In this paper, a discrete SIS epidemic model with immigrant and treatment effects is proposed. Stability analysis of the endemic equilibria and disease-free is presented. Numerical simulations are conformed the theoretical results, and it is illustrated how the immigrants, as well as treatment effects, change current model behavior

This study deals with the absence of state control over the whole of the Syrian geography in creating an environment conducive to the emergence of a new force represented by armed groups and organizations that point to fundamental changes in the conflict and to transform competition for control over the land into a struggle for influence. Which in itself represents the prospects of change in the Syrian scene, and that understanding their interests requires shedding light on the extent of the continuation of this competition and the conflict on land and expansion at the expense of the other, and thus contribute to complicate the Syrian scene, especially after attempts to bite Of land and annexation to each party's areas of influence, espe

Due to the fact that living organisms do not exist individually, but rather exist in clusters interacting with each other, which helps to spread epidemics among them. Therefore, the study of the prey-predator system in the presence of an infectious disease is an important topic because the disease affects the system's dynamics and its existence. The presence of the hunting cooperation characteristic and the induced fear in the prey community impairs the growth rate of the prey and therefore affects the presence of the predator as well. Therefore, this research is interested in studying an eco-epidemiological system that includes the above factors. Therefore, an eco-epidemiological prey-predator model incorporating predation fear and

A comparative study was carried out on ecological and genetical adaptation of three Iraqi
freshwater snails, Physa acuta, Melanopsis buccinoidea and Melanoides tuberculata, in
respect to acute toxicity of heavy metals (Zn, Cd and Hg). Longevity are used as poisoning
tolerance criterion. LT 50 and LT 100 were determined for the studied snails at (0.5, 1, 5, and
10 ppm), for the three metals. Results indicated that Physa acuta had a higher tolerance than
Melanopsis buccinoidea and Melanoides tuberculata, which was the lower one. Previous
exposure to heavy metals in the original habitat was affecting on experimental tolerance and
no relationships of physical and chemical factors (total hardness, temperature, D. O. and

In this experimental study, which was carried out in photonics laboratory at Strathclyde University, UK, dynamics of a multi-Quantum well semiconductor active medium laser, was studied. This is in order to study its emission stability and pulse shape development under the influence of strong optical feedback level with different deriving currents, in the free space transmission medium. An external stable resonator was constructed by inserting high reflectivity dielectric mirror outside the laser output, 20 cm apart from it, which is an extralarge external cavity. Controlling the reflected back optical power was done by using a nonpolarized (50:50) beam splitter. The external resonator supported by focusing (plano-convex) lens in order to

This study aimed to clarify the importance of ecological taxation in achieving sustainable development, by analyzing a set of economic measures such as taxes, taxes levied by the legislation in the field of ecology, to fight against pollution.       And we tried to evaluate this initiative in Algeria. The results of the study showed that economic measures of ecological taxation contribute to achieving sustainable development, and Although Algeria has adopted a series of ecological tax mechanisms, it is far from keeping pace with developments in this area. 

   The main elements of traditional foci of visceral leishmaniasis in the endemic area were studied. The complex relationships between biotic and abiotic factor in the study foci. Also the presence of possible reservoirs of disease with density of sandflies were examined.