We developed a novel method of creating intensity modulated proton arc therapy (IMPAT) plans that uses computing resources efficiently and may offer a dosimetric benefit for patients with ependymoma or similar tumor geometries. Our IMPAT planning method consists of a geometry-based energy selection step with major scanning spot contributions as inputs computed using ray-tracing and single-Gaussian approximation of lateral spot profiles. Based on the geometric relation of scanning spots and dose voxels, our energy selection module selects a minimum set of energy layers at each gantry angle such that each target voxel is covered by sufficient scanning spots as specified by the planner, with dose contributions above the specified threshold. Finally, IMPAT plans are generated by robustly optimizing scanning spots of the selected energy layers using a commercial proton treatment planning system. The IMPAT plan quality was assessed for four ependymoma patients. Reference three-field IMPT plans were created with similar planning objective functions and compared with the IMPAT plans. In all plans, the prescribed dose covered 95% of the clinical target volume (CTV) while maintaining similar maximum doses for the brainstem. While IMPAT and IMPT achieved comparable plan robustness, the IMPAT plans achieved better homogeneity and conformity than the IMPT plans. The IMPAT plans also exhibited higher relative biological effectiveness (RBE) enhancement than did the corresponding reference IMPT plans for the CTV in all four patients and brainstem in three of them. The proposed method demonstrated potential as an efficient technique for IMPAT planning and may offer a dosimetric benefit for patients with ependymoma or tumors in close proximity to critical organs. IMPAT plans created using this method had elevated RBE enhancement associated with increased linear energy transfer.
An proposal for soliton adiabatic amplification is presented that uses a erbium-doped fiber amplifier constructed from dispersion decressing fiber.Numerical simulations show that the proposal performs not only distortion-free amplification but also efficient adiabatic amplification of soliton.
We have experimentally investigated the propagation effect of terahertz (THz) radiation from a long filament by checking the evolution of THz temporal waveform through shifting the longitudinal position of a short filament. The results show that the relative delay and carrier-envelope phase of the THz waveform change linearly with the shifted distance of the filament. After measuring the longitudinal intensity distributions of laser fields in long filament, we reconstruct successfully the process of the polarization-controlled THz radiation in a long filament. Besides, we also discuss the efficiency and polarization of THz radiation from a long filament excited by a circularly polarized two-color laser field.
The history of research on the stroma production of Cordyceps militaris was reviewed and the biosynthetic pathway of cordycepin was summarized.Some of the factors that may affact stroma formation and growth,including first control and secondary control factors were discussed.The author also made some suggestion on the future cordyceps industry development.
The basic principle and characters of the erbium-doped fiber amplifiers are introduced, and their applications and recent advances in the wavelength division multiplexing and optical soliton transmission systems are summarized.
Erbium-doped fiber amplifier(EDFA) is considered to be the main device for ultrashort pulse amplification owing to its high gain(40～50 dB),broad bandwidth(～50 nm),and high pulse-saturation energy(～1 μJ).In this paper,ultrashort pulse amplification techniques based on EDFA are reviewed and discussed,with the emphasis on how to reduce the fiber nonlinear effects on the amplification of ultrashort pulse.The latest achievements in this field are also introduced.
This paper proposes a dual-polarized omnidirectional antenna for 2G/3G/LTE/5G-C band applications. The antenna mainly consists of a vertically polarized (VP) element and a horizontally polarized (HP) element. The HP element is composed of four printed dipoles and a four-way power divider, whereas the VP element is made up of two copper pieces that are placed perpendicular to each other. Simulation results indicate that the overlapping bandwidth of the dual ports is 74.3%(1.65-3.60 GHz). In addition, the port isolation is larger than 20 dB and the gain variations are within 3 dB in both the VP and HP planes.
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