scholarly journals THE EFFECTS OF VARYING PARAMETER VALUES AND HETEROGENEITY IN AN INDIVIDUAL-BASED MODEL OF PREDATOR-PREY INTERACTION

2003 ◽  
Vol 06 (03) ◽  
pp. 441-456 ◽  
Author(s):  
WILLIAM J. CHIVERS ◽  
RIC D. HERBERT
Keyword(s):  
Individual Variation ◽  
Traditional Approach ◽  
Common Finding ◽  
Individual Based Model ◽  
Individual Parameter ◽  
Predator Prey ◽  
State Variable ◽  
The Stability ◽  
The Individual ◽  
Parameter Values

An individual-based model which produces nonlinear predator-prey dynamics is described. The importance of individual variation to the stability of the population dynamics predicted by the model and the advantages of the individual-based approach to modelling ecological systems is discussed. The individual-based model is compared with the traditional approach of population ecology — the modelling of populations with state variable equations. The individual-based model built here produces similar patterns of mutual dependence of the populations to those produced by the state variable model but has additional utility. It greatly simplifies the adjustment of individual environmental parameters which may be built into the model and it makes it possible to follow individuals or individual parameter values through the simulation. The cost of the utility of the individual-based approach is in the complexity of the model itself, which is more difficult to build than many state variable models. A common finding in the literature of individual-based modelling in ecology is the importance of individual variation. The individual-based model described here is built with a minimum of biological complexity, but still we find that individual variation in the model has profound effects on the stability of the population levels over long time periods.

Text and Discourse Linguistic Creativity of Children's English-Language Adventure Fiction

2021 ◽  
pp. 5-15
Author(s):  
Maria I. Kiose ◽  
◽  
Keyword(s):  
Vector Space ◽  
English Language ◽  
Total Sample ◽  
Word Formation ◽  
Statistics Analysis ◽  
Individual Parameter ◽  
Creativity Assessment ◽  
Adventure Fiction ◽  
The Individual ◽  
Parameter Values

The article explores the specificity of linguistic creativity in the discourse of children's English-language adventure fiction of the 1950s. The aim of the research is to develop the parametrization and vector-space method of discourse and text linguistic creativity assessment to evaluate the linguistic creativity potential of individual texts displaying similar discourse features. To serve as the research data three discourse fragments were selected, which represent three basic narrative types, Orientation, Complicating Actions, Evaluation and Resolution. To achieve the aim, the author applies the procedure of parametrization analysis followed by general and analytic statistics analysis and vector-space modelling. With the system of 52 parameters featuring linguistic creativity in phonology, word-formation, morphology, lexicology and phraseology, syntax, and graphics, the author manually annotates and processes the discourse fragments of similar size exemplifying three narrative types of adventure fiction literature, with the total sample size of 55,000 characters. General statistics analysis allowed revealing the absolute and relative parameter values in three discourse fragments and defining the relative parametric activity of single parameters and parameter levels. Analysis of variance helped define the correlation indices of parameter paired combinations, which resulted in detecting significant binary parameter groups . Individual parameter values and their binary groups served to construe the vector-space models of discourse and text linguistic creativity for the discourse narrative types under consideration. Thus, the author obtained an efficient instrument for discourse linguistic creativity evaluation and, furthermore, for assessing the potential of each individual text in terms of displaying stronger or weaker correlation with the vector coordinates of the discourse linguistic creativity vector-space model. With the frequency and variance analysis, the author disclosed two types of discourse linguistic creativity performance techniques, that is the individual parameter activation and the parameter synchronization. Both must be considered when the decision on linguistic creativity assessment in a concrete text is made. The resulting model shows that the parameter values of linguistic creativity in individual texts can manifest themselves in appearing both higher and lower than the reference parameter values of discourse creativity, which can contribute to disclosing new directions in creativity processing and understanding.

