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1
Dochain, D., and M. Perrier. "Control Design for Nonlinear Wastewater Treatment Processes." Water Science and Technology 28, no. 11-12 (December 1, 1993): 283–93. http://dx.doi.org/10.2166/wst.1993.0668.
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This paper deals with the design of adaptive nonlinear control algorithms of biological wastewater treatment processes. The control design is based on the dynamical mass balance equations of the process and includes the on-line estimation of uncertain parameters (specific growth rates and yield coefficients). The procedure is illustrated by two examples (activated sludge process, anaerobic digestion).
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Upadhyay, Ranjit Kumar, Ashok Kumar Pal, Sangeeta Kumari, and Parimita Roy. "Dynamics of an SEIR epidemic model with nonlinear incidence and treatment rates." Nonlinear Dynamics 96, no. 4 (April 4, 2019): 2351–68. http://dx.doi.org/10.1007/s11071-019-04926-6.
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Kumar, Abhishek. "Stability of a Fractional-Order Epidemic Model with Nonlinear Incidences and Treatment Rates." Iranian Journal of Science and Technology, Transactions A: Science 44, no. 5 (August 27, 2020): 1505–17. http://dx.doi.org/10.1007/s40995-020-00960-x.
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Kumar, Abhishek, and Nilam. "Mathematical analysis of a delayed epidemic model with nonlinear incidence and treatment rates." Journal of Engineering Mathematics 115, no. 1 (March 7, 2019): 1–20. http://dx.doi.org/10.1007/s10665-019-09989-3.
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DUBEY, B., ATASI PATRA, P. K. SRIVASTAVA, and UMA S. DUBEY. "MODELING AND ANALYSIS OF AN SEIR MODEL WITH DIFFERENT TYPES OF NONLINEAR TREATMENT RATES." Journal of Biological Systems 21, no. 03 (September 2013): 1350023. http://dx.doi.org/10.1142/s021833901350023x.
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In this study, an SEIR epidemic model is proposed for treatment of infectives considering the development of acquired immunity in recovered individuals. We employed two different types of treatment functions. Stability analysis for disease-free as well as endemic equilibria is performed. It is observed that the existence of unique endemic equilibrium depends on the basic reproductive number R0as well as on treatment rate. Numerical simulations are performed on the proposed models to support and analyze theoretical findings.
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Li, Junhong, and Ning Cui. "Dynamic Behavior for an SIRS Model with Nonlinear Incidence Rate and Treatment." Scientific World Journal 2013 (2013): 1–5. http://dx.doi.org/10.1155/2013/209256.
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This paper considers an SIRS model with nonlinear incidence rate and treatment. It is assumed that susceptible and infectious individuals have constant immigration rates. We investigate the existence of equilibrium and prove the global asymptotical stable results of the endemic equilibrium. We then obtained that the model undergoes a Hopf bifurcation and existences a limit cycle. Some numerical simulations are given to illustrate the analytical results.
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Jin, Li, Yunxian Dai, Yu Xiao, and Yiping Lin. "RANK-ONE CHAOS IN A DELAYED SIR EPIDEMIC MODEL WITH NONLINEAR INCIDENCE AND TREATMENT RATES." Journal of Applied Analysis & Computation 11, no. 4 (2021): 1779–801. http://dx.doi.org/10.11948/20200190.
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Halder, Manisha, and Dr D. S. Sharma. "A Mathematical Analysis of Dynamical Behaviour of Epidemiological Models with Nonlinear Incidence Rates." International Journal of Scientific Research in Modern Science and Technology 2, no. 5 (May 31, 2023): 33–40. http://dx.doi.org/10.59828/ijsrmst.v2i5.86.
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An updated model of an epidemic is discussed, one in which incidence has plateaued but treatment has not been fully implemented. All equilibrium points are checked for existence. In this research, we examine how shifts from the SIR (susceptible-infectious-resistant) to the SIS (susceptible-infectious-susceptible) paradigm manifest in epidemiological models. These models hypothesize that the irresistible power is a nonlinear capability of the populace thickness of contaminated individuals. At last, this model might be utilized to research the elements of infection spread, provided that the two phenomena follow consistent patterns.
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Grey, T. L., D. C. Bridges, P. L. Raymer, and J. W. Davis. "Imazethapyr Rate Responses for Wild Radish, Conventional Canola, and Imidazolinone-tolerant Canola." Plant Health Progress 7, no. 1 (January 2006): 8. http://dx.doi.org/10.1094/php-2006-1018-01-rs.
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Greenhouse experiments were conducted to determine dose responses to imazethapyr for imidazolinone-tolerant canola (Brassica napus) Pioneer 45A71, conventional canola Oscar, and wild radish (Raphanus raphanistrum). Two weeks after treatment, foliar injury was rated and plants were harvested to determine plant dry weight. Plant responses to herbicide treatments were analyzed by nonlinear regression procedures using a modified Mitscherlich plant growth model for visual injury and the negative exponential growth function for plant dry weight. Pioneer 45A71 was tolerant of all rates of imazethapyr (0.055 to 0.60 g ai/liter). In contrast, wild radish and Oscar were sensitive to imazethapyr with significant injury and approximately 50% reduction in dry plant weight at rates of 0.275 g ai/liter and greater. For the model, increased injury from herbicide treatment resulted in significantly different asymptotic maximum (βo) injury for all plant types. The dry weight for the non-treated control was 1.3, 0.8, and 1.5 g/plant for wild radish, Pioneer 45A71, and Oscar, respectively. For the models, β1 parameters indicated significant differences in response to imazethapyr treatment between the Pioneer 45A71, wild radish, and Oscar dry weights. Accepted for publication 3 July 2006. Published 18 October 2006.
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Davies, Geraint R., Richard Brindle, Saye H. Khoo, and Leon J. Aarons. "Use of Nonlinear Mixed-Effects Analysis for Improved Precision of Early Pharmacodynamic Measures in Tuberculosis Treatment." Antimicrobial Agents and Chemotherapy 50, no. 9 (September 2006): 3154–56. http://dx.doi.org/10.1128/aac.00774-05.
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ABSTRACT Nonlinear mixed-effects analysis of serial sputum colony-counting data supports the existence of two bacillary subpopulations in sputum, eliminated at different rates. It distinguishes between combination regimens, removes bias, and greatly improves precision, with significant implications for the analysis of surrogate endpoints of “sterilization” in the development of new antituberculosis regimens.
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Overall, John E., Scott Tonidandel, and Joy M. Schmitz. "Testing the Significance of Difference in Average Rates of Change in Controlled Longitudinal Studies With High Dropout Rates." Methodology 5, no. 2 (January 2009): 46–54. http://dx.doi.org/10.1027/1614-2241.5.2.46.
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This article concerns methodology for testing the significance of differences in mean rates of change in controlled repeated measurements designs with limited sample sizes, autoregressive error structures, nonlinear patterns of underlying true mean change, dropout rates exceeding 50%, plus other missing data. Each of these is problematic for ordinary repeated measures analysis of variance, and a complex generalized linear mixed model formulation popularly advocated for the ability to deal with autoregressive error structures and missing data is shown to perform poorly in such circumstances. Monte Carlo simulation methods confirm that simple two-stage analyses of dropout-weighted linear slope coefficients provide conservative Type 1 error protection, although adequate power requires the presence of large treatment effects in studies with the limited sample sizes and high proportions of missing data. No other analysis has been documented to provide both conservative Type 1 error protection and competitive power under similarly taxing conditions.
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Hussaini, N., and M. Winter. "Travelling waves for an epidemic model with non-smooth treatment rates." Journal of Statistical Mechanics: Theory and Experiment 2010, no. 11 (November 9, 2010): P11019. http://dx.doi.org/10.1088/1742-5468/2010/11/p11019.
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Samuilik, Inna, and Felix Sadyrbaev. "Mathematical Modelling of Leukemia Treatment." WSEAS TRANSACTIONS ON COMPUTERS 20 (October 23, 2021): 274–81. http://dx.doi.org/10.37394/23205.2021.20.30.
