-field model constitutes a general simulations approach for different kinds of phase transformation phenomena that inherently include dislocation based accommodation processes. The approach does not only predict the final equilibrium topology, misfit, size, crystallography, and aspect ratio of martensite-austenite ensembles resulting from a transformation, but it also resolves the associated dislocation dynamics and the distribution, and the size of the crystals itself.

  13. EFFECTS OF SOIL FAUNA ON LITTER DECOMPOSITION

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Forest litter is the physical makeup part of forest ecosystem. The rate of decomposition of forest litter is low in temperate and cool temperate zones. There is important significance to search and utilize the function of soil animals, in order to probe the material circulation and energy flow in forest ecosystem. We selected three kinds of mesh bag with different mesh size, in which, large pore mesh bag is large enough to permit the activities of all kinds of soil animals, medium mesh bag is designed to exclude the function of soil macrofauna, while small mesh bag is small enough to exclude the effects of any kind of soil animals as far as possible. The decomposition time is three years. The studying results show that: the decomposing speed of the bags with big meshes, under functions of all kinds of soil animals, faster than the bags with medium meshes, under functions of medium and small soil animals, as well as the bags with small meshes that excluding all possibility of functions of soil animals; in the process of decomposition of litter, relationship of the litter lost weight with number of soil animals is not obvious clearly; the degree of functions of soil animals to soft litter higher than hard litter; according to the analysis of diversity index, no regular changes will happen to the diversity of soil animals as the time of decomposing samples lengthen.

  14. Climate change effects on macrofaunal litter decomposition: the interplay of temperature, body masses and stoichiometry.

    Science.gov (United States)

    Ott, David; Rall, Björn C; Brose, Ulrich

    2012-11-05

    Macrofauna invertebrates of forest floors provide important functions in the decomposition process of soil organic matter, which is affected by the nutrient stoichiometry of the leaf litter. Climate change effects on forest ecosystems include warming and decreasing litter quality (e.g. higher C : nutrient ratios) induced by higher atmospheric CO(2) concentrations. While litter-bag experiments unravelled separate effects, a mechanistic understanding of how interactions between temperature and litter stoichiometry are driving decomposition rates is lacking. In a laboratory experiment, we filled this void by quantifying decomposer consumption rates analogous to predator-prey functional responses that include the mechanistic parameters handling time and attack rate. Systematically, we varied the body masses of isopods, the environmental temperature and the resource between poor (hornbeam) and good quality (ash). We found that attack rates increased and handling times decreased (i) with body masses and (ii) temperature. Interestingly, these relationships interacted with litter quality: small isopods possibly avoided the poorer resource, whereas large isopods exhibited increased, compensatory feeding of the poorer resource, which may be explained by their higher metabolic demands. The combination of metabolic theory and ecological stoichiometry provided critically important mechanistic insights into how warming and varying litter quality may modify macrofaunal decomposition rates.

  15. A surplus production model including environmental effects: Application to the Senegalese white shrimp stocks

    Science.gov (United States)

    Thiaw, Modou; Gascuel, Didier; Jouffre, Didier; Thiaw, Omar Thiom

    2009-12-01

    In Senegal, two stocks of white shrimp ( Penaeusnotialis) are intensively exploited, one in the north and another in the south. We used surplus production models including environmental effects to analyse their changes in abundance over the past 10 years and to estimate their Maximum Sustainable Yield (MSY) and the related fishing effort ( EMSY). First, yearly abundance indices were estimated from commercial statistics using GLM techniques. Then, two environmental indices were alternatively tested in the model: the coastal upwelling intensity from wind speeds provided by the SeaWifs database and the primary production derived from satellite infrared images of chlorophyll a. Models were fitted, with or without the environmental effect, to the 1996-2005 time series. They express stock abundance and catches as functions of the fishing effort and the environmental index (when considered). For the northern stock, fishing effort and abundance fluctuate over the period without any clear trends. The model based on the upwelling index explains 64.9% of the year-to-year variability. It shows that the stock was slightly overexploited in 2002-2003 and is now close to full exploitation. Stock abundance strongly depends on environmental conditions; consequently, the MSY estimate varies from 300 to 900 tons according to the upwelling intensity. For the southern stock, fishing effort has strongly increased over the past 10 years, while abundance has been reduced 4-fold. The environment has a significant effect on abundance but only explains a small part of the year-to-year variability. The best fit is obtained using the primary production index ( R2 = 0.75), and the stock is now significantly overfished regardless of environmental conditions. MSY varies from 1200 to 1800 tons according to environmental conditions. Finally, in northern Senegal, the upwelling is highly variable from year to year and constitutes the major factor determining productivity. In the south, hydrodynamic

  16. Hybrid discrete-continuum modeling for transport, biofilm development and solid restructuring including electrostatic effects

    Science.gov (United States)

    Prechtel, Alexander; Ray, Nadja; Rupp, Andreas

    2017-04-01

    We want to present an approach for the mathematical, mechanistic modeling and numerical treatment of processes leading to the formation, stability, and turnover of soil micro-aggregates. This aims at deterministic aggregation models including detailed mechanistic pore-scale descriptions to account for the interplay of geochemistry and microbiology, and the link to soil functions as, e.g., the porosity. We therefore consider processes at the pore scale and the mesoscale (laboratory scale). At the pore scale transport by diffusion, advection, and drift emerging from electric forces can be taken into account, in addition to homogeneous and heterogeneous reactions of species. In the context of soil micro-aggregates the growth of biofilms or other glueing substances as EPS (extracellular polymeric substances) is important and affects the structure of the pore space in space and time. This model is upscaled mathematically in the framework of (periodic) homogenization to transfer it to the mesoscale resulting in effective coefficients/parameters there. This micro-macro model thus couples macroscopic equations that describe the transport and fluid flow at the scale of the porous medium (mesoscale) with averaged time- and space-dependent coefficient functions. These functions may be explicitly computed by means of auxiliary cell problems (microscale). Finally, the pore space in which the cell problems are defined is time and space dependent and its geometry inherits information from the transport equation's solutions. The microscale problems rely on versatile combinations of cellular automata and discontiuous Galerkin methods while on the mesoscale mixed finite elements are used. The numerical simulations allow to study the interplay between these processes.

  17. Environmental assessment of biofuel chains based on ecosystem modelling, including land-use change effects

    Science.gov (United States)

    Gabrielle, B.; Gagnaire, N.; Massad, R.; Prieur, V.; Python, Y.

    2012-04-01

    The potential greenhouse gas (GHG) savings resulting from the displacement of fossil energy sources by bioenergy mostly hinges on the uncertainty on the magnitude of nitrous oxide (N2O) emissions from arable soils occuring during feedstock production. These emissions are broadly related to fertilizer nitrogen input rates, but largely controlled by soil and climate factors which makes their estimation highly uncertain. Here, we set out to improve estimates of N2O emissions from bioenergy feedstocks by using ecosystem models and measurements and modeling of atmospheric N2O in the greater Paris (France) area. Ground fluxes were measured in two locations to assess the effect of soil type and management, crop type (including lignocellulosics such as triticale, switchgrass and miscanthus), and climate on N2O emission rates and dynamics. High-resolution maps of N2O emissions were generated over the Ile-de-France region (around Paris) with two ecosystem models using geographical databases on soils, weather data, land-use and crop management. The models were tested against ground flux measurements and the emission maps were fed into the atmospheric chemistry-transport model CHIMERE. The maps were tested by comparing the CHIMERE simulations with time series of N2O concentrations measured at various heights above the ground in two locations in 2007. The emissions of N2O, as integrated over the region, were used in a life-cycle assessment of representative biofuel pathways: bioethanol from wheat and sugar-beet (1st generation), and miscanthus (2nd generation chain); bio-diesel from oilseed rape. Effects related to direct and indirect land-use changes (in particular on soil carbon stocks) were also included in the assessment based on various land-use scenarios and literature references. The potential deployment of miscanthus was simulated by assuming it would be grown on the current sugar-beet growing area in Ile-de-France, or by converting land currently under permanent fallow

  18. Optimization of methane production in anaerobic co-digestion of poultry litter and wheat straw at different percentages of total solid and volatile solid using a developed response surface model.

    Science.gov (United States)

    Shen, Jiacheng; Zhu, Jun

    2016-01-01

    Poultry litter (PL) can be good feedstock for biogas production using anaerobic digestion. In this study, methane production from batch co-digestion of PL and wheat straw (WS) was investigated for two factors, i.e., total solid (2%, 5%, and 10%) and volatile solid (0, 25, and 50% of WS), constituting a 3 × 3 experimental design. The results showed that the maximum specific methane volume [197 mL (g VS)(‑1)] was achieved at 50% VS from WS at 5% TS level. It was estimated that the inhibitory threshold of free ammonia was about 289 mg L(--1), beyond which reduction of methanogenic activity by at least 54% was observed. The specific methane volume and COD removal can be expressed using two response surface models (R(2) = 0.9570 and 0.9704, respectively). Analysis of variance of the experimental results indicated that the C/N ratio was the most significant factor influencing the specific methane volume and COD removal in the co-digestion of these two materials.

  19. Validation of gyrokinetic modelling of light impurity transport including rotation in ASDEX Upgrade

    CERN Document Server

    Casson, F J; Angioni, C; Camenen, Y; Dux, R; Fable, E; Fischer, R; Geiger, B; Manas, P; Menchero, L; Tardini, G

    2013-01-01

    Upgraded spectroscopic hardware and an improved impurity concentration calculation allow accurate determination of boron density in the ASDEX Upgrade tokamak. A database of boron measurements is compared to quasilinear and nonlinear gyrokinetic simulations including Coriolis and centrifugal rotational effects over a range of H-mode plasma regimes. The peaking of the measured boron profiles shows a strong anti-correlation with the plasma rotation gradient, via a relationship explained and reproduced by the theory. It is demonstrated that the rotodiffusive impurity flux driven by the rotation gradient is required for the modelling to reproduce the hollow boron profiles at higher rotation gradients. The nonlinear simulations validate the quasilinear approach, and, with the addition of perpendicular flow shear, demonstrate that each symmetry breaking mechanism that causes momentum transport also couples to rotodiffusion. At lower rotation gradients, the parallel compressive convection is required to match the mos...

  20. Models that include supercoiling of topological domains reproduce several known features of interphase chromosomes.

    Science.gov (United States)

    Benedetti, Fabrizio; Dorier, Julien; Burnier, Yannis; Stasiak, Andrzej

    2014-03-01

    Understanding the structure of interphase chromosomes is essential to elucidate regulatory mechanisms of gene expression. During recent years, high-throughput DNA sequencing expanded the power of chromosome conformation capture (3C) methods that provide information about reciprocal spatial proximity of chromosomal loci. Since 2012, it is known that entire chromatin in interphase chromosomes is organized into regions with strongly increased frequency of internal contacts. These regions, with the average size of ∼1 Mb, were named topological domains. More recent studies demonstrated presence of unconstrained supercoiling in interphase chromosomes. Using Brownian dynamics simulations, we show here that by including supercoiling into models of topological domains one can reproduce and thus provide possible explanations of several experimentally observed characteristics of interphase chromosomes, such as their complex contact maps.

  1. Modeling and analysis of overmodulation in erbium-doped fiber amplifiers including amplified spontaneous emission

    Science.gov (United States)

    Sharma, Reena; Raghuwanshi, Sanjeev Kumar

    2017-02-01

    Line surveillance and management information in erbium-doped fiber amplifiers (EDFAs) can be broadcast by modulating the amplitude of the low-frequency lightwave information signal, the process termed as overmodulation in the literature. This paper presents systematic solutions for the overmodulated pump and information signal transfer functions for EDFA. It includes amplified spontaneous emission (ASE) that has an impact on outcomes in the high-gain system. To the extent of our belief, the methodical model simulated with the current approach leads to a distinct perspective of an outcome in the respective field. The test bed described here is realistic. It specifically represents the overmodulation behavior in an EDFA under the influence of ASE.

  2. Relocation of carbon from decomposition of {sup 14}C-labelled needle and fine root litter in peat soil

    Energy Technology Data Exchange (ETDEWEB)

    Domish, T.; Laine, J.; Laiho, R. [Helsinki Univ. (Finland). Dept. of Forest Ecology; Finer, L. [Finnish Forest Research Inst. (Finland). Joensuu Research Station; Karsisto, M. [Finnish Forest Research Inst. (Finland). Dept. of Forest Ecology

    1996-12-31

    Drainage of peatlands promotes a shift of biomass and production from the ground vegetation to the trees. Thus, the above-ground (e.g. needles) and below-ground (roots) litter production of trees increases. Fine roots in particular are an important factor in the carbon and nutrient cycle in forest ecosystems. A major part of the annual net primary production of trees may be allocated below ground, the relative proportion being smaller on fertile sites than on less fertile ones. For modelling the carbon balance of drained peatlands, it is important to know the fate of carbon from newly introduced and decomposing litter. Newly added and fertilised tree litter material may be decomposed at a rate different than litter from the ground vegetation. The objectives of this study are to study the pathways of decomposing litter carbon in peat soil and to evaluate the use of the litterbag method in a controlled environment. (9 refs.)

  3. Soil microbial responses to forest floor litter manipulation and nitrogen addition in a mixed-wood forest of northern China.

    Science.gov (United States)

    Sun, Xiao-Lu; Zhao, Jing; You, Ye-Ming; Jianxin Sun, Osbert

    2016-01-14

    Changes in litterfall dynamics and soil properties due to anthropogenic or natural perturbations have important implications to soil carbon (C) and nutrient cycling via microbial pathway. Here we determine soil microbial responses to contrasting types of litter inputs (leaf vs. fine woody litter) and nitrogen (N) deposition by conducting a multi-year litter manipulation and N addition experiment in a mixed-wood forest. We found significantly higher soil organic C, total N, microbial biomass C (MBC) and N (MBN), microbial activity (MR), and activities of four soil extracellular enzymes, including β-glucosidase (BG), N-acetyl-β-glucosaminidase (NAG), phenol oxidase (PO), and peroxidase (PER), as well as greater total bacteria biomass and relative abundance of gram-negative bacteria (G-) community, in top soils of plots with presence of leaf litter than of those without litter or with presence of only fine woody litter. No apparent additive or interactive effects of N addition were observed in this study. The occurrence of more labile leaf litter stimulated G-, which may facilitate microbial community growth and soil C stabilization as inferred by findings in literature. A continued treatment with contrasting types of litter inputs is likely to result in divergence in soil microbial community structure and function.

  4. Exergoeconomic performance optimization for a steady-flow endoreversible refrigeration model including six typical cycles

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lingen; Kan, Xuxian; Sun, Fengrui; Wu, Feng [College of Naval Architecture and Power, Naval University of Engineering, Wuhan 430033 (China)

    2013-07-01

    The operation of a universal steady flow endoreversible refrigeration cycle model consisting of a constant thermal-capacity heating branch, two constant thermal-capacity cooling branches and two adiabatic branches is viewed as a production process with exergy as its output. The finite time exergoeconomic performance optimization of the refrigeration cycle is investigated by taking profit rate optimization criterion as the objective. The relations between the profit rate and the temperature ratio of working fluid, between the COP (coefficient of performance) and the temperature ratio of working fluid, as well as the optimal relation between profit rate and the COP of the cycle are derived. The focus of this paper is to search the compromised optimization between economics (profit rate) and the utilization factor (COP) for endoreversible refrigeration cycles, by searching the optimum COP at maximum profit, which is termed as the finite-time exergoeconomic performance bound. Moreover, performance analysis and optimization of the model are carried out in order to investigate the effect of cycle process on the performance of the cycles using numerical example. The results obtained herein include the performance characteristics of endoreversible Carnot, Diesel, Otto, Atkinson, Dual and Brayton refrigeration cycles.

  5. Exergoeconomic performance optimization for a steady-flow endoreversible refrigeration model including six typical cycles

    Directory of Open Access Journals (Sweden)

    Lingen Chen, Xuxian Kan, Fengrui Sun, Feng Wu

    2013-01-01

    Full Text Available The operation of a universal steady flow endoreversible refrigeration cycle model consisting of a constant thermal-capacity heating branch, two constant thermal-capacity cooling branches and two adiabatic branches is viewed as a production process with exergy as its output. The finite time exergoeconomic performance optimization of the refrigeration cycle is investigated by taking profit rate optimization criterion as the objective. The relations between the profit rate and the temperature ratio of working fluid, between the COP (coefficient of performance and the temperature ratio of working fluid, as well as the optimal relation between profit rate and the COP of the cycle are derived. The focus of this paper is to search the compromised optimization between economics (profit rate and the utilization factor (COP for endoreversible refrigeration cycles, by searching the optimum COP at maximum profit, which is termed as the finite-time exergoeconomic performance bound. Moreover, performance analysis and optimization of the model are carried out in order to investigate the effect of cycle process on the performance of the cycles using numerical example. The results obtained herein include the performance characteristics of endoreversible Carnot, Diesel, Otto, Atkinson, Dual and Brayton refrigeration cycles.

  6. A Model for One-Dimensional Coherent Synchrotron Radiation including Short-Range Effects

    CERN Document Server

    Ryne, Robert D; Qiang, Ji; Yampolsky, Nikolai

    2012-01-01

    A new model is presented for simulating coherent synchrotron radiation (CSR) in one dimension. The method is based on convolving an integrated Green function (IGF) with the longitudinal charge density. Since it is based on an IGF, the accuracy of this approach is determined by how well one resolves the charge density and not by resolving the single particle wake function. Since short-range wakefield effects are included analytically, the approach can be much more efficient than ordinary (non-IGF) approaches in situations where the wake function and charge density have disparate spatial scales. Two cases are presented: one derived from the full wake including short-range effects, and one derived from the asymptotic wake. In the latter case the algorithm contains the same physics as others based on the asymptotic approximation, but requires only the line charge density and not its derivative. Examples are presented that illustrate the limitations of the asymptotic-wake approximation, and that illustrate how mic...

  7. INTERIOR MODELS OF SATURN: INCLUDING THE UNCERTAINTIES IN SHAPE AND ROTATION

    Energy Technology Data Exchange (ETDEWEB)

    Helled, Ravit [Department of Geophysics, Atmospheric and Planetary Sciences, Tel-Aviv University, Tel-Aviv (Israel); Guillot, Tristan [Universite de Nice-Sophia Antipolis, Observatoire de la Cote d' Azur, CNRS UMR 7293, BP 4229, F-06304 Nice (France)

    2013-04-20

    The accurate determination of Saturn's gravitational coefficients by Cassini could provide tighter constraints on Saturn's internal structure. Also, occultation measurements provide important information on the planetary shape which is often not considered in structure models. In this paper we explore how wind velocities and internal rotation affect the planetary shape and the constraints on Saturn's interior. We show that within the geodetic approach the derived physical shape is insensitive to the assumed deep rotation. Saturn's re-derived equatorial and polar radii at 100 mbar are found to be 54,445 {+-} 10 km and 60,365 {+-} 10 km, respectively. To determine Saturn's interior, we use one-dimensional three-layer hydrostatic structure models and present two approaches to include the constraints on the shape. These approaches, however, result in only small differences in Saturn's derived composition. The uncertainty in Saturn's rotation period is more significant: with Voyager's 10{sup h}39{sup m} period, the derived mass of heavy elements in the envelope is 0-7 M{sub Circled-Plus }. With a rotation period of 10{sup h}32{sup m}, this value becomes <4 M{sub Circled-Plus }, below the minimum mass inferred from spectroscopic measurements. Saturn's core mass is found to depend strongly on the pressure at which helium phase separation occurs, and is estimated to be 5-20 M{sub Circled-Plus }. Lower core masses are possible if the separation occurs deeper than 4 Mbar. We suggest that the analysis of Cassini's radio occultation measurements is crucial to test shape models and could lead to constraints on Saturn's rotation profile and departures from hydrostatic equilibrium.

  8. High performance computation of landscape genomic models including local indicators of spatial association.

    Science.gov (United States)

    Stucki, S; Orozco-terWengel, P; Forester, B R; Duruz, S; Colli, L; Masembe, C; Negrini, R; Landguth, E; Jones, M R; Bruford, M W; Taberlet, P; Joost, S

    2016-11-01

    With the increasing availability of both molecular and topo-climatic data, the main challenges facing landscape genomics - that is the combination of landscape ecology with population genomics - include processing large numbers of models and distinguishing between selection and demographic processes (e.g. population structure). Several methods address the latter, either by estimating a null model of population history or by simultaneously inferring environmental and demographic effects. Here we present samβada, an approach designed to study signatures of local adaptation, with special emphasis on high performance computing of large-scale genetic and environmental data sets. samβada identifies candidate loci using genotype-environment associations while also incorporating multivariate analyses to assess the effect of many environmental predictor variables. This enables the inclusion of explanatory variables representing population structure into the models to lower the occurrences of spurious genotype-environment associations. In addition, samβada calculates local indicators of spatial association for candidate loci to provide information on whether similar genotypes tend to cluster in space, which constitutes a useful indication of the possible kinship between individuals. To test the usefulness of this approach, we carried out a simulation study and analysed a data set from Ugandan cattle to detect signatures of local adaptation with samβada, bayenv, lfmm and an FST outlier method (FDIST approach in arlequin) and compare their results. samβada - an open source software for Windows, Linux and Mac OS X available at http://lasig.epfl.ch/sambada - outperforms other approaches and better suits whole-genome sequence data processing.

  9. Including oxygen enhancement ratio in ion beam treatment planning: model implementation and experimental verification

    Science.gov (United States)

    Scifoni, E.; Tinganelli, W.; Weyrather, W. K.; Durante, M.; Maier, A.; Krämer, M.

    2013-06-01

    We present a method for adapting a biologically optimized treatment planning for particle beams to a spatially inhomogeneous tumor sensitivity due to hypoxia, and detected e.g., by PET functional imaging. The TRiP98 code, established treatment planning system for particles, has been extended for including explicitly the oxygen enhancement ratio (OER) in the biological effect calculation, providing the first set up of a dedicated ion beam treatment planning approach directed to hypoxic tumors, TRiP-OER, here reported together with experimental tests. A simple semi-empirical model for calculating the OER as a function of oxygen concentration and dose averaged linear energy transfer, generating input tables for the program is introduced. The code is then extended in order to import such tables coming from the present or alternative models, accordingly and to perform forward and inverse planning, i.e., predicting the survival response of differently oxygenated areas as well as optimizing the required dose for restoring a uniform survival effect in the whole irradiated target. The multiple field optimization results show how the program selects the best beam components for treating the hypoxic regions. The calculations performed for different ions, provide indications for the possible clinical advantages of a multi-ion treatment. Finally the predictivity of the code is tested through dedicated cell culture experiments on extended targets irradiation using specially designed hypoxic chambers, providing a qualitative agreement, despite some limits in full survival calculations arising from the RBE assessment. The comparison of the predictions resulting by using different model tables are also reported.

  10. Regional contingencies in the relationship between aboveground Bbomass and litter in the world’s grasslands

    Science.gov (United States)

    O’Halloran, Lydia R.; Borer, Elizabeth T.; Seabloom, Eric W.; MacDougall, Andrew S.; Cleland, Elsa E.; McCulley, Rebecca L.; Hobbie, Sarah; Harpole, W. Stan; DeCrappeo, Nicole M.; Chu, Cheng-Jin; Bakker, Jonathan D.; Davies, Kendi F.; Du, Guozhen; Firn, Jennifer; Hagenah, Nicole; Hofmockel, Kirsten S.; Knops, Johannes M.H.; Li, Wei; Melbourne, Brett A.; Morgan, John W.; Orrock, John L.; Prober, Suzanne M.; Stevens, Carly J.

    2013-01-01

    Based on regional-scale studies, aboveground production and litter decomposition are thought to positively covary, because they are driven by shared biotic and climatic factors. Until now we have been unable to test whether production and decomposition are generally coupled across climatically dissimilar regions, because we lacked replicated data collected within a single vegetation type across multiple regions, obfuscating the drivers and generality of the association between production and decomposition. Furthermore, our understanding of the relationships between production and decomposition rests heavily on separate meta-analyses of each response, because no studies have simultaneously measured production and the accumulation or decomposition of litter using consistent methods at globally relevant scales. Here, we use a multi-country grassland dataset collected using a standardized protocol to show that live plant biomass (an estimate of aboveground net primary production) and litter disappearance (represented by mass loss of aboveground litter) do not strongly covary. Live biomass and litter disappearance varied at different spatial scales. There was substantial variation in live biomass among continents, sites and plots whereas among continent differences accounted for most of the variation in litter disappearance rates. Although there were strong associations among aboveground biomass, litter disappearance and climatic factors in some regions (e.g. U.S. Great Plains), these relationships were inconsistent within and among the regions represented by this study. These results highlight the importance of replication among regions and continents when characterizing the correlations between ecosystem processes and interpreting their global-scale implications for carbon flux. We must exercise caution in parameterizing litter decomposition and aboveground production in future regional and global carbon models as their relationship is complex.

