In this paper, we study a kind of special quintom models, which are made of a quintessence field φ 1 and a phantom field φ 2 , and their potential functions have the form of V (φ 2 1 − φ 2 2). These models have simple kinetic functions, so the analysis of them is simple. These models are separated into two kind: the hessence models, which have φ 2 1 > φ 2 2 , and the hantom, which have φ 2 1 < ...

We considered the phantom cosmology with the original B-I type scalar Field with the lagrangian L = 1 η [1 − 1 − ηg µν φ , µ φ , ν ] − u(φ),which is proposed by Born and Infeld in 1934. We find that there must exist a positive potential u(ϕ) for physical permit in our phantom model. We give the condition for an arbitrary potential to admit a late time attractor solution and then study a specifi...

Singularities in the dark energy universe are discussed, assuming that there is a bulk viscosity in the cosmic fluid. In particular, it is shown how the physically natural assumption of letting the bulk viscosity be proportional to the scalar expansion in a spatially flat FRW universe can drive the fluid into the phantom region (w < −1), even if lies in the quintessence region (w > −1) in the n...

introduction: in diagnostic and therapeutic procedures, dosimetric studies are performed on the dosimetric systems in order to comply the radiation safety standards. monte carlo methods are used due to the high complexity and cost of patient-specific phantom construction. the high complexity of the digitized phantoms greatly increases the time and computational task of the monte carlo calculati...

The paper presents an equivalent ellipsoid approach for interpretation and visualization of extended current distributions in biomagnetic inverse problems. The example of simulations performed with physical thorax phantom is also given.

In this paper, we investigate the dynamics of Born-Infeld(B-I) phantom model in the ω − ω ′ plane, which is defined by the equation of state parameter for the dark energy and its derivative with respect to N (the logarithm of the scale factor a). We find the scalar field equation of motion in ω − ω ′ plane, and show mathematically the property of attractor solutions which correspond to ωϕ ∼ −1,...

1Radiation Medicine Department, Nuclear Engineering Faculty, Shahid Beheshti University, Tehran, Iran 2Radiation Medicine Department, Nuclear Engineering Faculty, Shahid Beheshti University, Tehran, Iran 3Radiotherapy Physics Department, Cancer Institute of Tehran, Tehran, Iran 4Medical Physics Department, Medical Faculty, Iran University of Medical Science, Tehran, Iran 5Radiation Medicine Dep...