scholarly journals Competition among Predators and Allee Effect on Prey, Their Influence on a Gause-Type Predation Model

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Eduardo González-Olivares ◽  
Javier Cabrera-Villegas ◽  
Fernando Córdova-Lepe ◽  
Alejandro Rojas-Palma

Interference or competition among predators (CAP) has often been ruled out in depredation models, although there are varied mathematical forms to describe and incorporate it into this interaction. In this work, we present the most known of these descriptions and one of them will be used in a modified Volterra model. Moreover, of this ecological phenomenon, a simple and strong Allee effect affecting the prey population will be considered in the relationship. An important feature of the new model is to have until two positive equilibrium points, to the difference with the Volterra model (without Allee effect); hence different and interesting dynamic situations appear in the system. Conditions for the existence and local stability of equilibria are determined. The boundedness of solutions, the existence of a limit cycle and a separatrix curve are also proven. Besides, the main properties of the model are examined from an ecological point of view. To make a comparative discussion of our results, an Appendix is added with the main properties of models, in which neither the Allee effect nor the competition among predators is considered. Some simulations are shown to endorse our results.

Morphology ◽  
2021 ◽  
Author(s):  
Rossella Varvara ◽  
Gabriella Lapesa ◽  
Sebastian Padó

AbstractWe present the results of a large-scale corpus-based comparison of two German event nominalization patterns: deverbal nouns in -ung (e.g., die Evaluierung, ‘the evaluation’) and nominal infinitives (e.g., das Evaluieren, ‘the evaluating’). Among the many available event nominalization patterns for German, we selected these two because they are both highly productive and challenging from the semantic point of view. Both patterns are known to keep a tight relation with the event denoted by the base verb, but with different nuances. Our study targets a better understanding of the differences in their semantic import.The key notion of our comparison is that of semantic transparency, and we propose a usage-based characterization of the relationship between derived nominals and their bases. Using methods from distributional semantics, we bring to bear two concrete measures of transparency which highlight different nuances: the first one, cosine, detects nominalizations which are semantically similar to their bases; the second one, distributional inclusion, detects nominalizations which are used in a subset of the contexts of the base verb. We find that only the inclusion measure helps in characterizing the difference between the two types of nominalizations, in relation with the traditionally considered variable of relative frequency (Hay, 2001). Finally, the distributional analysis allows us to frame our comparison in the broader coordinates of the inflection vs. derivation cline.


1997 ◽  
Vol 50 (1) ◽  
pp. 1-38 ◽  
Author(s):  
Iain Provan

It is well known that the seeds from which the modern discipline of OT theology grew are already found in 17th and 18th century discussion of the relationship between Bible and Church, which tended to drive a wedge between the two, regarding canon in historical rather than theological terms; stressing the difference between what is transient and particular in the Bible and what is universal and of abiding significance; and placing the task of deciding which is which upon the shoulders of the individual reader rather than upon the church. Free investigation of the Bible, unfettered by church tradition and theology, was to be the way ahead. OT theology finds its roots more particularly in the 18th century discussion of the nature of and the relationship between Biblical Theology and Dogmatic Theology, and in particular in Gabler's classic theoreticalstatementof their nature and relationship. The first book which may strictly be called an OT theology appeared in 1796: an historical discussion of the ideas to be found in the OT, with an emphasis on their probable origin and the stages through which Hebrew religious thought had passed, compared and contrasted with the beliefs of other ancient peoples, and evaluated from the point of view of rationalistic religion. Here we find the unreserved acceptance of Gabler's principle that OT theology must in the first instance be a descriptive and historical discipline, freed from dogmatic constraints and resistant to the premature merging of OT and NT — a principle which in the succeeding century was accepted by writers across the whole theological spectrum, including those of orthodox and conservative inclination.


