scholarly journals Absence of mutual unbounded growth for almost all parameter values in the two-type Richardson model

2000 ◽  
Vol 90 (2) ◽  
pp. 207-222 ◽  
Author(s):  
Olle Häggström ◽  
Robin Pemantle
Keyword(s):  
Almost All ◽  
Parameter Values

Aromatic hydrocarbons from the Middle Jurassic fossil wood of the Polish Jura

2013 ◽  
Vol 2 (1) ◽  
pp. 82-90
Author(s):  
Justyna Smolarek ◽  
Leszek Marynowski
Keyword(s):  
Organic Matter ◽  
Aromatic Hydrocarbons ◽  
Middle Jurassic ◽  
Vitrinite Reflectance ◽  
Fossil Wood ◽  
Terrestrial Organic Matter ◽  
Weathering Processes ◽  
Diagenetic Processes ◽  
Almost All ◽  
Parameter Values

ABSTRACT Aromatic hydrocarbons are present in the fossil wood samples in relatively small amounts. In almost all of the tested samples the dominating aromatic hydrocarbon is perylene and its methyl and dimethyl derivatives. The most important biomarkers present in the aromatic fraction are dehydroabietane, siomonellite and retene, compounds characteristic for conifers. The distribution of discussed compounds is highly variable due to such early diagenetic processes affecting the wood as oxidation and the activity of microorganisms. MPI1 parameter values (methylphenanthrene index) for the majority of the samples are in the range of 0.1 to 0.5, which results in the highly variable values of Rc (converted value of vitrinite reflectance) ranging from 0.45 to 0.70%. Such values suggest that MPI1 parameter is not useful as maturity parameter in case of Middle Jurassic ore-bearing clays, even if measured strictly on terrestrial organic matter (OM). As a result of weathering processes (oxidation) the distribution of aromatic hydrocarbons changes. In the oxidized samples the amount of aromatic hydrocarbons, both polycyclic as well as aromatic biomarkers decreases.

Integrable deformations, bi-Hamiltonian structures and nonintegrability of a generalized Rikitake system

2019 ◽  
Vol 16 (04) ◽  
pp. 1950059 ◽  
Author(s):  
Kaiyin Huang ◽  
Shaoyun Shi ◽  
Zhiguo Xu
Keyword(s):  
Galois Groups ◽  
Point Of View ◽  
Integrable Case ◽  
Analytic First Integrals ◽  
Rikitake System ◽  
Constants Of Motion ◽  
Integrable Deformations ◽  
Particular Solution ◽  
Almost All ◽  
Parameter Values

The aim of this paper is to investigate a generalized Rikitake system from the integrability point of view. For the integrable case, we derive a family of integrable deformations of the generalized Rikitake system by altering its constants of motion, and give two classes of Hamilton–Poisson structures which implies these integrable deformations, including the generalized Rikitake system, are bi-Hamiltonian and have infinitely many Hamilton–Poisson realizations. By analyzing properties of the differential Galois groups of normal variational equations (NVEs) along certain particular solution, we show that the generalized Rikitake system is not rationally integrable in an extended Liouville sense for almost all parameter values, which is in accord with the fact that this system admits chaotic behaviors for a large range of its parameters. The non-existence of analytic first integrals are also discussed.

scholarly journals GC-MS vs. GC-MS-MS analysis of pentacyclic terpanes in crude oils from Libya and Serbia - a comparison of two methods

2017 ◽  
Vol 82 (11) ◽  
pp. 1315-1331 ◽  
Author(s):  
Musbah Faraj ◽  
Tatjana Solevic-Knudsen ◽  
Ksenija Stojanovic ◽  
Sonja Ivkovic-Pavlovic ◽  
Hans Nytoft ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Oil Field ◽  
Oil Fields ◽  
Gas Chromatography Mass Spectrometry ◽  
Crude Oils ◽  
Chromatography Mass Spectrometry ◽  
Almost All ◽  
Parameter Values ◽  
H 30

