When plane waves diffract through fractal-patterned apertures, the resulting far-field profiles or diffractals also exhibit iterated, self-similar features. Here we show that this specific architecture enables robust signal processing and spatial multiplexing: arbitrary parts of a diffractal contain sufficient information to recreate the entire original sparse signal.
A new instrument, GERB, is now operating on the European Meteosat-8 spacecraft, making unique, accurate, high-time-resolution measurements of the Earth's radiation budget for atmospheric physics and climate studies.
Single-wavelength fluorescent reporters allow visualization of specific neurotransmitters with high spatial and temporal resolution. We report variants of the glutamate sensor iGluSnFR that are functionally brighter; can detect sub-micromolar to millimolar concentrations of glutamate; and have blue, green or yellow emission profiles. These variants allow in vivo imaging where original-iGluSnFR was too dim, reveal glutamate transients at individual spine heads, and permit kilohertz imaging with inexpensive, powerful fiber lasers. Main TextThe intensity-based glutamate-sensing fluorescent reporter (iGluSnFR) 1 has become an invaluable tool for studying glutamate dynamics in diverse systems, including retina 2,3 , olfactory bulb 4 and visual cortex 5 . iGluSnFR also allows mesoscale "functional connectomic" mapping 6 and mechanistic studies of Huntington's disease 7 , synaptic spillover 8 , cortical spreading depression 9 and exocytotic vesicle fusion 10 . However, iGluSnFR is insufficient for some applications due to poor expression (in some preparations), and kinetics that do not match the time courses of some phenomena. Here we describe variants that are functionally brighter (due to increased membrane expression), have tighter or weaker affinity, and fluoresce blue, green, or yellow.Replacement of circularly permuted eGFP with circularly permuted "superfolder" GFP 11 (SFiGluSnFR) yielded 5-fold higher soluble-protein expression levels in bacteria (0.5 µmol/1L growth vs. 0.1 µmol/1L). Circular dichroism indicates an increase in melting temperature transition (T m ) of ~5˚C (Supp. Fig. S1). The 2-photon cross-section and excitation, emission, and absorption spectra of SF-iGluSnFR are similar to the original (Supp. Fig. S2a-d). Head-tohead comparison of SF-iGluSnFR with original-iGluSnFR in mouse somatosensory cortex shows substantially more robust expression by the former (Supp. Fig. S3a,b). Under typical imaging conditions (<20 mW, 130-nanosecond dwell time per pixel), SF-iGluSnFR is bright enough for repeated imaging, while original-iGluSnFR is too dim (Supp. Fig. S3c,d). While we observed a faster 2-photon in vivo photobleaching rate for SF-iGluSnFR in somatosensory cortex (Supp. Fig. S3e), partially-bleached SF-iGluSnFR was still brighter than iGluSnFR. Thus, SF-iGluSnFR will have superior expression in vivo, where the quantity of deliverable DNA can be limiting.While the affinity of membrane-displayed iGluSnFR (4 µM) is adequate for some in vivo applications, tighter variants are needed for circumstances of limiting glutamate concentrations, e.g. at sparsely-firing synapses. Additionally, measuring glutamate release events with raster scanning requires variants with slower off-rates so that the decay time from glutamate binding is long enough to be sufficiently sampled at the operating frame rate (typically <100 Hz). Replacement of eGFP with superfolder GFP increases the in vitro affinity of soluble SFiGluSnFR over original-iGluSnFR (40 µM vs. 80 µM, Supp. Fig. S4a). To further modulate affinity, w...
Following an overview of the scientific objectives and organization of the French-Russian-German Scanner for Radiation Budget (ScaRaB) project, brief descriptions of the instrument, its ground calibration, and in-flight operating and calibration procedures are given. During the year (24 February 1994-6 March 1995) of ScaRaB Flight Model 1 operation on board Meteor-317, radiometer performance was generally good and well understood. Accuracy of the radiances is estimated to be better than 1% in the longwave and 2% in the shortwave domains. Data processing procedures are described and shown to be compatible with those used for the National Aeronautics and Space Administration's (NASA) Earth Radiation Budget Experiment (ERBE) scanner data, even though time sampling properties of the Meteor-3 orbit differ considerably from the ERBE system orbits. The resulting monthly mean earth radiation budget distributions exhibit no global bias when compared to ERBE results, but they do reveal interesting strong regional differences. The "ERBE-like" scientific data products are now available to the general scientific research community. Prospects for combining data from ScaRaB Flight Model 2 (to fly on board Ressurs-1 beginning in spring 1998) with data from the NASA Clouds and the Earth's Radiant Energy System (CERES) instrument on board the Tropical Rainfall Measurement Mission (TRMM) are briefly discussed. 1 • Introduction a. The ScaRaB-1 mission The Scanner for Radiation Budget (ScaRaB) project is a cooperative project of France, Russia, and Germany. The first ScaRaB flight model (FM1) was
Measurements made by the second flight model of the Scanner for Radiation Budget (ScaRaB) instrument have been processed and are now available for the scientific community. Although this set of data is relatively short and sparse, it is of excellent quality and is the only global broadband scanner radiance information for the period between October 1998 and April 1999. This second flight model marks the conclusion of the ScaRaB cooperative program of France, Russia, and Germany. The two flight models of the ScaRaB instrument gave broadband radiance measurements comparable in quality to those made by the Earth Radiation Budget Experiment and the Clouds and Earth Radiant Energy System scanning instruments. In addition, the ScaRaB instrument gave unique results for the comparison between narrowband (visible and infrared atmospheric window) and broadband radiance measurements. These measurements were mostly used to improve the broadband data processing and to study the error budget resulting when narrowband channel data are used to estimate the earth radiation budget. These concomitant narrow-and broadband measurements made by the two flight models of ScaRaB contain original information of considerable interest for further scientific use.
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