Author(s):  
Hanaa Ebrahim Semran Al-Juhani, Randa Hariri Hanaa Ebrahim Semran Al-Juhani, Randa Hariri

The study aimed to discover the relationship between practicing creative leadership and school management crisis among female educational leaders of publicsecondary schools in Jeddah from the latter’s’ perspectives. The study adopted adescriptive, correlational-relational research design and used a questionnaire to randomly collect data from a sample of (357) female teachers during the first semester of the 1441/1442AH academic year. Findings revealed that female school leaders practice creative leadership, and school crisis management at a high degree, whereby, accommodation and cooperation styles ranked first and second respectively, and avoidance style ranked last. Findings also showed that there were statistically significant differences at the level of (0.5 = α) between the means of the degree of creative leadership and crisis management practices referred to the difference in experience. Moreover, results showed a positive correlation between the degree of creative leadership and crises management practices. The study recommended holding events in the education and schools’ management that highlight the role of creative leadership and its impact on enhancing schools’ ability to manage and face crises, along with offering training courses aboutcrisis management, and encouraging relevant practices by teachers and staff members.


Mathematics ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 1280
Author(s):  
Liyun Lai ◽  
Zhenliang Zhu ◽  
Fengde Chen

We proposed and analyzed a predator–prey model with both the additive Allee effect and the fear effect in the prey. Firstly, we studied the existence and local stability of equilibria. Some sufficient conditions on the global stability of the positive equilibrium were established by applying the Dulac theorem. Those results indicate that some bifurcations occur. We then confirmed the occurrence of saddle-node bifurcation, transcritical bifurcation, and Hopf bifurcation. Those theoretical results were demonstrated with numerical simulations. In the bifurcation analysis, we only considered the effect of the strong Allee effect. Finally, we found that the stronger the fear effect, the smaller the density of predator species. However, the fear effect has no influence on the final density of the prey.


1981 ◽  
Vol 11 (1) ◽  
pp. 44-46 ◽  
Author(s):  
D.P. Fourie

It is increasingly realized that hypnosis may be seen from an interpersonal point of view, meaning that it forms part of the relationship between the hypnotist and the subject. From this premise it follows that what goes on in the relationship prior to hypnosis probably has an influence on the hypnosis. Certain of these prior occurences can then be seen as waking suggestionns (however implicitly given) that the subject should behave in a certain way with regard to the subsequent hypnosis. A study was conducted to test the hypothesis that waking suggestions regarding post-hypnotic amnesia are effective. Eighteen female subjects were randomly divided into two groups. The groups listened to a tape-recorded talk on hypnosis in which for the one group amnesia for the subsequent hypnotic experience and for the other group no such amnesia was suggested. Thereafter the Stanford Hypnotic Susceptibility Scale was administered to all subjects. Only the interrogation part of the amnesia item of the scale was administered. The subjects to whom post-hypnotic amnesia was suggested tended to score lower on the amnesia item than the other subjects, as was expected, but the difference between the mean amnesia scores of the two groups was not significant.


2013 ◽  
Vol 23 (01) ◽  
pp. 1350003 ◽  
Author(s):  
DANIEL FRANCO ◽  
EDUARDO LIZ

We investigate a method of chaos control in which intervention is proportional to the difference between the current state and a fixed value. We prove that this method allows to stabilize the most usual one-dimensional maps used in discrete-time models of population dynamics about a globally stable positive equilibrium. From the point of view of targeting, this technique is very flexible, and we show how to choose the control parameter values to lead the system towards the desired target. Another important feature of this control scheme in the ecological context is that it can be designed to prevent the risk of extinction in models with the so-called Allee effect. We provide a useful geometrical interpretation, and give some examples to illustrate our theoretical results.


2014 ◽  
Vol 3 (2) ◽  
Author(s):  
Laura Tampieri

The paper examines the approach to usefulness of performance indicator systems in Public Administration (PA). There are many international studies about this subject, especially from the point of view of efficiency, effectiveness and adequacy. The used approach considers the difference among these indicators based on the level of difficulty in PA implementation. The research compares some indicator systems in European Public Administration considering their easiness and feasibility to apply and connecting these qualities to the basic structures of efficiency, effectiveness and adequacy. The paper aims to compare performance indicator systems of Austria, Italy and Slovenia, emphasizing the relationship between the indicators and their diffusion in government managerial control. In particular the paper underlines the connection between the difficulty of indexes application and the level of diffusion. in Public Administrations.


