The structural colour of the neon tetra is distinguishable from those of, e.g., butterfly wings and bird feathers, because it can change in response to the light intensity of the surrounding environment. This fact clearly indicates the variability of the colour-producing microstructures. It has been known that an iridophore of the neon tetra contains a few stacks of periodically arranged light-reflecting platelets, which can cause multilayer optical interference phenomena. As a mechanism of the colour variability, the Venetian blind model has been proposed, in which the light-reflecting platelets are assumed to be tilted during colour change, resulting in a variation in the spacing between the platelets. In order to quantitatively evaluate the validity of this model, we have performed a detailed optical study of a single stack of platelets inside an iridophore. In particular, we have prepared a new optical system that can simultaneously measure both the spectrum and direction of the reflected light, which are expected to be closely related to each other in the Venetian blind model. The experimental results and detailed analysis are found to quantitatively verify the model.

We have developed multi-gap resistive plate chambers (MRPCs) with 2.5 × 200 cm 2 readout strips for the time-of-flight (TOF) detector system of the LEPS2 experiment at SPring-8. These chambers consist of 2 stacks and 5 gas gaps per stack, in a mirrored configuration. A time resolution of σ ≃ 80 ps was achieved for any position within a strip (at above 99% detection efficiency); after performing the time-charge slewing correction, this value could be reduced to 60 ps. A link between the small contribution of the slewing correction to timing and the suppression of modal dispersion in the detector could be established.

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In order to rneasure the 3D shape of microcompolle 匣 lts ， a novel nano − CMM systeln has beell developed based on an oscillated probing technique ， which uses an optlcally trapped particle ． The trapPed particle is laterally oscillated at the focal pla τ le of the objective ． The frequency respor ユse Qf the uscillated partide typically agrees with the spring − mass − dampeT modeL HQwever the response disagrees with the theoretical curve of the conven しional model equa し iQn in the range Qf high fre ・ quency ． It is cons 正 dered the di幵erellce between experimellts arld the model equation is caused fr 〔 ⊃m the nulnerical error for the Huid effect ， which is applied rm c 〔 mdition of creeping flow past a sphere ． 1n this report ， we construct a nuid simulation using SMAC method that calcu 】 ates 刊uid resistan ¢ e against an oscil 】 ating sphere in noninertial frame of reference ． The Huidresistance damp the