Pipeline for 2-photon all-optical physiology in mouse: From viral titration and optical window implantation to binarization of calcium transients

Photochromic switching of fluorescence emission provides a viable principle to creation of all optical molecular memory. Successful operation of the fluorescence memory requires deliberate control of the energetics between a fluorophore and a photochrome. One essential requirement is that photoexcitation for fluorescence emission does not interfere with the photochromic processes. Gallium(III) corrole complexes outfit the condition because their fluorescence emissions display large Stokes shifts, permitting photoexcitation at the optical window where the photochromism of cis-1,2-dithienylethene is not executed. To demonstrate the capability for fluorescence memory, we prepared molecularly dispersed poly(methyl methacrylate) (PMMA) films of a gallium corrole complex and cis-1,2-dithienylethene. The memory cycle comprising fluorescence readout and reversible photochromic switching of the fluorescence emission is fully reversible without suffering from fatigue during repeated operation. The corresponding fluorescence on/off ratio is greater than those of previous memory based on porphyrins. Fluorescence lifetime measurements employing time-correlated single photon counting techniques reveal occurrence of fast energy transfer (~ 109 s-1) which is effectively gated by the photochromism.

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Correlation analysis of radiation damage

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108210 ◽

1978 ◽

Vol 36 (1) ◽

pp. 214-215

Author(s):

R. Hegerl ◽

A. Feltynowski ◽

B. Grill

Keyword(s):

Electron Microscopy ◽

Independent Random Variables ◽

Optical Parameters ◽

Bright Field Image ◽

Bright Field ◽

Expectation Value ◽

All Optical ◽

Image Element ◽

Stochastic Series ◽

The Common

Till now correlation functions have been used in electron microscopy for two purposes: a) to find the common origin of two micrographs representing the same object, b) to check the optical parameters e. g. the focus. There is a third possibility of application, if all optical parameters are constant during a series of exposures. In this case all differences between the micrographs can only be caused by different noise distributions and by modifications of the object induced by radiation.Because of the electron noise, a discrete bright field image can be considered as a stochastic series Pm,where i denotes the number of the image and m (m = 1,.., M) the image element. Assuming a stable object, the expectation value of Pm would be Ηm for all images. The electron noise can be introduced by addition of stationary, mutual independent random variables nm with zero expectation and the variance. It is possible to treat the modifications of the object as a noise, too.

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