  11. Regional contingencies in the relationship between aboveground biomass and litter in the world's grasslands.

    Science.gov (United States)

    O'Halloran, Lydia R; Borer, Elizabeth T; Seabloom, Eric W; MacDougall, Andrew S; Cleland, Elsa E; McCulley, Rebecca L; Hobbie, Sarah; Harpole, W Stan; DeCrappeo, Nicole M; Chu, Chengjin; Bakker, Jonathan D; Davies, Kendi F; Du, Guozhen; Firn, Jennifer; Hagenah, Nicole; Hofmockel, Kirsten S; Knops, Johannes M H; Li, Wei; Melbourne, Brett A; Morgan, John W; Orrock, John L; Prober, Suzanne M; Stevens, Carly J

    2013-01-01

    Based on regional-scale studies, aboveground production and litter decomposition are thought to positively covary, because they are driven by shared biotic and climatic factors. Until now we have been unable to test whether production and decomposition are generally coupled across climatically dissimilar regions, because we lacked replicated data collected within a single vegetation type across multiple regions, obfuscating the drivers and generality of the association between production and decomposition. Furthermore, our understanding of the relationships between production and decomposition rests heavily on separate meta-analyses of each response, because no studies have simultaneously measured production and the accumulation or decomposition of litter using consistent methods at globally relevant scales. Here, we use a multi-country grassland dataset collected using a standardized protocol to show that live plant biomass (an estimate of aboveground net primary production) and litter disappearance (represented by mass loss of aboveground litter) do not strongly covary. Live biomass and litter disappearance varied at different spatial scales. There was substantial variation in live biomass among continents, sites and plots whereas among continent differences accounted for most of the variation in litter disappearance rates. Although there were strong associations among aboveground biomass, litter disappearance and climatic factors in some regions (e.g. U.S. Great Plains), these relationships were inconsistent within and among the regions represented by this study. These results highlight the importance of replication among regions and continents when characterizing the correlations between ecosystem processes and interpreting their global-scale implications for carbon flux. We must exercise caution in parameterizing litter decomposition and aboveground production in future regional and global carbon models as their relationship is complex.

  12. The contribution of dominance and inbreeding depression in estimating variance components for litter size in Pannon White rabbits.

    Science.gov (United States)

    Nagy, I; Gorjanc, G; Curik, I; Farkas, J; Kiszlinger, H; Szendrő, Zs

    2013-08-01

    In a synthetic closed population of Pannon White rabbits, additive (VA ), dominance (VD ) and permanent environmental (VPe ) variance components as well as doe (bF d ) and litter (bF l ) inbreeding depression were estimated for the number of kits born alive (NBA), number of kits born dead (NBD) and total number of kits born (TNB). The data set consisted of 18,398 kindling records of 3883 does collected from 1992 to 2009. Six models were used to estimate dominance and inbreeding effects. The most complete model estimated VA and VD to contribute 5.5 ± 1.1% and 4.8 ± 2.4%, respectively, to total phenotypic variance (VP ) for NBA; the corresponding values for NBD were 1.9 ± 0.6% and 5.3 ± 2.4%, for TNB, 6.2 ± 1.0% and 8.1 ± 3.2% respectively. These results indicate the presence of considerable VD . Including dominance in the model generally reduced VA and VPe estimates, and had only a very small effect on inbreeding depression estimates. Including inbreeding covariates did not affect estimates of any variance component. A 10% increase in doe inbreeding significantly increased NBD (bF d  = 0.18 ± 0.07), while a 10% increase in litter inbreeding significantly reduced NBA (bF l  = -0.41 ± 0.11) and TNB (bF l  = -0.34 ± 0.10). These findings argue for including dominance effects in models of litter size traits in populations that exhibit significant dominance relationships. © 2012 Blackwell Verlag GmbH.

  13. Litter use by laying hens in a commercial aviary: dust bathing and piling.

    Science.gov (United States)

    Campbell, D L M; Makagon, M M; Swanson, J C; Siegford, J M

    2016-01-01

    The laying hen industry, including in the United States, is responding to social concerns about hen welfare by implementing alternative housing systems such as the aviary, to provide more space and resources to large groups of hens. Data detailing the behavior of hens in commercial aviaries is needed to determine hens' use of the resources in order to understand their impact on hen welfare. The open litter area of aviaries provides additional space for hens during the day. Litter is also a substrate for dust bathing which is a strongly motivated natural behavior. Hens are often synchronous in their performance of dust bathing, which may lead to overcrowding in the litter area. Additionally, the open litter area can facilitate expression of unusual behavior such as flock piling (defined as the occurrence of densely grouped clusters of hens, resulting from no obvious cause and occurring randomly throughout the day and flock cycle) which may be a welfare concern. Therefore, we conducted observations of hen occupancy of the open litter area and the performance of dust bathing and flock piling across 3 production points (peak lay, mid lay and end of lay) for two flocks of Lohmann White laying hens housed in a commercial aviary. All areas of the open litter area were occupied to the same degree. Hens performed dust bathing throughout the day but showed peak dust bathing activity in the afternoon for Flock 1 (all P litter area sometimes occurred during peak periods of synchronous dust bathing and when hens piled. Further research is needed to understand the welfare implications of individual hen use of the open litter area and the causes and welfare implications of hen piling.

  14. Leaf litter resource quality induces morphological changes in wood frog (Lithobates sylvaticus) metamorphs.

    Science.gov (United States)

    Stoler, Aaron B; Stephens, Jeffrey P; Relyea, Rick A; Berven, Keith A; Tiegs, Scott D

    2015-11-01

    For organisms that exhibit complex life cycles, resource conditions experienced by individuals before metamorphosis can strongly affect phenotypes later in life. Such resource-induced effects are known to arise from variation in resource quantity, yet little is known regarding effects stemming from variation in resource quality (e.g., chemistry). For larval anurans, we hypothesized that variation in resource quality will induce a gradient of effects on metamorph morphology. We conducted an outdoor mesocosm experiment in which we manipulated resource quality by rearing larval wood frogs (Lithobates sylvaticus) under 11 leaf litter treatments. The litter species represented plant species found in open- and closed-canopy wetlands and included many plant species of current conservation concern (e.g., green ash, common reed). Consistent with our hypothesis, we found a gradient of responses for nearly all mass-adjusted morphological dimensions. Hindlimb dimensions and gut mass were positively associated with litter nutrient content and decomposition rate. In contrast, forelimb length and head width were positively associated with concentrations of phenolic acids and dissolved organic carbon. Limb lengths and widths were positively related with the duration of larval period, and we discuss possible hormonal mechanisms underlying this relationship. There were very few, broad differences in morphological traits of metamorphs between open- and closed-canopy litter species or between litter and no-litter treatments. This suggests that the effects of litter on metamorph morphology are litter species-specific, indicating that the effects of changing plant community structure in and around wetlands will largely depend on plant species composition.

  15. Watching eyes on potential litter can reduce littering: evidence from two field experiments.

    Science.gov (United States)

    Bateson, Melissa; Robinson, Rebecca; Abayomi-Cole, Tim; Greenlees, Josh; O'Connor, Abby; Nettle, Daniel

    2015-01-01

    Littering constitutes a major societal problem, and any simple intervention that reduces its prevalence would be widely beneficial. In previous research, we have found that displaying images of watching eyes in the environment makes people less likely to litter. Here, we investigate whether the watching eyes images can be transferred onto the potential items of litter themselves. In two field experiments on a university campus, we created an opportunity to litter by attaching leaflets that either did or did not feature an image of watching eyes to parked bicycles. In both experiments, the watching eyes leaflets were substantially less likely to be littered than control leaflets (odds ratios 0.22-0.32). We also found that people were less likely to litter when there other people in the immediate vicinity than when there were not (odds ratios 0.04-0.25) and, in one experiment but not the other, that eye leaflets only reduced littering when there no other people in the immediate vicinity. We suggest that designing cues of observation into packaging could be a simple but fruitful strategy for reducing littering.

  16. Watching eyes on potential litter can reduce littering: evidence from two field experiments

    Directory of Open Access Journals (Sweden)

    Melissa Bateson

    2015-12-01

    Full Text Available Littering constitutes a major societal problem, and any simple intervention that reduces its prevalence would be widely beneficial. In previous research, we have found that displaying images of watching eyes in the environment makes people less likely to litter. Here, we investigate whether the watching eyes images can be transferred onto the potential items of litter themselves. In two field experiments on a university campus, we created an opportunity to litter by attaching leaflets that either did or did not feature an image of watching eyes to parked bicycles. In both experiments, the watching eyes leaflets were substantially less likely to be littered than control leaflets (odds ratios 0.22–0.32. We also found that people were less likely to litter when there other people in the immediate vicinity than when there were not (odds ratios 0.04–0.25 and, in one experiment but not the other, that eye leaflets only reduced littering when there no other people in the immediate vicinity. We suggest that designing cues of observation into packaging could be a simple but fruitful strategy for reducing littering.

  17. Litter NSV; marine litter monitoring by northern fulmars (a pilot study)

    NARCIS (Netherlands)

    Franeker, van J.A.; Meijboom, A.

    2002-01-01

    The northern fulmar is a seabird known to consume litter such as plastic. The Dutch government has asked for an investigation of the possibility to use stomach contents of beach-washed fulmars as a monitoring tool for the abundance of marine litter inthe North Sea. Such monitoring is of importance

  18. High-frequency fire alters C : N : P stoichiometry in forest litter.

    Science.gov (United States)

    Toberman, Hannah; Chen, Chengrong; Lewis, Tom; Elser, James J

    2014-07-01

    Fire is a major driver of ecosystem change and can disproportionately affect the cycling of different nutrients. Thus, a stoichiometric approach to investigate the relationships between nutrient availability and microbial resource use during decomposition is likely to provide insight into the effects of fire on ecosystem functioning. We conducted a field litter bag experiment to investigate the long-term impact of repeated fire on the stoichiometry of leaf litter C, N and P pools, and nutrient-acquiring enzyme activities during decomposition in a wet sclerophyll eucalypt forest in Queensland, Australia. Fire frequency treatments have been maintained since 1972, including burning every 2 years (2yrB), burning every 4 years (4 yrB) and no burning (NB). C : N ratios in freshly fallen litter were 29-42% higher and C : P ratios were 6-25% lower for 2 yrB than NB during decomposition, with correspondingly lower 2yrB N : P ratios (27-32) than for NB (34-49). Trends in litter soluble and microbial N : P ratios were similar to the overall litter N : P ratios across fire treatments. Consistent with these, the ratio of activities for N-acquiring to P-acquiring enzymes in litter was higher for 2 yrB than NB, whereas 4 yrB was generally intermediate between 2 yrB and NB. Decomposition rates of freshly fallen litter were significantly lower for 2 yrB (72 ± 2% mass remaining at the end of experiment) than for 4 yrB (59 ± 3%) and NB (62 ± 3%), a difference that may be related to effects of N limitation, lower moisture content, and/or litter C quality. Results for older mixed-age litter were similar to those for freshly fallen litter although treatment differences were less pronounced. Overall, these findings show that frequent fire (2 yrB) decoupled N and P cycling, as manifested in litter C : N : P stoichiometry and in microbial biomass N : P ratio and enzymatic activities. Furthermore, these data indicate that fire induced a transient shift to N-limited ecosystem conditions

  19. Can x-rays be used to increase litter size in the mouse

    Energy Technology Data Exchange (ETDEWEB)

    Rugh, R.

    1976-02-01

    The average litter size for normal CF/sub 1/ mice is close to 10.5, varying in the experiments from 9.75 to 11.73. Separate groups of controls were provided for each of the three major experiments. Resorptions were found even among the control groups, with an average of 1.5 percent. Among litters from matings immediately after (whole-body) x radiation from 10 to 200r, the variations in resorptions over exposure levels was minimal, while variation in average litter size was within the range of normal experience for these mice. Even among mice mated one week after exposure the differences in litter sizes were small and the statistical significance tenuous. It was found that even a maximum exposure of 200R altered neither the resorption rate or production of anomalies, nor induced any significant increase in litter size. When the various phases of the estrous cycle were segregated for irradiation to 100R it was found that those in estrus showed somewhat smaller mean litter size than those which were x irradiated during diestrus or metestrus. However, when compared with the control group, which probably included all phases of the estrous cycle, there was no statistically significant change. On the basis of the study of some 8000 offspring, there is no evidence of significant change in ova production following whole-body x radiation from 10R to 200R of mature CF/sub 1/ female mice, and no evidence of superovulation. (auth)

  20. Impact if hyperprolific line of litter size in multiplication herd

    Directory of Open Access Journals (Sweden)

    Zdeněk Tvrdoň

    2009-01-01

    Full Text Available The hyperprolific line is considered to be maximally effective in pursuit of progress in sow’s reproduction. Hyperprolific line efficiency is commonly evaluated in regard of breeding herd progress. We decided to study how effective it is with respect to increasing of litter size in multiplication herd. Our study is specific by using the data from practice, concretely it is based on the information about the ancestor of sows in multiplication herd. The ancestors could be the member either hyperprolific line or normal line. The information about performances of sows breed in multiplication herd was known. The mixed linear models in SAS for Windows 9.1.2. were conducted to statistical analysis. Our results indicated that no significant effect on litter size was achieved by selection criteria used in the hyperprolific line creation. In studied population no differences between TNB, NBA or NW were found on the 1st as well as on the 1st–5th litters. As we have mentioned above, the study is specific by using the data from practice. Therefore the studied population size is limited. It is necessary to take into consideration when the results are applied. Nevertheless, the results shown that other studies with larger population should be done to reevaluate the selection criteria.

  1. Lignin degradation during plant litter photodegradation

    Science.gov (United States)

    Lin, Y.; King, J. Y.

    2014-12-01

    Lignin is the second most abundant compound, after cellulose, synthesized by plants. Numerous studies have demonstrated that initial lignin concentration is negatively correlated with litter decomposition rate under both laboratory and field conditions. Thus lignin is commonly considered to be a "recalcitrant" compound during litter decomposition. However, lignin can also serve as a radiation-absorbing compound during photodegradation, the process through which solar radiation breaks down organic matter. Here, we synthesize recent studies concerning lignin degradation during litter photodegradation and report results from our study on how photodegradation changes lignin chemistry at a molecular scale. Recent field studies have found that litter with high initial lignin concentration does not necessarily exhibit high mass loss during photodegradation. A meta-analysis (King et al. 2012) even found a weak negative correlation between initial lignin concentration and photodegradation rate. Contradicting results have been reported with regard to the change in lignin concentration during photodegradation. Some studies have found significant loss of lignin during photodegradation, while others have not. In most studies, loss of lignin only accounts for a small proportion of the overall mass loss. Using NMR spectroscopy, we found significant loss of lignin structural units containing beta-aryl ether linkages during photodegradation of a common grass litter, Bromus diandrus, even though conventional forage fiber analysis did not reveal changes in lignin concentration. Both our NMR and fiber analyses supported the idea that photodegradation induced loss of hemicellulose, which was mainly responsible for the litter mass loss during photodegradation. Our results suggest that photodegradation induces degradation, but not necessarily complete breakdown, of lignin structures and consequently exposes hemicellulose and cellulose to microbial decomposition. We conclude that lignin

  2. Development of a quantitative real-time polymerase chain reaction assay to target a novel group of ammonia-producing bacteria found in poultry litter.

    Science.gov (United States)

    Rothrock, M J; Cook, K L; Lovanh, N; Warren, J G; Sistani, K

    2008-06-01

    Ammonia production in poultry houses has serious implications for flock health and performance, nutrient value of poultry litter, and energy costs for running poultry operations. In poultry litter, the conversion of organic N (uric acid and urea) to NH(4)-N is a microbially mediated process. The urease enzyme is responsible for the final step in the conversion of urea to NH(4)-N. Cloning and analysis of 168 urease sequences from extracted genomic DNA from poultry litter samples revealed the presence of a novel, dominant group of ureolytic microbes (representing 90% of the urease clone library). Specific primers and a probe were designed to target this novel poultry litter urease producer (PLUP) group, and a new quantitative real-time PCR assay was developed. The assay allowed for the detection of 10(2) copies of target urease sequences per PCR reaction (approximately 1 x 10(4) cells per gram of poultry litter), and the reaction was linear over 8 orders of magnitude. Our PLUP group was present only in poultry litter and was not present in environmental samples from diverse agricultural settings. This novel PLUP group represented between 0.1 to 3.1% of the total microbial populations (6.0 x 10(6) to 2.4 x 10(8) PLUP cells per gram of litter) from diverse poultry litter types. The PLUP cell concentrations were directly correlated to the total cell concentrations in the poultry litter and were found to be influenced by the physical parameters of the litters (bedding material, moisture content, pH), as well as the NH(4)-N content of the litters, based on principal component analysis. Chemical parameters (organic N, total N, total C) were not found to be influential in the concentrations of our PLUP group in the diverse poultry litters Future applications of this assay could include determining the efficacy of current NH(4)-N-reducing litter amendments or in designing more efficient treatment protocols.

  3. Detrital stoichiometry as a critical nexus for the effects of streamwater nutrients on leaf litter breakdown rates.

    Science.gov (United States)

    Manning, David W P; Rosemond, Amy D; Kominoski, John S; Gulis, Vladislav; Benstead, Jonathan P; Maerz, John C

    2015-08-01

    Nitrogen (N) and phosphorus (P) concentrations are elevated in many freshwater systems, stimulating breakdown rates of terrestrially derived plant litter; however, the relative importance of N and P in driving litter breakdown via microbial and detritivore processing are not fully understood. Here, we determined breakdown rates of two litter species, Acer rubrum (maple) and Rhododendron maximum (rhododendron), before (PRE) and during two years (YR1, YR2) of experimental N and P additions to five streams, and quantified the relative importance of hypothesized factors contributing to breakdown. Treatment streams received a gradient of P additions (low to high soluble reactive phosphorus [SRP]; ~10-85 µg/L) crossed with a gradient of N additions (high to low dissolved inorganic nitrogen [DIN]; ~472-96 µg/L) to achieve target molar N:P ratios ranging from 128 to 2. Litter breakdown rates increased above pre-treatment levels by an average of 1.1-2.2x for maple, and 2.7-4.9x for rhododendron in YR1 and YR2. We used path analysis to compare fungal biomass, shredder biomass, litter stoichiometry (nutrient content as C:N or C:P), discharge, and streamwater temperature as predictors of breakdown rates and compared models containing streamwater N, P or N + P and litter C:N or C:P using model selection criteria. Litter breakdown rates were predicted equally with either streamwater N or P (R2 = 0.57). In models with N or P, fungal biomass, litter stoichiometry, discharge, and shredder biomass predicted breakdown rates; litter stoichiometry and fungal biomass were most important for model fit. However, N and P effects may have occurred via subtly different pathways. Litter N content increased with fungal biomass (N-driven effects) and litter P content increased with streamwater P availability (P-driven effects), presumably via P storage in fungal biomass. In either case, the effects of N and P through these pathways were associated with higher shredder biomass and breakdown

  4. Mathematical and numerical model of directional solidification including initial and terminal transients of the process

    Directory of Open Access Journals (Sweden)

    W. Kapturkiewicz

    2008-12-01

    Full Text Available The, developed in this study, simple model and numerical solution of diffusion growth of the solid phase under the conditions of directional solidification allow for the effect of constituent diffusion in both liquid and solid phase and assume the process run in which (like in reality the preset parameter is the velocity of sample (pulling velocity at a preset temperature gradient. The solid/liquid interface velocity is not the process parameter (like it is in numerous other solutions proposed so far but a function of this process. The effect of convection outside the diffusion layer has been included in mass balance under the assumption that in the zone of convection the mixing is complete. The above assumptions enabled solving the kinetics of growth of the solid phase (along with the diffusion field in solid and liquid phase under the conditions of diffusion well reflecting the process run starting with the initial transient state, going through the steady state period in central part of the casting, and ending in a terminal transient state. In the numerical solution obtained by the finite difference method with variable grid dimensions, the error of the mass control balance over the whole process range was 1 - 2 %.

  5. Photodegradation of roxarsone in poultry litter leachates.

    Science.gov (United States)

    Bednar, A J; Garbarino, J R; Ferrer, I; Rutherford, D W; Wershaw, R L; Ranville, J F; Wildeman, T R

    2003-01-20

    Arsenic compounds have been used extensively in agriculture in the US for applications ranging from cotton herbicides to animal feed supplements. Roxarsone (3-nitro-4-hydroxyphenylarsonic acid), in particular, is used widely in poultry production to control coccidial intestinal parasites. It is excreted unchanged in the manure and introduced into the environment when litter is applied to farmland as fertilizer. Although the toxicity of roxarsone is less than that of inorganic arsenic, roxarsone can degrade, biotically and abiotically, to produce more toxic inorganic forms of arsenic, such as arsenite and arsenate. Experiments were conducted on aqueous litter leachates to test the stability of roxarsone under different conditions. Laboratory experiments have shown that arsenite can be cleaved photolytically from the roxarsone moiety at pH 4-8 and that the degradation rate increases with increasing pH. Furthermore, the rate of photodegradation increases with nitrate and natural organic matter concentration, reactants that are commonly found in poultry-litter-water leachates. Additional photochemical reactions rapidly oxidize the cleaved arsenite to arsenate. The formation of arsenate is not entirely undesirable, because it is less mobile in soil systems and less toxic than arsenite. A possible mechanism for the degradation of roxarsone in poultry litter leachates is proposed. The results suggest that poultry litter storage and field application practices could affect the degradation of roxarsone and subsequent mobilization of inorganic arsenic species.

  6. Genetic parameters and trends for litter traits in U.S. Yorkshire, Duroc, Hampshire, and Landrace pigs.

    Science.gov (United States)

    Chen, P; Baas, T J; Mabry, J W; Koehler, K J; Dekkers, J C M

    2003-01-01

    Records on 251,296 Yorkshire, 75,262 Duroc, 83,338 Hampshire, and 53,234 Landrace litters born between 1984 and April of 1999 in herds on the National Swine Registry Swine Testing and Genetic Evaluation System were analyzed. Animal model and restricted maximum likelihood procedures were used to estimate variances of animal genetic (a), maternal genetic (m), permanent environmental, and service sire, and the covariances between a and m for number born alive (NBA), litter weight at 21 d (L21WT), and number weaned (NW). Fixed effects of contemporary groups were included in the analysis. Based on a single-trait model, estimates of heritabilities were 0.10, 0.09, 0.08, and 0.08 for NBA; 0.08, 0.07, 0.08, and 0.09 for L21WT; and 0.05, 0.07, 0.05, and 0.05 for NW in the Yorkshire, Duroc, Hampshire, and Landrace breeds, respectively. Estimates of maternal genetic effects were low and ranged from 0.00 to 0.02 for all traits and all breeds. Estimates of permanent environmental effects ranged from 0.03 to 0.08. Estimates of service sire effects ranged from 0.02 to 0.05. A bivariate analysis was used to estimate the genetic correlations among traits. Average genetic correlations over the four breeds were 0.13, 0.15, and 0.71 for NBA with L21WT, NBA with NW, and L21WT with NW, respectively. Average genetic trends were 0.018 pigs/yr, 0.114 kg/yr, and 0.004 pigs/yr for NBA, L21WT, and NW, respectively. Although estimates of heritabilities for litter traits were low and similar across breeds, genetic variances for litter traits were sufficiently large to indicate that litter traits could be improved through selection. This study presents the first set of breed-specific estimates of genetic parameters available from large numbers of field records. It provides information for use in national genetic evaluations.

  7. Genetic analysis of age at first service, return rate, litter size, and weaning-to-first service interval of gilts and sows.

    Science.gov (United States)

    Holm, B; Bakken, M; Vangen, O; Rekaya, R

    2005-01-01

    The aim of this study was to estimate genetic parameters of seven traits related to sow reproductive performance. Data on all Norwegian Landrace pigs (NL) born in nucleus herds and raised in nucleus or multiplying herds from 1990 to 2000 were extracted from the Norwegian national recording scheme. Reproductive traits investigated were age at first service (AFS), return rate in gilts (RRg), age at first farrowing (AFF), live-born piglets in the first litter (NBA1), interval from weaning to first service after first litter (WTS1), return rate after first litter (RR1), live-born piglets in the second litter (NBA2), and interval from weaning to first service after second litter (WTS2). After editing, the data set comprised 12,583 to 56,042 records, depending on the trait. A mixed linear and a joint linear threshold animal model were used to estimate (co)variance components. A full Bayesian approach via Gibbs sampling was adopted. The statistical model used for analysis included contemporary groups of herd-year (-season), purebred or crossbred litter, single or double insemination, mating type, parity in which the animal was born, a regression on lactation length, and an additive genetic effect. Neither the estimated heritabilities nor the genetic correlations differed much between the two approaches, but there was a tendency for higher genetic correlations using the joint linear threshold model approach. Average heritabilities were as follows: AFS = 0.31; RRg = 0.03; RR1 = 0.02; NBA1 = 0.12; NBA2 = 0.14; WTS1 = 0.08; and WTS2 = 0.03. The highest genetic correlations were estimated between NBA1 and NBA2 (r(g) = 0.95), RR1 and WTS1 (r(g) = 0.93), and between WTS1 and WTS2 (r(g) = 0.78). The estimated genetic correlation between NBA and WTS were close to zero. Selection for increased NBA will slightly increase AFS and reduce the probability of a return. Selection for decreased AFS will have a favorable effect on WTS intervals; however, selection for decreased AFS seems to

  8. Modelling anaerobic digestion in an industrial biogas digester: Application of lactate-including ADM1 model (Part II).

