We report the design and development of a self-contained multi-band receiver (MBR) system, intended for use with a single large aperture to facilitate sensitive & high time-resolution observations simultaneously in 10 discrete frequency bands sampling a wide spectral span (100-1500 MHz) in a nearly log-periodic fashion. The development of this system was primarily motivated by need for tomographic studies of pulsar polar emission regions. Although the system design is optimized for the primary goal, it is also suited for several other interesting astronomical investigations. The system consists of a dual-polarization multi-band feed (with discrete responses corresponding to the 10 bands pre-selected as relatively RFI-free), a common wide-band RF front-end, and independent back-end receiver chains for the 10 individual sub-bands. The raw voltage time-sequences corresponding to 16 MHz bandwidth each for the two linear polarization channels -2and the 10 bands, are recorded at the Nyquist rate simultaneously. We present the preliminary results from the tests and pulsar observations carried out with the Green Bank Telescope using this receiver. The system performance implied by these results, and possible improvements are also briefly discussed.

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Capacitive accelerometers based on change in air gap measurement often experiences non-linearity. In order to overcome this drawback, the overlapping area of the device is changed which produces linear output. In this paper, four different types of beam springs (viz. Half-folded spring, Meander spring, Serpentine spring and ZigZag spring) were introduced in the capacitive accelerometer structure. All the springs are subjected to different accelerations and linear outputs are obtained. The cross-axis performance of the four springs is compared. Among the four springs, Halffolded spring and Serpentine spring provide low cross-axis sensitivity. The structures are designed, analysed and simulated using IntelliSuite software.

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To investigate the applicability of surface imaging for image guidance in the hypofractionated radiotherapy for intracranial metastasis with open face mask immobilization. Materials/Methods: Nineteen patients were treated with hypofractionated radiotherapy for intracranial metastasis were included. Before the start of treatment, each patient underwent simulation with open face mask immobilization. During treatment, CBCT images were collected for verification each time. Marking based positioning was used for the first fraction and new reference surface images were captured after first CBCT registration (6D of freedom,6DoF) for subsequent treatment. Subsequent treatment was randomly divided into marking guided positioning fraction group (MFG) and surface guided positioning fraction group (SFG). In the SFG, the patient was aligned manually by the therapist until the rotation tolerance was within 1˚. The residual translation and rotation errors were corrected using the "Move Couch" function of the optical surface system Align RT (Vision RT, London, UK). The six-dimensional error data of patients with the two positioning methods were compared and expressed as mean § standard deviation. Meanwhile, the correlation and consistency between the optical surface error data and the gold standard CBCT error data were compared during the MFG. A scientific 2D graphing and statistics software was used for data processing and mapping, and a statistical software was used for mean analysis and normality test. Pearson correlation analysis was used to analyze the correlation, and Bland-Altman plot analysis was used to test the coincidence between the two methods. Results: Total of 103 MFG CBCT images and 87 SFG CBCT images were analyzed. Compared with the marking guided positioning, the 3D magnitude error of the optical surface guided positioning was reduced from 0.35 § 0.16 cm to 0.14 § 0.07 cm and the rotation error was reduced from 0.06˚ § 1.36˚, 0.62˚ § 1.18˚, 0.21˚ § 1.19˚to -0.04˚ § 0.68˚, -0.03˚ § 0.73˚, 0.04˚ § 0.69˚on Pitch, Roll and Rotation. The Pearson coefficient R 2 was 0.91,0.70,0.78 on Lateral, Longitudinal and Vertical directions, R 2 was 0.75,0.85,0.77 on Pitch, Roll and Rtn directions, respectively (all P < 0.01). It showed high correlation between two methods. The 95% agreement limits of agreement were within preset 3 mm tolerance (lateral [-0.19-0.19cm], longitudinal [-0.25cm,0.25cm], vertical [-0.27cm,0.19cm]), and the 95% agreement limits of agreement were within preset 3 ˚tolerance (Pitch [-1.76˚,1.76˚], Roll [-1.54˚, 1.60˚], Rotation [-2.18˚,1.69˚]) for two methods. Conclusion:The optical surface error and cone-beam CT error have good correlation and coincidence. The optical surface guided positioning can reduce the setup errors and the results support the application of 3D surface imaging for image guidance in the hypofractionated radiotherapy for intracranial metastasis with open face mask immobilization.