Novel spatial harmonic magnetrons and their potential applications

This paper provides an overview of our recent progresses in theory, design, simulation, and fabrication of novel metamaterial based spatial harmonic magnetrons. The approximate analysis which provides the guidelines for the design and predicts the important characteristics of these devices will be presented. This analysis shows that the metamaterial loaded SHMs can start generating power with very small cathode current densities which is very important for designing THz sources based on SHMs. A design example with the operation frequency of 43 GHz together with the PIC simulation and measurement results will be examined

Low-current cathode spatial harmonic magnetrons: analysis and realization based on metamaterial loaded slow wave structures

AbstractThis paper provides an overview of theory, design, simulation, and fabrication of novel spatial harmonic magnetrons (SHMs). An approximate analysis which provides the guidelines for the design and predicts the important characteristics of these devices will be presented. This analysis shows that the metamaterial loaded SHMs can start generating power with very small cathode current densities which is very important for designing THz sources based on SHMs. A design example with the operation frequency of 43 GHz together with the design procedure, PIC simulations, and measurement results will be examined

Assessment of Beam Impedance for the CERN-PS Booster Wire Scanner

It is well known that performance of accelerators critically depends on the interaction of high intensity beams with the surrounding structures. As a result of these beam interactions, it is required at CERN to characterize the beam coupling impedance of each new machine element that is to be installed in the accelerator ring. In the framework of the LIU (LHC Injectors Upgrade) project, a new design of rotational wire scanner to be used in the PS Booster is currently under development. As an intermediate step, the prototype of this wire scanner was evaluated with respect to its longitudinal beam coupling impedance. Depending on the performance of this machine element, it is planned to replace existing wire scanners in other machines at CERN (e.g. PS-Booster, PS and SPS) with very similar designs. This paper presents the simulations and describes the measurement methods used for benchmarking electromagnetic simulations performed for the impedance evaluation of the LIU wire scanner for the PS-Booster. Additionally, the device was fitted with an RF feed-through in order to monitor and attenuate certain undesired modes supported by this structure

Equivalent circuit modelling of travelling wave accelerating structures and its applications

This paper presents an equivalent circuit model for the parallel bar 200 MHz travelling wave structure of the CERN Super Proton Synchrotron. This equivalent circuit will be used for studying the performance of the higher order mode couplers at 628 MHz. Currently, this mode presents a serious limitation for future beam intensities required for high luminosity LHC operatio

Evaluation of Longitudinal Beam Impedance in the Beam Gas Ionization Monitor of the CERN-PS Accelerator

The recently observed beam induced heating issues in the BGI monitors of the LHC which could have been occurred due to a strong coupling between the beam and the localized modes at the sensor location showed the general importance of a thorough evaluation of the beam coupling impedance and the corresponding heat deposit in beam monitoring equipments. This paper is devoted to the examination of the beam coupling impedance and beam induced heating for a currently under development beam gas ionization (BGI) monitor which is intended to be a part of the CERN Proton Synchrotron (PS) beam monitoring equipment. Details of the EM and wake field simulations for this BGI monitor together with the RF measurement results and power loss calculations will be presented

Developmental competence of IVF and SCNT goat embryos is improved by inhibition of canonical WNT signaling

The specific role of the canonical WNT/β-catenin signaling pathway during the preimplantation development of goat remains unclear. Our objective was to investigate the expression of β-CATENIN, one of the critical components of Wnt signaling pathway, in IVF embryos and compare it with SCNT embryos in goat. In addition, we evaluated the consequence of inhibition of β-catenin using IWR1. Initially, we observed cytoplasmic expression of β-CATENIN in 2 and 8–16 cell stage embryos and membranous expression of β-CATENIN in compact morula and blastocyst stages. Furthermore, while we observed exclusively membranous localization of β-catenin in IVF blastocysts, we observed both membranous and cytoplasmic localization in SCNT blastocysts. We observed that Inhibition of WNT signaling by IWR1 during compact morula to blastocyst transition (from day 4 till day 7 of in vitro culture) increased blastocyst formation rate in both IVF and SCNT embryos. In conclusion, it seems that WNT signaling system has functional role in the preimplantation goat embryos, and inhibition of this pathway during the period of compact morula to blastocyst transition (D4-D7) can improve preimplantation embryonic development

Developmental competence of IVF and SCNT goat embryos is improved by inhibition of canonical WNT signaling.

The specific role of the canonical WNT/β-catenin signaling pathway during the preimplantation development of goat remains unclear. Our objective was to investigate the expression of β-CATENIN, one of the critical components of Wnt signaling pathway, in IVF embryos and compare it with SCNT embryos in goat. In addition, we evaluated the consequence of inhibition of β-catenin using IWR1. Initially, we observed cytoplasmic expression of β-CATENIN in 2 and 8-16 cell stage embryos and membranous expression of β-CATENIN in compact morula and blastocyst stages. Furthermore, while we observed exclusively membranous localization of β-catenin in IVF blastocysts, we observed both membranous and cytoplasmic localization in SCNT blastocysts. We observed that Inhibition of WNT signaling by IWR1 during compact morula to blastocyst transition (from day 4 till day 7 of in vitro culture) increased blastocyst formation rate in both IVF and SCNT embryos. In conclusion, it seems that WNT signaling system has functional role in the preimplantation goat embryos, and inhibition of this pathway during the period of compact morula to blastocyst transition (D4-D7) can improve preimplantation embryonic development

Resistance pattern of Helicobacter pylori strains to clarithromycin, metronidazole, and amoxicillin in Isfahan, Iran

Background: Helicobacter pylori (H. pylori) resistance to antibiotics has become a global problem and is an important factor in determining the outcome of treatment of infected patients. The purpose of this study was to determine the H. pylori resistance to clarithromycin, metronidazole, and amoxicillin in gastrointestinal disorders patients. Materials and Methods: In this study, a total of 260 gastric antrum biopsy specimens were collected from patients with gastrointestinal disorders who referred to Endoscopy Section of the Isfahan Hospitals. The E-test and Modified Disk Diffusion Method (MDDM) were used to verify the prevalence of antibiotic resistance in 78 H. pylori isolates to the clarithromycin, metronidazole, and amoxicillin. Results: H. pylori resistance to clarithromycin, metronidazole, and amoxicillin were 15.3, 55.1, and 6.4%, respectively. In this studyΈ we had one multidrug resistance (MDR) isolates from patient with gastritis and peptic ulcer disease. Conclusion: Information on antibiotic susceptibility profile plays an important role in empiric antibiotic treatment and management of refractive cases. According to the results obtained in this study, H. pylori resistance to clarithromycin and metronidazole was relatively high. MDR strains are emerging and will have an effect on the combination therapy