The formation of singularities of self-focusing solutions of the nonlinear Schrodinger equation (NLS) in critical dimension is characterized by a delicate balance between the focusing nonlinearity and di raction (Laplacian), and is thus very sensitive to small perturbations. In this paper we introduce a systematic perturbation theory for analyzing the e ect of additional small terms on self fo...

As lasers become progressively higher in power, optical damage thresholds will become a limiting factor. Using the nonlinear optics of plasma may be a way to circumvent these limits. Here, we present a new self-compression mechanism for high-power, femtosecond laser pulses based on geometrical focusing and three dimensional spatiotemporal reshaping in an ionizing plasma. By propagating tightly ...

determining landslide size could be a difficult and expensive task. in this research, size parameters of 142 landslides recognized in tajan river basin, northern iran, have been assessed. the dataset was prepared through the extensive field surveys and using the satellite imagery available via google earth. dependence between landslides area (a-m2), volume (v-m3), and depth (d-m) was appointed ...

educational methods have always been one of the most important subjects for human societies. among iranian scientific and literary figures there are some, who have been closely involved with the process and the goal of educational ideas. thus, it is necessary that their ideas be taken into account by methodologists for educational and training systems. we will take a look at the opinions of far...

the present study considers the issue of verbal violence in the language of drama. in the evaluation of verbal violence, jeanette malkin (2004) proposes six maxims, through which language may be considered as an arrogant element. the characters in dramatic texts (as in other literary texts) are created, developed, evolved and - in some cases - destroyed by language. in a considerable number of ...