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Leukemia is a cancer that can be treated in a variety of ways: chemotherapy, radiation therapy and stem cell transplant. Recovery rates for this disease are relatively high, the treatment itself has a painful effect on the body and is accompanied by numerous side effects that can persist years after the patient is cured. For this reason, efforts are underway worldwide to develop more selective therapies that will only affect leukemia cells and not healthy cells. Knowledge of developmental GRN is yet scarce, and it is early for a systematic comparative effort. We consider mathematical model of genetic regulatory networks. This model consists of a nonlinear system of ordinary differential equations. We describe the changes that system undergoes if the entries of the regulatory matrix are perturbed in some way. We discuss, how attractors for high-dimensional systems can be constructed, using known attractors of low-dimensional systems. Examples and visualizations are provided.
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Wehtje, Glenn, Charles H. Gilliam, and J. Scott McElroy. "Poison Ivy (Toxicodendron radican) Control with Triclopyr and Metsulfuron, Applied Alone and in Tank Mixture." Weed Technology 27, no. 4 (December 2013): 725–28. http://dx.doi.org/10.1614/wt-d-13-00034.1.
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Dermatitis from poison ivy is an important health problem, and considerable effort is devoted to the control of this virulent weed. Triclopyr, metsulfuron, and two fixed-ratio tank mixtures of triclopyr and metsulfuron were evaluated across a series of rates for poison ivy control. The objective was to test whether tank mixtures are more effective than triclopyr alone. Triclopyr, metsulfuron, and 9 : 1 and 8 : 2 (by weight) mixtures of these two herbicides, respectively, were applied at eight rates to 1-yr old, pot-grown poison ivy plants. Rates ranged in phytotoxicity from none to death. Percentage of control as determined from plant fresh weight reduction relative to a nontreated control was determined at 1 and 4 mo after treatment (MAT). Data were subjected to ANOVA followed by nonlinear regression. Rates required for 95% control at 1 MAT, control of regrowth at 4 MAT, and the costs of these treatments were determined for the herbicides applied alone and the mixtures. Triclopyr alone and metsulfuron alone were consistently the least and the most expensive treatments, respectively. The mixtures were intermediate to these extremes.
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Goel, Kanica, and Nilam. "A mathematical and numerical study of a SIR epidemic model with time delay, nonlinear incidence and treatment rates." Theory in Biosciences 138, no. 2 (January 21, 2019): 203–13. http://dx.doi.org/10.1007/s12064-019-00275-5.
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Vyazovkin, Sergey. "Activation Energies and Temperature Dependencies of the Rates of Crystallization and Melting of Polymers." Polymers 12, no. 5 (May 7, 2020): 1070. http://dx.doi.org/10.3390/polym12051070.
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The objective of this review paper is to survey the phase transition kinetics with a focus on the temperature dependence of the rates of crystallization and melting, as well as on the activation energies of these processes obtained via the Arrhenius kinetic treatment, including the treatment by isoconversional methods. The literature is analyzed to track the development of the basic models and their underlying concepts. The review presents both theoretical and practical considerations regarding the kinetic analysis of crystallization and melting. Both processes are demonstrated to be kinetically complex, and this is revealed in the form of nonlinear Arrhenius plots and/or the variation of the activation energy with temperature. Principles which aid one to understand and interpret such results are discussed. An emphasis is also put on identifying proper computational methods and experimental data that can lead to meaningful kinetic interpretation.
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Milunovic, Milica, and Marija Krstic. "Long time behavior of an two diffusion stochastic sir epidemic model with nonlinear incidence and treatment." Filomat 36, no. 8 (2022): 2829–46. http://dx.doi.org/10.2298/fil2208829m.
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In this paper we propose a stochastic SIR epidemic model to evaluate effect of the randomness on treatment and nonlinear incidence rate. More precisely, we perturb both nonlinear incidence and treatment rates in deterministic SIR model with Gaussian white noise and obtain two diffusion stochastic model. For the model, we theoretically prove that it?s solution is positive and global, and then, we obtain the conditions under which we can claim the existence of the stationary distribution. Also, by constructing suitable Lyapunov functions, weestablish sufficient conditions for p-th moment and almost sure exponential stability of disease-free equilibrium. Conditions for disease extinction are obtained, as well. We close the paper by presenting numerical simulations to verify our theoretical results. For that purpose we use real-life data for spread of cholera in the Department of Artibonite in Haiti, as well as for influenza A H1N1 in Guangdong Province, China.
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Scott, Jessica, Samantha M. Thomas, James Emmett Herndon, Jeffrey M. Peppercorn, Pamela S. Douglas, Michel Khouri, Chau T. Dang, et al. "Effects of Non-Linear or Linear Aerobic Training (AT) Dosing Regimens on Impaired Cardiovascular (CV) Function in Patients with Operable Breast Cancer: A Randomized Controlled Trial (RCT)." Journal of Clinical Oncology 37, no. 15_suppl (May 20, 2019): 541. http://dx.doi.org/10.1200/jco.2019.37.15_suppl.541.
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541 Background: Breast cancer therapy causes marked impairments in CV function predisposing to elevated risk of CV morbidity. We investigated the effects of two AT dosing regimens on CV function in post-treatment patients with operable breast cancer. Methods: In a three-arm, parallel-group RCT, 174 post-menopausal patients (2.8 years post primary adjuvant therapy) with impaired age/sex-matched peak oxygen consumption (VO2peak) were randomized to: (1) conventional linear AT (uniform dose-intensity / session), (2) nonlinear AT (variable dose-intensity / session), or (3) stretching (attention control). AT consisted of 64 supervised treadmill walking sessions delivered four times weekly at either ~70% VO2peak for 40 mins/session (linear) or 55% to 100% VO2peak for 20-45 mins/session (nonlinear) for 16 consecutive weeks. Stretching was matched to AT on the basis of location, frequency, duration, and treatment length. The primary end point was change in VO2peak. Secondary end points were other markers of CV risk profile (biochemical CV risk profile, cardiac function, body composition), patient-reported outcomes (PROs), tolerability (e.g., relative dose intensity), and safety. All analyses followed the intention-to-treat principle. Results: Rates of lost-to-follow were < 10% in all arms. Relative dose intensity of AT was 73% ± 27% and 80% ± 21% in linear and nonlinear arms, respectively. No serious adverse events were observed. In adjusted analysis, compared to control, VO2peak (ml O2.kg-1.min-1) increased 0.7 (± 0.3) ml O2.kg-1.min-1 (p = 0.06) and 0.8 (± 0.4) ml O2.kg-1.min-1 (p = 0.02) in linear and nonlinear AT, respectively. Rates of VO2peak improvement greater than the technical error of measurement (i.e., ≥1.32ml O2.kg-1.min-1) were 33% and 39% in linear and nonlinear AT (p = 0.03), respectively. Both AT regimens were associated with improvements in several secondary CV end points but only nonlinear AT improved PROs compared with control (all p’s < 0.05). There were no differences between the two AT regimens. Conclusion: AT significantly improves CV function and PROs in post-treatment breast cancer patients. The efficacy-tolerability ratio favors the non-linear regimen over the conventional linear prescription approach. Clinical trial information: NCT01186367.
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Venkatramani, Ravindra, Emil Wierzbinski, David H. Waldeck, and David N. Beratan. "Breaking the simple proportionality between molecular conductances and charge transfer rates." Faraday Discuss. 174 (2014): 57–78. http://dx.doi.org/10.1039/c4fd00106k.
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A theoretical framework is presented to describe and to understand the observed relationship between molecular conductances and charge transfer rates across molecular bridges as a function of length, structure, and charge transfer mechanism. The approach uses a reduced density matrix formulation with a phenomenological treatment of system–bath couplings to describe charge transfer kinetics and a Green's function based Landauer–Buttiker method to describe steady-state currents. Application of the framework is independent of the transport regime and includes bath-induced decoherence effects. This model shows that the relationship between molecular conductances and charge transfer rates follows a power-law. The nonlinear rate–conductance relationship is shown to arise from differences in the charge transport barrier heights and from differences in environmental decoherence rates for the two experiments. This model explains otherwise puzzling correlations between molecular conductances and electrochemical kinetics.
