In this paper a prey-predator-scavenger food web model is proposed and studied. It is assumed that the model considered the effect of harvesting and all the species are infected by some toxicants released by some other species. The stability analysis of all possible equilibrium points is discussed. The persistence conditions of the system are established. The occurrence of local bifurcation around the equilibrium points is investigated. Numerical simulation is used and the obtained solution curves are drawn to illustrate the results of the model. Finally, the nonexistence of periodic dynamics is discussed analytically as well as numerically.
Background: Coated aesthetic archwires are currently the existing solutions for the esthetic problem, but the color of these archwires tends to change overtime. This study was aimed to evaluate the color stability of different types of esthetic archwires from four different companies at different time periods after immersion of two different staining drinks which are tea and Pepsi cola. Materials and methods: 48 specimens were prepared, each specimen contains 10 aesthetic archwires; and were divided according to type of solution into two groups: A (tea) &B (Pepsi cola); each group contained 24 specimens (12 specimens were immersed in the staining solution as 4 specimens for each time intervals and 12 specimens were immersed in distilled wa
... Show MoreAcrylic polymer/cement nanocomposites in dark and light colors have been developed for coating floors and swimming pools. This work aims to emphasize the effect of cement filling on the mechanical parameters, thermal stability, and wettability of acrylic polymer. The preparation was carried out using the casting method from acrylic polymer coating solution, which was added to cement nanoparticles (65 nm) with weight concentrations of (0, 1, 2, 4, and 8 wt%) to achieve high-quality specifications and good adhesion. Maximum impact strength and Hardness shore A were observed at cement ratios of 2 wt% and 4 wt%, respectively. Changing the filling ratio has a significant effect on the strain of the nanocomposites. The contact angle was i
... Show MoreIn this paper, we made comparison among different parametric ,nonparametric and semiparametric estimators for partial linear regression model users parametric represented by ols and nonparametric methods represented by cubic smoothing spline estimator and Nadaraya-Watson estimator, we study three nonparametric regression models and samples sizes n=40,60,100,variances used σ2=0.5,1,1.5 the results for the first model show that N.W estimator for partial linear regression model(PLM) is the best followed the cubic smoothing spline estimator for (PLM),and the results of the second and the third model show that the best estimator is C.S.S.followed by N.W estimator for (PLM) ,the
... Show MoreIn this paper, the general framework for calculating the stability of equilibria, Hopf bifurcation of a delayed prey-predator system with an SI type of disease in the prey population, is investigated. The impact of the incubation period delay on disease transmission utilizing a nonlinear incidence rate was taken into account. For the purpose of explaining the predation process, a modified Holling type II functional response was used. First, the existence, uniform boundedness, and positivity of the solutions of the considered model system, along with the behavior of equilibria and the existence of Hopf bifurcation, are studied. The critical values of the delay parameter for which stability switches and the nature of the Hopf bifurcat
... Show MoreAn integrated lithofacies and mineralogical assemblage was used to describe a depositional model and sequence stratigraphic framework of the Maastrichtian–Danian succession in the Western Desert of Iraq and eastern Jordan. Fifteen lithofacies types were grouped into three associations recognized in a distally steepened ramp characterized by an apparent, distinct increase in a gradient paleobathymetric deepening westward. The clay and nonclay minerals are dominated by smectite and palygorskite, with trace amounts of kaolinite, sepiolite, illite and chlorite. Meanwhile, quartz, calcite, dolomite, opal CT (Cristobalite - Tridymite), and apatite are the main nonclay minerals. The widely dominated smectite in the Western Phosphatic Basin of Ir
... Show MoreSince the beginning of 21st century, the prices of Agricultural crops have increased. This Increases is accompanied with that increases of crude oil prices and fluctuation of a dollar exchange rate as a dominant currency used in the global trade. The paper aimed to analysis the short run and long run cointegration relationships between prices of some of Agricultural crops imported by Iraq such as wheat and rice crops and both the crude oil prices and the Iraq dinar exchange rate a gained America dollar using ARDL model. The results show the long run equilibrium between they three variable throng the error correction mechanizem. The results also show the significant and economically sound effects of cru
... Show MoreOrganic Permeable Base Transistors (OPBTs) reach a very high transit frequency and large on-state currents. However, for a later commercial application of this technology, a high operational stability is essential as well. Here, the stability of OPBTs during continuous cycling and during base bias stress is discussed. It is observed that the threshold voltage of these transistors shifts toward more positive base voltages if stressed by applying a constant potential to the base electrode for prolonged times. With the help of a 2D device simulation, it is proposed that the observed instabilities are due to charges that are trapped on top of an oxide layer formed around the base electrode. These charges are thermally released after rem
... Show MoreThis research aims at identifying the communicative habits and content reflections on the communication process, especially the young audience which is one of the main group for whom the announcements are made. Because young people face life with passion and aspiration making them respond to each effect used by the media in the design of the advertising using all the effective techniques, attractive methods for young children like depending on drama, technical tricks, music and logos easily to be remembered and responded to the desires of the young in their entertainment. This research also aims at identifying the impact of the internet as a channel of commercial advertising on the purchasing behavior of young people at the universities
... Show MoreThe features of the actor's performance in the ritual theater are of great importance and chief in theatrical work since the first emergence of the theater, as the features of the performance were embodied in all Iraqi theatrical performances, but they took personal privacy in some ritual performances because of their differences and similarities between the ritual theatrical performance and the ritual show Al-Khalis, who wanted the researcher to know the similarities and differences in the features of the ritual performance and in the theatrical performance, despite the many transformations that occurred in the theater and affected the features of the performance, but it remained an important and attractive link between the recipient, t
... Show MoreIt is a moral presumption that includes the object for its sake, and it is called the object for it or the object for its sake, which is the present tense after (lam, ki, fa, willn, and then), and it is not an excuse for the occurrence of the matter (1), and it requires a connection between the two sides of (a cause with a cause) united by a reason for a specific purpose (2). The object has a reason or an excuse, because it is an explanation of what came before it, of the cause. The reason for the occurrence of the action, being the motive for causing the action and the bearer of it (3), indicates that the infinitive is restricted to a special reason. So if I said: (I came to you with the hope of honoring you), then I attributed the coming
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