    Science.gov (United States)

    Satpathy, Preseela; Biernacki, Piotr; Cypionka, Heribert; Steinigeweg, Sven

    2016-12-05

    A modified Anaerobic Digestion Model No. 1 (ADM1xp) including lactate was applied to a full-scale biogas plant. This model considers monosaccharides to degrade through lactic acid, which further degrades majorly into acetate followed by propionate and butyrate. Experimental data were derived from the previous works in the same laboratory, and the proposed parameters were validated against batch experiments. After successful validation, the biogas plant bearing a fermenter size of 7 dam(3) and operated with food waste and cattle manure was simulated. The biogas production and methane content were reliably simulated, and a good fit could be obtained against the experimental data with an average difference of less than 1%. When compared to the original ADM1 model, the performance of the lactate-incorporated model was found to be improved. Inclusion of lactate as a parameter in the ADM1xp model is recommended for an increased sensitivity and enhanced prediction principally for systems dealing with high carbohydrate and lactate loads.

  9. Numerical modelling of seawater intrusion in Shenzhen (China) using a 3D densitydependent model including tidal effects

    Indian Academy of Sciences (India)

    Wei Lu; Qingchun Yang; Jordi D Martín; Ricardo Juncosa

    2013-04-01

    During the 1990s, groundwater overexploitation has resulted in seawater intrusion in the coastal aquifer of the Shenzhen city, China. Although water supply facilities have been improved and alleviated seawater intrusion in recent years, groundwater overexploitation is still of great concern in some local areas. In this work we present a three-dimensional density-dependent numerical model developed with the FEFLOW code, which is aimed at simulating the extent of seawater intrusion while including tidal effects and different groundwater pumping scenarios. Model calibration, using waterheads and reported chloride concentration, has been performed based on the data from 14 boreholes, which were monitored from May 2008 to December 2009. A fairly good fitness between the observed and computed values was obtained by a manual trial-and-error method. Model prediction has been carried out forward 3 years with the calibrated model taking into account high, medium and low tide levels and different groundwater exploitation schemes. The model results show that tide-induced seawater intrusion significantly affects the groundwater levels and concentrations near the estuarine of the Dasha river, which implies that an important hydraulic connection exists between this river and groundwater, even considering that some anti-seepage measures were taken in the river bed. Two pumping scenarios were considered in the calibrated model in order to predict the future changes in the water levels and chloride concentration. The numerical results reveal a decreased tendency of seawater intrusion if groundwater exploitation does not reach an upper bound of about 1.32 × 104 m3/d. The model results provide also insights for controlling seawater intrusion in such coastal aquifer systems.

  10. ETM documentation update – including modelling conventions and manual for software tools

    DEFF Research Database (Denmark)

    Grohnheit, Poul Erik

    , it summarises the work done during 2013, and it also contains presentations for promotion of fusion as a future element in the electricity generation mix and presentations for the modelling community concerning model development and model documentation – in particular for TIAM collaboration workshops....

  11. Modelling stress-dependent permeability in fractured rock including effects of propagating and bending fractures

    NARCIS (Netherlands)

    Latham, J.P.; Xiang, J.; Belayneh, M.; Nick, H.M.; Tsang, C.F.; Blunt, M.J.

    2013-01-01

    The influence of in-situ stresses on flow processes in fractured rock is investigated using a novel modelling approach. The combined finite-discrete element method (FEMDEM) is used to model the deformation of a fractured rock mass. The fracture wall displacements and aperture changes are modelled in

  12. A sub-circuit MOSFET model with a wide temperature range including cryogenic temperature*

    Institute of Scientific and Technical Information of China (English)

    Jia Kan; Sun Weifeng; Shi Longxing

    2011-01-01

    A sub-circuit SPICE model ofa MOSFET for low temperature operation is presented. Two resistors are introduced for the freeze-out effect, and the explicit behavioral models are developed for them. The model can be used in a wide temperature range covering both cryogenic temperature and regular temperatures.

  13. Including Overweight or Obese Students in Physical Education: A Social Ecological Constraint Model

    Science.gov (United States)

    Li, Weidong; Rukavina, Paul

    2012-01-01

    In this review, we propose a social ecological constraint model to study inclusion of overweight or obese students in physical education by integrating key concepts and assumptions from ecological constraint theory in motor development and social ecological models in health promotion and behavior. The social ecological constraint model proposes…

  14. Natural zeolites in diet or litter of broilers.

    Science.gov (United States)

    Schneider, A F; Almeida, D S De; Yuri, F M; Zimmermann, O F; Gerber, M W; Gewehr, C E

    2016-04-01

    This study aims to analyse the influence of adding natural zeolites (clinoptilolite) to the diet or litter of broilers and their effects on growth performance, carcass yield and litter quality. Three consecutive flocks of broilers were raised on the same sawdust litter, from d 1 to d 42 of age, and distributed in three treatments (control with no added zeolites, addition of 5 g/kg zeolite to diet and addition of 100 g/kg zeolites to litter). The addition of zeolites to the diet or litter did not affect growth performance or carcass yield. The addition of zeolites to the diet did not influence moisture content of the litter, ammonia volatilisation was reduced only in the first flock and pH of litter was reduced in the second and third flock. However, the addition of zeolites to the litter reduced moisture content, litter pH and ammonia volatilisation in all flocks analysed. The addition of 5 g/kg zeolite to the diet in three consecutive flocks was not effective in maintaining litter quality, whereas the addition of 100 g/kg natural zeolites to sawdust litter reduced litter moisture and ammonia volatilisation in three consecutive flocks raised on the same litter.

  15. A methodology for including wall roughness effects in k-ε low-Reynolds turbulence models

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosini, W., E-mail: walter.ambrosini@ing.unipi.it; Pucciarelli, A.; Borroni, I.

    2015-05-15

    Highlights: • A model for taking into account wall roughness in low-Reynolds k-ε models is presented. • The model is subjected to a first validation to show its potential in general applications. • The application of the model in predicting heat transfer to supercritical fluids is also discussed. - Abstract: A model accounting for wall roughness effects in k-ε low-Reynolds turbulence models is described in the present paper. In particular, the introduction in the transport equations of k and ε of additional source terms related to roughness, based on simple assumptions and dimensional relationships, is proposed. An objective of the present paper, in addition to obtaining more realistic predictions of wall friction, is the application of the proposed model to the study of heat transfer to supercritical fluids. A first validation of the model is reported. The model shows the capability of predicting, at least qualitatively, some of the most important trends observed when dealing with rough pipes in very different flow conditions. Qualitative comparisons with some DNS data available in literature are also performed. Further analyses provided promising results concerning the ability of the model in reproducing the trend of friction factor when varying the flow conditions, though improvements are necessary for achieving better quantitative accuracy. First applications of the model in simulating heat transfer to supercritical fluids are also described, showing the capability of the model to affect the predictions of these heat transfer phenomena, in particular in the vicinity of the pseudo-critical conditions. A more extended application of the model to relevant deteriorated heat transfer conditions will clarify the usefulness of this modelling methodology in improving predictions of these difficult phenomena. Whatever the possible success in this particular application that motivated its development, this approach suggests a general methodology for accounting

  16. Effect of within-litter birth weight variation on piglet survival and pre-weaning weight gain in a commercial herd

    Directory of Open Access Journals (Sweden)

    Norest Marandu

    2015-09-01

    Full Text Available There are several factors that affect piglet survival and this has a bearing on sow productivity. Ten variables that influence pre-weaning vitality were analysed using records from the Pig Industry Board, Zimbabwe. These included individual piglet birth weight, piglet origin (nursed in original litter or fostered, sex, relative birth weight expressed as standard deviation units, sow parity, total number of piglets born, year and month of farrowing, within-litter variability and the presence of stillborn or mummified littermates. The main factors that influenced piglet mortality were fostering, parity and within-litter variability especially the weight of the individual piglet relative to the average of the litter (P<0.05. Presence of a mummified or stillborn littermate, which could be a proxy for unfavourable uterine environment or trauma during the birth process, did not influence pre-weaning mortality. Variability within a litter and the deviation of the weight of an individual piglet from the litter mean, influenced survival to weaning. It is, therefore, advisable for breeders to include uniformity within the litter as a selection criterion. The recording of various variables by farmers seems to be a useful management practice to identify piglets at risk so as to establish palliative measures. Further, farmers should know which litters and which piglets within a litter are at risk and require more attention.

  17. Two methods for modeling vibrations of planetary gearboxes including faults: Comparison and validation

    Science.gov (United States)

    Parra, J.; Vicuña, Cristián Molina

    2017-08-01

    Planetary gearboxes are important components of many industrial applications. Vibration analysis can increase their lifetime and prevent expensive repair and safety concerns. However, an effective analysis is only possible if the vibration features of planetary gearboxes are properly understood. In this paper, models are used to study the frequency content of planetary gearbox vibrations under non-fault and different fault conditions. Two different models are considered: phenomenological model, which is an analytical-mathematical formulation based on observation, and lumped-parameter model, which is based on the solution of the equations of motion of the system. Results of both models are not directly comparable, because the phenomenological model provides the vibration on a fixed radial direction, such as the measurements of the vibration sensor mounted on the outer part of the ring gear. On the other hand, the lumped-parameter model provides the vibrations on the basis of a rotating reference frame fixed to the carrier. To overcome this situation, a function to decompose the lumped-parameter model solutions to a fixed reference frame is presented. Finally, comparisons of results from both model perspectives and experimental measurements are presented.

  18. Power generation from poultry litter biomass

    Energy Technology Data Exchange (ETDEWEB)

    Giaier, T.A.; Morrow, R.S. [Detroit Stoker Co., Detroit (United States)

    1999-07-01

    The following paper presents the experiences of power plants utilizing poultry litter as a boiler fuel. The combustion of poultry litter provides an innovative solution to problems such as ground water run-off contamination while producing electric power with this renewable fuel. The ash from the combustion process can be utilized for resale as a fertilizer, thereby helping to provide a closed-loop environmental cycle. As with all biomass fuels, the power generated results in a net reduction in CO{sub 2} emissions and thus contributes to the solution of current greenhouse gas problems. (author)

  19. Characterization of Forest Structure and an Assessment of Litter ...

    African Journals Online (AJOL)

    Nafiisah

    Kristensen et al., 2008). ... the mangrove litter is not just restricted to the coastal line, but extends beyond it ... Litter dynamics in mangroves involve measurements of components such as .... The lagoon at Bambous Virieux is approximately 5 km large.

  20. A two-dimensional simulation model of phosphorus uptake including crop growth and P-response

    NARCIS (Netherlands)

    Mollier, A.; Willigen, de P.; Heinen, M.; Morel, C.; Schneider, A.; Pellerin, S.

    2008-01-01

    Modelling nutrient uptake by crops implies considering and integrating the processes controlling the soil nutrient supply, the uptake by the root system and relationships between the crop growth response and the amount of nutrient absorbed. We developed a model that integrates both dynamics of maize

  1. European column buckling curves and finite element modelling including high strength steels

    DEFF Research Database (Denmark)

    Jönsson, Jeppe; Stan, Tudor-Cristian

    2017-01-01

    Eurocode allows for finite element modelling of plated steel structures, however the information in the code on how to perform the analysis or what assumptions to make is quite sparse. The present paper investigates the deterministic modelling of flexural column buckling using plane shell element...

  2. Dipole model analysis of highest precision HERA data, including very low $Q^2$'s

    CERN Document Server

    Luszczak, Agnieszka

    2016-01-01

    We analyse, within a dipole model, the final, inclusive HERA DIS cross section data in the low $x$ region, using fully correlated errors. We show, that these highest precision data are very well described within the dipole model framework starting from $Q^2$ values of 3.5 GeV$^2$ to the highest values of $Q^2 =$ 250 GeV$^2$.

  3. A Two-Account Life Insurance Model for Scenario-Based Valuation Including Event Risk

    DEFF Research Database (Denmark)

    Jensen, Ninna Reitzel; Schomacker, Kristian Juul

    2015-01-01

    Using a two-account model with event risk, we model life insurance contracts taking into account both guaranteed and non-guaranteed payments in participating life insurance as well as in unit-linked insurance. Here, event risk is used as a generic term for life insurance events, such as death......, disability, etc. In our treatment of participating life insurance, we have special focus on the bonus schemes “consolidation” and “additional benefits”, and one goal is to formalize how these work and interact. Another goal is to describe similarities and differences between participating life insurance...... model by conducting scenario analysis based on Monte Carlo simulation, but the model applies to scenarios in general and to worst-case and best-estimate scenarios in particular. In addition to easy computations, our model offers a common framework for the valuation of life insurance payments across...

  4. A Two-Account Life Insurance Model for Scenario-Based Valuation Including Event Risk

    DEFF Research Database (Denmark)

    Jensen, Ninna Reitzel; Schomacker, Kristian Juul

    2015-01-01

    and unit-linked insurance. By use of a two-account model, we are able to illustrate general concepts without making the model too abstract. To allow for complicated financial markets without dramatically increasing the mathematical complexity, we focus on economic scenarios. We illustrate the use of our......Using a two-account model with event risk, we model life insurance contracts taking into account both guaranteed and non-guaranteed payments in participating life insurance as well as in unit-linked insurance. Here, event risk is used as a generic term for life insurance events, such as death...... product types. This enables comparison of participating life insurance products and unit-linked insurance products, thus building a bridge between the two different ways of formalizing life insurance products. Finally, our model distinguishes itself from the existing literature by taking into account...

  5. Gasification of biomass in a fixed bed downdraft gasifier--a realistic model including tar.

    Science.gov (United States)

    Barman, Niladri Sekhar; Ghosh, Sudip; De, Sudipta

    2012-03-01

    This study presents a model for fixed bed downdraft biomass gasifiers considering tar also as one of the gasification products. A representative tar composition along with its mole fractions, as available in the literature was used as an input parameter within the model. The study used an equilibrium approach for the applicable gasification reactions and also considered possible deviations from equilibrium to further upgrade the equilibrium model to validate a range of reported experimental results. Heat balance was applied to predict the gasification temperature and the predicted values were compared with reported results in literature. A comparative study was made with some reference models available in the literature and also with experimental results reported in the literature. Finally a predicted variation of performance of the gasifier by this validated model for different air-fuel ratio and moisture content was also discussed.

  6. Including Tropical Croplands in a Terrestrial Biosphere Model: Application to West Africa

    Science.gov (United States)

    Berg, A.; Sultan, B.; de Noblet, N.

    2008-12-01

    Studying the large-scale relationships between climate and agriculture raises two different issues: the impact of climate on crops, and the potential feedbacks to climate from croplands. A relevant framework to consistently address this twofold issue is to extend existing Dynamic Global Vegetation Models, which can be coupled to climate models, in order to explicitly account for croplands. Here we present the first results of such a strategy applied to tropical croplands over West Africa. We introduce directly into the terrestrial biosphere model ORCHIDEE (IPSL) adequate processes and parametrizations taken from the crop model SARRAH (CIRAD), which is calibrated for millet over this region. The resulting model, ORCH-mil, realistically simulates the growth and yield of millet when tested on an experimental station in Senegal. The model is then applied over West Africa using a 36-year climate reanalysis dataset. First the model is tested in terms of yield simulation, against national millet yields from the FAO database. The ability of the model to reproduce the spatial and temporal variability of millet yields is assessed. Then, the effects on land surface fluxes of explicitly accounting for croplands are examined, by comparison between ORCH-mil and ORCHIDEE. These first simulations show consistent results, but underline the need for some further development and validation of the model if it is to simulate yields accurately. In terms of land surface fluxes, significant differences between ORCH-mil and ORCHIDEE appear, mainly via changes in evaporation and albedo. The potential impact on the west African monsoon system of such differences needs to be investigated by coupling ORCH-mil to a climate model: first results from such an experiment will be presented.

  7. Spatial modelling of marine organisms in Forsmark and Oskarshamn. Including calculation of physical predictor variables

    Energy Technology Data Exchange (ETDEWEB)

    Carlen, Ida; Nikolopoulos, Anna; Isaeus, Martin (AquaBiota Water Research, Stockholm (SE))

    2007-06-15

    GIS grids (maps) of marine parameters were created using point data from previous site investigations in the Forsmark and Oskarshamn areas. The proportion of global radiation reaching the sea bottom in Forsmark and Oskarshamn was calculated in ArcView, using Secchi depth measurements and the digital elevation models for the respective area. The number of days per year when the incoming light exceeds 5 MJ/m2 at the bottom was then calculated using the result of the previous calculations together with measured global radiation. Existing modelled grid-point data on bottom and pelagic temperature for Forsmark were interpolated to create surface covering grids. Bottom and pelagic temperature grids for Oskarshamn were calculated using point measurements to achieve yearly averages for a few points and then using regressions with existing grids to create new maps. Phytoplankton primary production in Forsmark was calculated using point measurements of chlorophyll and irradiance, and a regression with a modelled grid of Secchi depth. Distribution of biomass of macrophyte communities in Forsmark and Oskarshamn was calculated using spatial modelling in GRASP, based on field data from previous surveys. Physical parameters such as those described above were used as predictor variables. Distribution of biomass of different functional groups of fish in Forsmark was calculated using spatial modelling based on previous surveys and with predictor variables such as physical parameters and results from macrophyte modelling. All results are presented as maps in the report. The quality of the modelled predictions varies as a consequence of the quality and amount of the input data, the ecology and knowledge of the predicted phenomena, and by the modelling technique used. A substantial part of the variation is not described by the models, which should be expected for biological modelling. Therefore, the resulting grids should be used with caution and with this uncertainty kept in mind. All

  8. Temporal trend of litter contamination at Cassino beach, Southern Brazil

    OpenAIRE

    Tourinho, Paula da Silva; Fillmann,Gilberto

    2011-01-01

    This study was undertaken to evaluate temporal trends of litter contamination at Cassino beach, Southern Brazil. Surveys were conducted between 1994 and 1995, and then resumed from 2003 to 2006. Litter composition was related to both land- anmarinebased origins. However, seasonal and spatial variations showed that in situ deposition by beach users is still a major source of litter at Cassino beach. The results indicated a significant increase in litter amount at Cassino beach over the survey ...

  9. Modeled hydraulic redistribution by Helianthus annuus L. matches observed data only after model modification to include nighttime transpiration

    Science.gov (United States)

    Neumann, R. B.; Cardon, Z. G.; Rockwell, F. E.; Teshera-Levye, J.; Zwieniecki, M.; Holbrook, N. M.

    2013-12-01

    The movement of water from moist to dry soil layers through the root systems of plants, referred to as hydraulic redistribution (HR), occurs throughout the world and is thought to influence carbon and water budgets and ecosystem functioning. The realized hydrologic, biogeochemical, and ecological consequences of HR depend on the amount of redistributed water, while the ability to assess these impacts requires models that correctly capture HR magnitude and timing. Using several soil types and two eco-types of Helianthus annuus L. in split-pot experiments, we examined how well the widely used HR modeling formulation developed by Ryel et al. (2002) could match experimental determination of HR across a range of water potential driving gradients. H. annuus carries out extensive nighttime transpiration, and though over the last decade it has become more widely recognized that nighttime transpiration occurs in multiple species and many ecosystems, the original Ryel et al. (2002) formulation does not include the effect of nighttime transpiration on HR. We developed and added a representation of nighttime transpiration into the formulation, and only then was the model able to capture the dynamics and magnitude of HR we observed as soils dried and nighttime stomatal behavior changed, both influencing HR.

  10. Constraints on gen4eralized Chaplygin gas model including gamma-ray bursts

    Institute of Scientific and Technical Information of China (English)

    Fa-Yin Wang; Zi-Gao Dai; Shi Qi

    2009-01-01

    Generalized Chaplygin gas (whose equation of state is PGCG = -A/PGCGα) was proposed as a candidate for unification of dark energy and dark matter. We inves-tigate constraints on this model with the latest observed data. We test the model with type-Ia supernovae (SNe Ia), cosmic microwave background (CMB) anisotropy, X-ray gas mass fractions in clusters, and gamma-ray bursts (GRBs). We calibrate the GRB lu-minosity relations without assuming any cosmological models using SNe Ia. We show that GRBs can extend the Hubble diagram to higher redshifts (z> 6). The GRB Hubble diagram is well behaved and delineates the shape of the Hubble diagram well. We mea-sure As≡A/PGCG,0α+1=0.68-0.08+0.04 (where PGCG,0 is the energy density today) and α=-0.22-0.13+0.15at the 1σconfidence level using all the datasets. Our results rule out the standard Chaplygin gas model (α = 1) at the 3a confidence level. The ACDM is allowed at the 2or confidence level. We find that acceleration could have started at a redshift of z ~ 0.70. The concordance of the generalized Chaplygin gas model with the age estimate of an old high redshift quasar is found. In addition, we show that GRBs can break the degeneracy between the generalized Chaplygin gas model and the XCDM model.

  11. Simulated village locations in Thailand: A multi-scale model including a neural network approach.

    Science.gov (United States)

    Tang, Wenwu; Malanson, George P; Entwisle, Barbara

    2009-04-01

    The simulation of rural land use systems, in general, and rural settlement dynamics in particular has developed with synergies of theory and methods for decades. Three current issues are: linking spatial patterns and processes, representing hierarchical relations across scales, and considering nonlinearity to address complex non-stationary settlement dynamics. We present a hierarchical simulation model to investigate complex rural settlement dynamics in Nang Rong, Thailand. This simulation uses sub-models to allocate new villages at three spatial scales. Regional and sub-regional models, which involve a nonlinear space-time autoregressive model implemented in a neural network approach, determine the number of new villages to be established. A dynamic village niche model, establishing pattern-process link, was designed to enable the allocation of villages into specific locations. Spatiotemporal variability in model performance indicates the pattern of village location changes as a settlement frontier advances from rice-growing lowlands to higher elevations. Experiments results demonstrate this simulation model can enhance our understanding of settlement development in Nang Rong and thus gain insight into complex land use systems in this area.

  12. A Two-Account Life Insurance Model for Scenario-Based Valuation Including Event Risk

    Directory of Open Access Journals (Sweden)

    Ninna Reitzel Jensen

    2015-06-01

    Full Text Available Using a two-account model with event risk, we model life insurance contracts taking into account both guaranteed and non-guaranteed payments in participating life insurance as well as in unit-linked insurance. Here, event risk is used as a generic term for life insurance events, such as death, disability, etc. In our treatment of participating life insurance, we have special focus on the bonus schemes “consolidation” and “additional benefits”, and one goal is to formalize how these work and interact. Another goal is to describe similarities and differences between participating life insurance and unit-linked insurance. By use of a two-account model, we are able to illustrate general concepts without making the model too abstract. To allow for complicated financial markets without dramatically increasing the mathematical complexity, we focus on economic scenarios. We illustrate the use of our model by conducting scenario analysis based on Monte Carlo simulation, but the model applies to scenarios in general and to worst-case and best-estimate scenarios in particular. In addition to easy computations, our model offers a common framework for the valuation of life insurance payments across product types. This enables comparison of participating life insurance products and unit-linked insurance products, thus building a bridge between the two different ways of formalizing life insurance products. Finally, our model distinguishes itself from the existing literature by taking into account the Markov model for the state of the policyholder and, hereby, facilitating event risk.

  13. Potential transformation of trace species including aircraft exhaust in a cloud environment. The `Chedrom model`

    Energy Technology Data Exchange (ETDEWEB)

    Ozolin, Y.E.; Karol, I.L. [Main Geophysical Observatory, St. Petersburg (Russian Federation); Ramaroson, R. [Office National d`Etudes et de Recherches Aerospatiales (ONERA), 92 - Chatillon (France)

    1997-12-31

    Box model for coupled gaseous and aqueous phases is used for sensitivity study of potential transformation of trace gases in a cloud environment. The rate of this transformation decreases with decreasing of pH in droplets, with decreasing of photodissociation rates inside the cloud and with increasing of the droplet size. Model calculations show the potential formation of H{sub 2}O{sub 2} in aqueous phase and transformation of gaseous HNO{sub 3} into NO{sub x} in a cloud. This model is applied for exploration of aircraft exhausts evolution in plume inside a cloud. (author) 10 refs.

  14. A Two-Dimensional Modeling Procedure to Estimate the Loss Equivalent Resistance Including the Saturation Effect

    Directory of Open Access Journals (Sweden)

    Rosa Ana Salas

    2013-11-01

    Full Text Available We propose a modeling procedure specifically designed for a ferrite inductor excited by a waveform in time domain. We estimate the loss resistance in the core (parameter of the electrical model of the inductor by means of a Finite Element Method in 2D which leads to significant computational advantages over the 3D model. The methodology is validated for an RM (rectangular modulus ferrite core working in the linear and the saturation regions. Excellent agreement is found between the experimental data and the computational results.

