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The Role of Fear and Predator Dependent Refuge on a Stage Structure Prey-Predator System
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The present paper investigates the role of fear and predator dependent refuge in the prey-predator system. The system describes the interaction between prey and a stage structure of predator that incorporates Holling II functional response. The predator splits into two compartments immature (juvenile) and mature (adult). The mature predators can hunt and reproduce but this capability is not found in the immature predators, the immature depend on their parents. The growth rate of prey decreases due to the existence of mature predators. The existence, uniqueness, and boundedness of the solution of the system are investigated. Three equilibrium points of the system are determined. The local stability of the system is studied. The global stability of the axial equilibrium point is discussed using the appropriate Lyapunov function, while the basin of attraction of the positive equilibrium point is investigated. The persistence constraints of the system are established. The local and Hopf bifurcation analyses of the system are examined. Lastly, numerical simulations are given to ensure the theoretical results with the help of Matlab program (version R2018b). It is found that the effect of fear plays a substantial role in the dynamic of the system. On the other hand, the refuge’s coefficient continuously affects the system. Furthermore, the variation of the refuge’s coefficient by utilizing different initial points leads to a change in the behavior of the system from stable to unstable and conversely.

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Publication Date
Sun Dec 03 2017
Journal Name
Baghdad Science Journal
Community Structure of Benthic Algae in a Lotic Ecosystem, Karbala Province-Iraq
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This study focused on benthic algae (epipelic and attached algae on concrete lining stream) in Bani-Hassan stream in Holly Karbala, Iraq. The qualitative and quantitative studies of benthic algae were done by collecting 240 samples from five sites in the study area for the period from December 2012 to November 2013. Also, the environmental variables of the stream were examined in term of temporary and spatial. The results showed that the stream was alkaline, hard, oligohaline and a well aerated. The total nitrogen to the total phosphorus (TN: TP) ratio indicates nitrogen limitation. 129 species of benthic algae belonging to 57 genera were identified. Bacillariophyceae (diatoms) was the predominant taxon (95 species) followed by Chlorophyce

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Publication Date
Sat Aug 30 2025
Journal Name
Gsc Biological And Pharmaceutical Sciences
The role of environmental stress in fish health: A review
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Fish are regarded as a crucial indicator of alterations in the aquatic environment due to their position at the apex of the food chain. Monitoring these alterations is crucial for identifying modifications in the aquatic ecosystem. The principal elements influencing fish health are temperature, pH, dissolved oxygen, salinity, pesticide contamination, microplastics, and algal presence. These elements substantially influence fish health regarding development, reproduction, respiration, oxygen stress, and the internal enzymes associated with digesting and other metabolic functions. Alterations in global environmental conditions and anthropogenic pollutants result in modifications to fish populations, their lives, and their behavior and

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Publication Date
Tue Dec 01 2015
Journal Name
Journal Of Economics And Administrative Sciences
The Impact of Combine Level of Capital Structure and Dividend Policy on Firm Stock Price An apply study of companies listed on Amman Stock Exchange
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Although a great deal of works has been done on the area of capital structure and dividend policy, there is still insufficient knowledge of how these policies affect stock prices. This shortcoming may have been originated from the separation between both policies when investigating their effect on stock prices. Based on this point, this research adopts a new technique (completely randomized design), to combine the effect of capital structure and dividend policy on stock prices rather than separating between them. The study used panel based regression analysis depending on the sample of 30 service and industrial Jordanian firms for the period of 2001-2010. The result of test hypotheses found the following; 1) dividend payout has a

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Publication Date
Wed Dec 01 2021
Journal Name
Open Biology
Structure and in silico simulations of a cold-active esterase reveals its prime cold-adaptation mechanism
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Here we determined the structure of a cold active family IV esterase (EstN7) cloned from Bacillus cohnii strain N1. EstN7 is a dimer with a classical α/β hydrolase fold. It has an acidic surface that is thought to play a role in cold-adaption by retaining solvation under changed water solvent entropy at lower temperatures. The conformation of the functionally important cap region is significantly different to EstN7's closest relatives, forming a bridge-like structure with reduced helical content providing greater access to the active site through more than one substrate access tunnel. However, dynamics do not appear to play a major role in cold adaption. Molecular dyn

