Propagation of light beams along line defects formed in a-Si/SiO2 three-dimensional photonic crystals: Fabrication and observation

科研費報告書収録論文(課題番号:09650339・基盤研究(C)(2)・H9～H10/研究代表者:花泉, 修/ファイバ集積型マイクロ光スイッチの作製とメカニズムの解明

Direct observation of speed fluctuations of flagellar motor rotation at extremely low load close to zero

The bacterial flagellar motor accommodates ten stator units around the rotor to produce large torque at high load. But when external load is low, some previous studies showed that a single stator unit can spin the rotor at the maximum speed, suggesting that the maximum speed does not depend on the number of active stator units, whereas others reported that the speed is also dependent on the stator number. To clarify these two controversial observations, much more precise measurements of motor rotation would be required at external load as close to zero as possible. Here, we constructed a Salmonella filament‐less mutant that produces a rigid, straight, twice longer hook to efficiently label a 60 nm gold particle and analyzed flagellar motor dynamics at low load close to zero. The maximum motor speed was about 400 Hz. Large speed fluctuations and long pausing events were frequently observed, and they were suppressed by either over‐expression of the MotAB stator complex or increase in the external load, suggesting that the number of active stator units in the motor largely fluctuates near zero load. We conclude that the lifetime of the active stator unit becomes much shorter when the motor operates near zero load

Single photon sources in 4H-SiC metal-oxide-semiconductor field-effect transistors

We present single photon sources (SPSs) embedded in 4H-SiC metal-oxide-semiconductor fieldeffect transistors (MOSFETs). They are formed in the SiC/SiO2 interface regions of wet-oxidation C-face 4H-SiC MOSFETs and were not found in other C-face and Si-face MOSFETs. Their bright room-temperature photoluminescence (PL) was observed in the range from 550 to 750 nm andrevealed variable multi-peak structures as well as variable peak shifts. We characterized a wide variety of their PL spectra as the inevitable variation of local atomic structures at the interface. Their polarization dependence indicates that they are formed at the SiC side of the interface. We also demonstrate that it is possible to switch on/off the SPSs by a bias voltage of the MOSFET

Problems in Temperature Estimation from Remotely Sensed Thermal IR Data

Through the comparison between temperatures estimated from remotely sensed data and those actually measured, we discuss causes of discrepancy between them. We apply regression analysis to the data and pay particular attention to regression coefficient which as a shole represents causes for the error. The coefficient obtained by taking ground truth data as independent variables and estimated temperatures as dependent variables tends to be less than 1. Atmospheric effect on the coefficient is studied, being based on a simple model. Vertical temperature profile, another possible cause for the tendency, is also discussed on the basis of laboratory experiments