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Yang, Junyuan, Xiaoxia Li, and Fengqin Zhang. "Global dynamics of a heroin epidemic model with age structure and nonlinear incidence." International Journal of Biomathematics 09, no. 03 (February 25, 2016): 1650033. http://dx.doi.org/10.1142/s1793524516500339.
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A heroin model with nonlinear incidence rate and age structure is investigated. The basic reproduction number is determined whether or not a heroin epidemic breaks out. By employing the Lyapunov functionals, the drug-free equilibrium is globally asymptotically stable if [Formula: see text]; while the drug spread equilibrium is also globally asymptotically stable if [Formula: see text]. Our results imply that improving detected rates and drawing up the efficient prevention play more important role than increasing the treatment for drug users.
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Chigutsa, Emmanuel, Jotam G. Pasipanodya, Marianne E. Visser, Paul D. van Helden, Peter J. Smith, Frederick A. Sirgel, Tawanda Gumbo, and Helen McIlleron. "Impact of Nonlinear Interactions of Pharmacokinetics and MICs on Sputum Bacillary Kill Rates as a Marker of Sterilizing Effect in Tuberculosis." Antimicrobial Agents and Chemotherapy 59, no. 1 (October 13, 2014): 38–45. http://dx.doi.org/10.1128/aac.03931-14.
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ABSTRACTThe relationships between antituberculosis drug exposure and treatment effects on humans receiving multidrug therapy are complex and nonlinear. In patients on treatment, an analysis of the rate of decline in the sputum bacillary burden reveals two slopes. The first is the α-slope, which is thought to reflect bactericidal effect, followed by a β-slope, which is thought to reflect sterilizing activity. We sought to characterize the effects of standard first-line treatment on sterilizing activity. Fifty-four patients receiving combination therapy for pulmonary tuberculosis in a clinical trial had drug concentrations measured andMycobacterium tuberculosisisolates available for MIC identification. Sputum sample cultures were performed at baseline and weekly for 8 weeks. A time-to-event model based on the days to positivity in the liquid cultures was used to estimate the β-slope. The pharmacokinetic parameters of rifampin, isoniazid, ethambutol, and pyrazinamide were determined for each patient. Multivariate adaptive regression splines analyses, which simultaneously perform linear and nonlinear analyses, were used to identify the relationships between the predictors and the β-slope. The potential predictors examined included HIV status, lung cavitation, 24-h area under the concentration-time curve (AUC), peak drug concentration (Cmax), AUC/MIC ratio,Cmax/MIC ratio, and the time that that concentration persisted above MIC. A rifampinCmaxof >8.2 mg/liter and a pyrazinamide AUC/MIC of >11.3 were key predictors of the β-slope and interacted positively to increase the β-slope. In patients with a rifampin AUC of <35.4 mg · h/liter, an increase in the pyrazinamide AUC/MIC and/or ethambutolCmax/MIC increased the β-slope, while increasing isoniazidCmaxdecreased it, suggesting isoniazid antagonism. Antibiotic concentrations and MICs interact in a nonlinear fashion as the main drivers of a sterilizing effect. The results suggest that faster speeds of sterilizing effect might be achieved by omitting isoniazid and by increasing rifampin, pyrazinamide, and ethambutol exposures. However, isoniazid and ethambutol exposures may only be of importance when rifampin exposure is low. These findings need confirmation in larger studies. (This study has been registered atcontrolled-trials.comunder registration no. ISRCTN80852505.)
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Huang, Zehua, Renren Wu, XiaoHui Yi, Hongbin Liu, Jiannan Cai, Guoqiang Niu, Mingzhi Huang, and Guangguo Ying. "A Novel Model with GA Evolving FWNN for Effluent Quality and Biogas Production Forecast in a Full-Scale Anaerobic Wastewater Treatment Process." Complexity 2019 (November 26, 2019): 1–13. http://dx.doi.org/10.1155/2019/2468189.
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The anaerobic treatment process is a complicated multivariable system that is nonlinear and time varying. Moreover, biogas production rates are an important indicator for reflecting operational performance of the anaerobic treatment system. In this work, a novel model fuzzy wavelet neural network based on the genetic algorithm (GA-FWNN) that combines the advantages of the genetic algorithm, fuzzy logic, neural network, and wavelet transform was established for prediction of effluent quality and biogas production rates in a full-scale anaerobic wastewater treatment process. Moreover, the dataset was preprocessed via a self-adapted fuzzy c-means clustering before training the network and a hybrid algorithm for acquiring the optimal parameters of the multiscale GA-FWNN for improving the network precision. The analysis results indicate that the FWNN with the optimal algorithm had a high speed of convergence and good quality of prediction, and the FWNN model was more advantageous than the traditional intelligent coupling models (NN, WNN, and FNN) in prediction accuracy and robustness. The determination coefficients R2 of the FWNN models for predicting both the effluent quality and biogas production rates were over 0.95. The proposed model can be used for analyzing both biogas (methane) production rates and effluent quality over the operational time period, which plays an important role in saving energy and eliminating pollutant discharge in the wastewater treatment system.
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Pitt, D. G., D. G. Thompson, N. J. Payne, and E. G. Kettela. "Response of woody eastern Canadian forest weeds to fall foliar treatments of glyphosate and triclopyr herbicides." Canadian Journal of Forest Research 23, no. 12 (December 1, 1993): 2490–98. http://dx.doi.org/10.1139/x93-310.
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Second-season post-treatment efficacy data are presented for a New Brunswick field study comparing three formulations of glyphosate (VISION®, MON14420, and TOUCHDOWN®) and a single formulation of triclopyr (RELEASE®). Five rates of each herbicide were broadcast applied to a 2-year-old clearcut in early September. Two growing seasons after treatment, percent control values (based on total woody crown area) ranged from 21% at glyphosate rates < 0.25 × label maximum to more than 80% at rates ≥ 0.75 × label maximum. Coefficients of variation for percent control values decreased from 104% at the lower glyphosate rates to 9% at the higher rates. Total woody control provided by triclopyr was generally equivalent to that of glyphosate at rates < 0.5 × label maximum. Beyond this rate, percent control values for triclopyr averaged only 59% and coefficients of variation remained high (40%). At the individual-species level, the three glyphosate formulations provided greater crown volume reduction than triclopyr for white ash (Fraxinusamericana L.), beech (Fagusgrandifolia Ehrh.), hazel (Coryluscornuta Marsh.), and sugar maple (Acersaccharum Marsh.). Control of mountain maple (Acerspicatum Lam.) by TOUCHDOWN® was found to be slightly inferior to that of the other two glyphosate formulations. Control of elderberry (Sambucuspubens Michx.) by MON14420 was inferior to that of the other three herbicides. Nonlinear regression curves relating second-season control and herbicide dose are presented as a guide for silvicultural use.
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Brorson, James R., and Zachary B. Bulwa. "Two-State Kinetic Model of Rates of Stroke Recurrence in the POINT Study Population." Stroke 52, no. 4 (April 2021): 1446–49. http://dx.doi.org/10.1161/strokeaha.120.031447.
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Background and Purpose: Following an acute ischemic stroke or transient ischemic attack, 2 rates of stroke recurrence are suggested by data from trials of acute secondary prevention treatments: a transient rapid rate followed by a persisting slower rate of stroke. Methods: A kinetic model was constructed based on underlying vulnerable and stabilized states of patients following acute ischemic events related by fixed transition rates. Its predictions were fitted by nonlinear regression to the observed timing of outcome events in patients in the POINT trial (Platelet-Oriented Inhibition in New TIA and Minor Ischemic Stroke). Results: The modeled survivor function produced a close fit to the observed data. The model's predicted kinetic rates suggest that, among subjects in the control group, the event rate was 100-fold higher in the vulnerable state than in the stabilized state. Active treatment halved this rapid rate and had little effect on event rates in the stabilized state. If at least one-tenth of the study population began in the vulnerable state, the rate of transition from the vulnerable to the stabilized state was still faster, with a half-life of only 1 to 2 days. Conclusions: Examination of kinetics of stroke occurrence, and of the rates associated with modeled state transitions, may provide insights into the underlying pathophysiological events that are targets for acute secondary prevention of stroke.