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Scopus
Publication Date
Sun Mar 01 2015
Journal Name
Baghdad Science Journal
Performance evolution of a hybrid thermal solar air conditioning system and compare it with a traditional system according to Iraq weather
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In a hybrid cooling solar thermal systems , a solar collector is used to convert solar energy into heat energy in order to super heat the refrigerant leaving the compressor, and this process helps in the transformation of refrigerant state from gaseous state to the liquid state in upper two-thirds of the condenser instead of the lower two-thirds such as in the traditional air-conditioning systems and this will reduce the energy needed to run the process of cooling .In this research two systems with a capacity of 2 tons each were used, a hybrid air-conditioning system with an evacuated tubes solar collector and a traditional air-conditioning system . The refrigerant of each type was R22.The comparison was in the amou

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Publication Date
Wed May 03 2023
Journal Name
Chalcogenide Letters
Preparation and analysis of Ag2Se1-xTe x thin film structure on the physical properties at various temperatures by thermal evaporation
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Silver selenide telluride Semiconducting (Ag2Se0.8Te0.2) thin films were by thermal evaporation at RT with thickness350 nm at annealing temperatures (300, 348, 398, and 448) °K for 1 hour on glass substrates .using X-ray diffraction, the structural characteristics were calculated as a function of annealing temperatures with no preferential orientation along any plane. Atomic force microscopy (AFM) and X-ray techniques are used to analyze the Ag2SeTe thin films' physical makeup and properties. AFM techniques were used to analyze the surface morphology of the Ag2SeTe films, and the results showed that the values for average diameter, surface roughness, and grain size mutation increased with annealing temperature (116.36-171.02) nm The transm

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Publication Date
Wed Mar 01 2023
Journal Name
Chalcogenide Letters
Preparation and analysis of Ag2Se1-xTe x thin film structure on the physical properties at various temperatures by thermal evaporation
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Silver selenide telluride Semiconducting (Ag2Se0.8Te0.2) thin films were by thermal evaporation at RT with thickness350 nm at annealing temperatures (300, 348, 398, and 448) °K for 1 hour on glass substrates .using X-ray diffraction, the structural characteristics were calculated as a function of annealing temperatures with no preferential orientation along any plane. Atomic force microscopy (AFM) and X-ray techniques are used to analyze the Ag2SeTe thin films' physical makeup and properties. AFM techniques were used to analyze the surface morphology of the Ag2SeTe films, and the results showed that the values for average diameter, surface roughness, and grain size mutation increased with annealing temperature (116.36-171.02) nm The transm

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Publication Date
Mon Mar 23 2020
Journal Name
Journal Of Engineering
Experimental and Numerical Investigation on the Performance of Straight-Bladed Vertical Axis Wind Turbine by Adding Cavities to it Structure
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As the prices of the fuel and power had fluctuated many times in the last decade and new policies appeared and signed by most of the world countries to eliminate global warming and environmental impact on the earth surface and humanity exciting, an urgent need appeared to develop the renewable energy harnessing technologies on the short-term and long-term and one of these promising technologies are the vertical axis wind turbines, and mostly the combined types. The purpose of the present work is to combine a cavity type Savonius with straight bladed Darrieus to eliminate the poor self-starting ability for Darrieus type and low performance for Savonius type and for this purpose, a three-bladed Darrieus type with symmetric

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Publication Date
Tue Mar 01 2022
Journal Name
Journal Of Engineering
A Impact of High Voltage Direct Current Link on Transmission Line in Kurdistan Power System
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Kurdistan power system is expanded along years ago. The electrical power is transmitted through long transmission lines. The main problem of transmission lines is active and reactive power losses. It is important to solve this issue, unless, the most of electrical energy will lost over transmission system. In this study, High Voltage Direct Current links/bipolar connection were connected in a power system to reduce the power losses. The 132kV, 50 Hz, 36 buses Kurdistan power system is used as a study case. The load flow analysis was implemented by using ETAP.16 program in which Newton-Raphson method for three cases. The results show that the losses are reduced after inserted HVDC links.

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Publication Date
Mon Nov 30 2020
Journal Name
Journal Of Economics And Administrative Sciences
The Role of Effective Leadership in Application of E-Human Resources Management System Applied research at Baghdad International Airport
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The research acquires its importance by motivating the behavioural side of the employees to apply modern technology in the work, because of its great importance in increasing the efficiency of employees’ performance and excellence. The research was based on two main hypotheses to show the relationship and impact between the variables through the adoption of a questionnaire to collect data and information related to the research, which consisted of (50) people from administrators working at different levels, based on personal interviews and field visits to collect research data. The data collection process was subjected to statistical analysis using the statistical program (SPSS) (Statistical package for social science) to reach

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