Abstract: Apparatus and methods for imaging sources of gamma rays with a large area, comparatively low-cost Compton telescope (20). The Compton telescope (20) uses multiple layers (24) of low-cost organic solid plastic or liquid scintillator, arranged in large arrays of identical scintillator pixels (28). Photodiodes, avalanche photodiodes (30), or solid-state photomultipliers are used to read out the fluorescent pulses from scintillator pixels (28). Multiple scintillator pixels (28) are multiplexed into a few fast digitizers (80) and a few fast FPGA programmable digital microprocessors (78). Selection rule methods are presented for processing multiple near-simultaneous gamma ray collisions within the Compton telescope (28) to identify trackable events that yield gamma ray image data of interest. A calibration method achieves improved energy resolution along with (x,y) position information in pixels (28) made of organic scintillator materials with multiple photodetectors (30).

Abstract: Apparatus and methods for imaging sources of gamma rays with a large area, comparatively low-cost Compton telescope (20). The Compton telescope (20) uses multiple layers (24) of low-cost organic solid plastic or liquid scintillator, arranged in large arrays of identical scintillator pixels (28). Photodiodes, avalanche photodiodes (30), or solid-state photomultipliers are used to read out the fluorescent pulses from scintillator pixels (28). Multiple scintillator pixels (28) are multiplexed into a few fast digitizers (80) and a few fast FPGA programmable digital microprocessors (78). Selection rule methods are presented for processing multiple near-simultaneous gamma ray collisions within the Compton telescope (28) to identify trackable events that yield gamma ray image data of interest. A calibration method achieves improved energy resolution along with (x,y) position information in pixels (28) made of organic scintillator materials with multiple photodetectors (30).

Abstract: A frequency stability analysis and design method for frequency robust resonators, such as MEMS resonators, is presented. The frequency characteristics of a laterally vibrating resonator are analyzed. With the fabrication error on the sidewall of the structure being considered, the first and second order frequency sensitivities to the fabrication error are derived. A relationship between the proof mass area and perimeter, and the beam width, is developed for single material structures, which expresses that the proof mass perimeter times the beam width should equal six times the area of the proof mass. Design examples are given for the single material and multi-layer structures. The results and principles presented in the paper can be used to analyze and design other MEMS resonators.

Abstract: A method and apparatus as described herein for substantially, but not entirely, blocking back-flow through a blood pump when the blood pump is not pumping blood wherein the method and apparatus can operate passively or actively if the blood pump stops pumping in order to provide a limited back-flow through the blood pump to prevent clot formation.

Abstract: A frequency stability analysis and design method for frequency robust resonators, such as MEMS resonators, is presented. The frequency characteristics of a laterally vibrating resonator are analyzed. With the fabrication error on the sidewall of the structure being considered, the first and second order frequency sensitivities to the fabrication error are derived. A relationship between the proof mass area and perimeter, and the beam width, is developed for single material structures, which expresses that the proof mass perimeter times the beam width should equal six times the area of the proof mass. Design examples are given for the single material and multi-layer structures. The results and principles presented in the paper can be used to analyze and design other MEMS resonators.