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Wallace, Dorothy I., Ann Dunham, Paula X. Chen, Michelle Chen, Milan Huynh, Evan Rheingold, and Olivia Prosper. "A Model for Spheroid versus Monolayer Response of SK-N-SH Neuroblastoma Cells to Treatment with 15-Deoxy-PGJ2." Computational and Mathematical Methods in Medicine 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/3628124.
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Researchers have observed that response of tumor cells to treatment varies depending on whether the cells are grown in monolayer, asin vitrospheroids orin vivo. This study uses data from the literature on monolayer treatment of SK-N-SH neuroblastoma cells with 15-deoxy-PGJ2and couples it with data on growth rates for untreated SK-N-SH neuroblastoma cells grown as multicellular spheroids. A linear model is constructed for untreated and treated monolayer data sets, which is tuned to growth, death, and cell cycle data for the monolayer case for both control and treatment with 15-deoxy-PGJ2. The monolayer model is extended to a five-dimensional nonlinear model ofin vitrotumor spheroid growth and treatment that includes compartments of the cell cycle (G1,S,G2/M) as well as quiescent (Q) and necrotic (N) cells. Monolayer treatment data for 15-deoxy-PGJ2is used to derive a prediction of spheroid response under similar treatments. For short periods of treatment, spheroid response is less pronounced than monolayer response. The simulations suggest that the difference in response to treatment of monolayer versus spheroid cultures observed in laboratory studies is a natural consequence of tumor spheroid physiology rather than any special resistance to treatment.
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Kwakye, Janet, and J. M. Tchuenche. "A simple two-strain HSV epidemic model with palliative treatment." Open Journal of Mathematical Analysis 5, no. 2 (November 1, 2021): 53–65. http://dx.doi.org/10.30538/psrp-oma2021.0093.
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A two-strain model of the transmission dynamics of herpes simplex virus (HSV) with treatment is formulated as a deterministic system of nonlinear ordinary differential equations. The model is then analyzed qualitatively, with numerical simulations provided to support the theoretical results. The basic reproduction number \(R_0\) is computed with \(R_0=\text{max}\lbrace R_1, R_2 \rbrace \) where \(R_1\) and \(R_2\) represent respectively the reproduction number for HSV1 and HSV2. We also compute the invasion reproductive numbers \(\tilde{R}_1\) for strain 1 when strain 2 is at endemic equilibrium and \(\tilde{R}_2\) for strain 2 when strain 1 is at endemic equilibrium. To determine the relative importance of model parameters to disease transmission, sensitivity analysis is carried out. The reproduction number is most sensitive respectively to the contact rates \(\beta_1\), \(\beta_2\) and the recruitment rate \(\pi\). Numerical simulations indicate the co-existence of the two strains, with HSV1, dominating but not driving out HSV2 whenever \(R_1 > R_2 > 1\) and vice versa.
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Borsali, Salima. "Forward-Backward Propagation to Identify the Maximum Specific Growth Rates of a Bioreactor." Engineering Innovations 5 (April 19, 2023): 39–48. http://dx.doi.org/10.4028/p-si0156.
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In this article, we are interested in identifying the parameters of an aerobic bioprocess modelused for wastewater treatment. In the field of biotechnology, various computer bugs caused by roundingerrors can induce an error interval that is too wide during data acquisition. For this reason, weare testing a new identification method using a set method based on interval arithmetic. The processstudied is the chemical transformation of ammoniacal nitrogen which takes place in two stages: Reactionof nitrificationdenitrification.The parameters chosen for the identification are the yields andthe maximum growth rates. Initially, the study of observability by a differential algebraic method willsimplify the study of the mathematical model. This nonlinear model is described by six differentialequations. Subsequently, we apply a set method, in particular the propagation of constraints also calledforwardbackward propagation, this technique allowed us to determine intervals containing the variablereturns as well as the maximum specific growth rates defined from the Monod model which describesthe operation of the bioreactor. This method also guarantees the result by rejecting all inconsistentvalues.
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Wehtje, Glenn, and Charles H. Gilliam. "Cost-Effectiveness of Glyphosate, 2,4-D, and Triclopyr, Alone and in Select Mixtures for Poison Ivy Control." Weed Technology 26, no. 3 (September 2012): 469–73. http://dx.doi.org/10.1614/wt-d-11-00183.1.
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Dermatitis from poison ivy is a significant health problem. Considerable effort is devoted to the control of this invasive and virulent weed in urban areas. Glyphosate, triclopyr, 2,4-D, a 1 : 1 mixture of glyphosate and 2,4-D, and a 9 : 1 mixture of glyphosate and triclopyr were evaluated for poison ivy control. Each of these three herbicides and two mixtures were applied at nine or ten rates, which ranged in phytotoxicity from none to death. Poison ivy plants had been propagated and container-grown. Percent control, as determined from plant fresh weight reduction, was determined at 1 and 4 mo after treatment (MAT). Data were subjected to ANOVA followed by nonlinear regression. Rates required for 95% control at 1 and 4 MAT and the associated costs were determined for each of the three herbicides and two mixtures. Acceptable control (i.e., ≥ 95%) at 1 and 4 MAT could be obtained at a much lower cost with either triclopyr or 2,4-D than with either glyphosate alone or with the two glyphosate-containing mixtures. Nonlinear regression also was used to evaluate whether the two mixtures were interactive (i.e., synergistic or antagonistic) or not (i.e., additive). Glyphosate plus triclopyr was synergistic for control at both 1 and 4 MAT. Glyphosate plus 2,4-D was synergistic for control at 4 MAT only. However, for both mixtures, synergism was only evident at rates that controlled poison ivy ≤ 80%. Both mixtures were noninteractive at rates required for acceptable control.
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Kumar, Abhishek, Nilam, and Raj Kishor. "A short study of an SIR model with inclusion of an alert class, two explicit nonlinear incidence rates and saturated treatment rate." SeMA Journal 76, no. 3 (April 10, 2019): 505–19. http://dx.doi.org/10.1007/s40324-019-00189-8.
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Remphrey, W. R., and C. G. Davidson. "Shoot and leaf growth in Fraxinuspennsylvanica and its relation to crown location and pruning." Canadian Journal of Forest Research 24, no. 10 (October 1, 1994): 1997–2005. http://dx.doi.org/10.1139/x94-256.
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Elongation of shoots in various crown locations, and of individual internodes and leaves of the leading shoot, were recorded at 2-day intervals throughout the 1991 growing season in four clones of Fraxinuspennsylvanica var. subintegerrima (Vahl) Fern. (green ash). Other trees were disbudded and pruned to a single leader. Using a logistic growth function, nonlinear regression equations were generated and parameter estimates were used to determine maximum growth rates. Terminal leading shoots had a longer growth duration and a greater maximum growth rate than lateral shoots. The pruning treatment resulted in larger shoots, which grew 2–3 weeks longer and had a higher maximum growth rate. Leaf emergence occurred at regular intervals but the rate of emergence varied among clones. Leaf maximum growth rates were not significantly different among clones. Leaf size declined acropetally whereas internode length increased and then decreased. The longest leaves and internodes had the highest maximum growth rates. The size and maximum growth rates of putative preformed leaves were larger than putative neoformed leaves. As a shoot expanded, growth of one internode tended to cease during the linear phase of growth of its associated leaf and that of the succeeding internode.
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HASSANI, M., P. MAÑAS, J. RASO, S. CONDÓN, and R. PAGÁN. "Predicting Heat Inactivation of Listeria monocytogenes under Nonisothermal Treatments." Journal of Food Protection 68, no. 4 (April 1, 2005): 736–43. http://dx.doi.org/10.4315/0362-028x-68.4.736.