  15. Recent Advances in Study on Thermodynamic Models for Real Systems Including Electrolytes

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A comprehensive review of recent advances in study on thermodynamic models for real electrolyte solutions is presented. The differences between primitive and non-primitive electrolyte models are demonstrated. Some new thermodynamic models for electrolyte solutions based on the mean spherical approximation and perturbation theory are introduced. An extended scaled-particle theory and modified CleggPitz er equation are presented for physical and chemical absorption processes with mixed solvents, respectively. A pseudo one-component two-Yukawa equation of state is used for the aqueous two-phase extraction process in charged colloidal systems.

  16. Extension of Lithium Ion Cell Model to Include Transient and Low-Temperature Behaviour

    Science.gov (United States)

    Dudley, G.

    2014-08-01

    Current-interruption resistance measurements have been analysed in detail allowing the ESTEC lithium ion cell electrical/thermal model to be extended to allow modelling of cell voltage in response to imposed current changes at low temperatures and short time scales where activation polarisation becomes important. Whilst an unnecessary complication in most cases, this extension is needed under certain circumstances such as the simulation of Mars rover batteries forced to operate at low temperature and possible effects of battery voltage transients on battery-bus power subsystems. Comparison with test data show that the model is capable of giving a good fit in these circumstances.

  17. [Tropical forest restoration in Costa Rica: the effect of several strategies on litter production, accumulation and decomposition].

    Science.gov (United States)

    Celentano, Danielle; Zahawi, Rakan A; Finegan, Bryan; Casanoves, Fernando; Ostertag, Rebecca; Cole, Rebecca J; Holl, Karen D

    2011-09-01

    Tropical forest restoration strategies have the potential to accelerate the recovery of the nutrient cycles in degraded lands. Litter production and its decomposition represent the main transfer of organic material and nutrients into the soil substrate. We evaluated litter production, accumulation on the forest floor, and its decomposition under three restoration strategies: plantation (entire area planted with trees), island (trees planted in patches of three different sizes) and control (natural regeneration) plots. We also compared restoration strategies to young secondary forest (7-9 yr). Restoration treatments were established in 50 x 50m plots in June 2004 at six sites in Southern Costa Rica. Planted tree species included two native timber species (Terminalia amazonia and Vochysia guatemalensis) interplanted with two N fixers (Erythrina poeppigiana and Inga edulis). Litter was collected every 15 days between September 2008 and August 2009 in 12 0.25m2 litter traps distributed within each plot; litter that accumulated on the soil surface was collected at four locations (0.25m2 quadrats) within each plot in February and May 2009. Total litter production in plantation (6.3Mg/ha) and secondary forest (7.3Mg/ha) did not differ, but were greater than in islands (3.5Mg/ha) and control (1.4 Mg/ha). Plantation had greatest accumulation of litter on the soil surface (10.6 Mg/ha) as compared to the other treatments (SF = 7.2; I = 6.7; C = 4.9). Secondary forest was the only treatment with a greater annual production of litter than litter accumulation on the soil surface. Carbon storage in litter was similar between plantation and secondary forest, and significantly greater than the other treatments. No differences were found for carbon concentration and storage in the soil among treatments. There was also high variability in the production and accumulation of litter and carbon among sites. Active restoration treatments accelerated the production of litter and carbon

  18. An accurate simulation model for single-photon avalanche diodes including important statistical effects

    Science.gov (United States)

    Qiuyang, He; Yue, Xu; Feifei, Zhao

    2013-10-01

    An accurate and complete circuit simulation model for single-photon avalanche diodes (SPADs) is presented. The derived model is not only able to simulate the static DC and dynamic AC behaviors of an SPAD operating in Geiger-mode, but also can emulate the second breakdown and the forward bias behaviors. In particular, it considers important statistical effects, such as dark-counting and after-pulsing phenomena. The developed model is implemented using the Verilog-A description language and can be directly performed in commercial simulators such as Cadence Spectre. The Spectre simulation results give a very good agreement with the experimental results reported in the open literature. This model shows a high simulation accuracy and very fast simulation rate.

  19. Extending the Scope of the Acculturation/Pidginization Model to Include Cognition.

    Science.gov (United States)

    Schumann, John H.

    1990-01-01

    Examines five cognitive models for second-language acquisition (SLA) and assesses how each might account for the Pidginized interlanguage found in the early stages of second-language acquisition. (23 references) (JL)

  20. A model for including Arduino microcontroller programming in the introductory physics lab

    CERN Document Server

    Haugen, Andrew J

    2014-01-01

    The paper describes a curricular framework for introducing microcontroller programming in the University Physics lab. The approach makes use of Modeling Instruction, an effective approach for teaching science at the secondary level in which student learn the standard material by developing and deploying models of the physical world. In our approach, students engage with a context-rich problem that can be solved with one or more sensors and a microcontroller. The solution path we describe then consists of developing a mathematical model for how the sensors' data can be mapped to a meaningful measurement, and further, developing an algorithmic model that will be implemented in the microcontroller. Once the system is developed and implemented, students are given an array of similar problems in which they can deploy their data collection system. Results from the implementation of this idea, in two University Physics sections, using Arduino microcontrollers, are also described.

  1. Global warming in a coupled climate model including oceanic eddy-induced advection

    Science.gov (United States)

    Hirst, Anthony C.; Gordon, Hal B.; O'Farrell, Siobhan P.

    The Gent and McWilliams (GM) parameterization for large-scale water transport caused by mesoscale oceanic eddies is introduced into the oceanic component of a global coupled ocean-atmosphere model. Parallel simulations with and without the GM scheme are performed to examine the effect of this parameterization on model behavior under constant atmospheric CO2 and on the model response to increasing CO2. The control (constant CO2) runs show substantial differences in the oceanic stratification and extent of convection, similar to differences found previously using uncoupled ocean models. The transient (increasing CO2) runs show moderate differences in the rate of oceanic heat sequestration (less in the GM case), as expected based on passive tracer uptake studies. However, the surface warming is weaker in the GM case, especially over the Southern Ocean, which is contrary to some recent supposition. Reasons for the reduced warming in the GM case are discussed.

  2. Empirical Validation of a Thermal Model of a Complex Roof Including Phase Change Materials

    CERN Document Server

    Guichard, Stéphane; Bigot, Dimitri; Malet-Damour, Bruno; Libelle, Teddy; Boyer, Harry

    2015-01-01

    This paper deals with the empirical validation of a building thermal model using a phase change material (PCM) in a complex roof. A mathematical model dedicated to phase change materials based on the heat apparent capacity method was implemented in a multi-zone building simulation code, the aim being to increase understanding of the thermal behavior of the whole building with PCM technologies. To empirically validate the model, the methodology is based both on numerical and experimental studies. A parametric sensitivity analysis was performed and a set of parameters of the thermal model have been identified for optimization. The use of a generic optimization program called GenOpt coupled to the building simulation code enabled to determine the set of adequate parameters. We first present the empirical validation methodology and main results of previous work. We then give an overview of GenOpt and its coupling with the building simulation code. Finally, once the optimization results are obtained, comparisons o...

  3. A Coupled MHD and Thermal Model Including Electrostatic Sheath for Magnetoplasmadynamic Thruster Simulation

    Science.gov (United States)

    Kawasaki, Akira; Kubota, Kenichi; Funaki, Ikkoh; Okuno, Yoshihiro

    2016-09-01

    Steady-state and self-field magnetoplasmadynamic (MPD) thruster, which utilizes high-intensity direct-current (DC) discharge, is one of the prospective candidates of future high-power electric propulsion devices. In order to accurately assess the thrust performance and the electrode temperature, input electric power and wall heat flux must correctly be evaluated where electrostatic sheaths formed in close proximity of the electrodes affect these quantities. Conventional model simulates only plasma flows occurring in MPD thrusters with the absence of electrostatic sheath consideration. Therefore, this study extends the conventional model to a coupled magnetohydrodynamic (MHD) and thermal model by incorporating the phenomena relevant to the electrostatic sheaths. The sheaths are implemented as boundary condition of the MHD model on the walls. This model simulated the operation of the 100-kW-class thruster at discharge current ranging from 6 to 10 kA with argon propellant. The extended model reproduced the discharge voltages and wall heat load which are consistent with past experimental results. In addition, the simulation results indicated that cathode sheath voltages account for approximately 5-7 V subject to approximately 20 V of discharge voltages applied between the electrodes. This work was supported by JSPS KAKENHI Grant Numbers 26289328 and 15J10821.

  4. Including sugar cane in the agro-ecosystem model ORCHIDEE-STICS: calibration and validation

    Science.gov (United States)

    Valade, A.; Vuichard, N.; Ciais, P.; Viovy, N.

    2011-12-01

    Sugarcane is currently the most efficient bioenergy crop with regards to the energy produced per hectare. With approximately half the global bioethanol production in 2005, and a devoted land area expected to expand globally in the years to come, sugar cane is at the heart of the biofuel debate. Dynamic global vegetation models coupled with agronomical models are powerful and novel tools to tackle many of the environmental issues related to biofuels if they are carefully calibrated and validated against field observations. Here we adapt the agro-terrestrial model ORCHIDEE-STICS for sugar cane simulations. Observation data of LAI are used to evaluate the sensitivity of the model to parameters of nitrogen absorption and phenology, which are calibrated in a systematic way for six sites in Australia and La Reunion. We find that the optimal set of parameters is highly dependent on the sites' characteristics and that the model can reproduce satisfactorily the evolution of LAI. This careful calibration of ORCHIDEE-STICS for sugar cane biomass production for different locations and technical itineraries provides a strong basis for further analysis of the impacts of bioenergy-related land use change on carbon cycle budgets. As a next step, a sensitivity analysis is carried out to estimate the uncertainty of the model in biomass and carbon flux simulation due to its parameterization.

  5. Macro-detritivore identity drives leaf litter diversity effects

    NARCIS (Netherlands)

    Vos, V.C.A.; Ruijven, van J.; Berg, M.P.; Peeters, E.T.H.M.; Berendse, F.

    2011-01-01

    The importance of leaf litter diversity for decomposition, an important process in terrestrial ecosystems, is much debated. Previous leaf litter-mixing studies have shown that non-additive leaf litter diversity effects can occur, but it is not clear why they occurred in only half of the studies and

  6. Large Eddy simulation of turbulence: A subgrid scale model including shear, vorticity, rotation, and buoyancy

    Science.gov (United States)

    Canuto, V. M.

    1994-01-01

    The Reynolds numbers that characterize geophysical and astrophysical turbulence (Re approximately equals 10(exp 8) for the planetary boundary layer and Re approximately equals 10(exp 14) for the Sun's interior) are too large to allow a direct numerical simulation (DNS) of the fundamental Navier-Stokes and temperature equations. In fact, the spatial number of grid points N approximately Re(exp 9/4) exceeds the computational capability of today's supercomputers. Alternative treatments are the ensemble-time average approach, and/or the volume average approach. Since the first method (Reynolds stress approach) is largely analytical, the resulting turbulence equations entail manageable computational requirements and can thus be linked to a stellar evolutionary code or, in the geophysical case, to general circulation models. In the volume average approach, one carries out a large eddy simulation (LES) which resolves numerically the largest scales, while the unresolved scales must be treated theoretically with a subgrid scale model (SGS). Contrary to the ensemble average approach, the LES+SGS approach has considerable computational requirements. Even if this prevents (for the time being) a LES+SGS model to be linked to stellar or geophysical codes, it is still of the greatest relevance as an 'experimental tool' to be used, inter alia, to improve the parameterizations needed in the ensemble average approach. Such a methodology has been successfully adopted in studies of the convective planetary boundary layer. Experienc e with the LES+SGS approach from different fields has shown that its reliability depends on the healthiness of the SGS model for numerical stability as well as for physical completeness. At present, the most widely used SGS model, the Smagorinsky model, accounts for the effect of the shear induced by the large resolved scales on the unresolved scales but does not account for the effects of buoyancy, anisotropy, rotation, and stable stratification. The

  7. Accurate and efficient modeling of global seismic wave propagation for an attenuative Earth model including the center

    Science.gov (United States)

    Toyokuni, Genti; Takenaka, Hiroshi

    2012-06-01

    We propose a method for modeling global seismic wave propagation through an attenuative Earth model including the center. This method enables accurate and efficient computations since it is based on the 2.5-D approach, which solves wave equations only on a 2-D cross section of the whole Earth and can correctly model 3-D geometrical spreading. We extend a numerical scheme for the elastic waves in spherical coordinates using the finite-difference method (FDM), to solve the viscoelastodynamic equation. For computation of realistic seismic wave propagation, incorporation of anelastic attenuation is crucial. Since the nature of Earth material is both elastic solid and viscous fluid, we should solve stress-strain relations of viscoelastic material, including attenuative structures. These relations represent the stress as a convolution integral in time, which has had difficulty treating viscoelasticity in time-domain computation such as the FDM. However, we now have a method using so-called memory variables, invented in the 1980s, followed by improvements in Cartesian coordinates. Arbitrary values of the quality factor (Q) can be incorporated into the wave equation via an array of Zener bodies. We also introduce the multi-domain, an FD grid of several layers with different grid spacings, into our FDM scheme. This allows wider lateral grid spacings with depth, so as not to perturb the FD stability criterion around the Earth center. In addition, we propose a technique to avoid the singularity problem of the wave equation in spherical coordinates at the Earth center. We develop a scheme to calculate wavefield variables on this point, based on linear interpolation for the velocity-stress, staggered-grid FDM. This scheme is validated through a comparison of synthetic seismograms with those obtained by the Direct Solution Method for a spherically symmetric Earth model, showing excellent accuracy for our FDM scheme. As a numerical example, we apply the method to simulate seismic

  8. A two-phase solid/fluid model for dense granular flows including dilatancy effects

    Science.gov (United States)

    Mangeney, Anne; Bouchut, Francois; Fernandez-Nieto, Enrique; Koné, El-Hadj; Narbona-Reina, Gladys

    2016-04-01

    Describing grain/fluid interaction in debris flows models is still an open and challenging issue with key impact on hazard assessment [{Iverson et al.}, 2010]. We present here a two-phase two-thin-layer model for fluidized debris flows that takes into account dilatancy effects. It describes the velocity of both the solid and the fluid phases, the compression/dilatation of the granular media and its interaction with the pore fluid pressure [{Bouchut et al.}, 2016]. The model is derived from a 3D two-phase model proposed by {Jackson} [2000] based on the 4 equations of mass and momentum conservation within the two phases. This system has 5 unknowns: the solid and fluid velocities, the solid and fluid pressures and the solid volume fraction. As a result, an additional equation inside the mixture is necessary to close the system. Surprisingly, this issue is inadequately accounted for in the models that have been developed on the basis of Jackson's work [{Bouchut et al.}, 2015]. In particular, {Pitman and Le} [2005] replaced this closure simply by imposing an extra boundary condition at the surface of the flow. When making a shallow expansion, this condition can be considered as a closure condition. However, the corresponding model cannot account for a dissipative energy balance. We propose here an approach to correctly deal with the thermodynamics of Jackson's model by closing the mixture equations by a weak compressibility relation following {Roux and Radjai} [1998]. This relation implies that the occurrence of dilation or contraction of the granular material in the model depends on whether the solid volume fraction is respectively higher or lower than a critical value. When dilation occurs, the fluid is sucked into the granular material, the pore pressure decreases and the friction force on the granular phase increases. On the contrary, in the case of contraction, the fluid is expelled from the mixture, the pore pressure increases and the friction force diminishes. To

  9. Including the effects of debris cover in a distributed glacier energy balance model (Invited)

    Science.gov (United States)

    Pellicciotti, F.; Reid, T.; Carenzo, M.; Brock, B. W.

    2010-12-01

    Distributed models of glacier energy balance, which make use of digital elevation models and extensive spatial data on local meteorology, have become very useful tools for predicting glacial ablation and runoff in recent years. They generally function by running a one-dimensional energy balance model at every point on a grid on the glacier surface - for each point in the grid the ablation is calculated based on the balance of heat fluxes at the ice-air boundary. However, one key component has been missing from distributed models to date, namely the effects of debris cover. Many glacier ablation zones are mantled in near-continuous blankets of rock debris, and debris-covered glaciers are important drivers of the water cycle in the European Alps, Andes and Himalayas. Moreover, debris covers have been seen to expand in recent years, so it is essential to assess exactly how the presence of debris may affect a glacier’s surface energy balance and potential responses to climate changes. The effects of a debris cover are complicated by the varying surface roughness, albedo and thermal properties of the debris in question, but generally a debris cover reduces glacier melt rate by insulating the glacier surface from direct solar radiation. Even on glaciers where the debris cover is not continuous, isolated patches of debris caused by rockfalls can affect the glacier evolution by introducing differential ablation across the glacier surface, thus creating ice-cored moraines that may persist after ‘clean’ parts of the glacier have wasted away. This paper presents the results of incorporating a one-dimensional ‘debris energy balance model’ called DEB-Model (Reid and Brock 2010) into a distributed melt model for Haut Glacier d’Arolla, Switzerland. DEB-Model numerically estimates debris surface temperature by considering the balance of heat fluxes at the air-debris interface, then calculates heat conduction through the debris in order to estimate melt rates at the

  10. Mangrove litter fall: Extrapolation from traps to a large tropical macrotidal harbour

    Science.gov (United States)

    Metcalfe, Kristin N.; Franklin, Donald C.; McGuinness, Keith A.

    2011-11-01

    Mangrove litter is a major source of organic matter for detrital food chains in many tropical coastal ecosystems, but scant attention has been paid to the substantial challenges in sampling and extrapolation of rates of litter fall. The challenges arise due to within-stand heterogeneity including incomplete canopy cover, and canopy that is below the high tide mark. We sampled litter monthly for three years at 35 sites across eight mapped communities in the macrotidal Darwin Harbour, northern Australia. Totals were adjusted for mean community canopy cover and the occurrence of canopy below the high tide mark. The mangroves of Darwin Harbour generate an estimated average of 5.0 t ha -1 yr -1 of litter. This amount would have been overestimated by 32% had we not corrected for limited canopy cover and underestimated by 11% had we not corrected for foliage that is below the high tide mark. Had we made neither correction, we would have overestimated litter fall by 17%. Among communities, rates varied 2.6-fold per unit area of canopy, and 3.9-fold among unit area of community. Seaward fringe mangroves were the most productive per unit of canopy area but the canopy was relatively open; Tidal creek forest was the most productive per unit area of community. Litter fall varied 1.1-fold among years and 2.0-fold among months though communities exhibited a range of seasonalities. Our study may be the most extensively stratified and sampled evaluation of mangrove litter fall in a tropical estuary. We believe our study is also the first such assessment to explicitly deal with canopy discontinuities and demonstrates that failure to do so can result in considerable overestimation of mangrove productivity.

  11. Effects of litter position on mass loss and nitrogen release in the semiarid Patagonian steppe

    Science.gov (United States)

    Austin, A. T.

    2007-05-01

    The patchy distribution of vegetation in arid and semiarid ecosystems results in a mosaic of microsites of soil properties and variable abiotic conditions, including the well-documented "islands of fertility", low nutrient conditions in exposed bare soil and large amounts of standing dead material. I evaluated the relative importance of litter position on mass loss and nutrient release in a variety of realistic litter positions both in vegetated, unvegetated, aerial and buried microsites in a natural semiarid steppe in Patagonia, Argentina. Position demonstrated a highly significant effect on mass loss for all litter types (P<0.0001), but surprisingly, the fastest decomposition occurred in litter that was suspended in aerial positions or buried (k=0.25 and 0.32 year-1, respectively), intermediate values for mass loss of litter in bare soil and in shrub removal patches (k=0.21 and 0.24 year-1, respectively), and markedly slowest decomposition occurring under shrub patches (k = 0.018 year-1). In contrast, nutrient release showed a very different pattern with nutrient immobilization occurring only in shrub and buried microsites while all other positions demonstrated a gradual decrease in nitrogen over time. These results support the idea that abiotic photodegradation may be an important driver affecting carbon losses in litter in positions exposed to solar radiation, while nutrient dynamics appear to be largely biotically mediated and concentrated in photoprotected areas where biotic activity dominates. Global change may differentially affect carbon and nutrient turnover due to the relative importance of abiotic and biotic factors affecting litter decomposition in semiarid ecosystems.

  12. An induction machine model including interbar currents for studying performances during transients and steady state

    Energy Technology Data Exchange (ETDEWEB)

    Razik, H. [Universite Henri Poincare, GREEN, CNRS-UMR 7037, BP 239, F-54506 Vandoeuvre-les-Nancy Cedex (France); Henao, H. [University of Picardie, CREA, 33 rue Saint Leu, F-80039 Amiens Cedex 1 (France); Carlson, R. [GRUCAD/CTC/UFSC, Campus Universitario, C.P. 436, Florianopolis - SC, 88040-900 (Brazil)

    2009-01-15

    This paper presents a mathematical model of a three-phase induction motor taking into consideration the interbar contacts. Several models have been available in the references. However, they consider the rotor of the induction motor as being constituted either a three-phase or a squirrel cage even if it operates under stator and/or rotor faults condition. Nonetheless, the contact between a bar and the iron core for the machine has to be considered, especially when a rotor fault occurs. It is obvious that rotor currents are under the influence of rotor constitution materials. So, the paper aim's concerns a transient model of the induction motors which can consider the rotor broken bars defect. Despite its increasing complexity, it could be able to provide with useful indications for diagnostic purposes. This model is advocated for the simulation of motors behavior under rotor defect which takes into account the interbar currents. The proposed technique is based on the mesh model analysis of the squirrel cage. As low power induction motors are prevalent in industrial plants, we pay a special attention on them. Notwithstanding, additional currents are due to the contact between the non-insulated bar constituting the squirrel cage to the rotor iron core. The monitoring of induction motors is predominantly made through the stator current analysis of the motor when it operates at nominal condition. Moreover, this one is observed in steady state operating system, knowing that the motor is generally fed by a sinusoidal supply. Consequently, simulation results showed in this paper prove the effectiveness of the proposed approach, and the impact of interbar resistance both on the model and the line current spectrum for the diagnostic. An experimental test proves the effectiveness of this model. (author)

  13. Including crystal structure attributes in machine learning models of formation energies via Voronoi tessellations

    Science.gov (United States)

    Ward, Logan; Liu, Ruoqian; Krishna, Amar; Hegde, Vinay I.; Agrawal, Ankit; Choudhary, Alok; Wolverton, Chris

    2017-07-01

    While high-throughput density functional theory (DFT) has become a prevalent tool for materials discovery, it is limited by the relatively large computational cost. In this paper, we explore using DFT data from high-throughput calculations to create faster, surrogate models with machine learning (ML) that can be used to guide new searches. Our method works by using decision tree models to map DFT-calculated formation enthalpies to a set of attributes consisting of two distinct types: (i) composition-dependent attributes of elemental properties (as have been used in previous ML models of DFT formation energies), combined with (ii) attributes derived from the Voronoi tessellation of the compound's crystal structure. The ML models created using this method have half the cross-validation error and similar training and evaluation speeds to models created with the Coulomb matrix and partial radial distribution function methods. For a dataset of 435 000 formation energies taken from the Open Quantum Materials Database (OQMD), our model achieves a mean absolute error of 80 meV/atom in cross validation, which is lower than the approximate error between DFT-computed and experimentally measured formation enthalpies and below 15% of the mean absolute deviation of the training set. We also demonstrate that our method can accurately estimate the formation energy of materials outside of the training set and be used to identify materials with especially large formation enthalpies. We propose that our models can be used to accelerate the discovery of new materials by identifying the most promising materials to study with DFT at little additional computational cost.

  14. High resolution multi model Climate change scenario over India including first uncertainty assessment

    Science.gov (United States)

    Kumar, P.; Wiltshire, A.; Asharaf, S.; Ahrens, B.; Lucas-Picher, P.; Christensen, J. H.; Gobiet, A.; Saeed, F.; Hagemann, S.; Jacob, D.

    2011-12-01

    This study presents the possible regional climate change over SA with a focus over India as simulated by three very-high-resolution regional climate models. The models are driven by the same lateral boundary conditions from two global models (ECHAM5-MPIOM and HadCM3) under the IPCC AR4 SRES A1B scenario at horizontal resolution of ~25km, except one model which is simulated for only one GCM. The results are presented for two time slices 2021-2050 and 2070-2099. The analysis concentrates along precipitation and temperature over land and focuses mainly on the monsoon season. The circulation parameter is also discussed. In general all models show a clear signal of gradual wide-spread warming throughout the 21st century. The ensemble-mean warming evident at the end of 2050 is 1-2K, whereas it is 3-5K at the end of century. The projected pattern of the precipitation change shows spatial variability. The increase in precipitation is noticed over peninsular and coastal areas and no change or decrease over areas away from the ocean. The influence of the driving GCM on projected precipitation change simulated with each RCM is as strong as the variability among the RCMs driven with one GCM. Some results of the first uncertainties assessment are also presented.

