Background and Aims: Root canal obturation is of great importance in root canal treatment. Its purpose is to eliminate microleakage, re-entry and growth of micro-organisms in the root canal system. The aim of this study was to compare coronal salivary microleakage in obturated root canals using lateral compaction, single cone gutta-percha and System B vertical compaction methods.Materials and Methods: In this in-vitro study, 80 single rooted, human extracted teeth were randomly divided into 3 experimental groups (n=20) and 2 positive and negative control groups (n=10). The specimens in each experimental group were obturated by using cold lateral compaction, single cone obturation, or continuous wave of condensation (System B). After that, coronal saliva leakage was evaluated. Data were analyzed using Survival analysis and Log-rank test.Results: The results showed that all the specimens in the positive control group showed evidences of leakage during the first 7 days of study. None of the specimens in negative control group showed leakage during the 30-days period of the experiment. Survival test and Log-rank test showed that at the end of the 30 days, there was significantly less resistance to coronal salivary leakage in single cone method compared with lateral compaction (P=0.039)and continuous wave of condensation (P=0.019) groups. No significant difference was observed between lateral compaction and System B vertical continuous method (P=0.564).Conclusion: Based on the results of this study, lateral compaction and System B groups showed higher resistance against the coronal leakage compared with single cone group.

The superiority of multiple-input multiple-output (MIMO) radars over conventional radars has been recently shown in many aspects. These radars consist of many transmitters and receivers located far from each other. In this scenario, the MIMO radar is able to observe the targets from different directions. One of the advantages of these radars is exploitation of Doppler frequencies from different transmitter-target-receiver paths. The extracted Doppler frequencies can be used for estimation of target velocity vector so that, the radar can be able to track the targets by use of its velocity vector with reasonable accuracy. In this paper, two different processing systems are considered for MIMO radars. First one is the pulse Doppler system, and the second one is continuous wave (CW) system without range processing. The measurement of the velocity vector of the target and its counterpart errors are taken into account. Also, the extended Kalman target tracking by using its velocity vector is considered. Besides, its performance is compared with those of MIMO target tracking without using the velocity vector and conventional radars. The simulation results show that the MIMO radars using velocity vector have superior performance over other above-mentioned radars in fast maneuvering target tracking. Since the range processing is ignored in CW MIMO radar systems, the complexity of this system is much lower than that of Pulse Doppler MIMO radar system, but has lower performance in tracking fast maneuvering target.

In this study, two- and three-dimensional polyester fabrics were coated with nickel via electroless plating method in order to produce X-band radar absorbing coatings. Morphology, thickness, coating composition, conductivity and radar absorption behavior of them were evaluated. After coating, the conduction of two- and three-dimensional fabrics was increased to 0.023 and 0.0043 cm2/Ω, respectively. Checking the morphology of the coatings by scanning electron microscopy showed that the nickel particles on the surface of fibers have the dome-shaped structures.Microstructure investigation of fabricated polyester coatings by X-ray spectral energy distribution showed that the amount of loaded nickel is 64.56%. The study of the radar absorption behavior of two- and three-dimensional coatings showed that the both of them can absorb more than 96.45% X-band radar waves (8-12 GHz). The investigation of the washing, rubbing and light fastness of fabricated coatings showed that electroless plating method can fix nickel on the surface of fibers well so that these coatings show high stability against these environmental factors.

Recently, the use of the loran system in navigation has gained much attention respect to its jamming security and possibility of improving the performance using hardware and new algorithms. Various sources of the error, continuous wave interference as the main one, cause error in the phase tracing and consequently cause error in measuring the time of arrival which finally result in the accuracy of navigation. In this paper, using the structure of loran pulses in the time domain, a new algorithm is proposed in order to removing the continuous wave interference. This algorithm has low complexity, has better performance than the conventional scenario, and its implementation causes improving of performance and accuracy of navigation. The simulation results show that the performance of the proposed algorithm is approximately independent of SIR of the received signal, and the limiter factor is the SNR of the received signal only. The proposed algorithm for measuring the time of arrival (TOA) result in removing the effect of coherent interference (improvement compared to the other conventional scenario averaging and phase decoding with coefficient 1023). This noticeable improvement is provided in the cost of decreasing the received SIR caused by the non-coherent continuous wave interference with maximum value 3 dB which can be simply removed by use of a band pass filter.

Purpose: To investigate the therapeutic effect of clinically invisible subthreshold continuous wave autofluorescence‑ controlled laser treatment on visual acuity and macular status of patients with chronic central serous chorioretinopathy (CSCR). Methods: In this prospective case series, patients with clinical and fluorescein angiographic (FA) findings of CSCR and chronic visual loss (>6 months) were included. Complete ocular examination, FA, and optical coherence tomography (OCT) tests were performed. Each eye was subjected to a direct laser treatment of leakage points by 532 nm continuous wave low energy laser pulses, which were kept invisible by reducing the power to 70% of the threshold test spot. Considering the lack of visible effect on the retinal pigment epithelium (RPE), the laser effect was monitored by pre‑ and post ‑ treatment infrared and autofluorescence images. Results: A total of 20 patients were included in this study, of whom 12 patients (9 male and 3 female patients) with an average age of 38 years had complete follow‑ up (Average: 3. 5 months). The mean preoperative visual acuity was 20/80, which improved to 20/40 at the final visit. The mean preoperative central macular thickness (CMT) was 330 µ m and the average final CMT in the last OCT test was 188 µ m (P = 0. 001). Conclusion: Subthreshold continuous wave autofluorescence‑ controlled laser treatment may be a good treatment for chronic CSCR to avoid the risks of retinal damage by clinically suprathreshold laser therapy.

According to high costs of phase shifters in antenna arrays, new methods for beam steering without phase shifter are introduced. Frequency Diverse Array (FDA) concept is another approach to beam steering problem. In this structure, the subsequent antenna elements are fed with stepped discrete frequencies causing continuous scanning of space in time. So a range-angle dependent scanning is made possible. There are several ways to implement, which the simplest of them is using Linear Frequency Modulated continuous wave (LFMCW) source. In this paper, a new implementation scheme is proposed and analyzed where a Square Frequency Modulated continuous wave (SFMCW) source is used for feeding a special beam forming network. Also radiation pattern of SFMCW and LFMCW was compared.

Local site conditions have a strong effect on ground response during earthquakes. Two important soil parameters that control the amplification effects of seismic motions by a soil column are the soil hysteretic damping ratio and shear wave velocity. This paper presents the results of in situ damping ratio measurements performed using continuous surface wave attenuation data at a site in Semnan University campus and analysis used to obtain the near surface soils damping ratio profile. Once the frequency dependent attenuation coefficients are determined, the shear damping ratio profile is calculated using an algorithm based on constrained inversion analysis. A computer code is developed to calculate the shear damping ratio in each soil layer. Comparisons of the in situ shear damping ratio profile determined from continuous surface wave with cross hole independent test measurements are also presented. Values of shear damping ratio, obtained using continuous surface wave measurements, were less than the measured using cross hole tests, possibly because of the higher frequencies used in cross hole tests.