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The aim of this study was to find a model that accurately predicts the heat inactivation of Listeria monocytogenes (ATCC 15313) at constantly rising heating rates (0.5 to 9°C/min) in media of different pH values (4.0 to 7.4). Survival curves of L. monocytogenes obtained under isothermal treatments at any temperature were nearly linear. Estimations of survival curves under nonisothermal treatments obtained from heat resistance parameters of isothermal treatments adequately fit experimental values obtained at pH 4.0. On the contrary, survivors were much higher than estimations at pH 5.5 and 7.4. The slower the heating rate and the longer the treatment time, the greater the differences between the experimental and estimated values. An equation based on the Weibullian-like distribution, log S(t) = (t/δ)p, accurately described survival curves of L. monocytogenes obtained under nonisothermal conditions within the range of heating rates investigated. A nonlinear relationship was observed between the scale parameter (δ) and the heating rate, which allowed the development of an equation capable of predicting the inactivation rate of L. monocytogenes under nonisothermal treatments at pH 5.5 and 7.4. The model predictions were a good fit to the measured data independent of the magnitude of the thermotolerance increase. This work might contribute to the increase in safety of those food products that require long heating lag phases during the pasteurization process.
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Kwon, Tae-Jin, Douglas L. Young, Frank L. Young, and Chris M. Boerboom. "Palweed:Wheat: A Bioeconomic Decision Model for Postemergence Weed Management in Winter Wheat (Triticum aestivum)." Weed Science 43, no. 4 (December 1995): 595–603. http://dx.doi.org/10.1017/s0043174500081704.
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Based on six years of data from a field experiment near Pullman, WA, a bioeconomic decision model was developed to annually estimate the optimal post-emergence herbicide types and rates to control multiple weed species in winter wheat under various tillage systems and crop rotations. The model name, PALWEED:WHEAT, signifies a Washington-Idaho Palouse region weed management model for winter wheat The model consists of linear preharvest weed density functions, a nonlinear yield response function, and a profit function. Preharvest weed density functions were estimated for four weed groups: summer annual grasses, winter annual grasses, summer annual broadleaves, and winter annual broadleaves. A single aggregated weed competition index was developed from the four density functions for use functions for use in the yield model. A yield model containing a logistic damage function performed better than a model containing a rectangular hyperbolic damage function. Herbicides were grouped into three categories: preplant nonselective, postemergence broadleaf, and postemergence grass. PALWEED:WHEAT was applied to average conditions of the 6-yr experiment to predict herbicide treatments that maximized profit. In comparison to average treatment rates in the 6-yr experiment, the bioeconomic decision model recommended less postemergence herbicide. The weed management recommendations of PALWEED:WHEAT behaved as expected by agronomic and economic theory in response to changes in assumed weed populations, herbicide costs, crop prices, and possible restrictions on herbicide application rates.
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Jing, Teng, Tianye Xin, Fangqun Wang, Zhihao Zhang, and Ling Zhou. "Control Strategy Design of a Microblood Pump Based on Heart-Rate Feedback." Micromachines 13, no. 3 (February 24, 2022): 358. http://dx.doi.org/10.3390/mi13030358.
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Based on the nonlinear relationship between heart rate and stroke volume, a flow model of left ventricular circulation was improved, and a variable-speed blood-pump control strategy based on heart-rate feedback was proposed. The control strategy was implemented on a system combining the rotary blood pump and blood circulation models of heart failure. The aortic flow of a healthy heart at different heart rates was the desired control goal. Changes in heart rate were monitored and pump speed was adjusted so that the output flow and aortic pressure of the system would match a normal heart in real time to achieve the best auxiliary state. After simulation with MATLAB, the cardiac output satisfied the ideal perfusion requirements at different heart rates, and aortic pressure demonstrated lifting and had good pulsatile performance when a variable-speed blood pump was used. The coupled model reflected the relationship between hemodynamic parameters at different heart rates with the use of the variable-speed blood pump, providing a theoretical basis for the blood-pump-assisted treatment of heart failure and the design of physiological control strategies.
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MATTICK, K. L., J. D. LEGAN, T. J. HUMPHREY, and M. PELEG. "Calculating Salmonella Inactivation in Nonisothermal Heat Treatments from Isothermal Nonlinear Survival Curves." Journal of Food Protection 64, no. 5 (May 1, 2001): 606–13. http://dx.doi.org/10.4315/0362-028x-64.5.606.
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Salmonella cells in two sugar-rich media were heat treated at various constant temperatures in the range of 55 to 80°C and their survival ratios determined at various time intervals. The resulting nonlinear semilogarithmic survival curves are described by the model log10S(t) = −b(T)tn(T), where S(t) is the momentary survival ratio N(t)/N0, and b(T) and n(T) are coefficients whose temperature dependence is described by two empirical mathematical models. When the temperature profile, T(t), of a nonisothermal heat treatment can also be expressed algebraically, b(T) and n(T) can be transformed into a function of time, i.e., b[T(t)] and n[T(t)]. If the momentary inactivation rate primarily depends on the momentary temperature and survival ratio, then the survival curve under nonisothermal conditions can be constructed by solving a differential equation, previously suggested by Peleg and Penchina, whose coefficients are expressions that contain the corresponding b[T(t)] and n[T(t)] terms. The applicability of the model and its underlying assumptions was tested with a series of eight experiments in which the Salmonella cells, in the same media, were heated at various rates to selected temperatures in the range of 65 to 80°C and then cooled. In all the experiments, there was an agreement between the predicted and observed survival curves. This suggests that, at least in the case of Salmonella in the tested media, survival during nonisothermal inactivation can be estimated without assuming any mortality kinetics.
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Jeong, Woncheol, Sergei Alexandrov, and Lihui Lang. "Effect of Plastic Anisotropy on the Distribution of Residual Stresses and Strains in Rotating Annular Disks." Symmetry 10, no. 9 (September 19, 2018): 420. http://dx.doi.org/10.3390/sym10090420.
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Hill’s quadratic orthotropic yield criterion is used for revealing the effect of plastic anisotropy on the distribution of stresses and strains within rotating annular polar orthotropic disks of constant thickness under plane stress. The associated flow rule is adopted for connecting the stresses and strain rates. Assuming that unloading is purely elastic, the distribution of residual stresses and strains is determined as well. The solution for strain rates reduces to one nonlinear ordinary differential equation and two linear ordinary differential equations, even though the boundary value problem involves two independent variables. The aforementioned differential equations can be solved one by one. This significantly simplifies the numerical treatment of the general boundary value problem and increases the accuracy of its solution. In particular, comparison with a finite difference solution is made. It is shown that the finite difference solution is not accurate enough for some applications.
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Sun, Mingye, Youjin Zheng, Lei Zhang, Liping Zhao, and Bing Zhang. "Influence of heat treatment on hole transfer dynamics in core-shell quantum dot/organic hole conductor hybrid films." Modern Physics Letters B 31, no. 23 (August 20, 2017): 1750218. http://dx.doi.org/10.1142/s0217984917502189.
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The influence of heat treatment on hole transfer (HT) processes from the CdSe/ZnS and CdSe/CdS/ZnS quantum dots (QDs) to 4,4[Formula: see text],4[Formula: see text]-Tris(carbazol-9-yl)-triphenylamine (TCTA) in QD/TCTA hybrid films has been researched with time-resolved photoluminescence (PL) spectroscopy. The PL dynamic results demonstrated a heat-treatment-temperature-dependent HT process from the core-shell CdSe QDs to TCTA. The HT rates and efficiencies can be effectively increased due to reduced distance between core-shell CdSe QDs and TCTA after heat treatment. The CdS shell exhibited a more obvious effect on HT from the core-shell CdSe QDs to TCTA than on electron transfer to TiO2, due to higher barrier for holes to tunnel through CdS shell and larger effective mass of holes in CdS than electrons. These results indicate that heat treatment would be an effective means to further optimize solid-state QD sensitized solar cells and rational design of CdS shell is significant.