  15. HIV model parameter estimates from interruption trial data including drug efficacy and reservoir dynamics.

    Directory of Open Access Journals (Sweden)

    Rutao Luo

    Full Text Available Mathematical models based on ordinary differential equations (ODE have had significant impact on understanding HIV disease dynamics and optimizing patient treatment. A model that characterizes the essential disease dynamics can be used for prediction only if the model parameters are identifiable from clinical data. Most previous parameter identification studies for HIV have used sparsely sampled data from the decay phase following the introduction of therapy. In this paper, model parameters are identified from frequently sampled viral-load data taken from ten patients enrolled in the previously published AutoVac HAART interruption study, providing between 69 and 114 viral load measurements from 3-5 phases of viral decay and rebound for each patient. This dataset is considerably larger than those used in previously published parameter estimation studies. Furthermore, the measurements come from two separate experimental conditions, which allows for the direct estimation of drug efficacy and reservoir contribution rates, two parameters that cannot be identified from decay-phase data alone. A Markov-Chain Monte-Carlo method is used to estimate the model parameter values, with initial estimates obtained using nonlinear least-squares methods. The posterior distributions of the parameter estimates are reported and compared for all patients.

  16. Kinetic modelling of anaerobic hydrolysis of solid wastes, including disintegration processes

    Energy Technology Data Exchange (ETDEWEB)

    García-Gen, Santiago [Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela (Spain); Sousbie, Philippe; Rangaraj, Ganesh [INRA, UR50, Laboratoire de Biotechnologie de l’Environnement, Avenue des Etangs, Narbonne F-11100 (France); Lema, Juan M. [Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela (Spain); Rodríguez, Jorge, E-mail: jrodriguez@masdar.ac.ae [Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela (Spain); Institute Centre for Water and Environment (iWater), Masdar Institute of Science and Technology, PO Box 54224 Abu Dhabi (United Arab Emirates); Steyer, Jean-Philippe; Torrijos, Michel [INRA, UR50, Laboratoire de Biotechnologie de l’Environnement, Avenue des Etangs, Narbonne F-11100 (France)

    2015-01-15

    Highlights: • Fractionation of solid wastes into readily and slowly biodegradable fractions. • Kinetic coefficients estimation from mono-digestion batch assays. • Validation of kinetic coefficients with a co-digestion continuous experiment. • Simulation of batch and continuous experiments with an ADM1-based model. - Abstract: A methodology to estimate disintegration and hydrolysis kinetic parameters of solid wastes and validate an ADM1-based anaerobic co-digestion model is presented. Kinetic parameters of the model were calibrated from batch reactor experiments treating individually fruit and vegetable wastes (among other residues) following a new protocol for batch tests. In addition, decoupled disintegration kinetics for readily and slowly biodegradable fractions of solid wastes was considered. Calibrated parameters from batch assays of individual substrates were used to validate the model for a semi-continuous co-digestion operation treating simultaneously 5 fruit and vegetable wastes. The semi-continuous experiment was carried out in a lab-scale CSTR reactor for 15 weeks at organic loading rate ranging between 2.0 and 4.7 g VS/L d. The model (built in Matlab/Simulink) fit to a large extent the experimental results in both batch and semi-continuous mode and served as a powerful tool to simulate the digestion or co-digestion of solid wastes.

  17. A void ratio dependent water retention curve model including hydraulic hysteresis

    Directory of Open Access Journals (Sweden)

    Pasha Amin Y.

    2016-01-01

    Full Text Available Past experimental evidence has shown that Water Retention Curve (WRC evolves with mechanical stress and structural changes in soil matrix. Models currently available in the literature for capturing the volume change dependency of WRC are mainly empirical in nature requiring an extensive experimental programme for parameter identification which renders them unsuitable for practical applications. In this paper, an analytical model for the evaluation of the void ratio dependency of WRC in deformable porous media is presented. The approach proposed enables quantification of the dependency of WRC on void ratio solely based on the form of WRC at the reference void ratio and requires no additional parameters. The effect of hydraulic hysteresis on the evolution process is also incorporated in the model, an aspect rarely addressed in the literature. Expressions are presented for the evolution of main and scanning curves due to loading and change in the hydraulic path from scanning to main wetting/drying and vice versa as well as the WRC parameters such as air entry value, air expulsion value, pore size distribution index and slope of the scanning curve. The model is validated using experimental data on compacted and reconstituted soils subjected to various hydro-mechanical paths. Good agreement is obtained between model predictions and experimental data in all the cases considered.

  18. A discrete model for the apparent viscosity of polydisperse suspensions including maximum packing fraction

    CERN Document Server

    Dörr, Aaron; Mehdizadeh, Amirfarhang

    2012-01-01

    Based on the notion of a construction process consisting of the stepwise addition of particles to the pure fluid, a discrete model for the apparent viscosity as well as for the maximum packing fraction of polydisperse suspensions of spherical, non-colloidal particles is derived. The model connects the approaches by Bruggeman and Farris and is valid for large size ratios of consecutive particle classes during the construction process. Furthermore, a new general form of the well-known Krieger equation allowing for the choice of a second-order Taylor coefficient for the volume fraction is proposed and then applied as a monodisperse reference equation in the course of polydisperse modeling. By applying the polydisperse viscosity model to two different particle size distributions (Rosin-Rammler and uniform distribution), the influence of polydispersity on the apparent viscosity is examined. The extension of the model to the case of small size ratios as well as to the inclusion of shear rate effects is left for fut...

  19. Complete Loss and Thermal Model of Power Semiconductors Including Device Rating Information

    DEFF Research Database (Denmark)

    Ma, Ke; Bahman, Amir Sajjad; Beczkowski, Szymon;

    2015-01-01

    loading but also the device rating as input variables. The quantified correlation between the power loss, thermal impedance and silicon area of Insulated Gate Bipolar Transistor (IGBT) is mathematically established. By this new modeling approach, all factors that have impacts to the loss and thermal......Thermal loading of power devices are closely related to the reliability performance of the whole converter system. The electrical loading and device rating are both important factors that determine the loss and thermal behaviors of power semiconductor devices. In the existing loss and thermal...... models, only the electrical loadings are focused and treated as design variables, while the device rating is normally pre-defined by experience with limited design flexibility. Consequently, a more complete loss and thermal model is proposed in this paper, which takes into account not only the electrical...

  20. A Simple Model of Fields Including the Strong or Nuclear Force and a Cosmological Speculation

    Directory of Open Access Journals (Sweden)

    David L. Spencer

    2016-10-01

    Full Text Available Reexamining the assumptions underlying the General Theory of Relativity and calling an object's gravitational field its inertia, and acceleration simply resistance to that inertia, yields a simple field model where the potential (kinetic energy of a particle at rest is its capacity to move itself when its inertial field becomes imbalanced. The model then attributes electromagnetic and strong forces to the effects of changes in basic particle shape. Following up on the model's assumption that the relative intensity of a particle's gravitational field is always inversely related to its perceived volume and assuming that all black holes spin, may create the possibility of a cosmic rebound where a final spinning black hole ends with a new Big Bang.

  1. Numerical models of single- and double-negative metamaterials including viscous and thermal losses

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Sánchez-Dehesa, José

    2017-01-01

    Negative index acoustic metamaterials are artificial structures made of subwavelength units arranged in a lattice, whose effective acoustic parameters, bulk modulus and mass density, can be negative. In these materials, sound waves propagate inside the periodic structure, assumed rigid, showing...... extraordinary properties. We are interested in two particular cases: a double-negative metamaterial, where both parameters are negative at some frequencies, and a single-negative metamaterial with negative bulk modulus within a broader frequency band. In previous research involving the double......-negative metamaterial, numerical models with viscous and thermal losses were used to explain that the extraordinary behavior, predicted by analytical models and numerical simulations with no losses, disappeared when the metamaterial was measured in physical setups. The improvement of the models is allowing now a more...

  2. Damped structural dynamics models of large wind-turbine blades including material and structural damping

    Energy Technology Data Exchange (ETDEWEB)

    Chortis, D I; Chrysochoidis, N A; Saravanos, D A [Department of Mechanical Engineering and Aeronautics, University of Patras, Patras 26500 (Greece)

    2007-07-15

    The paper presents a brief description of composite damping mechanics for blade sections of arbitrary lamination and geometry. A damped 3-D shear beam element is presented enabling the assembly of damped structural dynamic models of blades with hollow multi-cell tubular laminated sections. Emphasis is placed to the inclusion of composite material coupling effects, first in the blade section stiffness and damping matrices and finally into the stiffness and damping matrices of the finite element. Evaluations of the beam element are presented, to quantify the material coupling effect on composite beams of simple box sections. Correlations between predicted and measured modal frequencies and damping values in small model Glass/Epoxy are also shown. Finally, the damped modal characteristics of a 35m realistic wind-turbine blade model design, are predicted.

  3. A study of a hamiltonian model for martensitic phase transformations including microkinetic energy

    CERN Document Server

    Theil, F

    1998-01-01

    How can a system in a macroscopically stable state explore energetically more favorable states, which are far away from the current equilibrium state? Based on continuum mechanical considerations we derive a Boussinesq-type equation which models the dynamics of martensitic phase transformations. The solutions of the system, which we refer to as microkinetically regularized wave equation exhibit strong oscillations after short times, thermalization can be confirmed. That means that macroscopic fluctuations of the solutions decay at the benefit of microscopic fluctuations. First analytical and numerical results on the propagation of phase boundaries and thermalization effects are presented. Despite the fact that model is conservative, it exhibits the hysteretic behavior. Such a behavior is usually interpreted in macroscopic models in terms of dissipative threshold which the driving force has to overcome to ensure that the phase transformation proceeds. The threshold value depends on the amount of the transforme...

  4. Hybrid Model Representation of a TLP Including Flexible Topsides in Non-Linear Regular Waves

    Directory of Open Access Journals (Sweden)

    Christof Wehmeyer

    2014-08-01

    Full Text Available The rising demand for renewable energy solutions is forcing the established industries to expand and continue evolving. For the wind energy sector, the vast resources in deep sea locations have encouraged research towards the installation of turbines in deeper waters. One of the most promising technologies able to solve this challenge is the floating wind turbine foundation. For the ultimate limit state, where higher order wave loads have a significant influence, a design tool that couples non-linear excitations with structural dynamics is required. To properly describe the behavior of such a structure, a numerical model is proposed and validated by physical test results. The model is applied to a case study of a tension leg platform with a flexible topside mimicking the tower and a lumped mass mimicking the rotor-nacelle assembly. The model is additionally compared to current commercial software, where the need for the coupled higher order dynamics proposed in this paper becomes evident.

  5. Loss and thermal model for power semiconductors including device rating information

    DEFF Research Database (Denmark)

    Ma, Ke; Bahman, Amir Sajjad; Beczkowski, Szymon;

    2014-01-01

    The electrical loading and device rating are both important factors that determine the loss and thermal behaviors of power semiconductor devices. In the existing loss and thermal models, only the electrical loadings are focused and treated as design variables, while the device rating is normally...... pre-defined by experience with poor design flexibility. Consequently a more complete loss and thermal model is proposed in this paper, which takes into account not only the electrical loading but also the device rating as input variables. The quantified correlation between the power loss, thermal...... impedance and silicon area of Insulated Gate Bipolar Transistor (IGBT) is mathematically established. By this new modeling approach, all factors that have impacts to the loss and thermal profiles of power devices can be accurately mapped, enabling more design freedom to optimize the efficiency and thermal...

  6. Complete Loss and Thermal Model of Power Semiconductors Including Device Rating Information

    DEFF Research Database (Denmark)

    Ma, Ke; Bahman, Amir Sajjad; Beczkowski, Szymon

    2015-01-01

    profiles of the power devices can accurately be mapped, enabling more design freedom to optimize the efficiency and thermal loading of the power converter. The proposed model can be further improved by experimental tests, and it is well agreed by both circuit and Finite Element Method (FEM) simulation......Thermal loading of power devices are closely related to the reliability performance of the whole converter system. The electrical loading and device rating are both important factors that determine the loss and thermal behaviors of power semiconductor devices. In the existing loss and thermal...... models, only the electrical loadings are focused and treated as design variables, while the device rating is normally pre-defined by experience with limited design flexibility. Consequently, a more complete loss and thermal model is proposed in this paper, which takes into account not only the electrical...

  7. Loss and thermal model for power semiconductors including device rating information

    DEFF Research Database (Denmark)

    Ma, Ke; Bahman, Amir Sajjad; Beczkowski, Szymon

    2014-01-01

    impedance and silicon area of Insulated Gate Bipolar Transistor (IGBT) is mathematically established. By this new modeling approach, all factors that have impacts to the loss and thermal profiles of power devices can be accurately mapped, enabling more design freedom to optimize the efficiency and thermal......The electrical loading and device rating are both important factors that determine the loss and thermal behaviors of power semiconductor devices. In the existing loss and thermal models, only the electrical loadings are focused and treated as design variables, while the device rating is normally...... pre-defined by experience with poor design flexibility. Consequently a more complete loss and thermal model is proposed in this paper, which takes into account not only the electrical loading but also the device rating as input variables. The quantified correlation between the power loss, thermal...

  8. A biomechanical model of the face including muscles for the prediction of deformations during speech production

    CERN Document Server

    Groleau, Julie; Marecaux, Christophe; Payrard, Natacha; Segaud, Brice; Rochette, Michel; Perrier, Pascal; Payan, Yohan

    2008-01-01

    A 3D biomechanical finite element model of the face is presented. Muscles are represented by piece-wise uniaxial tension cable elements linking the insertion points. Such insertion points are specific entities differing from nodes of the finite element mesh, which makes possible to change either the mesh or the muscle implementation totally independently of each other. Lip/teeth and upper lip/lower lip contacts are also modeled. Simulations of smiling and of an Orbicularis Oris activation are presented and interpreted. The importance of a proper account of contacts and of an accurate anatomical description is shown

  9. European air quality modelled by CAMx including the volatility basis set scheme

    Directory of Open Access Journals (Sweden)

    G. Ciarelli

    2015-12-01

    Full Text Available Four periods of EMEP (European Monitoring and Evaluation Programme intensive measurement campaigns (June 2006, January 2007, September–October 2008 and February–March 2009 were modelled using the regional air quality model CAMx with VBS (Volatility Basis Set approach for the first time in Europe within the framework of the EURODELTA-III model intercomparison exercise. More detailed analysis and sensitivity tests were performed for the period of February–March 2009 and June 2006 to investigate the uncertainties in emissions as well as to improve the modelling of organic aerosols (OA. Model performance for selected gas phase species and PM2.5 was evaluated using the European air quality database Airbase. Sulfur dioxide (SO2 and ozone (O3 were found to be overestimated for all the four periods with O3 having the largest mean bias during June 2006 and January–February 2007 periods (8.93 and 12.30 ppb mean biases, respectively. In contrast, nitrogen dioxide (NO2 and carbon monoxide (CO were found to be underestimated for all the four periods. CAMx reproduced both total concentrations and monthly variations of PM2.5 very well for all the four periods with average biases ranging from −2.13 to 1.04 μg m-3. Comparisons with AMS (Aerosol Mass Spectrometer measurements at different sites in Europe during February–March 2009, showed that in general the model over-predicts the inorganic aerosol fraction and under-predicts the organic one, such that the good agreement for PM2.5 is partly due to compensation of errors. The effect of the choice of volatility basis set scheme (VBS on OA was investigated as well. Two sensitivity tests with volatility distributions based on previous chamber and ambient measurements data were performed. For February–March 2009 the chamber-case reduced the total OA concentrations by about 43 % on average. On the other hand, a test based on ambient measurement data increased OA concentrations by about 47 % for the same

  10. Viscoelastic Model of Cross-Linked Polyethylene Including Effects of Temperature and Crystallinity

    Science.gov (United States)

    Olasz, L.; Gudmundson, P.

    2005-12-01

    Characterization of the mechanical behavior of cross-linked polyethylene (XLPE) commonly used in high voltage cable insulation was performed by an extensive set of isothermal uniaxial tensile relaxation tests. Tensile relaxation experiments were complemented by pressure-volume-temperature experiments as well as density and crystallinity measurements. Based on the experimental results, a viscoelastic power law model with four parameters was formulated, incorporating temperature and crystallinity dependence. It was found that a master curve can be developed by both horizontal and vertical shifting of the relaxation curves. The model was evaluated by making comparisons of the predicted stress responses with the measured responses in relaxation tests with transient temperature histories.

  11. Litter Study: A School Research Project

    Science.gov (United States)

    McCollum, Dannel

    1976-01-01

    Describes a project done to verify or dispute the breakdown in litter content proposed by Keep America Beautiful, Inc. (KAB). Decisions made relating to quantity of materials, area to be studied, and a complete description of the project are given. (EB)

  12. Utilization of poultry litter for pesticide bioremediation

    Science.gov (United States)

    Agricultural chemical products such as pesticides have been used to increase crop production, especially in undeveloped countries. Poultry litter, the combination of feces and bedding materials, has also been used as an alternative to improve soil quality for crop production. However, information re...

  13. The global stoichiometry of litter nitrogen mineralization

    Science.gov (United States)

    Stefano Manzoni; Robert B. Jackson; John A. Trofymow; Amilcare Porporato

    2008-01-01

    Plant residue decomposition and the nutrient release to the soil play a major role in global carbon and nutrient cycling. Although decomposition rates vary strongly with climate, nitrogen immobilization into litter and its release in mineral forms are mainly controlled by the initial chemical composition of the residues. We used a data set of ~2800 observations to show...

  14. Ballonnen in zee = balloons as marine litter

    NARCIS (Netherlands)

    Franeker, van J.A.

    2008-01-01

    Releasing balloons seems harmless. However, remains of balloons, especially valves and ribbons are becoming a common and persistent type of marine litter found on beaches. Following Dutch Queens day 2007, large numbers of Dutch balloons were found in Normandy, France. Animals may become entangled in

  15. Climate history shapes contemporary leaf litter decomposition

    Science.gov (United States)

    Michael S. Strickland; Ashley D. Keiser; Mark A. Bradford

    2015-01-01

    Litter decomposition is mediated by multiple variables, of which climate is expected to be a dominant factor at global scales. However, like other organisms, traits of decomposers and their communities are shaped not just by the contemporary climate but also their climate history. Whether or not this affects decomposition rates is underexplored. Here we source...

  16. Converting Poultry Litter into Activated Carbon

    Science.gov (United States)

    Disposal of animal manure is one of the biggest problems facing agriculture today. Now new technology has been designed to covert manure into environmentally friendly and highly valued activated carbon. When pelletized and activated under specific conditions, the litter becomes a highly porous mat...

  17. Ballonnen in zee = balloons as marine litter

    NARCIS (Netherlands)

    Franeker, van J.A.

    2008-01-01

    Releasing balloons seems harmless. However, remains of balloons, especially valves and ribbons are becoming a common and persistent type of marine litter found on beaches. Following Dutch Queens day 2007, large numbers of Dutch balloons were found in Normandy, France. Animals may become entangled in

  18. The island coalescence problem: scaling of reconnection in extended fluid models including higher-order moments

    CERN Document Server

    Ng, Jonathan; Hakim, Ammar; Bhattacharjee, Amitava; Stanier, Adam; Daughton, William; Wang, Liang; Germaschewski, Kai

    2015-01-01

    As modeling of collisionless magnetic reconnection in most space plasmas with realistic parameters is beyond the capability of today's simulations, due to the separation between global and kinetic length scales, it is important to establish scaling relations in model problems so as to extrapolate to realistic scales. Recently, large scale particle-in-cell (PIC) simulations of island coalescence have shown that the time averaged reconnection rate decreases with system size, while fluid systems at such large scales in the Hall regime have not been studied. Here we perform the complementary resistive MHD, Hall MHD and two fluid simulations using a ten-moment model with the same geometry. In contrast to the standard Harris sheet reconnection problem, Hall MHD is insufficient to capture the physics of the reconnection region. Additionally, motivated by the results of a recent set of hybrid simulations which show the importance of ion kinetics in this geometry, we evaluate the efficacy of the ten-moment model in re...

  19. Situational effects of the school factors included in the dynamic model of educational effectiveness

    NARCIS (Netherlands)

    Creerners, Bert; Kyriakides, Leonidas

    2009-01-01

    We present results of a longitudinal study in which 50 schools, 113 classes and 2,542 Cypriot primary students participated. We tested the validity of the dynamic model of educational effectiveness and especially its assumption that the impact of school factors depends on the current situation of th

  20. Turbulent combustion modelling of a confined premixed jet flame including heat loss effects using tabulated chemistry

    NARCIS (Netherlands)

    Gövert, S.; Mira, D.; Kok, J.B.W.; Vázquez, M.; Houzeaux, G.

    2015-01-01

    The present work addresses the coupling of a flamelet database, to a low-Mach approximation of the Navier–Stokes equations using scalar controlling variables. The model is characterized by the chemistry tabulation based on laminar premixed flamelets in combination with an optimal choice of the react

  1. Kinetic modelling of anaerobic hydrolysis of solid wastes, including disintegration processes.

    Science.gov (United States)

    García-Gen, Santiago; Sousbie, Philippe; Rangaraj, Ganesh; Lema, Juan M; Rodríguez, Jorge; Steyer, Jean-Philippe; Torrijos, Michel

    2015-01-01

    A methodology to estimate disintegration and hydrolysis kinetic parameters of solid wastes and validate an ADM1-based anaerobic co-digestion model is presented. Kinetic parameters of the model were calibrated from batch reactor experiments treating individually fruit and vegetable wastes (among other residues) following a new protocol for batch tests. In addition, decoupled disintegration kinetics for readily and slowly biodegradable fractions of solid wastes was considered. Calibrated parameters from batch assays of individual substrates were used to validate the model for a semi-continuous co-digestion operation treating simultaneously 5 fruit and vegetable wastes. The semi-continuous experiment was carried out in a lab-scale CSTR reactor for 15 weeks at organic loading rate ranging between 2.0 and 4.7 gVS/Ld. The model (built in Matlab/Simulink) fit to a large extent the experimental results in both batch and semi-continuous mode and served as a powerful tool to simulate the digestion or co-digestion of solid wastes.

  2. New phases in an extended Hubbard model explicitly including atomic polarizabilities

    NARCIS (Netherlands)

    Brink, van de J.; Meinders, M.B.J.; Lorenzana, J.; Eder, R.; Sawatzky, G.A.

    1996-01-01

    We consider the influence of a nearest-neighbor Coulomb interaction in an extended Hubbard model and introduce a new interaction term which simulates atomic polarizabilities. This has the effect of screening the on-site Coulomb interaction for charged excitations, unlike a neighbor Coulomb interacti

  3. Modeling of etch profile evolution including wafer charging effects using self consistent ion fluxes

    Energy Technology Data Exchange (ETDEWEB)

    Hoekstra, R.J.; Kushner, M.J. [Univ. of Illinois, Urbana, IL (United States). Dept. of Electrical and Computer Engineering

    1996-12-31

    As high density plasma reactors become more predominate in industry, the need has intensified for computer aided design tools which address both equipment issues such as ion flux uniformity onto the water and process issues such etch feature profile evolution. A hierarchy of models has been developed to address these issues with the goal of producing a comprehensive plasma processing design capability. The Hybrid Plasma Equipment Model (HPEM) produces ion and neutral densities, and electric fields in the reactor. The Plasma Chemistry Monte Carlo Model (PCMC) determines the angular and energy distributions of ion and neutral fluxes to the wafer using species source functions, time dependent bulk electric fields, and sheath potentials from the HPEM. These fluxes are then used by the Monte Carlo Feature Profile Model (MCFP) to determine the time evolution of etch feature profiles. Using this hierarchy, the effects of physical modifications of the reactor, such as changing wafer clamps or electrode structures, on etch profiles can be evaluated. The effects of wafer charging on feature evolution are examined by calculating the fields produced by the charge deposited by ions and electrons within the features. The effect of radial variations and nonuniformity in angular and energy distribution of the reactive fluxes on feature profiles and feature charging will be discussed for p-Si etching in inductively-coupled plasma (ICP) sustained in chlorine gas mixtures. The effects of over- and under-wafer topography on etch profiles will also be discussed.

  4. Surface-wave mode coupling : modelling and inverting waveforms including body-wave phases

    NARCIS (Netherlands)

    Marquering, H.A.

    1996-01-01

    This thesis is concerned with a similar problem as addressed by Li & Tanimoto (1993) in the surfacewave mode approach. In this thesis it is shown that surface-wave mode coupling is required when body-wave phases in laterally heterogeneous media are modelled by surface-wave mode summation. An efficie

  5. The island coalescence problem: Scaling of reconnection in extended fluid models including higher-order moments

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Jonathan; Huang, Yi-Min; Hakim, Ammar; Bhattacharjee, A. [Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States); Stanier, Adam; Daughton, William [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Wang, Liang; Germaschewski, Kai [Space Science Center and Physics Department, University of New Hampshire, Durham, New Hampshire 03824 (United States)

    2015-11-15

    As modeling of collisionless magnetic reconnection in most space plasmas with realistic parameters is beyond the capability of today's simulations, due to the separation between global and kinetic length scales, it is important to establish scaling relations in model problems so as to extrapolate to realistic scales. Recently, large scale particle-in-cell simulations of island coalescence have shown that the time averaged reconnection rate decreases with system size, while fluid systems at such large scales in the Hall regime have not been studied. Here, we perform the complementary resistive magnetohydrodynamic (MHD), Hall MHD, and two fluid simulations using a ten-moment model with the same geometry. In contrast to the standard Harris sheet reconnection problem, Hall MHD is insufficient to capture the physics of the reconnection region. Additionally, motivated by the results of a recent set of hybrid simulations which show the importance of ion kinetics in this geometry, we evaluate the efficacy of the ten-moment model in reproducing such results.

