In this paper, a set of two-fluids equations based on the quantum magnetic hydrodynamic Model (QMHD) for Electron-positron plasma were considered and the role of spin in different spin-spin, and spin-field interactions were briefly discussed. Furthermore, effects of density and heterogeneity in the equations were considered. For each of the two Electron and positron fluids, the complete theory of spin-1/2 Electron-positron quantum plasmas when Electrons and positrons move with velocities much smaller than the speed of light was discussed. By considering the two regimes of non-spin and spin plasma separately, new dispersion relations was extracted and analyzed. We also examined the limits of weak and strong magnetic fields and the effect of spin polarization on ripple waves in plasma medium. Results show that the spin-current evolution in a magnetized plasma creates a new dispersion Mode. The fast Mode generates in the direction perpendicular to the direction of propagation of the waves. The speed of this Mode is equal to the speed of the Mode in the parallel direction plus an additional term that depends on the characteristics of the system. For high-density plasma, this correction is negligible, but for very low densities and weak magnetic fields, this effect is significant.

Context: This study was done to review the Electron contamination sources and measurement based on dosimetry and simulation techniques for radiotherapy and also to investigate factors affecting Electron contamination reduction. Methods: We systematically searched five major indexing databases, including PubMed, Scopus, Embase, ISI web of science, and Cochrane central, using keywords of Electron contamination, Electron contamination AND measurement, Electron contamination AND simulation, and Electron contamination AND reduction until Dec 2020. Results: Overall, 35 studies were reviewed, including articles reporting the theory of Electron contamination, papers on dosimetry methods to measure Electron contamination, studies about simulation methods to assess Electron contamination, and articles about reducing Electron contamination. The results indicated an increase in Electron contamination using a flattering filter, an increase in field size, the presence of prosthesis in the patient’ s body, and a rise in photon energy. Conclusions: It can be concluded that the excessive delivered doses by Electron contamination can cause skin complications, such as erythema, desquamation, and telangiectasia inside or outside the photon field. The amount of Electron contamination depends on factors, such as radiation field size, beam energy, and materials placed in the photon path. Electron contamination can be decreased by increasing the source distance to the point of measurement by the dosimeter, applying a lead foil, magnetic deflector, or replacing a portion of air column between patient and radiotherapy system head by helium gas, and also limiting the treatment field.

Background: Neutron contamination is produced in Electron beams of linac when tooth or dental materials are located in the path of beam. Objective: This study aims to determine the neutron dose contamination from different dental restoration materials in Electron Mode of a linac. Material and Methods: In this experimental study, the neutron dose contamination was calculated in the presence of tooth and tooth restored by Ceramco C3 veneer, Eclipse or amalgam. The Electron Mode included 8, 12, and 14 MeV Electron beams of Siemens Primus linac at different depths before and after tooth. MCNPX code was used to simulate the linear accelerator and dental restoration materials. Tooth and tooth restoration materials were located in the beams’ central axis and the neutron dose was scored in 3 × 3 × 1 cm3 voxels at different depths before and after the tooth. Results: The highest neutron dose contamination was observed for the combination of the tooth and Eclipse in 12 and 14 MeV beams and the maximum calculated relative neutron dose was 1. 53 for tooth and Eclipse for 14 MeV Electron beam. Conclusion: Tooth and dental materials lead to neutron dose contamination production, therefore, in order to avoid having harmful effects on normal tissues due to the neutron beam in head and neck cancer, it is recommended that treatment planning performed should not place tooth with dental restoration materials in the path of the beam and lower energy Electron beams be used.

Magnetically confined plasma can be heated with high power microwave sources. In spherical torus the Electron plasma frequency exeeds the Electron cyclotron frequency (EC) and, as a consequence, electromagnetic waves at fundamental and low harmonic EC cannot propagate within the plasma. In contrast, Electron Bernstein waves (EBWs) readily propagate in spherical torus plasma and are absorbed strongly at the Electron cyclotron resonances. In order to propagate EBWs beyond the upper hybrid resonance (UHR), that surrounds the plasma, the EBWs must convert via one of two processes to either ordinary (O-Mode) or extraordinary (X-Mode) electromagnetic waves. O-Mode and X-Mode electromagnetic waves lunched at the plasma edge can convert to the Electron Bernstein waves (EBWs) which can propagate without and cut-off into the core of the plasma and damp on Electrons. Since the Electron Bernstein wave (EBW) has no cut-off limits, it is well suited to heat over-dense plasma by resonant absorption. An important problem is to calculate Mode conversion coefficient that is very sensitive to density. Mode conversion coefficient depends on Budden parameter (h) and density scale length (Ln) in upper hybrid resonance (UHR). In Mega Ampere Spherical Tokamak (MAST), the optimized conversion efficiency approached 72.5% when Ln was 4.94 cm and the magnetic field was 0.475 Tesla in the core of the plasma.

