A model for data acquired with the use of a charge-coupled-device camera is given and is then used for developing a new iterative method for restoring intensities of objects observed with such a camera. The model includes the effects of point spread, photoconversion noise, readout noise, nonuniform flat-field response, nonuniform spectral response, and extraneous charge carriers resulting from bias, dark current, and both internal and external background radiation. An iterative algorithm is identified that produces a sequence of estimates converging toward a constrained maximum-likelihood estimate of the intensity distribution of an imaged object. An example is given for restoring images from data acquired with the use of the Hubble Space Telescope.

Intracellular ATP (ATPi)-sensitive K+ [K+(ATP)] channels are now a recognized site of action of clinically useful hypoglycemic and hyperglycemic sulfonamides. We have further examined the action of these agents on single K+ channels in rat pancreatic B-cells 1) Tolbutamide and glyburide, two hypoglycemic sulfonylureas which decrease K+(ATP) channel activity in the cell-attached patch, affect the kinetics of K+(ATP) channel in a manner similar to glucose. They shorten the duration of the "burst," or cluster of open channel events, while lengthening the intervals between bursts. 2) The hyperglycemic vasodilator diazoxide increases mean K+(ATP) channel activity in the cell-attached patch as well as in the inside-out excised patch exposed to ATPi. It appears to lengthen channel bursts and shorten the intervals between them. Two structurally similar diuretics, hydrochlorothiazide and furosemide, which have mild hyperglycemic effects, do not increase K+(ATP) channel activity even at clinically toxic concentrations. 3) Neither the sulfonylureas nor diazoxide directly affect the activity of single delayed rectifier K+ channels or single calcium and voltage-activated K+ channels in normal B-cells.

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The expectation-maximization algorithm, as formulated in 1977 by Dempster, Laird, and Rubin [1], is a numerical procedure for computing constrained maximum-likelihood estimates of unknown parameters that influence measured data. It’s use for image restoration from quantum-limited data was first suggested by Shepp and Vardi [2] in 1982 in the context of determining concentrations of radioactive substances within the human body; applications and extensions of this method for estimating radionuclide distributions have grown enormously in the intervening years, with contributions by numerous investigators.

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