  6. Analytical and numerical modelling of thermoviscous shocks in their interactions in nonlinear fluids including dissipation

    DEFF Research Database (Denmark)

    Rasmussen, Anders Rønne; Sørensen, Mads Peter; Gaididei, Yuri Borisovich

    2010-01-01

    A wave equation, that governs finite amplitude acoustic disturbances in a thermoviscous Newtonian fluid, and includes nonlinear terms up to second order, is proposed. The equation preserves the Hamiltonian structure of the fundamental fluid dynamical equations in the non dissipative limit. An exact...

  7. Fallout volume and litter type affect (137)Cs concentration difference in litter between forest and stream environments.

    Science.gov (United States)

    Sakai, Masaru; Gomi, Takashi; Negishi, Junjiro N

    2016-11-01

    It is important to understand the changes in the (137)Cs concentration in litter through leaching when considering that (137)Cs is transferred from basal food resources to animals in forested streams. We found that the difference of (137)Cs activity concentration in litter between forest and stream was associated with both litter type and (137)Cs fallout volume around Fukushima, Japan. The (137)Cs activity concentrations in the litter of evergreen conifers tended to be greater than those in the litter of broad-leaved deciduous trees because of the absence of deciduous leaves during the fallout period in March 2011. Moreover, (137)Cs activity concentrations in forest litter were greater with respect to the (137)Cs fallout volume. The (137)Cs activity concentrations in stream litter were much lower than those in forest litter when those in forest litter were higher. The (137)Cs leaching patterns indicated that the differences in (137)Cs activity concentration between forest and stream litter could change with changes in both fallout volume and litter type. Because litter is an important basal food resource in the food webs of both forests and streams, the (137)Cs concentration gradient reflects to possible (137)Cs transfer from lower to higher trophic animals. Our findings will improve our understanding of the spatial heterogeneity and variability of (137)Cs concentrations in animals resident to the contaminated landscape.

  8. Effects of litter manipulation on litter decomposition in a successional gradients of tropical forests in southern China

    DEFF Research Database (Denmark)

    Chen, Hao; Gurmesa, Geshere A.; Liu, Lei

    2014-01-01

    decomposition to litter removal/addition in three successional forests in southern China, namely masson pine forest (MPF), mixed coniferous and broadleaved forest (MF) and monsoon evergreen broadleaved forest (MEBF). Results showed that litter removal decreased litter decomposition rates by 27%, 10% and 8...

  9. A model for heterogeneous traffic flows including non-motorized vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Oketch, T.G.

    2001-07-01

    This study is concerned with developing a traffic flow and emissions model suitable for heterogeneous traffic streams containing motorised and non-motorised vehicles. Such streams contain vehicle types such as private cars, buses and trucks as well as bicycles, motorcycles and other vehicular forms. The model covers the different vehicle types and allows for peculiar behaviours prevalent in such streams. In addition to an existing deterministic car following rule, the model incorporates detailed lateral movement algorithm with gradual lane change manoeuvres, the decisions of which are governed by fuzzy logic rules. For determination of pollutant emissions, the travel lane was divided into finite elements and total emissions aggregated for each element depending on the vehicle speeds and types. A methodology for estimation of emission rates, based on vehicle maintenance history, for countries without reliable inventories was proposed and used to obtain emission coefficients of CO, HC, NOx and Pb emissions in Kenya. In conclusion, the model has demonstrated that heterogeneous traffic can be effectively analysed by approaches that take their peculiar characteristics into consideration. In addition, it has also provided new insight in the performance and emission patterns of heterogeneous traffic streams which can be used to formulate regulatory directives governing the usage of lanes or provision of auxiliary carriageways for slower vehicles. (orig.) [German] In dieser Arbeit wurde ein Verkehrsfluss- und Emissions-Model fuer heterogene Verkehrsstroeme entwickelt. Solche Verkehrsstroeme enthalten nicht nur motorisierte Fahrzeuge wie Pkw, Lkw, Omnibus, Motorrad usw. sondern auch nicht-motorisierte Fahrzeuge wie Fahrrad und auch besondere Fahrzeugtypen, die auf Motorraedern oder Fahrraedern basieren. Im Modell wurden auch die entsprechenden besonderen Verhaeltnisse dieser Fahrzeugtypen beruecksichtigt. Die Bewegung von Fahrzeugen wurde in zwei Dimensionen modelliert. Auf

  10. Roughing It Up: Including Jump Components in the Measurement, Modeling and Forecasting of Return Volatility

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Andersen, Torben G.; Diebold, Francis X.

    A rapidly growing literature has documented important improvements in financial return volatility measurement and forecasting via use of realized variation measures constructed from high-frequency returns coupled with simple modeling procedures. Building on recent theoretical results in Barndorff...... bond yield, we find that jumps are both highly prevalent and distinctly less persistent than the continuous sample path variation process. Moreover, many jumps appear directly associated with specific macroeconomic news announcements. Separating jump from non-jump movements in a simple...... but sophisticated volatility forecasting model, we find that almost all of the predictability in daily, weekly, and monthly return volatilities comes from the non-jump component. Our results thus set the stage for a number of interesting future econometric developments and important financial applications...

  11. Ion-biomolecule collisions studied within the independent atom model including geometric screening corrections

    Science.gov (United States)

    Lüdde, H. J.; Achenbach, A.; Kalkbrenner, T.; Jankowiak, H. C.; Kirchner, T.

    2016-05-01

    A recently introduced model to account for geometric screening corrections in an independent-atom-model description of ion-molecule collisions is applied to proton collisions from amino acids and DNA and RNA nucleobases. The correction coefficients are obtained from using a pixel counting method (PCM) for the exact calculation of the effective cross sectional area that emerges when the molecular cross section is pictured as a structure of (overlapping) atomic cross sections. This structure varies with the relative orientation of the molecule with respect to the projectile beam direction and, accordingly, orientation-independent total cross sections are obtained from averaging the pixel count over many orientations. We present net capture and net ionization cross sections over wide ranges of impact energy and analyze the strength of the screening effect by comparing the PCM results with Bragg additivity rule cross sections and with experimental data where available. Work supported by NSERC, Canada.

  12. Mathematical analysis of a two-dimensional population model of metastatic growth including angiogenesis

    CERN Document Server

    Benzekry, Sebastien

    2010-01-01

    Angiogenesis is a key process in the tumoral growth which allows the cancerous tissue to impact on its vasculature in order to improve the nutrient's supply and the metastatic process. In this paper, we introduce a model for the density of metastasis which takes into account for this feature. It is a two dimensional structured equation with a vanishing velocity field and a source term on the boundary. We present here the mathematical analysis of the model, namely the well-posedness of the equation and the asymptotic behavior of the solutions, whose natural regularity led us to investigate some basic properties of the space $\\Wd(\\Om)=\\{V\\in L^1;\\;\\div(GV)\\in L^1\\}$, where $G$ is the velocity field of the equation.

  13. A model for thermal oxidation of Si and SiC including material expansion

    Energy Technology Data Exchange (ETDEWEB)

    Christen, T., E-mail: thomas.christen@ch.abb.com; Ioannidis, A. [ABB Corporate Research, Segelhofstrasse 1K, CH-5405 Baden (Switzerland); Winkelmann, C. [ETH Zürich, Seminar for Applied Mathematics, Rämistrasse 101, CH-8092 Zürich (Switzerland)

    2015-02-28

    A model based on drift-diffusion-reaction kinetics for Si and SiC oxidation is discussed, which takes the material expansion into account with an additional convection term. The associated velocity field is determined self-consistently from the local reaction rate. The approach allows a calculation of the densities of volatile species in an nm-resolution at the oxidation front. The model is illustrated with simulation results for the growth and impurity redistribution during Si oxidation and for carbon and silicon emission during SiC oxidation. The approach can be useful for the prediction of Si and/or C interstitial distribution, which is particularly relevant for the quality of metal-oxide-semiconductor electronic devices.

  14. A roller chain drive model including contact with guide-bars

    DEFF Research Database (Denmark)

    Pedersen, Sine Leergaard; Hansen, John Michael; Ambrósio, J. A. C.

    2004-01-01

    and continuous force methods, respectively. In the unilateral constraint methodology the kinematic constraints are introduced in the system anytime a contact between the rollers and the sprockets is detected. The condition for the constraint addition is based on the relative distance between the roller centre...... and the sprocket centre, i.e. a constraint is added when such distance is less than the pitch radius. The unilateral kinematic constraint is removed when its associated constraint reaction force, applied on the roller, is in the direction of the root of the sprocket teeth. In order to improve the numerical...... as continuous force. The model of the roller-chain drive now proposed departs from an earlier model where two contact/impact methods are proposed to describe the contact between the rollers of the chain and the teeth of the sprockets. These different formulations are based on unilateral constraints...

  15. Roughing It Up: Including Jump Components in the Measurement, Modeling and Forecasting of Return Volatility

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Andersen, Torben G.; Diebold, Francis X.

    -Nielsen and Shephard (2004a, 2005) for related bi-power variation measures, the present paper provides a practical and robust framework for non-parametrically measuring the jump component in asset return volatility. In an application to the DM/$ exchange rate, the S&P500 market index, and the 30-year U.S. Treasury......A rapidly growing literature has documented important improvements in financial return volatility measurement and forecasting via use of realized variation measures constructed from high-frequency returns coupled with simple modeling procedures. Building on recent theoretical results in Barndorff...... but sophisticated volatility forecasting model, we find that almost all of the predictability in daily, weekly, and monthly return volatilities comes from the non-jump component. Our results thus set the stage for a number of interesting future econometric developments and important financial applications...

  16. Micromagnetic model for studies on Magnetic Tunnel Junction switching dynamics, including local current density

    Energy Technology Data Exchange (ETDEWEB)

    Frankowski, Marek, E-mail: mfrankow@agh.edu.pl; Czapkiewicz, Maciej; Skowronski, Witold; Stobiecki, Tomasz

    2014-02-15

    We present a model introducing the Landau–Lifshitz–Gilbert equation with a Slonczewski's Spin-Transfer-Torque (STT) component in order to take into account spin polarized current influence on the magnetization dynamics, which was developed as an Object Oriented MicroMagnetic Framework extension. We implement the following computations: magnetoresistance of vertical channels is calculated from the local spin arrangement, local current density is used to calculate the in-plane and perpendicular STT components as well as the Oersted field, which is caused by the vertical current flow. The model allows for an analysis of all listed components separately, therefore, the contribution of each physical phenomenon in dynamic behavior of Magnetic Tunnel Junction (MTJ) magnetization is discussed. The simulated switching voltage is compared with the experimental data measured in MTJ nanopillars.

  17. Solution model of nonlinear integral adjustment including different kinds of observing data with different precisions

    Institute of Scientific and Technical Information of China (English)

    郭金运; 陶华学

    2003-01-01

    In order to process different kinds of observing data with different precisions, a new solution model of nonlinear dynamic integral least squares adjustment was put forward, which is not dependent on their derivatives. The partial derivative of each component in the target function is not computed while iteratively solving the problem. Especially when the nonlinear target function is more complex and very difficult to solve the problem, the method can greatly reduce the computing load.

  18. A Multiscale Progressive Failure Modeling Methodology for Composites that Includes Fiber Strength Stochastics

    Science.gov (United States)

    Ricks, Trenton M.; Lacy, Thomas E., Jr.; Bednarcyk, Brett A.; Arnold, Steven M.; Hutchins, John W.

    2014-01-01

    A multiscale modeling methodology was developed for continuous fiber composites that incorporates a statistical distribution of fiber strengths into coupled multiscale micromechanics/finite element (FE) analyses. A modified two-parameter Weibull cumulative distribution function, which accounts for the effect of fiber length on the probability of failure, was used to characterize the statistical distribution of fiber strengths. A parametric study using the NASA Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC) was performed to assess the effect of variable fiber strengths on local composite failure within a repeating unit cell (RUC) and subsequent global failure. The NASA code FEAMAC and the ABAQUS finite element solver were used to analyze the progressive failure of a unidirectional SCS-6/TIMETAL 21S metal matrix composite tensile dogbone specimen at 650 degC. Multiscale progressive failure analyses were performed to quantify the effect of spatially varying fiber strengths on the RUC-averaged and global stress-strain responses and failure. The ultimate composite strengths and distribution of failure locations (predominately within the gage section) reasonably matched the experimentally observed failure behavior. The predicted composite failure behavior suggests that use of macroscale models that exploit global geometric symmetries are inappropriate for cases where the actual distribution of local fiber strengths displays no such symmetries. This issue has not received much attention in the literature. Moreover, the model discretization at a specific length scale can have a profound effect on the computational costs associated with multiscale simulations.models that yield accurate yet tractable results.

  19. A quark model calculation of yy->pipi including final-state interactions

    CERN Document Server

    Blundell, H G; Hay, G; Swanso, E

    2000-01-01

    A quark model calculation of the processes yy->pi+pi- and yy->pipi is performed. At tree level, only charged pions couple to the initial state photons and neutral pions are not exceeded in the final state. However a small but significant cross section is observed. We demonstrate that this may be accounted for by a rotation in isospin space induced by final-state interactions.

  20. Paint Pavement Marking Performance Prediction Model That Includes the Impacts of Snow Removal Operations

    Science.gov (United States)

    2011-03-01

    Hypothesized that snow plows wear down mountain road pavement markings. 2007 Craig et al. -Edge lines degrade slower than center/skip lines 2007...retroreflectivity to create the models. They discovered that paint pavement markings last 80% longer on Portland Cement Concrete than Asphalt Concrete at low AADT...retroreflectivity, while yellow markings lost 21%. Lu and Barter attributed the sizable degradation to snow removal, sand application, and studded

  1. Molten pool-lower head integrity. Heat transfer models including advanced numerical simulations (DNS)

    Energy Technology Data Exchange (ETDEWEB)

    Seiler, J.M.; Bonnet, J.M.; Bernaz, L. [CEA Grenoble (France)

    2001-07-01

    Extensive studies have been performed to investigate the heat transfer within a molten corium pool (homogeneous, stratified and with miscibility gap): Synthesis of heat transfer correlations in molten pool (homogeneous and stratified), Focusing effect in stratified metal layer, DNS analysis of Rayleigh Benard instabilities at the top boundary; interpretation of the different convection regimes and exponents affecting the Rayleigh number in the heat transfer correlations, Molten pool model for corium presenting a miscibility gap. Condition for de-stratification. (authors)

  2. Modeling the Corona and Solar Wind using ADAPT Maps that Include Far-Side Observations

    Science.gov (United States)

    2013-11-01

    document for any purpose other than Government procurement does not in any way obligate the U.S. Government. The fact that the Government formulated...Government’s approval or disapproval of its ideas or findings. Approved for public release; distribution is unlimited. REPORT DOCUMENTATION PAGE...Los Alamos National Laboratory ( LANL ) and the National Solar Observatory (NSO), has developed a model that produces more realistic estimates of the

  3. Numerical modelling of the transport of trace gases including methane in the subsurface of Mars

    Science.gov (United States)

    Stevens, Adam H.; Patel, Manish R.; Lewis, Stephen R.

    2015-04-01

    We model the transport of gas through the martian subsurface in order to quantify the timescales of release of a trace gas with a source at depth using a Fickian model of diffusion through a putative martian regolith column. The model is then applied to the case of methane to determine if diffusive transport of gas can explain previous observations of methane in the martian atmosphere. We investigate which parameters in the model have the greatest effect on transport timescales and show that the calculated diffusivity is very sensitive to the pressure profile of the subsurface, but relatively insensitive to the temperature profile, though diffusive transport may be affected by other temperature dependent properties of the subsurface such as the local vapour pressure. Uncertainties in the structure and physical conditions of the martian subsurface also introduce uncertainties in the timescales calculated. It was found that methane may take several hundred thousand Mars-years to diffuse from a source at depth. Purely diffusive transport cannot explain transient release that varies on timescales of less than one martian year from sources such as serpentinization or methanogenic organisms at depths of more than 2 km. However, diffusion of gas released by the destabilisation of methane clathrate hydrates close to the surface, for example caused by transient mass wasting events or erosion, could produce a rapidly varying flux of methane into the atmosphere of more than 10-3 kg m-2 s-1 over a duration of less than half a martian year, consistent with observations of martian methane variability. Seismic events, magmatic intrusions or impacts could also potentially produce similar patterns of release, but are far more complex to simulate.

  4. Numerical modeling of shallow flows including bottom topography and friction effects

    OpenAIRE

    Lukácová-Medvid'ová, Maria

    2004-01-01

    The aim of the paper is numerical modeling of the shallow water equation with source terms by genuinely multdimensional finite volume evolution Galerkin schemes. The shallow water system, or its one-dimensional analogy the Saint-Venant equation, is used extensively for numerical simulation of natural rivers. Mathematically the shallow water system belongs to the class of balance laws. A special treatment of the source terms describing the bottom topography as well as frictions effects is nece...

  5. A numerical model of the ionosphere, including the E-region above EISCAT

    Directory of Open Access Journals (Sweden)

    P.-Y. Diloy

    Full Text Available It has been previously demonstrated that a two-ion (O+ and H+ 8-moment time-dependent fluid model was able to reproduce correctly the ionospheric structure in the altitude range probed by the EISCAT-VHF radar. In the present study, the model is extended down to the E-region where molecular ion chemistry (NO+ and O+2, essentially prevails over transport; EISCAT-UHF observations confirmed previous theoretical predictions that during events of intense E×B induced convection drifts, molecular ions (mainly NO+ predominate over O+ ions up to altitudes of 300 km. In addition to this extension of the model down to the E-region, the ionization and heating resulting from both solar insolation and particle precipitation is now taken into account in a consistent manner through a complete kinetic transport code. The effects of E×B induced convection drifts on the E- and F-region are presented: the balance between O+ and NO+ ions is drastically affected; the electric field acts to deplete the O+ ion concentration. The [NO+]/[O+] transition altitude varies from 190 km to 320 km as the perpendicular electric field increases from 0 to 100 mV m-1. An interesting additional by-product of the model is that it also predicts the presence of a noticeable fraction of N+ ions in the topside ionosphere in good agreement with Retarding Ion Mass Spectrometer measurements onboard Dynamic Explorer.

  6. Climate change impact modelling needs to include cross-sectoral interactions

    Science.gov (United States)

    Harrison, Paula A.; Dunford, Robert W.; Holman, Ian P.; Rounsevell, Mark D. A.

    2016-09-01

    Climate change impact assessments often apply models of individual sectors such as agriculture, forestry and water use without considering interactions between these sectors. This is likely to lead to misrepresentation of impacts, and consequently to poor decisions about climate adaptation. However, no published research assesses the differences between impacts simulated by single-sector and integrated models. Here we compare 14 indicators derived from a set of impact models run within single-sector and integrated frameworks across a range of climate and socio-economic scenarios in Europe. We show that single-sector studies misrepresent the spatial pattern, direction and magnitude of most impacts because they omit the complex interdependencies within human and environmental systems. The discrepancies are particularly pronounced for indicators such as food production and water exploitation, which are highly influenced by other sectors through changes in demand, land suitability and resource competition. Furthermore, the discrepancies are greater under different socio-economic scenarios than different climate scenarios, and at the sub-regional rather than Europe-wide scale.

  7. Kinetic model of water disinfection using peracetic acid including synergistic effects.

    Science.gov (United States)

    Flores, Marina J; Brandi, Rodolfo J; Cassano, Alberto E; Labas, Marisol D

    2016-01-01

    The disinfection efficiencies of a commercial mixture of peracetic acid against Escherichia coli were studied in laboratory scale experiments. The joint and separate action of two disinfectant agents, hydrogen peroxide and peracetic acid, were evaluated in order to observe synergistic effects. A kinetic model for each component of the mixture and for the commercial mixture was proposed. Through simple mathematical equations, the model describes different stages of attack by disinfectants during the inactivation process. Based on the experiments and the kinetic parameters obtained, it could be established that the efficiency of hydrogen peroxide was much lower than that of peracetic acid alone. However, the contribution of hydrogen peroxide was very important in the commercial mixture. It should be noted that this improvement occurred only after peracetic acid had initiated the attack on the cell. This synergistic effect was successfully explained by the proposed scheme and was verified by experimental results. Besides providing a clearer mechanistic understanding of water disinfection, such models may improve our ability to design reactors.

  8. Including A-Priori Assessment of Actual Evapotranspiration for Green Roof Daily Scale Hydrological Modelling

    Directory of Open Access Journals (Sweden)

    Mirka Mobilia

    2017-01-01

    Full Text Available In the last decades, there has been a widespread implementation of Green Infrastructures worldwide. Among these, green roofs appear to be particularly flexible sustainable drainage facilities. To predict their effectiveness for planning purposes, a tool is required that provides information as a function of local meteorological variables. Thus, a relatively simple daily scale, one-dimensional water balance approach has been proposed. The crucial evapotranspiration process, usually considered as a water balance dependent variable, is replaced here by empirical relationships providing an a-priori assessment of soil water losses through actual evapotranspiration. The modelling scheme, which under some simplification can be used without a calibration process, has been applied to experimental runoff data monitored at a green roof located near Bernkastel (Germany, between April 2005 and December 2006. Two different empirical relationships have been used to model actual evapotranspiration, considering a water availability limited and an energy limited scheme. Model errors quantification, ranging from 2% to 40% on the long-term scale and from 1% to 36% at the event scale, appear strongly related to the particularly considered relationship.

  9. Modelling topical photodynamic therapy treatment including the continuous production of Protoporphyrin IX

    Science.gov (United States)

    Campbell, C. L.; Brown, C. T. A.; Wood, K.; Moseley, H.

    2016-11-01

    Most existing theoretical models of photodynamic therapy (PDT) assume a uniform initial distribution of the photosensitive molecule, Protoporphyrin IX (PpIX). This is an adequate assumption when the prodrug is systematically administered; however for topical PDT this is no longer a valid assumption. Topical application and subsequent diffusion of the prodrug results in an inhomogeneous distribution of PpIX, especially after short incubation times, prior to light illumination. In this work a theoretical simulation of PDT where the PpIX distribution depends on the incubation time and the treatment modality is described. Three steps of the PpIX production are considered. The first is the distribution of the topically applied prodrug, the second in the conversion from the prodrug to PpIX and the third is the light distribution which affects the PpIX distribution through photobleaching. The light distribution is modelled using a Monte Carlo radiation transfer model and indicates treatment depths of around 2 mm during daylight PDT and approximately 3 mm during conventional PDT. The results suggest that treatment depths are not only limited by the light penetration but also by the PpIX distribution.

  10. A stepped leader model for lightning including charge distribution in branched channels

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Wei; Zhang, Li [School of Electrical Engineering, Shandong University, Jinan 250061 (China); Li, Qingmin, E-mail: lqmeee@ncepu.edu.cn [Beijing Key Lab of HV and EMC, North China Electric Power University, Beijing 102206 (China); State Key Lab of Alternate Electrical Power System with Renewable Energy Sources, Beijing 102206 (China)

    2014-09-14

    The stepped leader process in negative cloud-to-ground lightning plays a vital role in lightning protection analysis. As lightning discharge usually presents significant branched or tortuous channels, the charge distribution along the branched channels and the stochastic feature of stepped leader propagation were investigated in this paper. The charge density along the leader channel and the charge in the leader tip for each lightning branch were approximated by introducing branch correlation coefficients. In combination with geometric characteristics of natural lightning discharge, a stochastic stepped leader propagation model was presented based on the fractal theory. By comparing simulation results with the statistics of natural lightning discharges, it was found that the fractal dimension of lightning trajectory in simulation was in the range of that observed in nature and the calculation results of electric field at ground level were in good agreement with the measurements of a negative flash, which shows the validity of this proposed model. Furthermore, a new equation to estimate the lightning striking distance to flat ground was suggested based on the present model. The striking distance obtained by this new equation is smaller than the value estimated by previous equations, which indicates that the traditional equations may somewhat overestimate the attractive effect of the ground.

  11. Numerical Modeling of the Surface Fatigue Crack Propagation Including the Closure Effect

    Science.gov (United States)

    Guchinsky, Ruslan; Petinov, Sergei

    2016-01-01

    Presently modeling of surface fatigue crack growth for residual life assessment of structural elements is almost entirely based on application of the Linear Elastic Fracture Mechanics (LEFM). Generally, it is assumed that the crack front does not essentially change its shape, although it is not always confirmed by experiment. Furthermore, LEFM approach cannot be applied when the stress singularity vanishes due to material plasticity, one of the leading factors associated with the material degradation and fracture. Also, evaluation of stress intensity factors meets difficulties associated with changes in the stress state along the crack front circumference. An approach proposed for simulation the evolution of surface cracks based on application of the Strain-life criterion for fatigue failure and of the finite element modeling of damage accumulation. It takes into account the crack closure effect, the nonlinear behavior of damage accumulation and material compliance increasing due to the damage advance. The damage accumulation technique was applied to model the semi-elliptical crack growth from the initial defect in the steel compact specimen. The results of simulation are in good agreement with the published experimental data.

