Iranian Journal of science and Technology (A: Siences)
Volume:35 Issue: 1, Winter 2011

Here, the concept of quantum potential that has been illustrated in Extended Phase Space (EPS) in previous works is explored for its marginal behavior. Unlike in configuration space, different representations of the quantum mechanics can be found in EPS when exploiting appropriate canonical transformations. These canonical transformations revealed that there exist several representations in which the quantum potential could be removed not only for a particle in constant, linear and quadratic potentials, but also for a free particle. In these representations one still has the form-invariance of the ordinary Hamilton-Jacobi equation. The present work is an attempt to show that the Squeezed Wigner representation is a possible representation in which, for large values of squeezing parameter, the quantum potential disappears from the dynamical equation for a particle in the general potential.

In this paper, the approximate solution of the differential system modeling HIV infection of CD4+ T cells is obtained by a reliable algorithm based on an adaptation of the standard variational iteration method (VIM), which is called the multi-stage variational iteration method(MSVIM). A comparison between MSVIM and the fourthorderRunge-Kutta method (RK4-method) reveal that the proposed technique is a promising tool to solve theconsidered problem.

Soil surfaces in arid and semi-arid lands often lack photoautotrophic life but are covered by communities of soil surface covering organisms able to tolerate dehydration, and thus adapted to aridity. One important objective of multi-spectral remote sensing instruments is the detection of the optical characteristics of the Earth’s surface using high spectral resolution bands. In this study ASTER imagery and reflected radiation in VNIR bands were used to investigate biological Soil Crusts (BSCs) in the field. By applying IARR (Internal Average Relative Reflectance), FCC (False Color Composite), MNF (Minimum Noise Fraction Transform), and MEM (Mathematical Evaluation Method) techniques, BSCs are successfully detected in the Chadormalu desert area of central Iran. This study clearly shows the capability of ASTER data (VNIR bands) to detect BSC or cyanobacteria soil crusts. The proposed MEM method, despite being approximative is suitable for detecting microorganisms in inaccessible areas such as other planet surfaces or remote areas on earth.

The growth rate of carbon nanotubes in chemical vapor deposition is simulated by using a theoretical analysis of the phonon vibration of the system. Simulations demonstrate that the growth rate of carbon nanotubes with larger diameters is smaller because of higher damping factors and carbon nanotube inertia. An optimum temperature for the growth rate is calculated for a carbon nanotube on Fe catalyst. Simulations from the theory are in good agreement with reported experimental results.

In this article, we demonstrate an analytic-numeric solution for some dynamical systems using the multistage homotopy perturbation method. The method yields results that are in complete agreement with their numerical counterparts.

This paper shows how multifractal analysis can be used to characterize the spatial distribution of epicenters in the Zagros and Alborz-Kopeh Dagh regions of Iran. The main multifractal characteristics, Dq, f(αq), τq, αq and a set of multifractal parameters defined from the shape of the f(αq)-spectrum including the width of f(αq)-spectrum, onuniformit factor, combined parameter, coefficients of steepness and asymmetry, and vertex of the τ(q)-spectrum have been determined. The results show that, in comparison with the Alborz-Kopeh Dagh region the epicentral distribution in the Zagros has a weak multifractal (i.e. less heterogeneous) structure. Although the f(αq) spectra of both regions were skewed, the directions of skewing were different. The two distinct multifractal distribution patterns in these regions reflect different underlying seismotectonic processes related to earthquake activity. The diffused seismicity with fewer larger earthquakes relative to smaller ones in the Zagros and relatively low level of discontinuous seismicity with sporadic occurrence of strong destructive events in the Alborz-Kopeh Dagh confirm our findings. The results further suggest that multifractal analysis provides us with a deep insight into the complex nature of distribution and geometry associated with earthquake-related phenomena that could not be discovered by any other means.

In this paper, differentiable connections on top spaces are studied and some conditions on which there is no differentiable connection passing from a given point in the top space are found. In a special case, the Euclidean space is considered as a top space and the existence of differentiable connections is studied. Finally, we prove that the smoothness condition of the inverse map in the definition of a top space is redundant.

The impacts of salicylic acid and silicon on some physiological parameters of maize seedlings in the presence ofcadmium (100 μM) were investigated. Inhibitory effects of cadmium on seedling growth resulted in reduced shoot and root fresh weight, low percentage of relative water content, low chlorophyll, free proline and soluble sugars contents and a low rate of lipid peroxidation. Results indicated that salicylic acid and silicon alleviate the inhibitory effects of cadmium on maize seedlings by increasing both their chlorophyll content and fresh weight Although individual treatments of salicylic acid and silicon reduced plants free proline, soluble sugars and cadmium uptake and lipid peroxidation rate, they improved root and shoot fresh weights in both cadmium stressed and unstressed seedlings. When combined, salicylic acid and silicon alleviated the inhibitory effects of cadmium on seedlings significantly.