Operator Gauge Symmetry in QED

In this paper, operator gauge transformation, first introduced by Kobe, is applied to Maxwell's equations and continuity equation in QED. The gauge invariance is satisfied after quantization of electromagnetic fields. Inherent nonlinearity in Maxwell's equations is obtained as a direct result due to the nonlinearity of the operator gauge transformations. The operator gauge invariant Maxwell's equations and corresponding charge conservation are obtained by defining the generalized derivatives of the first and second kinds. Conservation laws for the real and virtual charges are obtained too. The additional terms in the field strength tensor are interpreted as electric and magnetic polarization of the vacuum.Comment: Published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA

Effects of Short-term Whole Body Vibration Training on Knee Proprioception in Healthy Adults and People with Knee Osteoarthritis

Introduction: many researches have studied the short and long term effects of whole body vibration on muscle strength and proprioception. The effect of this modality in athletes and healthy population have been studied by several researchers; however, to accept it as a therapeutic procedure, it needs more studies.  In knee osteoarthritis, muscle weakness and joint instability can affect proprioception. Since some researchers reported the effect of whole body vibration on kinematic and neuromuscular control and some others have rejected this effect, the purpose of this study is to investigate the short term effect of whole body vibration on proprioception of the knee joint in patients with knee osteoarthritis and healthy individuals. Materials and Methods: In this experimental study, two groups of the same size (21 in healthy and patient groups) went through whole body vibration ( 60 Hz frequency, low amplitude and 25 Hz frequency , high amplitude) and the knee joint properioception accuracy was assessed ( by joint angle replication test) and was compared with the no-vibration baseline results. Results The joint angle reconstruction error was different between two groups and also before and after whole body vibration. Whole body vibration with 25Hz frequency and high Amplitude was ineffective in improvement of knee properioception in osteoarthritis patients (p=0.09). But the vibration with 60 Hz and low amplitude was effective significantly in properiception improvement and decrease of joint angle reconstruction error in healthy (p=0.01) and patients groups. (p=0.02). Discussion: This study shows that the whole body vibration with proper frequency and amplitude (60 Hz and low amplitude) can have immediate effect on the knee joint properioception in patients with knee osteoarthritis and healthy people.Key words: Whole Body Vibration; Knee; Osteoarthritis; Properioceptio

Optical bistability and multistability in four-level atoms with a diamond configuration

The phenomena of optical bistability and multistability are investigated for four-level atoms with a diamond configuration trapped in a unidirectional optical ring cavity, driven by a probe as well as three coupling fields. Moreover, the optical properties of the atoms are studied considering the spontaneously generated coherence and Rabi frequencies. The results indicate that the optical bistability and multistability of the corresponding atom-cavity system can be controlled by two spontaneously generated coherences in upper and lower decay channels and the Rabi frequency of the coupling fields

An Exact Scheme for the EIT for a Three-level L-Type Atom in a Quantum Cavity

Semi-quantum or full-quantum electromagnetically induced transparency has been fully studied for three-level atoms in a weak field approximation method, where probe field is very weaker than the coupling field. The weak field approximation is not valid in full-quantum model where the number of coupling photons is not so large. In the present article, the master equations for the interaction of two-mode photons with a three-level L-type atom are exactly solved and the exact dispersion and absorption spectra for the probe beam photons are also obtained analytically. The results of the exact scheme are compared with the corresponding results in the weak field approximation method in full-quantum and semi-classical models