  12. Developing parameters for multi-mode ambient air models including the nanometer mode

    Science.gov (United States)

    Tronville, Paolo; Rivers, Richard

    2017-06-01

    The particle count, surface and mass in an occupied space can be modeled when the HVAC system airflows are known, along with the particle-size distribution for outdoor air, internal generation rates as a function of particle size, and the efficiency as a function of particle size for filters present. Outdoor air particle-size distribution is rarely available, but measures of particle mass concentration, PM2.5 and PM10, are often available for building locations. Outdoor air aerosol size distributions are well modeled by sums of two or three log-normal distributions, with essentially all mass in two larger modes. Studies have also shown that some mode parameters are, in general, related by simple functions. This paper shows how these relationships can be combined with known characteristics of PM2.5 and PM10 samplers to create reasonable inclusive models of outdoor air aerosol-size distributions. This information plus knowledge of indoor particle generation allows calculation of aerosol mass in occupied spaces. Estimation of parameters of aerosol modes with sizes below100 nm and measurement of filter efficiencies in that range are described.

  13. Don't Be a Quitter - Pick Up Litter: An Environmental Message for Girls and Boys [and] Environmental Education Basic Reader [Teacher Guide, Notes to the Teacher].

    Science.gov (United States)

    Holmes, Helen D.

    Instructions are provided for constructing a learning center on littering. Activity sheets (focusing on words, spelling, story order, and art) which may be duplicated for use with the center and lists of resource materials are also provided. These materials include resources for teachers, a list of litter/ecology books for students, and a list of…

  14. Welfare and performance in layers following temporary exclusion from the litter area on introduction to the layer facility.

    Science.gov (United States)

    Alm, M; Wall, H; Holm, L; Wichman, A; Palme, R; Tauson, R

    2015-04-01

    When introduced to the laying facility, pullets are sometimes temporarily excluded from the litter area in order to help them locate food and water, and to prevent floor-laid eggs. This procedure is not permitted in Sweden, because it involves denying access to both litter and space, which may have a negative effect on bird welfare. The present study investigated how the welfare and performance of layers were affected by this temporary exclusion on introduction of hens to the laying facility. The study included 600 floor-reared Dekalb White layers obtained at 16 wk age and housed in 6 groups of 100 in a conventional single-tier floor-laying system. Birds were either given full access to the litter area during the whole study or were excluded from the litter area during the first 2 wk after transfer to the laying facility. From 18 to 72 wk age, birds in both treatments had full access to the litter area. Excluding birds from the litter area for 2 wk resulted in better feather cover and reduced fearfulness, according to novel object and tonic immobility tests. Furthermore, birds initially excluded from the litter area produced eggs with a lower proportion of shell irregularities than birds with full access to the litter area throughout. No difference was found in corticosterone metabolites in droppings rate of lay, mortality, or proportion of floor-laid eggs. In conclusion, none of the parameters studied indicated that the welfare of laying hens was compromised by temporary exclusion from the litter area on introduction to the laying facility. In fact, some of the data suggested that bird welfare had improved.

  15. Galactic habitable zone around M and FGK stars with chemical evolution models that include dust

    Science.gov (United States)

    Spitoni, E.; Gioannini, L.; Matteucci, F.

    2017-09-01

    Context. The Galactic habitable zone is defined as the region with a metallicity that is high enough to form planetary systems in which Earth-like planets could be born and might be capable of sustaining life. Life in this zone needs to survive the destructive effects of nearby supernova explosion events. Aims: Galactic chemical evolution models can be useful tools for studying the galactic habitable zones in different systems. Our aim here is to find the Galactic habitable zone using chemical evolution models for the Milky Way disk, adopting the most recent prescriptions for the evolution of dust and for the probability of finding planetary systems around M and FGK stars. Moreover, for the first time, we express these probabilities in terms of the dust-to-gas ratio of the interstellar medium in the solar neighborhood as computed by detailed chemical evolution models. Methods: At a fixed Galactic time and Galactocentric distance, we determined the number of M and FGK stars that host earths (but no gas giant planets) that survived supernova explosions, using the formalism of our Paper I. Results: The probabilities of finding terrestrial planets but not gas giant planets around M stars deviate substantially from the probabilities around FGK stars for supersolar values of [Fe/H]. For both FGK and M stars, the maximum number of stars hosting habitable planets is at 8 kpc from the Galactic Center when destructive effects by supernova explosions are taken into account. Currently, M stars with habitable planets are ≃10 times more frequent than FGK stars. Moreover, we provide a sixth-order polynomial fit (and a linear fit, but that is more approximated) for the relation found with chemical evolution models in the solar neighborhood between the [Fe/H] abundances and the dust-to-gas ratio. Conclusions: The most likely Galactic zone in which to find terrestrial habitable planets around M and FGK stars is the annular 2 kpc wide region that is centered at 8 kpc from the

  16. Comparison of lead isotopes with source apportionment models, including SOM, for air particulates.

    Science.gov (United States)

    Gulson, Brian; Korsch, Michael; Dickson, Bruce; Cohen, David; Mizon, Karen; Davis, J Michael

    2007-08-01

    We have measured high precision lead isotopes in PM(2.5) particulates from a highly-trafficked site (Mascot) and rural site (Richmond) in the Sydney Basin, New South Wales, Australia to compare with isotopic data from total suspended particulates (TSP) from other sites in the Sydney Basin and evaluate relationships with source fingerprints obtained from multi-element PM(2.5) data. The isotopic data for the period 1998 to 2004 show seasonal peaks and troughs that are more pronounced in the rural site for the PM(2.5).samples but are consistent with the TSP. The Self Organising Map (SOM) method has been applied to the multi-element PM(2.5) data to evaluate its use in obtaining fingerprints for comparison with standard statistical procedures (ANSTO model). As seasonal effects are also significant for the multi-element data, the SOM modelling is reported as site and season dependent. At the Mascot site, the ANSTO model exhibits decreasing (206)Pb/(204)Pb ratios with increasing contributions of fingerprints for "secondary smoke" (industry), "soil", "smoke" and "seaspray". Similar patterns were shown by SOM winter fingerprints for both sites. At the rural site, there are large isotopic variations but for the majority of samples these are not associated with increased contributions from the main sources with the ANSTO model. For two winter sampling times, there are increased contributions from "secondary industry", "smoke", "soil" and seaspray with one time having a source or sources of Pb similar to that of Mascot. The only positive relationship between increasing (206)Pb/(204)Pb ratio and source contributions is found at the rural site using the SOM summer fingerprints, both of which show a significant contribution from sulphur. Several of the fingerprints using either model have significant contributions from black carbon (BC) and/or sulphur (S) that probably derive from diesel fuels and industrial sources. Increased contributions from sources with the SOM summer

  17. Contrasting patterns of litterfall seasonality and seasonal changes in litter decomposability in a tropical rainforest region

    Directory of Open Access Journals (Sweden)

    S. A. Parsons

    2014-06-01

    Full Text Available The seasonality of litter inputs in forests has important implications for understanding ecosystem processes and biogeochemical cycles. We quantified the drivers of seasonality in litterfall and leaf decomposability, using plots throughout the Australian wet tropical region. Litter fell mostly in the summer (wet, warm months in the region, but other peaks occurred throughout the year. Litterfall seasonality was modelled well with the level of deciduousness of the site (plots with more deciduous species had lower seasonality than evergreen plots, temperature (higher seasonality in the uplands, disturbance (lower seasonality with more early secondary species and soil fertility (higher seasonality with higher N : P/P limitation (SL total litterfall model 1 = deciduousness + soil N : P + early secondary sp: r2 = 0.63, n = 30 plots; model 2 = temperature + early secondary sp. + soil N : P: r2 = 0.54, n = 30; SL leaf = temperature + early secondary sp. + rainfall seasonality: r2 = 0.39, n = 30. Leaf litter decomposability was lower in the dry season than in the wet season, driven by higher phenolic concentrations in the dry, with the difference exacerbated particularly by lower dry season moisture. Our results are contrary to the global trend for tropical rainforests; in that seasonality of litterfall inputs were generally higher in wetter, cooler, evergreen forests, compared to generally drier, warmer, semi-deciduous sites that had more uniform monthly inputs. We consider this due to more diverse litter shedding patterns in semi-deciduous and raingreen rainforest sites, and an important consideration for ecosystem modellers. Seasonal changes in litter quality are likely to have impacts on decomposition and biogeochemical cycles in these forests due to the litter that falls in the dry being more recalcitrant to decay.

  18. Changes in litter near an aluminum reduction plant

    Science.gov (United States)

    Beyer, W.N.; Fleming, W.J.; Swineford, D.

    1987-01-01

    Litter was collected from eight sites at distances as far as 33 km from an AI reduction plant in western Tennessee. As a result of an accumulation of fine litter (Porcellio scaber Latr.) had an abnormally high mortality in litter that contained 440 mg/kg or more of acid-extractable F-. However, when F- was added as NaF to litter, a significant increase in mortality was observed only in treatments exceeding 800 mg/kg. The decrease in the rate of decomposition of the litter might eventually induce a deficiency of soil macronutrients, but none was detected.

  19. Able but unintelligent: including positively stereotyped black subgroups in the stereotype content model.

    Science.gov (United States)

    Walzer, Amy S; Czopp, Alexander M

    2011-01-01

    The stereotype content model (SCM) posits that warmth and competence are the key components underlying judgments about social groups. Because competence can encompass different components (e.g., intelligence, talent) different group members may be perceived to be competent for different reasons. Therefore, we believe it may be important to specify the type of competence being assessed when examining perceptions of groups that are positively stereotyped (i.e., Black athletes and musical Blacks). Consistent with the SCM, these subgroups were perceived as high in competence-talent but not in competence-intelligence and low in warmth. Both the intelligence and talent frame of competence fit in the SCM's social structural hypothesis.

  20. Microregion model of a contact line including evaporation, kinetics and slip

    Science.gov (United States)

    Anderson, Daniel; Janecek, Vladislav

    2016-11-01

    We consider the evaporation of a liquid on a uniformly heated solid substrate. In the framework of lubrication theory we consider hydrodynamics, heat conduction, phase change, evaporation kinetics, and slip. Our model focuses only on the contact line 'inner' region which allows us to quantify the impact of evaporation on the apparent contact angle and microregion heat transfer. The linearized problem with respect to the substrate overheating is solved analytically. The analytical solutions are compared with full numerical solutions and to predictions of Hocking.

  1. Mathematical modeling of the hypothalamic–pituitary–adrenal gland (HPA) axis, including hippocampal mechanisms

    DEFF Research Database (Denmark)

    Andersen, Morten; Vinther, Frank; Ottesen, Johnny T.

    2013-01-01

    non-negative and bounded, which can be interpreted as a mathematical formulation of homeostasis. No oscillating solutions are present when using physiologically reasonable parameter values. This indicates that the ultradian rhythm originate from different mechanisms.Using physiologically reasonable......This paper presents a mathematical model of the HPA axis. The HPA axis consists of the hypothalamus, the pituitary and the adrenal glands in which the three hormones CRH, ACTH and cortisol interact through receptor dynamics. Furthermore, it has been suggested that receptors in the hippocampus have...

  2. Nuclear monopole charge form factor calculation for relativistic models including center-of-mass corrections

    Energy Technology Data Exchange (ETDEWEB)

    Avancini, S.S.; Marinelli, J.R. [Universidade Federal de Santa Catarina Florianopolis, Depto de Fisica - CFM, Florianopolis (Brazil); Carlson, B.V. [Instituto Tecnologico de Aeronautica, Sao Jose dos Campos (Brazil)

    2013-06-15

    Relativistic models for finite nuclei contain spurious center-of-mass motion in most applications for the nuclear many-body problem, where the nuclear wave function is taken as a single Slater determinant within a space-fixed frame description. We use the Peierls-Yoccoz projection method, previously developed for relativistic approaches together with a reparametrization of the coupling constants that fits binding energies and charge radius and apply our results to calculate elastic electron scattering monopole charge form factors for light nuclei. (orig.)

  3. Double pendulum model for a tennis stroke including a collision process

    Science.gov (United States)

    Youn, Sun-Hyun

    2015-10-01

    By means of adding a collision process between the ball and racket in the double pendulum model, we analyzed the tennis stroke. The ball and the racket system may be accelerated during the collision time; thus, the speed of the rebound ball does not simply depend on the angular velocity of the racket. A higher angular velocity sometimes gives a lower rebound ball speed. We numerically showed that the proper time-lagged racket rotation increased the speed of the rebound ball by 20%. We also showed that the elbow should move in the proper direction in order to add the angular velocity of the racket.

  4. Modeling the elastic behavior of ductile cast iron including anisotropy in the graphite nodules

    DEFF Research Database (Denmark)

    Andriollo, Tito; Thorborg, Jesper; Hattel, Jesper Henri

    2016-01-01

    This paper presents a micro-mechanical approach to model the intrinsic elastic anisotropy of the graphite particles in ductile iron. Contrary to most of the published works in the field, the constitutive behavior is directly derived on the basis of the nodule characteristic internal structure......, composed of graphite platelets arranged into conical sectors. In this way, the large uncertainty traditionally associated with local mechanical measurements of micro-hardness is eliminated. The proposed anisotropic description is validated by simulating the macroscopic ductile iron elastic response...

  5. Tea polyphenols dominate the short-term tea (Camellia sinensis) leaf litter decomposition*

    Science.gov (United States)

    Fan, Dong-mei; Fan, Kai; Yu, Cui-ping; Lu, Ya-ting; Wang, Xiao-chang

    2017-01-01

    Polyphenols are one of the most important secondary metabolites, and affect the decomposition of litter and soil organic matter. This study aims to monitor the mass loss rate of tea leaf litter and nutrient release pattern, and investigate the role of tea polyphenols played in this process. High-performance liquid chromatography (HPLC) and classical litter bag method were used to simulate the decomposition process of tea leaf litter and track the changes occurring in major polyphenols over eight months. The release patterns of nitrogen, potassium, calcium, and magnesium were also determined. The decomposition pattern of tea leaf litter could be described by a two-phase decomposition model, and the polyphenol/N ratio effectively regulated the degradation process. Most of the catechins decreased dramatically within two months; gallic acid (GA), catechin gallate (CG), and gallocatechin (GC) were faintly detected, while others were outside the detection limits by the end of the experiment. These results demonstrated that tea polyphenols transformed quickly and catechins had an effect on the individual conversion rate. The nutrient release pattern was different from other plants which might be due to the existence of tea polyphenols. PMID:28124839

  6. Including Antenna Models in Microwave Imaging for Breast-Cancer Screening

    DEFF Research Database (Denmark)

    Rubæk, Tonny; Meincke, Peter

    2006-01-01

    Microwave imaging is emerging as a tool for screening for breast cancer, but the lack of methods for including the characteristics of the antennas of the imaging systems in the imaging algorithms limits their performance. In this paper, a method for incorporating the full antenna characteristics......, in terms of the transmission-matrix representation, in a frequency-domain imaging algorithm is presented. The algorithm is tested on a simulation of the Physical-Anomaly Tomography (PAT) scanner imaging system developed at the Technical University of Denmark and is shown to have superior performance when...

  7. Priming in the microbial landscape: periphytic algal stimulation of litter-associated microbial decomposers.

    Science.gov (United States)

    Kuehn, Kevin A; Francoeur, Steven N; Findlay, Robert H; Neely, Robert K

    2014-03-01

    Microbial communities associated with submerged detritus in aquatic ecosystems often comprise a diverse mixture of autotrophic and heterotrophic microbes, including algae, bacteria, protozoa, and fungi. Recent studies have documented increased rates of plant litter mass loss when periphytic algae are present. We conducted laboratory and field experiments to assess potential metabolic interactions between natural autotrophic and heterotrophic microbial communities inhabiting submerged decaying plant litter of Typha angustifolia and Schoenoplectus acutus. In the field, submerged plant litter was either exposed to natural sunlight or placed under experimental canopies that manipulated light availability and growth of periphytic algae. Litter was collected and returned to the laboratory, where algal photosynthesis was manipulated (light/dark incubation), while rates of bacterial and fungal growth and productivity were simultaneously quantified. Bacteria and fungi were rapidly stimulated by exposure to light, thus establishing the potential for algal priming of microbial heterotrophic decay activities. Experimental incubations of decaying litter with 14C- and 13C-bicarbonate established that inorganic C fixed by algal photosynthesis was rapidly transferred to and assimilated by heterotrophic microbial decomposers. Periphytic algal stimulation of microbial heterotrophs, especially fungal decomposers, is an important and largely unrecognized interaction within the detrital microbial landscape, which may transform our current conceptual understanding of microbial secondary production and organic matter decomposition in aquatic ecosystems.

  8. A Field Experiment on Behavioural Effects of Humorous, Environmentally Oriented and Authoritarian Posters against Littering

    Directory of Open Access Journals (Sweden)

    Ralph Hansmann

    2016-06-01

    Full Text Available A humorous, an environmentally oriented and an authoritarian poster against littering were tested in a field experiment on their behavioural effectiveness. Corresponding slogans were placed on anti-littering posters designed for this study and used experimentally at four railway stations. The experimental design entailed 4 communication conditions including a control condition where no poster was presented. In each experimental run (N = 96, flyers were distributed for 30 minutes. The number of distributed flyers was counted, and the proportion of littered flyers was determined for each experimental run. It was found that the humorous and environmentally oriented posters achieved a reduction of 58% and 64%, respectively, in littering as compared with the control condition. The authoritarian poster was significantly less effective, but achieved a significant reduction of 25%. Considered together with some previous findings and theories, the results indicate that environmentally oriented and humorous anti-littering posters are more effective than authoritarian onesDOI: http://dx.doi.org/10.5755/j01.erem.72.1.14169

  9. The effects of leaf litter nutrient pulses on Alliaria petiolata performance

    Directory of Open Access Journals (Sweden)

    Robert W. Heckman

    2015-08-01

    Full Text Available Nutrient pulses can facilitate species establishment and spread in new habitats, particularly when one species more effectively uses that nutrient pulse. Biological differences in nutrient acquisition between native and exotic species may facilitate invasions into a variety of habitats including deciduous forest understories. Alliaria petiolata (Bieb. Cavara & Grande is an important invader of deciduous forest understories throughout much of North America. These understory communities contain many species which perform the majority of their growth and reproduction before canopy closure in spring. Because A. petiolata is a wintergreen biennial that can be active during autumn and winter, it may utilize nutrients released from decaying leaf litter before its competitors. To investigate this we manipulated the timing of leaf litter addition (fall or spring and experimentally simulated the nutrient pulse from decaying leaves using artificial fertilizer. To determine whether A. petiolata affected the abundance of understory competitors, we also removed A. petiolata from one treatment. A. petiolata that received early nutrients exhibited greater growth. Treatments receiving fall leaf litter or artificial nutrients had greater A. petiolata adult biomass than plots receiving spring nutrient additions (leaf litter or artificial nutrients. However, fall leaf litter addition had no effect on the richness of competitor species. Thus, wintergreen phenology may contribute to the spread of A. petiolata through deciduous forest understories, but may not explain community-level impacts of A. petiolata in deciduous forests.

  10. The evolution of massive stars including mass loss - Presupernova models and explosion

    Science.gov (United States)

    Woosley, S. E.; Langer, Norbert; Weaver, Thomas A.

    1993-01-01

    The evolution of massive stars of 35, 40, 60, and 85 solar masses is followed through all stages of nuclear burning to the point of Fe core collapse. Critical nuclear reaction and mass-loss rates are varied. Efficient mass loss during the Wolf-Rayet (WR) stage is likely to lead to final masses as small as 4 solar masses. For a reasonable parameterization of the mass loss, there may be convergence of all WR stars, both single and in binaries, to a narrow band of small final masses. Our representative model, a 4.25 solar-mass WR presupernova derived from a 60 solar mass star, is followed through a simulated explosion, and its explosive nucleosynthesis and light curve are determined. Its properties are similar to those observed in Type Ib supernovae. The effects of the initial mass and mass loss on the presupernova structure of small mass WR models is also explored. Important properties of the presupernova star and its explosion can only be obtained by following the complete evolution starting on the main sequence.

  11. Model for external influences on cellular signal transduction pathways including cytosolic calcium oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Eichwald, C.; Kaiser, F. [Technical Univ. of Darmstadt (Germany)

    1995-06-01

    Experiments on the effects of extremely-low-frequency (ELF) electric and magnetic fields on cells of the immune system, T-lymphocytes in particular, suggest that the external field interacts with the cell at the level of intracellular signal transduction pathways. These are directly connected with changes in the calcium-signaling processes of the cell. Based on these findings, a theoretical model for receptor-controlled cytosolic calcium oscillations and for external influences on the signal transduction pathway is presented. The authors discuss the possibility that the external field acts on the kinetics of the signal transduction between the activated receptors at the cell membrane and the G-proteins. It is shown that, depending on the specific combination of cell internal biochemical and external physical parameters, entirely different responses of the cell can occur. The authors compare the effects of a coherent (periodic) modulation and of incoherent perturbations (noise). The model and the calculations are based on the theory of self-sustained, nonlinear oscillators. It is argued that these systems form an ideal basis for information-encoding processes in biological systems.

  12. An Improved Heat Budget Estimation Including Bottom Effects for General Ocean Circulation Models

    Science.gov (United States)

    Carder, Kendall; Warrior, Hari; Otis, Daniel; Chen, R. F.

    2001-01-01

    This paper studies the effects of the underwater light field on heat-budget calculations of general ocean circulation models for shallow waters. The presence of a bottom significantly alters the estimated heat budget in shallow waters, which affects the corresponding thermal stratification and hence modifies the circulation. Based on the data collected during the COBOP field experiment near the Bahamas, we have used a one-dimensional turbulence closure model to show the influence of the bottom reflection and absorption on the sea surface temperature field. The water depth has an almost one-to-one correlation with the temperature rise. Effects of varying the bottom albedo by replacing the sea grass bed with a coral sand bottom, also has an appreciable effect on the heat budget of the shallow regions. We believe that the differences in the heat budget for the shallow areas will have an influence on the local circulation processes and especially on the evaporative and long-wave heat losses for these areas. The ultimate effects on humidity and cloudiness of the region are expected to be significant as well.

  13. On the modelling of semi-insulating GaAs including surface tension and bulk stresses

    Energy Technology Data Exchange (ETDEWEB)

    Dreyer, W.; Duderstadt, F.

    2004-07-01

    Necessary heat treatment of single crystal semi-insulating Gallium Arsenide (GaAs), which is deployed in micro- and opto- electronic devices, generate undesirable liquid precipitates in the solid phase. The appearance of precipitates is influenced by surface tension at the liquid/solid interface and deviatoric stresses in the solid. The central quantity for the description of the various aspects of phase transitions is the chemical potential, which can be additively decomposed into a chemical and a mechanical part. In particular the calculation of the mechanical part of the chemical potential is of crucial importance. We determine the chemical potential in the framework of the St. Venant-Kirchhoff law which gives an appropriate stress/strain relation for many solids in the small strain regime. We establish criteria, which allow the correct replacement of the St. Venant-Kirchhoff law by the simpler Hooke law. The main objectives of this study are: (i) We develop a thermo-mechanical model that describes diffusion and interface motion, which both are strongly influenced by surface tension effects and deviatoric stresses. (ii) We give an overview and outlook on problems that can be posed and solved within the framework of the model. (iii) We calculate non-standard phase diagrams, i.e. those that take into account surface tension and non-deviatoric stresses, for GaAs above 786 C, and we compare the results with classical phase diagrams without these phenomena. (orig.)

  14. Grids of stellar models including second harmonic and colours: Solar composition

    CERN Document Server

    Yildiz, Mutlu

    2015-01-01

    Grids of stellar evolution are required in many fields of astronomy/astrophysics, such as planet hosting stars, binaries, clusters, chemically peculiar stars, etc. In this study, a grid of stellar evolution models with updated ingredients and {recently determined solar abundaces} is presented. The solar values for the initial abundances of hydrogen, heavy elements and mixing-length parameter are 0.0172, 0.7024 and 1.98, respectively. The mass step is small enough (0.01 M$_\\odot$) that interpolation for a given star mass is not required. The range of stellar mass is 0.74 to 10.00 M$_\\odot$. We present results in different forms of tables for easy and general application. The second stellar harmonic, required for analysis of apsidal motion of eclipsing binaries, is also listed. We also construct rotating models to determine effect of rotation on stellar structure and derive fitting formula for luminosity, radius and the second stellar harmonic as a function of rotational parameter. We also compute and list colo...

  15. Analysis of the R-symmetric supersymmetric models including quantum corrections

    CERN Document Server

    Kotlarski, Wojciech

    2016-01-01

    We study the Minimal R-symmetric Supersymmetric Standard Model (MRSSM) at the quantum level. The thesis consists of two parts. First one treats about the electroweak sector of the model. Among others, it identifies the parameter region allowed by the electroweak precision observables. Since the MRSSM contains an $SU(2)_L$-triplet with a non-zero vacuum expectation value the emphasis is put on the calculation of the $W$ boson mass. To that end, a full one-loop calculation of $m_W$ augmented with the leading two-loop SM result is presented. The region is then checked against the measurement of the Higgs boson mass. For this, the full one-loop and leading two-loop corrections to the Higgs boson mass in the MRSSM are calculated. Devised benchmark points, consistent with both of these observables, are shown to fulfill also a number of additional experimental constraints like properties of the Higgs boson(s), $b$-physics observables and vacuum stability. Correlating all of these observables allows to put bounds on ...