2003 ◽  
Vol 31 (2) ◽  
pp. 132-142 ◽  
Author(s):  
Osman Kopmaz ◽  
Ömer Gündoğdu

This paper deals with different approaches to describing the relationship between the bending moment and curvature of a Euler—Bernoulli beam undergoing a large deformation, from a tutorial point of view. First, the concepts of the mathematical and physical curvature are presented in detail. Then, in the case of a cantilevered beam subjected to a single moment at its free end, the difference between the linear theory and the nonlinear theory based on both the mathematical curvature and the physical curvature is shown. It is emphasized that a careless use of the nonlinear mathematical curvature and moment relationship given in most standard textbooks may lead to erroneous results. Furthermore, a numerical example is given for the reader to make a quantitative assessment.


2018 ◽  
Vol 28 (05) ◽  
pp. 1850062 ◽  
Author(s):  
Limin Zhang ◽  
Lan Zou

In this paper, the bifurcations and the control of a discrete predator–prey model with strong Allee effect on the prey are investigated. This shows that the model undergoes a supercritical Neimark–Sacker bifurcation. Meanwhile, the explicit approximate expression of the stable closed invariant curve caused by the Neimark–Sacker bifurcation is given. 1:3 strong resonance is investigated through approximation by a flow, and the bifurcation curves around 1:3 resonance are obtained. Moreover, for the sake of regulating the stability of the biological system, we extend the hybrid control strategy to control the Neimark–Sacker bifurcation and 1:3 strong resonance. The theoretical analyses are validated by numerical simulations and are explained from the biological point of view.


2009 ◽  
Vol 5 ◽  
Author(s):  
Inez Martinez

Jung claims that visionary imaginative literature, because its source is the collective unconscious, helps the collective psyche self-regulate. Proving Jung’s claim is difficult since shifts in collective consciousness have many causes, but an instance of literature’s playing a part in such a shift is Robert Browning’s The Ring and the Book which contributed to collective realization of the inherent limitations of point of view. Sometimes literature contributes to collective consciousness through tales bringing into focus a collective crisis, such as Jorge Luis Borges’s stories “The Garden of Forking Paths,” “The Library of Babel,” and “The Secret Miracle” which convey the modern dilemma of loss of absolute transcendent truths. Literature, however, cannot bring unconscious contents to consciousness if readers read with rigid ego boundaries, what I call ego readings.  Slipping free from ego readings is more likely if one becomes aware that one is so reading. If readers already have experience of psyche beyond ego, they are more likely to be able to read for psyche. Still, even if readers do not have such experience, literature itself can initiate one into the existence of psyche as my reading of Mark Twain’s The Mysterious Stranger initiated me. One can become aware of performing ego readings through clues such as habitually discovering in the text what one already thinks, reading for plot, becoming angry at a text, discovering that one has been in denial about a text, and reading to find support for an argument. This latter practice characterizes literary criticism, as illustrated by Jacques Lacan’s, Jacques Derrida’s, and Barbara Johnson’s responses to Edgar Allen Poe’s “The Purloined Letter.” Paradoxically, the professional response to literature may obstruct reading literature for psyche. If one can overcome ego resistance to a text, as I suggest through my experience of reading D.H. Lawrence’s “The Rocking Horse Winner,” one can garner a story’s psychological riches. Still, resistance may arise from ethical concerns, including responsibility to oneself, so that the relationship between self and text requires conscious and conscientious negotiation, an unsettling process as I detail in reference to my reading of Roberto Bolano’s 2666. Once readers are aware of performing ego readings, they can attempt to loosen their ego boundaries through focused attention (an insight emerging from reading Virginia Woolf’s “Kew Gardens”), particularly toward numinous moments for characters in a text or numinous responses in themselves. Reading for psyche also is furthered  through re-reading, conscious intention, and reflection. For the institutions of literary criticism and of teaching to help readers be open to the contents of the unconscious psyche in literature, teachers and critics need to be aware of the difference between ego readings and reading for psyche. Jungian literature teachers and literary critics can take the lead.


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