A Physiological Theory of Phonetics

1966 ◽  
Vol 9 (1) ◽  
pp. 5-67 ◽  
Author(s):  
Gordon E. Peterson ◽  
June E. Shoup
Keyword(s):  
Speech Production ◽  
Biological Science ◽  
Physiological Parameters ◽  
Basic Theory ◽  
Individual Parameter ◽  
Essential Components ◽  
The Individual ◽  
Parameter Values ◽  
Physiological Theory

This paper presents a phonetic theory based on physiological parameters. The motivation for and requirements of a phonetic theory are first considered. The theory assumes, without restatement, various known facts from physical and biological science. Certain essential components of the speech mechanism are defined in a set of preliminary definitions. Assumptions about the actions of the vocal mechanism which directly underlie the theory are next presented in a set of axioms. Following the axioms is an extensive set of definitions that specifies the concepts of phonetics and their relationships. A phonetic chart presents the various physiological speech parameters and their values. These parameters include the primary and secondary phonetic parameters and the prosodic parameters. The chart includes a phonetic diagram which presents a basic phonetic symbolization according to the values of the primary parameters. Secondary parameters implicit in the symbols of the diagram are shown in a second chart. The individual parameter values for the various parameters are next defined. The article presents a basic theory of the parameter values and the dynamics of speech production, and also presents a systematic symbolization for descriptive phonetics.

Stability and Bifurcation Analysis in a Nonlinear Harvested Predator–Prey Model with Simplified Holling Type IV Functional Response

2020 ◽  
Vol 30 (14) ◽  
pp. 2050205
Author(s):  
Zuchong Shang ◽  
Yuanhua Qiao ◽  
Lijuan Duan ◽  
Jun Miao
Keyword(s):  
Functional Response ◽  
Limit Cycle ◽  
Bifurcation Analysis ◽  
Homoclinic Loop ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Type Iv ◽  
Prey Model ◽  
The Stability ◽  
Parameter Values

In this paper, a type of predator–prey model with simplified Holling type IV functional response is improved by adding the nonlinear Michaelis–Menten type prey harvesting to explore the dynamics of the predator–prey system. Firstly, the conditions for the existence of different equilibria are analyzed, and the stability of possible equilibria is investigated to predict the final state of the system. Secondly, bifurcation behaviors of this system are explored, and it is found that saddle-node and transcritical bifurcations occur on the condition of some parameter values using Sotomayor’s theorem; the first Lyapunov constant is computed to determine the stability of the bifurcated limit cycle of Hopf bifurcation; repelling and attracting Bogdanov–Takens bifurcation of codimension 2 is explored by calculating the universal unfolding near the cusp based on two-parameter bifurcation analysis theorem, and hence there are different parameter values for which the model has a limit cycle, or a homoclinic loop; it is also predicted that the heteroclinic bifurcation may occur as the parameter values vary by analyzing the isoclinic of the improved system. Finally, numerical simulations are done to verify the theoretical analysis.

Implications of Person Fluctuation for the Stability and Validity of Test Scores

Methodology ◽  
2006 ◽  
Vol 2 (4) ◽  
pp. 142-148 ◽  
Author(s):  
Pere J. Ferrando
Keyword(s):  
Item Response ◽  
Test Scores ◽  
Temporal Stability ◽  
Person Fit ◽  
Item Parameters ◽  
Individual Trait ◽  
The Stability ◽  
The Individual ◽  
Different Levels ◽  
Fluctuation Model

In the IRT person-fluctuation model, the individual trait levels fluctuate within a single test administration whereas the items have fixed locations. This article studies the relations between the person and item parameters of this model and two central properties of item and test scores: temporal stability and external validity. For temporal stability, formulas are derived for predicting and interpreting item response changes in a test-retest situation on the basis of the individual fluctuations. As for validity, formulas are derived for obtaining disattenuated estimates and for predicting changes in validity in groups with different levels of fluctuation. These latter formulas are related to previous research in the person-fit domain. The results obtained and the relations discussed are illustrated with an empirical example.