The values of parameters calculated from distribution and abundance of the selected pentacyclic terpanes in crude oils from Libya and Serbia, which were originally derived from gas chromatography-mass spectrometry (GC?MS) were compared with results of quantification based on gas chromatography? ?mass spectrometry-mass spectrometry (GC?MS-MS). The parameters analyzed are the most often used terpane source and maturity parameters, which were applied to a large sample set of 70 oils, originating from five oil fields. The aim of the paper was to investigate to which extent the measurements of the selected parameters by these two instrumental techniques agree and to determine the influence of differences between parameter values on geochemical interpretation. For that purpose two methods, concordance correlation coefficient and mean-difference plot were used. The obtained results indicate that calculation of C2718?(H)-22,29,30-trisnorneohopane/(C2718?(H)-22,29,30- -trisnorneohopane + C2717?(H)-22,29,30-trisnorhopane), C2918?(H)-30-norneohopane/ C2917?(H)21?(H)-30-norhopane and C2917?(H)21?(H)-30-norhopane/ C3017?(H)21?(H)-hopane ratios either by GC?MS or GC?MS-MS do not significantly influence interpretation. On the other hand, the determination of C3017?(H)21?(H)-moretane/C3017?(H)21?(H)-hopane ratio, gammacerane index and oleanane index by GC?MS vs. GC-MS-MS could notably affect interpretation. These differences can be explained by the co-elution and the peak overlapping in GC?MS but also by better separation, higher precision and better selectivity of the GC?MS-MS. Deviation of the almost all studied parameters from the line of equality was similar for the oils from the same oil field but some differences were observed for the oils from different oil fields. Therefore, when GC?MS-MS results are to be used in organic geochemical interpretations, a regional calibration of GC?MS vs. GC-MS-MS relationship for each petroleum system is highly recommended.

scholarly journals A mathematical model of the defence mechanism of a bombardier beetle

2013 ◽  
Vol 10 (79) ◽  
pp. 20120801 ◽  
Author(s):  
Alex James ◽  
Ken Morison ◽  
Simon Todd
Keyword(s):  
Mathematical Model ◽  
Pulsed Discharge ◽  
Defence Mechanism ◽  
Cyclic Behaviour ◽  
Realistic Parameter ◽  
Almost All ◽  
Parameter Values ◽  
Continuous Discharge

Previous studies of bombardier beetles have shown that some species have a continuous discharge while others exhibit a pulsed discharge. Here, a mathematical model of the defence mechanism of the bombardier beetle is developed and the hypothesis that almost all bombardiers' defences have some sort of cyclic behaviour at frequencies much higher than previously thought is put forward. The observation of pulses arises from secondary lower frequency cycles that appear for some parameter values. For realistic parameter values, the model can exhibit all the characteristics seen in the various species of bombardier. The possibility that all bombardiers have the same underlying defence mechanism gives weight to the theory that all bombardiers' explosive secretory mechanisms have diversified from a common ancestral mechanism.

scholarly journals Should Urban Transit Subsidies Be Reduced?

2009 ◽  
Vol 99 (3) ◽  
pp. 700-724 ◽  
Author(s):  
Ian W. H Parry ◽  
Kenneth A Small
Keyword(s):  
Los Angeles ◽  
Operating Costs ◽  
Optimal Pricing ◽  
Washington Dc ◽  
Urban Transit ◽  
Transit Service ◽  
Bus Transit ◽  
Large Current ◽  
Almost All ◽  
Parameter Values

This paper derives empirically tractable formulas for the welfare effects of fare adjustments in passenger peak and off-peak rail and bus transit, and for optimal pricing of those services. The formulas account for congestion, pollution, accident externalities, scale economies, and agency adjustment of transit service offerings. We apply them using parameter values for Washington (DC), Los Angeles, and London. The results support the efficiency of the large current fare subsidies; even starting with fares at 50 percent of operating costs, incremental fare reductions are welfare improving in almost all cases. These findings are robust to alternative assumptions and parameters. (JEL L92, R41, R42, R48)