One of the most important limitations of gas detectors is the phenomenon of polymerization. This factor can disrupt the overall performance of the detector. The occurrence of this phenomenon has been observed and proven in wired detectors. In this paper, the polymerization phenomenon on thick gas Electron multiplier detectors (THGEM) in self-quenching streamer (SQS) Mode has been investigated using a 137Cs gamma source with 3.95µCi(1.46×105Bq) activity. In the presence of an approximate amount (10%) of a hydrocarbon gas such as methane, which is used as a quencher in the P10 gas composition, it is observed that after three days the detector is used an average of three to four hours per day. Sudden changes in the counting rate and also electrical sparks are seen. According to the images and observations, the harmful effects of hydrocarbon gas polymerization, which is one of the main factors of this phenomenon, have been proven in THGEM detectors, and suggestions have been made to improve and extend the life of the system.

Introduction: Patent ducfus arteriosus (PDA) is the persistence of a normal fetal structure between left pulmonary artery and descending aorta. Persistence of this fetal structure beyond 10 days of life is considered abnormal. In this study we compared M-Mode and Doppler echocardiography in diagnosis of PDA in children at Aliasghar Hospital in Zahedan and Children hospital in Bandar Abbas for one year. methods: We selected 62 patients that were suspicious to have PDA on physical examination. It should be mentioned that we omitted patients with other cgngenital cardiac abnormalities such as truncus arteriosus, ASD, VSD and AZSD. Our patients were below 15years old. Before echocardiography, physical examination, CXR and ECG were done for the patients. Then, they were evluated with both M-Mode and Doppler Echocardiography and finally results were statistically analyzed.Results: Out of 62 patients, 34 were female and 28 were male. 51.6% patients were less than one year old and others were older. 85% of patients had cardiac murmur on physical examination and in 50% of them pulmonary component of second heart sound was increased. Peripheral pounding pulses were present in 85% of patients. In chest X-Ray, 82.3% of patients had increased cardiothoracic ratio and pulmonary vascular markings were increased in 85.5% of them. On ECG, 58.1 % of patients had signs of right and left or bilateral ventricular hypertrophy. Pulmonary hypertension was also seen in 51.6% of patients. PDA was diagnosed with M-Mode echocardiography in 56 patients (90.3 %) and with Doppler echocardiography in 61 patients (98.4%). According to McNemar statistical analysis, there was not an obvious difference between these two. methods of echocardiography in PDA diagnosis (p=0.125).Conclusion: Findings of this study showed that M-Mode and Doppler echocardiography for diagnosis of PDA in children are similar and again attention to M-Mode echocardiography can be helpful in diagnosis of PDA in children especially restless infants and neonates.

This paper is proposed a novel topology of a single phase grid connected inverter in order to conquest the common Mode leakage current. There are many topologies presented so far, But none of them has the efficiency more than 98 percent. In this paper, a Modern configuration is presented that, not only delete the common Mode leakage current, but also increase the efficiency and power density and is affordable. this inverter consists of 6 switches and 2 diodes that in compare with similar ones, it has less element number. Than the famous topologies like H5, H6 and HERIC, the power loss and voltage stress on switches are decreased. These aspects are appears due to exclusive leg configuration and the placement of switches and diodes. The freewheel path revealed, decoupled DC side from AC side of Inverter which results in disconnecting the common Mode current. This issue will modify the network reliability indices and maintain safety standards. Finally the performances of proposed inverter will be compared and evaluated with some available Inverters.

Background: The present study has been an attempt to devise a new approach to cancer therapy so that the rate of success in treatment is increased to several thousands times more than that of the normal treatments.Materials & Methods: The present study utilized some tests through homo-energetic beam with the highest photo-electric absorption whose result was an increased output. In other words, the ratio of the tumor dose to that of sound tissue was over several thousand percents. Then a special device was designed and invented for this purpose, which is unique in the world. The device, along with its accessories, is well capable for photo-Electron therapy with optimum efficiency. In this approach, without exposing the sound tissue to a fatal dose of the beam, the tumor absorbed dose is increased to hundreds of Grays, so that the malignant cells are damaged and the malignancy regression is reduced to a minimum. Moreover, the disadvantage of relatively sound tissue dose-and tumor dose-equality-damage, which occurs in conventional radio therapy, is reduced to a minimum and the tumor cells are fatally damaged.Findings: In designing and making this device along with relying on physical parameters in coordination with all points of photo-Electron therapy performance, the other significant facilities are considered. All the technical points of remote controlling, simplicity and speed operation, ability of high maneuver, protection, patient apd technologist safety, low price, and ability to install in most cancer treatment centers are taken into account.Conclusion: It is expected that with this new device, some projects for modification and improvement of this system be pursued in future. All stages of national and international patent processes of this new system have already been completed successfully.