By changing the material commonly used to make devices for generating entangled photons, researchers create a quantum light source that is significantly brighter than others.

This paper reports three experiments that attempted to answer questions about the conditions under which brightness assimilation and brightness contrast are obtained. Brightness assimilation was found only under circumstances in which the gray portion of the visual display-the gray portion being compared with some other standard gray--was not the focus of attention. When attention was focused o...

1. Visual acuity depends on the brightness contrast between test object and background; and conversely, brightness discrimination depends on the target size. Both functions vary with the brightness of the background. Measurements with rectangular targets of length-width ratio 2 were made over a range of sizes, contrasts, and brightnesses sufficient to determine the relations among these three v...

We present a new method for studying the intrinsic brightness temperatures of the parsec-scale jet cores of active galactic nuclei (AGNs). Our method uses observed superluminal motions and observed brightness temperatures for a large sample of AGNs to constrain the characteristic intrinsic brightness temperature of the sample as a whole. To study changes in intrinsic brightness temperature, we ...