<p>The objective of this paper is to study the dynamical behavior of an aquatic food web system. A mathematical model that includes nutrients, phytoplankton and zooplankton is proposed and analyzed. It is assumed that, the phytoplankton divided into two compartments namely toxic phytoplankton which produces a toxic substance as a defensive strategy against predation by zooplankton, and a nontoxic phytoplankton. All the feeding processes in this food web are formulating according to the Lotka-Volterra functional response. This model is represented mathematically by the set of nonlinear differential equations. The existence, uniqueness and boundedness of the solution of this model are investigated. The local and global stability conditions of all possible equilibrium points are established. The occurrence of local bifurcation and Hopf bifurcation are investigated. Finally, numerical simulation is used to study the global dynamics of this model.</p>
The language that consists of only twenty-eight letters, but it is so broad that we are unable to understand it from all sides and this expansion is mainly caused by imagination, so Arab imagination, whose language goes in all directions And as it always responds to our ears, ancient critics divide imagination into holistic and partial But the language is not limited to these parts only. Do we wonder, where is the structural method of wishing, hope, questions and other methods of all this? In this paper, we try to show the importance of the method of writing in moving imagination in an interactive way, and what is related to human feelings in most, if not all, of its methods By studying the poetry of the believers in the Ahl al-Bayt, pea
... Show MoreTakbiratul Ehram "The First Takbeer to Start Prayer" means: the words that the worshiper says to start his prayers, and refrain from anything invalidates it. the findings revealed that the four school jurists agreed that the prayer is not valid without Takbiratul Ehram "The First Takbeer to Start Prayer", and they disagreed on its description, so the majority of jurists said that it is a pillar, and some of them called it an obligatory, but Hanafi made it a condition. Likewise, the four jurists agreed that the one who articulates Takbiratul Ehram "The First Takbeer to Start Prayer" with the word: “Allahu Akbar,”; his Takbeer is correct, and they disagreed about the one who adds a word, or replaced it with another, where the m
... Show MoreMultilateral wells require a sophisticated type of well model to be applied in reservoir simulators to represent them. The model must be able to determine the flow rate of each fluid and the pressure throughout the well. The production rate calculations are very important because they give an indication about some main issues associated with multi-lateral wells such as one branch may produce water or gas before others, no production rate from one branch, and selecting the best location of a new branch for development process easily.  
... Show MoreThe goal of the extant revision was to explore the influence of caffeic acid (CA) extracted from Arctium lappa L. on lipid profile and histology of aorta in rats . Analytical study demonstrated a high percentage of both chlorogenic and caffeic acid in the 80 % methanol extract of the aerial parts (leaves and stems) of Arctium lappa L. from the family Asteraceace. Hypolipidemic activity of caffeic acid was studied against cholesterol induced hypercholesterolemia in Wistar albino rats for thirty days. Rats were separated into normal group (A), hypercholesterolemic positive controller group (B). While, the rest three groups (C, D and E) attended as hypercholesterol
... Show MoreThe parameter and system reliability in stress-strength model are estimated in this paper when the system contains several parallel components that have strengths subjects to common stress in case when the stress and strengths follow Generalized Inverse Rayleigh distribution by using different Bayesian estimation methods. Monte Carlo simulation introduced to compare among the proposal methods based on the Mean squared Error criteria.
This work describes the enhancement of phenol red decolorization through immobilizing of laccase in chitosan and enzyme recycling. Commercial laccase from white rot fungus, Trametesversicolor (Tvlac), was immobilizedin to freshly prepared chitosan beads by using glutaraldehyde as a cross linker. Characterization of prepared chitosan was confirmed by FTIR and scanning electron microscope (SEM). Tvlac (46.2 U/mL) immobilized into chitosan beads at 0.8 % glutaraldehyde (v/v) within 24 hrs. Synthetic (HBT) and natural (vanillin) mediators were used to enhance dye decolorizoation. It was found that 89 % of phenol red was decolorized by chitosan beads within 180 min. in the absence of enzyme and mediator, while decolorization percenta
... Show More The research addresses the feminist lament and its representations in the contemporary Arab theatrical text as one of the purposes of the Arabic poetry and its images, samples, and reasons developed and its incentives multiplied through different time periods in which a dramatic image and representations have been manifested that harmonized with the art of theatre. In order to shed light on these representations, this study has come to look for the representations of lament phenomenon in the Arab theatre texts.
The study consists of an introduction in which the two researchers put forward the research problem, significance and objectives, and a theoretical framework which tackles a theoretical foundation for the research consi