Intra-individual variation in adults and children: measuring and conceptualizing individual dialect–standard repertoires

2021 ◽  
Vol 7 (s2) ◽  
Author(s):  
Irmtraud Kaiser ◽  
Andrea Ender
Keyword(s):  
Language Acquisition ◽  
Individual Variation ◽  
The Other ◽  
Standard Language ◽  
Methodological Choices ◽  
Standard Spectrum ◽  
Speech Data ◽  
Adults And Children ◽  
The One ◽  
The Individual

Abstract This paper explores intra-individual variation as a manifestation of language-internal multilingualism in the Central-Bavarian Austrian context. Based on speech data from children and adults in different contexts, we discuss different methods of measuring and analyzing inter-situational variation along the dialect and standard language spectrum. By contrasting measures of dialectality, on the one hand, and proportions of turns in dialect, standard language or intermediate/mixed forms on the other, we gain complementary insights not only into the individual dialect-standard repertoires but also into the consequences of different methodological choices. The results indicate that intra-individual variation is ubiquitous in adults and children and that individual repertoires need to be taken into account from the beginning of the language acquisition process. We suggest that while intra-individual variation can be attested through the use of various methods, the revealed level of granularity and the conclusions that can be drawn as to the individual repertoires on the dialect-standard spectrum largely depend on the measures used and their inherent assumptions and intrinsically necessary categorizations.

Examining sharp restart in a Monte Carlo method for the linearized Poisson–Boltzmann equation

2020 ◽  
Vol 26 (3) ◽  
pp. 223-244
Author(s):  
W. John Thrasher ◽  
Michael Mascagni
Keyword(s):  
Monte Carlo ◽  
Free Energy ◽  
Monte Carlo Algorithm ◽  
Significant Bias ◽  
Poisson Boltzmann ◽  
Electrostatic Free Energy ◽  
Poisson Boltzmann Equation ◽  
The Stability ◽  
Potential Methods ◽  
The Individual

AbstractIt has been shown that when using a Monte Carlo algorithm to estimate the electrostatic free energy of a biomolecule in a solution, individual random walks can become entrapped in the geometry. We examine a proposed solution, using a sharp restart during the Walk-on-Subdomains step, in more detail. We show that the point at which this solution introduces significant bias is related to properties intrinsic to the molecule being examined. We also examine two potential methods of generating a sharp restart point and show that they both cause no significant bias in the examined molecules and increase the stability of the run times of the individual walks.

scholarly journals Hopf bifurcation in a diffusive predator–prey model with Smith growth rate and herd behavior

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Heping Jiang ◽  
Huiping Fang ◽  
Yongfeng Wu
Keyword(s):  
Hopf Bifurcation ◽  
Neumann Boundary ◽  
Herd Behavior ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Dynamical Behaviors ◽  
Prey System ◽  
Prey Model ◽  
Homogeneous Neumann Boundary Condition ◽  
The Stability

Abstract This paper mainly aims to consider the dynamical behaviors of a diffusive delayed predator–prey system with Smith growth and herd behavior subject to the homogeneous Neumann boundary condition. For the analysis of the predator–prey model, we have studied the existence of Hopf bifurcation by analyzing the distribution of the roots of associated characteristic equation. Then we have proved the stability of the periodic solution by calculating the normal form on the center of manifold which is associated to the Hopf bifurcation points. Some numerical simulations are also carried out in order to validate our analysis findings. The implications of our analytical and numerical findings are discussed critically.

The great Chinese surprise: the rupture with the United States is real and is happening

2020 ◽  
Vol 96 (2) ◽  
pp. 419-437
Author(s):  
Xiangfeng Yang
Keyword(s):  
United States ◽  
The United States ◽  
Donald Trump ◽  
Ample Evidence ◽  
Pendulum Swing ◽  
The Us ◽  
Methodological Problems ◽  
Trade War ◽  
The Stability ◽  
The Individual