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Hayat, Tasawar, Muhammad Waqar Ahmad, Sohail A. Khan, and Ahmed Alsaedi. "Computational treatment of statistical declaration probable error for flow of nanomaterials with irreversibility." Advances in Mechanical Engineering 14, no. 1 (January 2022): 168781402110709. http://dx.doi.org/10.1177/16878140211070937.
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The current investigation deals with entropy analysis for radiative flow of nanomaterials between two heated rotating disks. Titanium ([Formula: see text] and [Formula: see text]) and Graphene oxides are taken as nanoparticles. Water ([Formula: see text]) is used as a conventional base liquid. Dissipation and radiation effects are incorporated in energy equation. Rotating disks have different angular velocities. Both disks have different stretching rates. Attention is focused for statistical declaration and probable error. Physical feature of entropy analysis is studied through thermodynamics second law. Nonlinear partial system (PDEs) is reduced to ordinary one (ODEs). Homotopy analysis technique (HAM) is used for convergent series solution. Features of sundry variables on entropy optimization, temperature, Bejan number, and velocity are discussed for both nanoparticles ([Formula: see text] and [Formula: see text]). Computational outcomes for velocity gradient and Nusselt number are addressed through tabulated values. For larger Reynold number the radial and axial velocities are decreased. Temperature is augmented for against higher Eckert number and radiation parameter. Bejan number and entropy rate are augmented versus radiation parameter. Bejan number and Entropy rate have opposite trend via Reynold number. Statistical declaration and probable error are deliberated via Tables.
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Fernandez, George C. J., and Belinda Love. "Comparing Turfgrass Cumulative Evapotranspiration Curves." HortScience 28, no. 7 (July 1993): 732–34. http://dx.doi.org/10.21273/hortsci.28.7.732.
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Twenty-five commercially available turfgrass cultivars were evaluated for cumulative evapotranspiration (ETcum) attributes under progressive water stress for 0 to 21 and 0 to 24 days using the gravimetric mass balance method in two greenhouse studies. At the end of the water-stress treatment, the cultivars were scored visually for their green appearance on a 0 (no green) to 10 (100% green) scale. The Gompertz nonlinear model gave a best fit to ETcum vs. days adjusted for pan evaporation variation in the greenhouse compared with monomolecular and logistic nonlinear regression models. Two ETcum attributes—maximum evapotranspiration rates (ETmax) and inflection time (ti) (the time when the change in ET becomes zero)—were estimated for each cultivar using the Gompertz model. Based on final ETcum, ETmax, ti, and greenness score, `Bristol', `Challenger', and `Wabash' Kentucky bluegrass (Poa pratensis L.); `Shademaster' creeping fescue (Festuca rubra L.); `FRT-30149' fine fescue (F. rubra L.); and `Aurora' hard fescue (F. ovina var. duriuscula L. Koch.) were identified as low water-use cultivars.
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GULA, J., V. ZEITLIN, and F. BOUCHUT. "Instabilities of buoyancy-driven coastal currents and their nonlinear evolution in the two-layer rotating shallow water model. Part 2. Active lower layer." Journal of Fluid Mechanics 665 (October 22, 2010): 209–37. http://dx.doi.org/10.1017/s0022112010003903.
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This paper is the second part of the work on linear and nonlinear stability of buoyancy-driven coastal currents. Part 1, concerning a passive lower layer, was presented in the companion paper Gula & Zeitlin (J. Fluid Mech., vol. 659, 2010, p. 69). In this part, we use a fully baroclinic two-layer model, with active lower layer. We revisit the linear stability problem for coastal currents and study the nonlinear evolution of the instabilities with the help of high-resolution direct numerical simulations. We show how nonlinear saturation of the ageostrophic instabilities leads to reorganization of the mean flow and emergence of coherent vortices. We follow the same lines as in Part 1 and, first, perform a complete linear stability analysis of the baroclinic coastal currents for various depths and density ratios. We then study the nonlinear evolution of the unstable modes with the help of the recent efficient two-layer generalization of the one-layer well-balanced finite-volume scheme for rotating shallow water equations, which allows the treatment of outcropping and loss of hyperbolicity associated with shear, Kelvin–Helmholtz type, instabilities. The previous single-layer results are recovered in the limit of large depth ratios. For depth ratios of order one, new baroclinic long-wave instabilities come into play due to the resonances among Rossby and frontal- or coastal-trapped waves. These instabilities saturate by forming coherent baroclinic vortices, and lead to a complete reorganization of the initial current. As in Part 1, Kelvin fronts play an important role in this process. For even smaller depth ratios, short-wave shear instabilities with large growth rates rapidly develop. We show that at the nonlinear stage they produce short-wave meanders with enhanced dissipation. However, they do not change, globally, the structure of the mean flow which undergoes secondary large-scale instabilities leading to coherent vortex formation and cutoff.
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Hummel, Nicolas, and Serge A. Shapiro. "Nonlinear diffusion-based interpretation of induced microseismicity: A Barnett Shale hydraulic fracturing case study." GEOPHYSICS 78, no. 5 (September 1, 2013): B211—B226. http://dx.doi.org/10.1190/geo2012-0242.1.
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For the successful development and operation of hydrocarbon or geothermal reservoirs, knowledge of the hydraulic transport is of crucial importance. Because fundamental physical processes of borehole fluid injections are still insufficiently understood, gathering information about transport properties of rocks under field conditions is quite difficult. However, a substantial contribution in determining the permeability evolution can be obtained by understanding the distribution of induced seismicity in space and time. We have analyzed spatio-temporal characteristics of seismicity recorded during a hydraulic fracturing treatment in the Barnett Shale. In this study, we show that the fluid-rock interaction is nonlinear. To explain corresponding spatio-temporal features of induced seismicity, we considered pore pressure diffusion based on a power-law pressure dependence of permeability. A scaling approach was used to transform clouds of hypocenters of events obtained in a hydraulically anisotropic nonlinear medium into a cloud which would be obtained in an equivalent isotropic but still nonlinear medium. For this, we used a concept of a factorized anisotropic pressure dependence of permeability and found that it is in agreement with the microseismic data under consideration. We used a numerical modeling approach to generate synthetic seismicity by solving nonlinear diffusion equations. The pore-pressure field obtained from flow rates was calibrated with the pore-pressure field computed for injection pressures. This yielded an estimate of the uniaxial storage coefficient and permitted us to compute the permeability evolution inside the fracture stimulated reservoir. Following our modeling, we generated synthetic seismicity whose spatio-temporal features are similar to the ones observed in the case study. This indicates that a nonlinear diffusion with a pressure-dependent permeability seems to provide a reasonable model of the hydraulic-fracture stimulation under consideration. A power-law pressure dependence of stimulated permeability may be a more general characteristic for shales.
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Al-Sawaf, Othman, Can Zhang, Tong Lu, Michael Z. Liao, Anesh Panchal, Sandra Robrecht, Travers Ching, et al. "Minimal Residual Disease Dynamics after Venetoclax-Obinutuzumab Treatment: Extended Off-Treatment Follow-up From the Randomized CLL14 Study." Journal of Clinical Oncology 39, no. 36 (December 20, 2021): 4049–60. http://dx.doi.org/10.1200/jco.21.01181.
