background: stereotactic radiosurgery is an important clinical tool for the treatment of small lesions in the brain, including benign conditions, malignant and localized metastatic tumors. a dosimetry study was performed for elekta ‘synergy s ’ as a dedicated stereotactic radiosurgery unit, capable of generating circular radiation fields with diameters of 1-5 cm at isocentre using the beam/egs4...

The simultaneous transmission of data by more than one transmitter leads to interference in the destination. Though this can be overcome by introducing cooperative communication, still the SNR performance is poor. In this paper, Dual Beam Array (DBA) is considered to reduce interference in the place of two single beam arrays. The Dual Beam Array has the advantage of narrow beam width as it can ...

introduction: esophageal cancer is one of the most frequently occurring cancers in iran and having a  high  incidence  rate  among  other  countries.  radiotherapy  is  one  of  the  three  methods  (surgery,  radiotherapy and chemotherapy) for radical or palliative treatment of esophageal cancer. in this method  of treatment, the organs such as heart and spinal cord are regarded as organs at r...

The scalar theory of the self-focusing of an optical beam is not valid for a very narrow beam, and a correct description of the beam behavior requires a vector analysis in this case. A vector nonparaxial theory is developed from the vector Maxwell equations by application of an order-of-magnitude analysis method. For the same input beam, the numerical results of self-focusing from both scalar a...

Supporting information a Adjustments performed to optimize the infrared spectra: 1) The cell was centered under the beam 2) The opening of the diaphragm was adapted to the sample to meet two requirements: it had to be not too large to avoid the detection of surrounding CO 2 but not too narrow to obtain a sufficient signal to noise ratio. A preliminary study was performed for each geometry and s...

background: physical wedges are still widely used as beam modifiers in external beam radiotherapy. however the presence of them in the beam trace may cause beam hardening which may not be considered in many treatment planning systems. the aim of this study is to investigate the beam hardening effect generated by physical wedges via different beam quality indexes as photon spectrum, half value l...

We propose an original nonlinear beam cleaning fiber laser architecture to obtain high energy pulses with a good beam quality and a narrow linewidth. The output beam of a large core Er:Yb co-doped multimode fiber amplifier (M(2) approximately 6, 220 microJ) is converted into a near diffraction limited beam (M(2) = 1.6) through a stimulated Brillouin scattering injection seeded beam cleanup proc...

The PEP-I1 high energy ring (HER) vacuum chamber consists of a copper tube with periodically spaced p u m p ing slots. The impedance of the vacuum chamber due to the slots is analyzed. Both narrow-band and broadband impedances are considered as well as longitudinal and transverse components thereof. It is found that although the broad-band impedance is tolerable, the narrow-band impedance may e...

Geometry of eccentrically braced frames (EBFs) in some cases causes the connection of link beam to the column. The details of such conditions should be studied carefully due to the full plastic rotation in the link beam. In this research, the behavior of link-to-column connection is modeled and the failure modes are considered. Based on the previous researches shear link can exhibit better beha...

A simple scheme to steer optical beams is proposed. The basic idea is to impose a sinusoidal phase modulation on the optical beam and then propagate it in a nonlinear Kerr medium. Spatial phase modulation splits the input beam into multiple subbeams, while the nonlinear medium shapes a particular subbeam into a spatial soliton in such a way that most of the beam power appears in a narrow beam w...