Abstract Ample evidence exists that China was caught off guard by the Trump administration's onslaught of punishing acts—the trade war being a prime, but far from the only, example. This article, in addition to contextualizing their earlier optimism about the relations with the United States under President Trump, examines why Chinese leaders and analysts were surprised by the turn of events. It argues that three main factors contributed to the lapse of judgment. First, Chinese officials and analysts grossly misunderstood Donald Trump the individual. By overemphasizing his pragmatism while downplaying his unpredictability, they ended up underprepared for the policies he unleashed. Second, some ingrained Chinese beliefs, manifested in the analogies of the pendulum swing and the ‘bickering couple’, as well as the narrative of the ‘ballast’, lulled officials and scholars into undue optimism about the stability of the broader relationship. Third, analytical and methodological problems as well as political considerations prevented them from fully grasping the strategic shift against China in the US.

scholarly journals Temporal Stability and Biodiversity of Two Complex Antilisterial Cheese-Ripening Microbial Consortia

2003 ◽  
Vol 69 (7) ◽  
pp. 4012-4018 ◽  
Author(s):  
Ariel Maoz ◽  
Ralf Mayr ◽  
Siegfried Scherer
Keyword(s):  
Species Composition ◽  
Bacterial Species ◽  
Temporal Stability ◽  
Individual Characteristics ◽  
Microbial Consortia ◽  
Cheese Ripening ◽  
Safe Food ◽  
The Stability ◽  
The Individual ◽  
First Time

ABSTRACT The temporal stability and diversity of bacterial species composition as well as the antilisterial potential of two different, complex, and undefined microbial consortia from red-smear soft cheeses were investigated. Samples were collected twice, at 6-month intervals, from each of two food producers, and a total of 400 bacterial isolates were identified by Fourier-transform infrared spectroscopy and 16S ribosomal DNA sequence analysis. Coryneform bacteria represented the majority of the isolates, with certain species being predominant. In addition, Marinolactobacillus psychrotolerans, Halomonas venusta, Halomonas variabilis, Halomonas sp. (106 to 107 CFU per g of smear), and an unknown, gram-positive bacterium (107 to 108 CFU per g of smear) are described for the first time in such a consortium. The species composition of one consortium was quite stable over 6 months, but the other consortium revealed less diversity of coryneform species as well as less stability. While the first consortium had a stable, extraordinarily high antilisterial potential in situ, the antilisterial activity of the second consortium was lower and decreased with time. The cause for the antilisterial activity of the two consortia remained unknown but is not due to the secretion of soluble, inhibitory substances by the individual components of the consortium. Our data indicate that the stability over time and a potential antilisterial activity are individual characteristics of the ripening consortia which can be monitored and used for safe food production without artificial preservatives.

DESIGN OF ADAPTIVE FUZZY SLIDING MODE CONTROL FOR NONLINEAR SYSTEMS

1999 ◽  
Vol 07 (05) ◽  
pp. 463-474 ◽  
Author(s):  
JEN-YANG CHEN
Keyword(s):  
Sliding Mode ◽  
Membership Functions ◽  
System Specification ◽  
Pendulum System ◽  
Control Rules ◽  
Inverted Pendulum System ◽  
Equivalent Control ◽  
Fuzzy Sliding Mode ◽  
The Stability ◽  
The Individual

In this paper, a fuzzy sliding mode controller (FSMC), which is synthesized by a collection of linguistic control rules whose membership functions of THEN-part is adapted, is proposed. Both the membership functions of IF-part and THEN-part are arranged symmetrically and distributed equally in the individual universe of discourse. In particular, the membership functions of the THEN-part can be adapted via one parameter adaptation to meet the required system specification. The proposed direct adaptive FSMC can be synthesized through the following stages. First, the control rules are constructed according to the concepts of SMC, and the fuzzy sets whose membership functions are symmetrically covered in state space. Then, the derived adaptive law is used to adjust the membership functions of the THEN-part. The FSMC is employed to approximate the equivalent control of SMC without knowing the mathematical model of the controlled system. Third, a hitting control is developed to guarantee the stability of the control system. Finally, we apply this FSMC to control a nonlinear inverted pendulum system for confirming the validity of the proposed approach.

Sign in / Sign up

Export Citation Format

Share Document