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PURPOSE The CLL14 study has established one-year fixed-duration treatment of venetoclax and obinutuzumab (Ven-Obi) for patients with previously untreated chronic lymphocytic leukemia. With all patients off treatment for at least three years, we report a detailed analysis of minimal residual disease (MRD) kinetics and long-term outcome of patients treated in the CLL14 study. PATIENTS AND METHODS Patients were randomly assigned to receive six cycles of obinutuzumab with 12 cycles of venetoclax or 12 cycles of chlorambucil (Clb-Obi). Progression-free survival (PFS) was the primary end point. Key secondary end points included rates of undetectable MRD and overall survival. To analyze MRD kinetics, a population-based growth model with nonlinear mixed effects approach was developed. RESULTS Of 432 patients, 216 were assigned to Ven-Obi and 216 to Clb-Obi. Three months after treatment completion, 40% of patients in the Ven-Obi arm (7% in the Clb-Obi arm) had undetectable MRD levels < 10−6 by next-generation sequencing in peripheral blood. Median MRD doubling time was longer after Ven-Obi than Clb-Obi therapy (median 80 v 69 days). At a median follow-up of 52.4 months, a sustained significant PFS improvement was observed in the Ven-Obi arm compared with Clb-Obi (median not reached v 36.4 months; hazard ratio 0.33; 95% CI, 0.25 to 0.45; P < .0001). The estimated 4-year PFS rate was 74.0% in the Ven-Obi and 35.4% in the Clb-Obi arm. No difference in overall survival was observed (hazard ratio 0.85; 95% CI, 0.54 to 1.35; P = .49). No new safety signals occurred. CONCLUSION Appearance of MRD after Ven-Obi is significantly slower than that after Clb-Obi with more effective MRD reduction. These findings translate into a superior long-term efficacy with the majority of Ven-Obi–treated patients remaining in remission.
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Simon, S. I., and G. W. Schmid-Scho¨nbein. "Kinematics of Cytoplasmic Deformation in Neutrophils During Active Motion." Journal of Biomechanical Engineering 112, no. 3 (August 1, 1990): 303–10. http://dx.doi.org/10.1115/1.2891188.
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A procedure is proposed to measure the cytoplasmic deformation in active motile neutrophils in the form of cytoplasmic strains and strain rates. Three neighboring microspheres in a local region of the cytoplasm serve as markers for local motion. Their positions are tracked by means of a high resolution light microscope and serve to compute nonlinear measures of strains and strain rates together with the principal strains and principal directions. Active neutrophils exhibit large cytoplasmic strains both during periodic pseudopod projections and during continuous locomotion in a polarized shape. The cytoplasmic motion is often synchronized with the whole cell deformation. The local cytoplasmic strains exceed the strains estimated for the whole cell and are not reversible except in some cases of single pseudopod projections. Large strains are observed both in attached and freely suspended cells. Strain rates are relatively constant but show an increase during the pseudopod retraction phase. Local cytoplasmic strains in neutrophils are inhomogeneous and reach large values during passage of the contraction rings. Neutrophils rendered passive by treatment with cytochalasin or EDTA show a random motion of microspheres with much smaller displacements. These observations suggest that the cytoplasm of active neutrophil exhibits large cytoplasmic strains and strain rates in the absence of an external stress resulting in a high degree of intracellular mixing. The proposed technique may be applied to a wide range of problems in cell biology.
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Leblanc, Jean L. "Nonlinear Viscoelasticity of (Unvulcanized) Natural Rubber, Derived Materials, and Compounds Through LAOS Testing." Rubber Chemistry and Technology 83, no. 1 (March 1, 2010): 65–96. http://dx.doi.org/10.5254/1.3548267.
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Abstract Natural rubber (NR) is by far the most important elastic material but its production specifications remain relatively poor when compared to synthetic elastomers. The so-called technically specified NR grades (i.e., technically specified rubber) are indeed characterized with respect to basic rubber test techniques, such as the Mooney viscosity, the (Wallace) plasticity (P0), and the Plasticity Retention Index, but high elasticity grades like ribbed smoked sheets are classified with respect to visual inspection criteria only. In addition, NR exhibits by nature more variation than synthetic polymers, owing to inevitable production differences from around 50 different clones of Hevea Brasiliensis, which are further enhanced by climate, soil, and other local effects, as well as seasonal effects on tapping. Most rubber processing operations occur at high rates of strain, and therefore it is essentially the nonlinear viscoelastic response of rubber materials that is of interest. This prompted the development of advanced investigation testing, such as large amplitude oscillatory strain (LAOS) experiments, which over the last decade were developed into powerful techniques to document the nonlinear viscoelastic behavior of polymer materials. First, the standard rheological tests for characterizing gum NR grades are briefly reviewed and discussed. Second, the equipment, test protocols, data treatment, and results modeling necessary to apply nonlinear viscoelastic testing are presented. Third, a number of LAOS experimental results obtained on various grades of NR, on a few chemically modified NR materials, and on two carbon black-filled NR compounds are reported and discussed.
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Paparozzi, Ellen T., Walter W. Stroup, and M. Elizabeth Conley. "How to Investigate Four-way Nutrient Interactions in Plants: A New Look at Response Surface Methods." Journal of the American Society for Horticultural Science 130, no. 3 (May 2005): 459–68. http://dx.doi.org/10.21273/jashs.130.3.459.
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Response surface methods refer to a set of experimental design and analysis methods to study the effect of quantitative treatments on a response of interest. In theory, these methods have a broad range of applicability. While they have gained widespread acceptance and application in manufacturing and quality improvement research, they have never caught on in the agricultural sciences. We propose that this is because there has not been specific research demonstrating their usage. In this paper, two 34 factorial experiments were performed using 100 poinsettia plants (Euphorbia pulcherrima Willd. ex Klotzsch) to measure nutrient element concentrations in leaves at three rates each of nitrogen (N), sulfur (S), iron (Fe), and manganese (Mn). Three different methods of analysis were compared—the standard analysis of variance with no regression model, the quadratic regression model commonly assumed for most standard response surface methods and the Hoerl model regression, a nonlinear alternative to quadratic response. Actual nutrient element values were compared with the values predicted by each regression model and then also evaluated to see if the visual symptomology of yellowing related to those nutrient concentrations in leaves. The Hoerl model demonstrated better ability to detect biologically relevant nonlinear two-, three-, and four-way nutrient interactions. Though there was minimal replication this model characterized the treatment effects while keeping the size of the experiment manageable both in terms of time (labor) and cost of plant analyses. Additionally, it was shown that when S, Fe, and/or Mn were deficient along with N, their visual deficiency symptoms were masked by the overall yellowing associated with N deficiency. This model is recommended as the initial experiment in a series where scientists are looking to expand information already determined for two factors. Other treatment systems that this can be used with include: levels of irrigation, pesticides, and plant growth regulators.
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Chen, Jingjing, Hui Hua, Jing Pang, Xianglong Shi, Weiqun Bi, Yingduan Li, and Wenjian Xu. "The Value of Diffusion-Weighted Magnetic Resonance Imaging in Predicting the Efficacy of Radiation and Chemotherapy in Cervical Cancer." Open Life Sciences 13, no. 1 (September 14, 2018): 305–11. http://dx.doi.org/10.1515/biol-2018-0037.
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AbstractBackgroundTo analyze the application value of apparent diffusion coefficient (ADC) and exponent apparent diffusion coefficient (EADC) in evaluating the efficacy of radiation and chemotherapy in cervical cancer using pre- and posttreatment diffusion-weighted magnetic resonance imaging (DW-MRI) scans.Methods52 patients with cervical cancer were administered radiation and chemotherapy. Both MRI and DW-MRI were obtained at different stages. The ADC and EADC values, as well as the maximum tumor diameter, were measured and analyzed.ResultsWe found that the ADC value increased after treatment, and the EADC value decreased. Changes in the calculated ADC occurred earlier than the morphologic changes of the tumors. A negative correlation was detected between reduced rates in the maximum tumor diameter two months after treatment and pretreatment ADC value (r = –0.658, P < 0.05). An ROC curve and nonlinear regression analysis showed that the formula, y = (1525500.122x2 – 4689.962x + 3.482) × 100%, can be used to calculate the percentage of complete remission after treatment according to the pretreatment ADC value.ConclusionOur data suggest that pretreatment ADC and EADC values are predictive of the efficacy of radiation and chemotherapy. Both ADC and EADC values during treatment were instrumental in early monitoring and dynamic observation.
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Teklu, Shewafera Wondimagegnhu, and Temesgen Tibebu Mekonnen. "HIV/AIDS-Pneumonia Coinfection Model with Treatment at Each Infection Stage: Mathematical Analysis and Numerical Simulation." Journal of Applied Mathematics 2021 (September 16, 2021): 1–21. http://dx.doi.org/10.1155/2021/5444605.