  16. Description and Application of A Model of Seepage under A Weir Including Mechanical Clogging

    Directory of Open Access Journals (Sweden)

    Sroka Zbigniew

    2014-07-01

    Full Text Available The paper discusses seepage flow under a damming structure (a weir in view of mechanical clogging in a thin layer at the upstream site. It was assumed that in this layer flow may be treated as one-dimensional (perpendicular to the layer, while elsewhere flow was modelled as two-dimensional. The solution in both zones was obtained in the discrete form using the finite element method and the Euler method. The effect of the clogging layer on seepage flow was modelled using the third kind boundary condition. Seepage parameters in the clogging layer were estimated based on laboratory tests conducted by Skolasińska [2006]. Typical problem was taken to provide simulation and indicate how clogging affects the seepage rate and other parameters of the flow. Results showed that clogging at the upstream site has a significant effect on the distribution of seepage velocity and hydraulic gradients. The flow underneath the structure decreases with time, but these changes are relatively slow.

  17. Simulation of the contraction of the ventricles in a human heart model including atria and pericardium.

    Science.gov (United States)

    Fritz, Thomas; Wieners, Christian; Seemann, Gunnar; Steen, Henning; Dössel, Olaf

    2014-06-01

    During the contraction of the ventricles, the ventricles interact with the atria as well as with the pericardium and the surrounding tissue in which the heart is embedded. The atria are stretched, and the atrioventricular plane moves toward the apex. The atrioventricular plane displacement (AVPD) is considered to be a major contributor to the ventricular function, and a reduced AVPD is strongly related to heart failure. At the same time, the epicardium slides almost frictionlessly on the pericardium with permanent contact. Although the interaction between the ventricles, the atria and the pericardium plays an important role for the deformation of the heart, this aspect is usually not considered in computational models. In this work, we present an electromechanical model of the heart, which takes into account the interaction between ventricles, pericardium and atria and allows to reproduce the AVPD. To solve the contact problem of epicardium and pericardium, a contact handling algorithm based on penalty formulation was developed, which ensures frictionless and permanent contact. Two simulations of the ventricular contraction were conducted, one with contact handling of pericardium and heart and one without. In the simulation with contact handling, the atria were stretched during the contraction of the ventricles, while, due to the permanent contact with the pericardium, their volume increased. In contrast to that, in the simulations without pericardium, the atria were also stretched, but the change in the atrial volume was much smaller. Furthermore, the pericardium reduced the radial contraction of the ventricles and at the same time increased the AVPD.

  18. Effect of neurosteroids on a model lipid bilayer including cholesterol: An Atomic Force Microscopy study.

    Science.gov (United States)

    Sacchi, Mattia; Balleza, Daniel; Vena, Giulia; Puia, Giulia; Facci, Paolo; Alessandrini, Andrea

    2015-05-01

    Amphiphilic molecules which have a biological effect on specific membrane proteins, could also affect lipid bilayer properties possibly resulting in a modulation of the overall membrane behavior. In light of this consideration, it is important to study the possible effects of amphiphilic molecule of pharmacological interest on model systems which recapitulate some of the main properties of the biological plasma membranes. In this work we studied the effect of a neurosteroid, Allopregnanolone (3α,5α-tetrahydroprogesterone or Allo), on a model bilayer composed by the ternary lipid mixture DOPC/bSM/chol. We chose ternary mixtures which present, at room temperature, a phase coexistence of liquid ordered (Lo) and liquid disordered (Ld) domains and which reside near to a critical point. We found that Allo, which is able to strongly partition in the lipid bilayer, induces a marked increase in the bilayer area and modifies the relative proportion of the two phases favoring the Ld phase. We also found that the neurosteroid shifts the miscibility temperature to higher values in a way similarly to what happens when the cholesterol concentration is decreased. Interestingly, an isoform of Allo, isoAllopregnanolone (3β,5α-tetrahydroprogesterone or isoAllo), known to inhibit the effects of Allo on GABAA receptors, has an opposite effect on the bilayer properties.

  19. Thermo-mechanical modeling of turbulent heat transfer in gas-solid flows including particle collisions

    Energy Technology Data Exchange (ETDEWEB)

    Mansoori, Zohreh; Saffar-Avval, Majid; Basirat-Tabrizi, Hassan; Ahmadi, Goodarz; Lain, Santiago

    2002-12-01

    A thermo-mechanical turbulence model is developed and used for predicting heat transfer in a gas-solid flow through a vertical pipe with constant wall heat flux. The new four-way interaction model makes use of the thermal k{sub {theta}}-{tau}{sub {theta}} equations, in addition to the hydrodynamic k-{tau} transport, and accounts for the particle-particle and particle-wall collisions through a Eulerian/Lagrangian formulation. The simulation results indicate that the level of thermal turbulence intensity and the heat transfer are strongly affected by the particle collisions. Inter-particle collisions attenuate the thermal turbulence intensity near the wall but somewhat amplify the temperature fluctuations in the pipe core region. The hydrodynamic-to-thermal times-scale ratio and the turbulent Prandtl number in the region near the wall increase due to the inter-particle collisions. The results also show that the use of a constant or the single-phase gas turbulent Prandtl number produces error in the thermal eddy diffusivity and thermal turbulent intensity fields. Simulation results also indicate that the inter-particle contact heat conduction during collision has no significant effect in the range of Reynolds number and particle diameter studied.

  20. The evolution of massive stars including mass loss - Presupernova models and explosion

    Science.gov (United States)

    Woosley, S. E.; Langer, Norbert; Weaver, Thomas A.

    1993-01-01

    The evolution of massive stars of 35, 40, 60, and 85 solar masses is followed through all stages of nuclear burning to the point of Fe core collapse. Critical nuclear reaction and mass-loss rates are varied. Efficient mass loss during the Wolf-Rayet (WR) stage is likely to lead to final masses as small as 4 solar masses. For a reasonable parameterization of the mass loss, there may be convergence of all WR stars, both single and in binaries, to a narrow band of small final masses. Our representative model, a 4.25 solar-mass WR presupernova derived from a 60 solar mass star, is followed through a simulated explosion, and its explosive nucleosynthesis and light curve are determined. Its properties are similar to those observed in Type Ib supernovae. The effects of the initial mass and mass loss on the presupernova structure of small mass WR models is also explored. Important properties of the presupernova star and its explosion can only be obtained by following the complete evolution starting on the main sequence.

  1. Three-Dimensional Magnetohydrodynamic Modeling of the Solar Wind Including Pickup Protons and Turbulence Transport

    Science.gov (United States)

    Usmanov, Arcadi V.; Goldstein, Melvyn L.; Matthaeus, William H.

    2012-01-01

    To study the effects of interstellar pickup protons and turbulence on the structure and dynamics of the solar wind, we have developed a fully three-dimensional magnetohydrodynamic solar wind model that treats interstellar pickup protons as a separate fluid and incorporates the transport of turbulence and turbulent heating. The governing system of equations combines the mean-field equations for the solar wind plasma, magnetic field, and pickup protons and the turbulence transport equations for the turbulent energy, normalized cross-helicity, and correlation length. The model equations account for photoionization of interstellar hydrogen atoms and their charge exchange with solar wind protons, energy transfer from pickup protons to solar wind protons, and plasma heating by turbulent dissipation. Separate mass and energy equations are used for the solar wind and pickup protons, though a single momentum equation is employed under the assumption that the pickup protons are comoving with the solar wind protons.We compute the global structure of the solar wind plasma, magnetic field, and turbulence in the region from 0.3 to 100 AU for a source magnetic dipole on the Sun tilted by 0 deg - .90 deg and compare our results with Voyager 2 observations. The results computed with and without pickup protons are superposed to evaluate quantitatively the deceleration and heating effects of pickup protons, the overall compression of the magnetic field in the outer heliosphere caused by deceleration, and the weakening of corotating interaction regions by the thermal pressure of pickup protons.

  2. Perceptual-center modeling is affected by including acoustic rate-of-change modulations.

    Science.gov (United States)

    Harsin, C A

    1997-02-01

    This study investigated the acoustic correlates of perceptual centers (p-centers) in CV and VC syllables and developed an acoustic p-center model. In Part 1, listeners located syllables' p-centers by a method-of-adjustment procedure. The CV syllables contained the consonants /s/,/r/,/n/,/t/,/d/,/k/, and /g/; the VCs, the consonants /s/,/r/, and /n/. The vowel in all syllables was /a/. The results of this experiment replicated and extended previous findings regarding the effects of phonetic variation on p-centers. In Part 2, a digital signal processing procedure was used to acoustically model p-center perception. Each stimulus was passed through a six-band digital filter, and the outputs were processed to derive low-frequency modulation components. These components were weighted according to a perceived modulation magnitude function and recombined to create six psychoacoustic envelopes containing modulation energies from 3 to 47 Hz. In this analysis, p-centers were found to be highly correlated with the time-weighted function of the rate-of-change in the psychoacoustic envelopes, multiplied by the psychoacoustic envelope magnitude increment. The results were interpreted as suggesting (1) the probable role of low-frequency energy modulations in p-center perception, and (2) the presence of perceptual processes that integrate multiple articulatory events into a single syllabic event.

  3. Influence of litter thickness on the structure of litter macrofauna of deciduous forests of Ukraine’s steppe zone

    Directory of Open Access Journals (Sweden)

    V. V. Brygadyrenko

    2016-02-01

    Full Text Available The litter in a forest ecosystem acts as a trophic substrate, and at the same time it is the environment for litter invertebrates. But despite this fact, there has been very little research conducted on the influence of litter thickness on the structure of litter macrofauna. The litter of steppe forests contains most types of integrated communities of forest ecosystems. This means that its thickness cannot avoid playing a significant role in the functioning of the ecosystem. Following to the standard methodologies, Invertebrates were collected using pit-fall traps in deciduous forests of Nikolaev, Zaporizhzhya, Dnipropetrovsk, Donetsk and Kharkiv oblasts, which are characterized by different types of geomorphological profile, different moisture conditions, soil salinity, tree crown and herbaceous vegetation density, soil texture and other factors. The total number of macrofauna increases in conditions where litter thickness exceeds40 mmin comparison with forest ecosystems with fragmented and average capacity litter. The number of litter macrofauna species also increases from 11–23 to 38 species on average when litter thickness increases to more than40 mm. The Shannon and Pielou diversity indexes show no definite tendencies to change in relation to changing degrees of litter thickness. At sites of greater thickness of the litter layer, the corresponding increase in the absolute number of litter mesofauna invertebrates is mostly due to saprophages, and the increase the number of species – due to zoophages. The optimum structure of domination was observed at sites with maximum thickness of litter. The proportion of large species shows no statistically significant change in relation to variations in litter thickness. The qualitative compound of the fauna at sites with thick litter changes mainly due to an increase in the number of Carabidae species.

  4. Subtidal littering: Indirect effects on soft substratum macrofauna?

    Directory of Open Access Journals (Sweden)

    I. AKOUMIANAKI

    2012-12-01

    Full Text Available Changes in macrofauna community structure, abundance and species richness were examined both before and one year after the deployment of plastic and glass bottles at littered (litter density: 16 items / 100 m2 and non-littered (control surfaces at three unimpacted coastal areas of the western Saronikos Gulf (Greece. In parallel, LOI% at the adjacent sediments and changes in the composition of feeding types of the megaepifauna that colonized the litter were examined across treatments. Significant changes in macrofauna community structure were demonstrated between before and after littering. At only one of the sites was there detected a significant difference in macrofauna community structure between control and littered plots after littering. This difference was linked with a significant increase in the abundance of opportunistic polychaete species and LOI% levels in the sediment surface due to the entrapment of macrophytal debris within the littered surface. The study did not show a consistent direct response of macroinfauna community to litter and the associated megafauna. Unlike the megafauna attracted by litter items, soft-substratum macrofauna is less responsive to the addition of novel hard substrates in adjacent sediments. Alternatively, it could be that the impact of littering with small items triggers a macrofauna response detectable in the long-run.

  5. The effects of UV radiation, litter chemistry, and drought on desert litter decomposition

    Science.gov (United States)

    Lee, H.; Nieto, B.; Hewins, D. B.; Barnes, P. W.; McDowell, N. G.; Pockman, W.; Rahn, T.; Throop, H. L.

    2011-12-01

    Recent studies suggest that photodegradation by solar UV radiation can be a major driver of litter decomposition in dryland ecosystems. The importance of photodegradation in litter decomposition appears to decline with precipitation, suggesting that the relative importance of photodegradation may increase given current projections of future increases in drought severity in the southwestern USA. Several previous studies indicate that UV-B radiation (280-320 nm) is the most effective waveband in breaking chemical bonds forming organic material, but whether UV-B exposure may facilitate subsequent decomposition by microbes (i.e., photo-priming) has received little attention. In this study, we tested the effects of pre-exposure UV radiation (photo-priming), litter chemistry (lignin and cellulose content and nitrogen content), and drought on the rate of litter decomposition in a semi-arid ecosystem. To understand the effects of UV radiation on litter decomposition, we pre-exposed litter to three radiation treatments: control (no radiation), UV-A+visible, UV-A+UV-B+visible. Litter was exposed to the equivalent of three months' solar radiation of southern New Mexico prior to microbial decomposition. There were three litter types: basswood sheets (high lignin content), pure cellulose filter paper, and mesquite (Prosopis glandulosa) leaflets. Following radiation treatment, litter was placed in mesh litterbags that were buried within a large-scale precipitation manipulation experiment at the Sevilleta Long-Term Ecological Research site: control (ambient precipitation), elevated precipitation (x2 ambient precipitation), and drought (x0.5 ambient precipitation). We collected a subset of bags at 0, 1, 3, and 6 months and measured mass remaining and carbon (C) and nitrogen (N) content. After 6 months, mass remaining of filter paper and basswood sheets did not differ from the initial mass, but mesquite mass remaining declined over 30%. The pre-exposure UV effects had minimal

  6. Experimental cell transplantation therapy in rat myocardial infarction model including nude rat preparation.

    Science.gov (United States)

    Dai, Wangde; Kloner, Robert A

    2010-01-01

    As a novel potential therapeutic strategy for cardiac disease, cell transplantation therapy has been extensively investigated in experimental studies and clinical trials. Although encouraging results have been demonstrated, a number of critical questions still remain to be answered. For example, what kind of stem cell and how many cells should be used; what is the best time for cell transplantation after acute myocardial infarction; which delivery approach is better, intravenous injection or direct intramyocardial injection? Transplantation of cells derived from human tissues into experimental animals may elicit an immune rejection. Immunodeficient nude rats provide a useful myocardial infarction model for cell transplantation therapy studies. We introduce our detailed methods of direct intramyocardial injection of immature heart cells and stem cells into the myocardial infarction region of rats and nude rats. Careful maintenance under aseptic conditions and proper surgical technique are essential to improve the survival of immunodeficient rats after surgery.

  7. Including ethical considerations in models for first-trimester screening for pre-eclampsia

    DEFF Research Database (Denmark)

    Jørgensen, Jennifer Maureen; Hedley, Paula L.; Gjerris, Mickey;

    2014-01-01

    Recent efforts to develop reliable and efficient early pregnancy screening programmes for pre-eclampsia have focused on com-bining clinical, biochemical and biophysical markers. The same model has been used for first-trimester screening for fetal aneuploidies i.e. prenatal diagnosis (PD), which...... is routinely offered to all pregnant women in many developed countries. Some studies suggest combining PD and pre-eclampsia screening, so women can be offered testing for a number of conditions at the same clinical visit. A combination of these tests may be practical in terms of saving time and resources......; however, the combination raises ethical issues. First-trimester PD and pre-eclampsia screening entail qualitative differences which alter the requirements for disclosure, non-directedness and consent with regard to the informed consent process. This article explores the differences related to the ethical...

  8. Memory of the Vernalized State in Plants including the Model Grass Brachypodium distachyon

    Directory of Open Access Journals (Sweden)

    Daniel P Woods

    2014-03-01

    Full Text Available Plant species that have a vernalization requirement exhibit variation in the ability to remember winter—i.e., variation in the stability of the vernalized state. Studies in Arabidopsis have demonstrated that molecular memory involves changes in the chromatin state and expression of the flowering repressor FLOWERING LOCUS C, and have revealed that single-gene differences can have large effects on the stability of the vernalized state. In the perennial Arabidopsis relative Arabis alpina, the lack of memory of winter is critical for its perennial life history. Our studies of flowering behavior in the model grass Brachypodium distachyon reveal extensive variation in the vernalization requirement, and studies of a particular Brachypodium accession that has a qualitative requirement for both cold exposure and inductive daylength reveals that Brachypodium can exhibit a highly stable vernalized state.

  9. The economic production lot size model extended to include more than one production rate

    DEFF Research Database (Denmark)

    Larsen, Christian

    2001-01-01

    btween the demand rate and the production rate which minimizes unit production costs, and should be used in an increasing order. Then, given the production rates, we derive closed-form expressions for all optimal runtimes as well as the minimum average cost. This analysis reveals that it is the size......We study an extension of the economic production lot size model, where more than one production rate can be used during a cycle. Moreover, the production rates, as well as their corresponding runtimes are decision variables. First, we show that all production rates should be choosen in the interval...... of the setup cost that determines the need for being able to use several production rates. Finally, we show how to derive a near-optimal solution of the general problem....

  10. The economic production lot size model extended to include more than one production rate

    DEFF Research Database (Denmark)

    Larsen, Christian

    2005-01-01

    production rates should be chosen in the interval between the demand rate and the production rate which minimizes unit production costs, and should be used in an increasing order. Then, given the production rates, we derive closed-form expressions for all optimal runtimes as well as the minimum average cost......We study an extension of the economic production lot size model, where more than one production rate can be used during a cycle. Moreover, the production rates, as well as their corresponding runtimes are decision variables. We decompose the problem into two subproblems. First, we show that all....... This analysis reveals that it is the size of the setup cost that determines the need for being able to use several production rates. We also show how to derive a near-optimal solution of the general problem....

  11. Modelling of safety barriers including human and organisational factors to improve process safety

    DEFF Research Database (Denmark)

    Markert, Frank; Duijm, Nijs Jan; Thommesen, Jacob

    2013-01-01

    explosion, and the Mont Blanc Tunnel Fire, such an approach may have helped to maintain the integrity of the designed provisions against major deviations resulting in these disasters. In order to make this paradigm operational, safety management and in particular risk assessment tools need to be refined....... A valuable approach is the inclusion of human and organisational factors into the simulation of the reliability of the technical system using event trees and fault trees and the concept of safety barriers. This has been demonstrated e.g. in the former European research project ARAMIS (Accidental Risk...... Assessment Methodology for IndustrieS, see Salvi et al 2006). ARAMIS employs the bow-tie approach to modelling hazardous scenarios, and it suggests the outcome of auditing safety management to be connected to a semi-quantitative assessment of the quality of safety barriers. ARAMIS discriminates a number...

  12. Non-insect crustacean models in developmental genetics including an encomium to Parhyale hawaiensis.

    Science.gov (United States)

    Stamataki, Evangelia; Pavlopoulos, Anastasios

    2016-08-01

    The impressive diversity of body plans, lifestyles and segmental specializations exhibited by crustaceans (barnacles, copepods, shrimps, crabs, lobsters and their kin) provides great material to address longstanding questions in evolutionary developmental biology. Recent advances in forward and reverse genetics and in imaging approaches applied in the amphipod Parhyale hawaiensis and other emerging crustacean model species have made it possible to probe the molecular and cellular basis of crustacean diversity. A number of biological and technical qualities like the slow tempo and holoblastic cleavage mode, the stereotypy of many cellular processes, the functional and morphological diversity of limbs along the body axis, and the availability of various experimental manipulations, have made Parhyale a powerful system to study normal development and regeneration. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Robust and Adaptive OMR System Including Fuzzy Modeling, Fusion of Musical Rules, and Possible Error Detection

    Directory of Open Access Journals (Sweden)

    Isabelle Bloch

    2007-01-01

    Full Text Available This paper describes a system for optical music recognition (OMR in case of monophonic typeset scores. After clarifying the difficulties specific to this domain, we propose appropriate solutions at both image analysis level and high-level interpretation. Thus, a recognition and segmentation method is designed, that allows dealing with common printing defects and numerous symbol interconnections. Then, musical rules are modeled and integrated, in order to make a consistent decision. This high-level interpretation step relies on the fuzzy sets and possibility framework, since it allows dealing with symbol variability, flexibility, and imprecision of music rules, and merging all these heterogeneous pieces of information. Other innovative features are the indication of potential errors and the possibility of applying learning procedures, in order to gain in robustness. Experiments conducted on a large data base show that the proposed method constitutes an interesting contribution to OMR.

  14. Robust and Adaptive OMR System Including Fuzzy Modeling, Fusion of Musical Rules, and Possible Error Detection

    Science.gov (United States)

    Rossant, Florence; Bloch, Isabelle

    2006-12-01

    This paper describes a system for optical music recognition (OMR) in case of monophonic typeset scores. After clarifying the difficulties specific to this domain, we propose appropriate solutions at both image analysis level and high-level interpretation. Thus, a recognition and segmentation method is designed, that allows dealing with common printing defects and numerous symbol interconnections. Then, musical rules are modeled and integrated, in order to make a consistent decision. This high-level interpretation step relies on the fuzzy sets and possibility framework, since it allows dealing with symbol variability, flexibility, and imprecision of music rules, and merging all these heterogeneous pieces of information. Other innovative features are the indication of potential errors and the possibility of applying learning procedures, in order to gain in robustness. Experiments conducted on a large data base show that the proposed method constitutes an interesting contribution to OMR.

  15. Parsing recursive sentences with a connectionist model including a neural stack and synaptic gating.

    Science.gov (United States)

    Fedor, Anna; Ittzés, Péter; Szathmáry, Eörs

    2011-02-21

    It is supposed that humans are genetically predisposed to be able to recognize sequences of context-free grammars with centre-embedded recursion while other primates are restricted to the recognition of finite state grammars with tail-recursion. Our aim was to construct a minimalist neural network that is able to parse artificial sentences of both grammars in an efficient way without using the biologically unrealistic backpropagation algorithm. The core of this network is a neural stack-like memory where the push and pop operations are regulated by synaptic gating on the connections between the layers of the stack. The network correctly categorizes novel sentences of both grammars after training. We suggest that the introduction of the neural stack memory will turn out to be substantial for any biological 'hierarchical processor' and the minimalist design of the model suggests a quest for similar, realistic neural architectures.

  16. Areal rainfall estimation using moving cars - computer experiments including hydrological modeling

    Science.gov (United States)

    Rabiei, Ehsan; Haberlandt, Uwe; Sester, Monika; Fitzner, Daniel; Wallner, Markus

    2016-09-01

    The need for high temporal and spatial resolution precipitation data for hydrological analyses has been discussed in several studies. Although rain gauges provide valuable information, a very dense rain gauge network is costly. As a result, several new ideas have emerged to help estimating areal rainfall with higher temporal and spatial resolution. Rabiei et al. (2013) observed that moving cars, called RainCars (RCs), can potentially be a new source of data for measuring rain rate. The optical sensors used in that study are designed for operating the windscreen wipers and showed promising results for rainfall measurement purposes. Their measurement accuracy has been quantified in laboratory experiments. Considering explicitly those errors, the main objective of this study is to investigate the benefit of using RCs for estimating areal rainfall. For that, computer experiments are carried out, where radar rainfall is considered as the reference and the other sources of data, i.e., RCs and rain gauges, are extracted from radar data. Comparing the quality of areal rainfall estimation by RCs with rain gauges and reference data helps to investigate the benefit of the RCs. The value of this additional source of data is not only assessed for areal rainfall estimation performance but also for use in hydrological modeling. Considering measurement errors derived from laboratory experiments, the result shows that the RCs provide useful additional information for areal rainfall estimation as well as for hydrological modeling. Moreover, by testing larger uncertainties for RCs, they observed to be useful up to a certain level for areal rainfall estimation and discharge simulation.

  17. ECO: a generic eutrophication model including comprehensive sediment-water interaction.

    Directory of Open Access Journals (Sweden)

    Johannes G C Smits

    Full Text Available The content and calibration of the comprehensive generic 3D eutrophication model ECO for water and sediment quality is presented. Based on a computational grid for water and sediment, ECO is used as a tool for water quality management to simulate concentrations and mass fluxes of nutrients (N, P, Si, phytoplankton species, detrital organic matter, electron acceptors and related substances. ECO combines integral simulation of water and sediment quality with sediment diagenesis and closed mass balances. Its advanced process formulations for substances in the water column and the bed sediment were developed to allow for a much more dynamic calculation of the sediment-water exchange fluxes of nutrients as resulting from steep concentration gradients across the sediment-water interface than is possible with o