Strange Nonchaotic Attractors From a Family of Quasiperiodically Forced Piecewise Linear Maps

2021 ◽  
Vol 31 (07) ◽  
pp. 2150111
Author(s):  
Denghui Li ◽  
Zhenbang Cao ◽  
Xiaoming Zhang ◽  
Celso Grebogi ◽  
Jianhua Xie
Keyword(s):  
Continuous Function ◽  
Lyapunov Exponents ◽  
Piecewise Linear ◽  
Almost Everywhere ◽  
Linear Maps ◽  
Piecewise Linear Maps ◽  
Strange Nonchaotic Attractors ◽  
Almost All ◽  
Parameter Values ◽  
Theoretical Results

In this paper, a family of quasiperiodically forced piecewise linear maps is considered. It is proved that there exists a unique strange nonchaotic attractor for some set of parameter values. It is the graph of an upper semi-continuous function, which is invariant, discontinuous almost everywhere and attracts almost all orbits. Moreover, both Lyapunov exponents on the attractor is nonpositive. Finally, to demonstrate and validate our theoretical results, numerical simulations are presented to exhibit the corresponding phase portrait and Lyapunov exponents portrait.

scholarly journals Combination of Anns and Heuristic Algorithms in Modelling and Optimizing of Fenton Processes for Industrial Wastewater Treatment

2021 ◽  
Author(s):  
Hüseyin Cüce ◽  
Ozge Cagcag Yolcu ◽  
Fulya AYDIN TEMEL
Keyword(s):  
Neural Networks ◽  
Industrial Wastewater ◽  
Prediction Models ◽  
Heuristic Algorithms ◽  
Batch Reactors ◽  
Multi Layer Perceptron ◽  
Data Set ◽  
Almost All ◽  
Parameter Values ◽  
Maximum Removal

Abstract In this study, it is aimed to evaluate COD removal performance of Classical-Fenton and Photo-Fenton Processes from cosmetic wastewater by different prediction models. Besides Response Surface Methodology (RSM), three neural networks were used to more reliably and effectively predict the behavior of dependent variable at different values of relevant parameters. These neural networks; multi-layer perceptron trained by Levenberg-Marquardt (MLP-LM); multi-layer perceptron and single multiplicative neuron model trained by particle swarm optimization algorithm (MLP-PSO; SMN-PSO). H2O2 doses, Fe(II) doses, and H2O2/Fe(II) rates were independent variables of prediction models to optimize both processes in batch reactors. The generated predictions for whole data set were compared with each other. The prediction performances of models were evaluated by RMSE and MAPE error criteria. Regression analysis was also applied to determine the performance of the best model. The results obtained from all prediction tools showed that the model produces the best predictive results in almost all cases is SMN-PSO model in terms of both criteria. In addition, the genetic algorithm was utilized for SMN-PSO model results to find the optimum values of the study. Thus, without the need to perform many different experiments, the optimum parameter values can be determined to get maximum removal ratios.

Does Model Calibration Reduce Uncertainty in Climate Projections?

2022 ◽  
pp. 1-39
Keyword(s):  
Model Calibration ◽  
Large Scale ◽  
Climate Model ◽  
Climate Projections ◽  
Transient Climate Response ◽  
Model Configuration ◽  
Model Ensembles ◽  
Almost All ◽  
Parameter Values ◽  
Better Than

