Background: In radiotherapy, wedge filters are used for optimizing the tumor dose distribution in patients. The attenuation in beam intensity due to the presence of wedge filter is compensated by means of a wedge factor measured at the central axis of the beam. The field size, depth and SSD dependence of wedge factor have been assessed for 9MV radiations of Neptun PC linear accelerator. Materia...

in order to assess the adaptation of elaeagnus angustifolia l. and fraxinus rotundifolia mill afforestation around tabriz international airport, the qualitative and quantitative characteristics of trees were measured in 96 experimental circular plots with a size of 300 m2. to study the edaphic effects of these species, nine samples were randomly collected from 0-10 cm and 10-20 cm depth of soil...

soil particle-size distribution (psd) is one of the most important physical attributes due to its great influence on soil physical, chemical, and biological properties. water infiltration rate, land-use change, soil erosion, and biological soil crusts (bscs) may influence psd in a soil. the multifractal measures were useful tools in characterization of psd in soils. the objective of the current...

density or gravity currents have been always one of the main causes for sedimentation along many of the dam reservoirs. so controlling this phenomenon is very important for increasing useful life of such reservoirs. in this research study the effect of a combination of rough bed and obstacle on the control of sedimentary density current has been investigated. experiments were conducted in a til...

background: the dosimetric performance of eclipse 6.5 three dimensional treatment planning system (3dtps) is evaluated by comparing the calculated and measured dose in two dimensions following the guide lines of american association for physicists in medicine task group 53. materials and methods: the calculations were performed by the 3dtps for symmetric as well as asymmetric fields for standar...

The optical depth $\tau$ is the least well determined parameter in standard model of cosmology, and one whose precise value important for both understanding reionization inferring fundamental physics from cosmological measurements. We forecast how future epoch experiments could constraint using a symmetries-based bias expansion that highlights special role played by anisotropies power spectrum ...

OBJECTIVE Radiographically, a central venous catheter (CVC) tip should lie at the level of the right tracheobronchial angle. Precalculation of length of CVC insertion may avoid unnecessary catheter malposition. The purpose of this study was to assess the accuracy of a method of CVC positioning, based on external topographic landmarks. DESIGN A prospective, randomized study. SETTING Universi...

Background: The dosimetric performance of Eclipse 6.5 three dimensional treatment planning system (3DTPS) is evaluated by comparing the calculated and measured dose in two dimensions following the guide lines of American Association for Physicists in Medicine Task Group 53. Materials and Methods: The calculations were performed by the 3DTPS for symmetric as well as asymmetric fields for standar...

abstract methods of tillage and organic matter affect root growth and distribution and therefore nutrient uptake by plant and its growth. this study was performed consecutive two years. tillage treatments included disk harrowing + two disk harrowings as reduced tillage (15 cm plowing depth) and moldboard plowing + two disk harrowings as conventional tillage system (30 cm plowing depth). also, t...