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In the paper, we have considered a nonlinear compartmental mathematical model that assesses the effect of treatment on the dynamics of HIV/AIDS and pneumonia coinfection in a human population at different infection stages. Our model revealed that the disease-free equilibrium points of the HIV/AIDS and pneumonia submodels are both locally and globally asymptotically stable whenever the associated basic reproduction numbers ( R H and R P ) are less than unity. Both the submodel endemic equilibrium points are locally and globally asymptotically stable whenever the associated basic reproduction numbers ( R P and R H ) are greater than unity. The full HIV/AIDS-pneumonia coinfection model has both locally and globally asymptotically stable disease-free equilibrium points whenever the basic reproduction number of the coinfection model R H P is less than unity. Using standard values of parameters collected from different kinds of literature, we found that the numerical values of the basic reproduction numbers of the HIV/AIDS-only submodel and pneumonia-only submodel are 17 and 7, respectively, and the basic reproduction number of the HIV/AIDS-pneumonia coinfection model is max 7 , 17 = 17 . Applying sensitive analysis, we identified the most influential parameters to change the behavior of the solution of the considered coinfection dynamical system are the HIV/AIDS and pneumonia transmission rates β 1 and β 2 , respectively. The coinfection model was numerically simulated to investigate the stability of the coinfection endemic equilibrium point, the impacts of transmission rates, and treatment strategies for HIV/AIDS-only, pneumonia-only, and HIV/AIDS-pneumonia coinfected individuals. Finally, we observed that numerical simulations indicate that treatment against infection at every stage lowers the rate of infection or disease prevalence.
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Kim, J. W., J. Kim, H. Choi, and F. W. Schwartz. "Modeling the fate and transport of organic and nitrogen species in soil aquifer treatment process." Water Science and Technology 50, no. 2 (July 1, 2004): 255–61. http://dx.doi.org/10.2166/wst.2004.0138.
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Soil aquifer treatment (SAT) is a promising technique for wastewater reclamation and reuse. This treatment strategy takes advantage of physicochemical and biological processes in the subsurface. The model employed in this study is based on MODFLOW-SURFACT (HydroGeoLogic, Inc.), a three-dimensional model for variably saturated flow and reactive mass transport. The model accounts for reactions including the nitrification of ammonium, the denitrification of nitrate, and the oxidation of organic carbon. Concentration of dissolved oxygen and biomasses involved in aerobic and anaerobic biological reactions forms the basis for estimates of nonlinear reaction rates formulated using a multiple-Monod expression. Illustrative simulations were conducted in a two-dimensional cross-sectional domain, with unsaturated and saturated zones. They examine the effects that site and operational conditions have on the performance of a SAT system. The parameters and conditions of concern included length of the wet/dry cycle, ground surface condition, and infiltration rate. From the simulations, we found that organic carbon was effectively removed in all cases. The availability of oxygen was a key factor in predicting the production and removal of nitrate. Overall, the model successfully described the fate and transport of the key constituents during the wet/dry operational periods in both unsaturated and saturated subsurface.
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Kniss, Andrew R., and Dennis C. Odero. "Interaction between Preemergence Ethofumesate and Postemergence Glyphosate." Weed Technology 27, no. 1 (March 2013): 47–53. http://dx.doi.org/10.1614/wt-d-12-00050.1.
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Greenhouse and field experiments were conducted to determine whether PRE-applied ethofumesate increased POST spray retention and weed control with glyphosate. In greenhouse studies, ethofumesate was applied PRE at rates from 0 to 224 g ai ha−1followed by POST treatment with either water or glyphosate (840 g ae ha−1) to which a red dye had been added. Plants were immediately washed and spray retention determined spectrophotometrically. Common lambsquarters retained more glyphosate solution compared to water, regardless of PRE ethofumesate rate. Increasing the rate of PRE ethofumesate increased the POST spray retention of both water and glyphosate. PRE application of ethofumesate increased POST spray retention of water by 114% and glyphosate solution by 18% compared to no ethofumesate treatment as determined by nonlinear regression. Ethofumesate rates of 90 g ha−1increased POST spray retention to at least 95% of the total observed response. In field studies, common lambsquarters, redroot pigweed, and hairy nightshade densities were all reduced by ethofumesate, although the duration of ethofumesate effect varied by species and ethofumesate application timing. PRE ethofumesate had no significant effect on hairy nightshade density until after POST glyphosate was applied, whereas common lambsquarters densities were most affected by PRE ethofumesate early in the season. Late-season redroot pigweed density was reduced by ethofumesate regardless of application timing.
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Bove, Colleen B., Justin B. Ries, Sarah W. Davies, Isaac T. Westfield, James Umbanhowar, and Karl D. Castillo. "Common Caribbean corals exhibit highly variable responses to future acidification and warming." Proceedings of the Royal Society B: Biological Sciences 286, no. 1900 (April 3, 2019): 20182840. http://dx.doi.org/10.1098/rspb.2018.2840.
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We conducted a 93-day experiment investigating the independent and combined effects of acidification (280−3300 µatm p CO 2 ) and warming (28°C and 31°C) on calcification and linear extension rates of four key Caribbean coral species ( Siderastrea siderea , Pseudodiploria strigosa , Porites astreoides , Undaria tenuifolia ) from inshore and offshore reefs on the Belize Mesoamerican Barrier Reef System. All species exhibited nonlinear declines in calcification rate with increasing p CO 2 . Warming only reduced calcification in Ps. strigosa . Of the species tested, only S. siderea maintained positive calcification in the aragonite-undersaturated treatment . Temperature and p CO 2 had no effect on the linear extension of S. siderea and Po. astreoides, and natal reef environment did not impact any parameter examined. Results suggest that S. siderea is the most resilient of these corals to warming and acidification owing to its ability to maintain positive calcification in all treatments, Ps. strigosa and U. tenuifolia are the least resilient, and Po. astreoides falls in the middle. These results highlight the diversity of calcification responses of Caribbean corals to projected global change.
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Irfan, Muhammad, Farman Ali, Fazal Muhammad, Abdullah S. Alwadie, Adam Glowacz, Iwona Goldasz, Ryszard Mielnik, Fahad Salem Alkahtani, and Hidayatullah Khan. "An Optimal Framework for WDM Systems Using Analytical Characterization of Refractive Index-Related Nonlinear Impairments." Electronics 10, no. 3 (January 20, 2021): 221. http://dx.doi.org/10.3390/electronics10030221.
Full textAbstract:
Nonlinear effects in the optical transmission systems (OTSs) are considered as the major performance limiting factor to provide high transmission rates over ultra-long distances. As the demands for system capacity, transmission range and the number of users is increasing exponentially with the development of mobile broadband, new challenges are being faced by the backbone optical networks. Mainly, the refractive index related non-linearities (RIrNLs) need to be characterized to design an optimal OTS for error-free transmission with provision of wavelength division multiplexing (WDM) to support for multiple channels. This paper provides an estimation technique of RIrNLs for long-haul transmission and their treatment for different channel spacing and the number of channels in a WDM system operating frequency domain multiple in multiple out (FD-MIMO) equalizer based digital signal processing (DSP) receiver and microstrip Chebyshev low pass filter. The main focus of this work is to utilize the existing structure of OTS for RIrNLs treatment with a low cost solution. Thus, by varying the parameters of the third order dispersion parameters, group velocity dispersion parameters, phase modulation dispersion and nonlinear refractive index, the impact of RIrNLs is investigated in detail to enhance the transmission range and capacity of the current OTS. The proposed system is analyzed in terms of range of input power, fiber length and received power for OTS figure of merits including bit error rate (BER) and optical signal-to-noise ratio (OSNR). Using duo-binary modulation, the BER achieved in this work is <10−5 till 500 km range, for maximum number of 32 channels, with 100 Gbps aggregate data rate, which shows the feasibility and effectiveness of our proposed model.