Abstract Uncertainty in climate projections is large as shown by the likely uncertainty ranges in Equilibrium Climate Sensitivity (ECS) of 2.5-4K and in the Transient Climate Response (TCR) of 1.4-2.2K. Uncertainty in model projections could arise from the way in which unresolved processes are represented, the parameter values used, or the targets for model calibration. We show that, in two climate model ensembles which were objectively calibrated to minimise differences from observed large scale atmospheric climatology, uncertainties in ECS and TCR are about two to six times smaller than in the CMIP5 or CMIP6 multi-model ensemble. We also find that projected uncertainties in surface temperature, precipitation and annual extremes are relatively small. Residual uncertainty largely arises from unconstrained sea-ice feedbacks. The 20+ year old HadAM3 standard model configuration simulates observed hemispheric scale observations and pre-industrial surface temperatures about as well as the median CMIP5 and CMIP6 ensembles while the optimised configurations simulates these better than almost all the CMIP5 and CMIP6 models. Hemispheric scale observations and pre-industrial temperatures are not systematically better simulated in CMIP6 than in CMIP5 though the CMIP6 ensemble seems to better simulate patterns of large-scale observations than the CMIP5 ensemble and the optimised HadAM3 configurations. Our results suggest that most CMIP models could be improved in their simulation of large scale observations by systematic calibration. However, the uncertainty in climate projections (for a given scenario) likely largely arises from the choice of parametrisation schemes for unresolved processes (“structural uncertainty”), with different tuning targets another possible contributor.

Habitat Association of Klebsiella Species

1985 ◽  
Vol 6 (2) ◽  
pp. 52-58 ◽  
Author(s):  
Susan T. Bagley
Keyword(s):  
Drinking Water ◽  
Gastrointestinal Tract ◽  
Surface Waters ◽  
Industrial Effluents ◽  
Opportunistic Pathogen ◽  
Habitat Associations ◽  
Habitat Association ◽  
Klebsiella Species ◽  
Almost All ◽  
Polluted Waters

AbstractThe genus Klebsiella is seemingly ubiquitous in terms of its habitat associations. Klebsiella is a common opportunistic pathogen for humans and other animals, as well as being resident or transient flora (particularly in the gastrointestinal tract). Other habitats include sewage, drinking water, soils, surface waters, industrial effluents, and vegetation. Until recently, almost all these Klebsiella have been identified as one species, ie, K. pneumoniae. However, phenotypic and genotypic studies have shown that “K. pneumoniae” actually consists of at least four species, all with distinct characteristics and habitats. General habitat associations of Klebsiella species are as follows: K. pneumoniae—humans, animals, sewage, and polluted waters and soils; K. oxytoca—frequent association with most habitats; K. terrigena— unpolluted surface waters and soils, drinking water, and vegetation; K. planticola—sewage, polluted surface waters, soils, and vegetation; and K. ozaenae/K. rhinoscleromatis—infrequently detected (primarily with humans).

SEM Cold Stage Techniques for the Observation of Vegetative and Floral Apices of Oat (Avena sativa L.) Plants

1977 ◽  
Vol 35 ◽  
pp. 590-591
Author(s):  
B. K. Kirchoff ◽  
L.F. Allard ◽  
W.C. Bigelow
Keyword(s):  
Critical Point ◽  
Avena Sativa ◽  
Substantial Improvement ◽  
Fresh Tissue ◽  
Cold Stage ◽  
Critical Point Drying ◽  
Almost All ◽  
Cell Collapse ◽  
Conductive Paint ◽  
Carbon Based

In attempting to use the SEM to investigate the transition from the vegetative to the floral state in oat (Avena sativa L.) it was discovered that the procedures of fixation and critical point drying (CPD), and fresh tissue examination of the specimens gave unsatisfactory results. In most cases, by using these techniques, cells of the tissue were collapsed or otherwise visibly distorted. Figure 1 shows the results of fixation with 4.5% formaldehyde-gluteraldehyde followed by CPD. Almost all cellular detail has been obscured by the resulting shrinkage distortions. The larger cracks seen on the left of the picture may be due to dissection damage, rather than CPD. The results of observation of fresh tissue are seen in Fig. 2. Although there is a substantial improvement over CPD, some cell collapse still occurs.Due to these difficulties, it was decided to experiment with cold stage techniques. The specimens to be observed were dissected out and attached to the sample stub using a carbon based conductive paint in acetone.

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